Stem cell transplantation helps patients with diabetes become insulin free

The majority of patients with type 1 diabetes who underwent a certain type of stem cell transplantation became insulin free, several for more than three years, with good glycemic control, and also increased C-peptide levels, an indirect measure of beta-cell function, according to a study in the April 15 issue of JAMA, a theme issue on diabetes.

Richard K. Burt, M.D., of the Northwestern University Feinberg School of Medicine, Chicago, presented the findings of the study at a JAMA media briefing at the National Press Club in Washington, D.C.

Clinical evidence indicates that there is an inverse association between beta-cell (a type of cell in the pancreas that secretes insulin) preservation and function and chronic complications of type 1 diabetes mellitus (DM), and the higher the C-peptide levels (a byproduct of insulin production, made up of amino acids), the lower the incidence of some types of complications of type 1 DM. A previous study found that autologous nonmyeloablative hematopoietic stem cell transplantation (HSCT) in 15 patients with newly diagnosed type 1 DM resulted in the majority of patients becoming insulin free during the follow-up, which averaged about 19 months. "However, it was suggested that subsequent insulin independence was a prolonged honeymoon period due to dietary and exercise changes associated with close posttransplant medical observation," the authors write, and it was not known if this change was because of an improvement in beta-cell preservation.

HSCT, which uses a patient's own blood stem cells, involves the removal and treatment of the stem cells, and their return to the patient by intravenous injection.

Dr. Burt and colleagues conducted a study to determine if posttransplant insulin independence was due to improved beta-cell function by monitoring the C-peptide levels of 23 patients who underwent stem cell transplantation. The patients, with type 1 DM, were ages 13-31 years.

Of the 23 patients, 20 experienced time free from insulin (12 continuously and 8 transiently). Patients remained continuously insulin free for an average time of 31 months (range, 14-52 months). One patient had more than 4 years with no exogenous (produced outside the body) insulin use, 4 patients for at least 3 years, 3 patients for at least 2 years, and 4 patients for at least 1 year. Eight patients relapsed and resumed insulin use at low doses. The majority of patients achieved good glycemic control.

In the continuously insulin-free group, average area under the curve (AUC; a type of measurement) of C-peptide levels before transplantation (225.0 ng/mL per 2 hours) showed a significant increase at 24 months after transplantation (785.4 ng/mL per 2 hours) and at 36 months after transplantation (728.1 ng/mL per 2 hours). In the transient insulin–independent group, average AUC of C-peptide levels also increased from 148.9 ng/mL per 2 hours pretransplantation to 546.8 ng/mL per 2 hours at 36 months, which was sustained at 48 months. In this group, 2 patients regained insulin independence after treatment with the antihyperglycemic drug sitagliptin, which was associated with an increase in C-peptide levels.

Two patients developed pneumonia in the hospital, 3 patients developed late endocrine dysfunction, and 9 patients developed oligospermia (sperm deficiency). There were no deaths.

"In conclusion, autologous nonmyeloablative HSCT was able to induce prolonged and significant increases of C-peptide levels associated with absence of or reduction of daily insulin doses in a small group of patients with type 1 DM," the researchers write. "At the present time, autologous nonmyeloablative HSCT remains the only treatment capable of reversing type 1 DM in humans. Randomized controlled trials and further biological studies are necessary to confirm the role of this treatment in changing the natural history of type 1 DM."

K-State engineers create DNA sensors that could identify cancer using material only one atom thick

Kansas State University engineers think the possibilities are deep for a very thin material.

Vikas Berry, assistant professor of chemical engineering, is leading research combining biological materials with graphene, a recently developed carbon material that is only a single atom thick.

"The biological interfacing of graphene is taking this material to the next level," Berry said. "Discovered only four years ago, this material has already shown a large number of capabilities. K-Staters are the first to do bio-integrated research with graphene."

To study graphene, researchers rely on an atomic force microscope to help them observe and manipulate these single atom thick carbon sheets.

"It's a fascinating material to work with," Berry said. "The most significant feature of graphene is that the electrons can travel without interruptions at speeds close to that of light at room temperature. Usually you have to go near zero Kelvin -- that's about 450 degrees below zero Fahrenheit -- to get electrons to move at ultra high speeds."

One of Berry's developments is a graphene-based DNA sensor. When electrons flow on the graphene, they change speed if they encounter DNA. The researchers notice this change by measuring the electrical conductivity. The work was published in Nano-Letters.

"Most DNA sensors are optical, but this one is electrical," Berry said. "We are currently collaborating with researchers from Harvard Medical School to sense cancer cells in blood."

Another area he is exploring is loading graphene with antibodies and flowing bacteria across the surface.

"Most researchers focus on pristine graphene, but we're making it dirty," he said.

Berry and Nihar Mohanty, a graduate student in chemical engineering, used a type of bacteria commonly found in rice and interfaced it with graphene. They found that the graphene with tethered antibodies will wrap itself around an individual bacterium, which remains alive for 12 hours.

Berry said that possible applications include a high-efficiency bacteria-operated battery, where by using geobater, a type of bacteria known to produce electrons, can be wrapped with graphene to produce electricity. The research was presented at the annual American Physical Society conference in Pittsburgh and the American Institute for Chemical Engineers conference in Philadelphia.

"Materials science is an incredible field with several exploitable quantum effects occurring at molecular scale, and biology is a remarkable field with a variety of specific biochemical mechanisms," Berry said. "But for the most part the two fields are isolated. If you join these two fields, the possibilities are going to be immense. For example, one can think of a bacterium as a machine with molecular scale components and one can exploit the functioning of those components in a material device."

For his doctoral research, Berry used bacteria to make a humidity sensor.

"That was only possible through combining materials science with biological science," he said.

Another area of his current research is compressing and stretching molecular-junctions between nanoparticles. Berry said that his group has developed a molecular-spring device where they can compress and stretch molecules, which then act like springs, allowing researchers to study how they relax back. He said that this technology could be used to create molecular-timers in which the spring action from a decompressed molecule on a chip could trigger a circuit, for instance.

Berry said for stretching the molecules, Kabeer Jasuja, a doctoral student in chemical engineering, came up with the idea to place the device on a centrifuge to stretch the molecules with centrifugal force.

The work was published in the journal Small.

Creating ideal neural cells for clinical use

A JOLLA, Calif., April 13, 2009 -- Investigators at the Burnham Institute for Medical Research (Burnham) have developed a protocol to rapidly differentiate human embryonic stem cells (hESCs) into neural progenitor cells that may be ideal for transplantation. The research, conducted by Alexei Terskikh, Ph.D., and colleagues, outlines a method to create these committed neural precursor cells (C-NPCs) that is replicable, does not produce mutations in the cells and could be useful for clinical applications. The research was published on March 13 in the journal Cell Death and Differentiation.

When the C-NPCs created using the Terskikh protocol were transplanted into mice, they became active neurons and integrated into the cortex and olfactory bulb. The transplanted cells did not generate tumor outgrowth.

"The uniform conversion of embryonic stem cells into neural progenitors is the first step in the development of cell-based therapies for neurodegenerative disorders or spinal injuries," said Dr. Terskikh. "Many of the methods used to generate neural precursor cells for research in the lab would never work in therapeutic applications. This protocol is very well suited for clinical application because it is robust, controllable and reproducible."

Dr. Terskikh notes that the extensive passaging (moving cells from plate to plate) required by some protocols to expand the numbers of neural precursor cells limits the plasticity of the cells, can introduce mutations and may lead to the expression of oncogenes. The Terskikh protocol avoids this by using efficient conversion of hESCs into primary neuroepithelial cells without the extensive passaging.

The scientists were able to rapidly neuralize the hESCs by culturing them in small clusters in a liquid suspension. The cells developed the characteristic "rosettes" seen in neuroepithelial cells. The C-NPCs were then cultured in monolayers. Immunochemical and RT-PCR analysis of the cells demonstrated that they were uniformly C-NPCs. Whole-genome analysis confirmed this finding. Immunostaining and imaging showed that the cells could be differentiated into three distinct types of neural cells. The team then demonstrated that the C-NPCs differentiated into neurons after transplantation into the brains of neonatal mice.

This research received funding from the National Institutes of Health and the California Institute for Regenerative Medicine.

When cancer cells can't let go

Like a climber scaling a rock face, a migrating cancer cell has to keep a tight grip on the surface but also let go at the right moment to move ahead. Chan et al. reveal that the focal adhesion kinase (FAK) coordinates these processes to permit forward movement. The study will be published online April 13 (http://www.jcb.org/) and will appear in the April 20 print issue of the Journal of Cell Biology.
Crawling cancer cells send out extensions called invadopodia. By releasing enzymes that dissolve the extracellular matrix (ECM), invadopodia clear a path for the cell to wriggle through. As they move, cancer cells get traction by temporarily attaching to the ECM through focal adhesions. FAK spurs focal adhesions to disengage, and it is more abundant in metastatic tumors. Whether FAK also regulates invadopodia was unknown.
When Chan et al. removed FAK, breast cancer cells were much less invasive. But to the team's surprise, the FAK-lacking cells sprouted extra invadopodia. The cells also sported large focal adhesions that were particularly sticky. The protein Src serves as FAK's helper. FAK and Src work together to phosphorylate tyrosines in proteins such as paxillin, which then disassemble the focal adhesion. But the team found that in cells missing FAK, the phosphorylated proteins accumulated in invadopodia. Src's localization reflects this difference. In control cells, Src accumulated in focal adhesions. In FAK's absence, Src headed to the invadopodia.
The work suggests that FAK controls movement by balancing the number of invadopodia that create a path for migration and the number of focal adhesions that hold the cell back. The next question, the researchers say, is how FAK and Src integrate these events to promote invasion.

UCSF team closer to creating safe embryonic-like stem cells

A team of UCSF researchers has for the first time used tiny molecules called microRNAs to help turn adult mouse cells back to their embryonic state. These reprogrammed cells are pluripotent, meaning that, like embryonic stem cells, they have the capacity to become any cell type in the body.
The findings suggest that scientists will soon be able to replace retroviruses and even genes currently used in laboratory experiments to induce pluripotency in adult cells. This would make potential stem cell-based therapies safer by eliminating the risks posed to humans by these DNA-based methods, including alteration of the genome and risk of cancer.
"Using small molecules such as microRNAs to manipulate cells will play a major role in the future of stem cell biology," says senior author Robert Blelloch, MD, PhD, of the Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research at UCSF.
Scientists are interested in reprogramming because it would offer a way to create cells that provide a genetic match for individual patients. A patient's skin cells could be reverted to pluripotent cells in the culture dish and then prompted to differentiate into adult cells, such as those of the heart, lung and brain. These cells could then be transplanted into patients, without the fear of rejection.
The study, reported in the April 12, 2009 advanced online edition of the journal "Nature Biotechnology" and scheduled for the May 8, 2009 print issue, used a combination of microRNAs and retrovirus-introduced genes to transform fibroblast cells -- found throughout the body of mice and humans -- into pluripotent cells.
The current finding comes on the heels of a study published by the group in the December 2008 print edition of "Nature Genetics" that showed that microRNAs, which can be synthesized in the lab, encouraged embryonic stem cells to self-replicate, a finding that has implications for replicating stem cells in the culture dish and exploring stem cells' role in cancers.
Previous methods for creating embryonic stem cell-like cells have relied on the introduction of DNA that encodes four transcription factors, proteins that play a role in the production of genes. The limitation of this method is that three of the four genes that code for these transcription factors -- oct4, klf4 and c-myc – are oncogenes, meaning they promote the uncontrolled cell growth characteristic of cancer.
In the current study, led by Robert Judson, a graduate student in the Blelloch lab, the scientists induced pluripotency using a combination of infection and transfection. The infection involved introducing three viruses, each containing a transcription factor known to induce pluripotency. The transcription factor for c-myc was not included. The transfection involved a simple process in which the tiny microRNA molecules were mixed with a lipid, allowing them to pass through the cell membrane. By labeling the fibroblast cells, they showed that the treated cells could be incorporated into a mouse embryo and become every cell type in the adult animal -- including germline cells that would produce the next generation of mice.
"These are transient, non-coding molecules that do not incorporate into the genome, but promote self-replication and have the potential to induce pluripotency," Blelloch says. "They do their thing -- turn a somatic cell into an embryonic stem cell-like one -- and then they're gone."
"MicroRNAs give us a new tool to manipulate the fate of cells," Blelloch says.
MicroRNAs are snippets of single-stranded RNA that prevent a gene's code from being translated from messenger RNA into protein. They were debuted in 1993, when scientists reported the discovery of a microRNA in the microscopic roundworm C. elegans. Since then, the field has "exploded," says Blelloch, with hundreds of microRNAs discovered in the last eight years across a broad range of species, from plants to animals.
Produced in the nucleus and released into the cytoplasm, microRNAs home in on messenger RNAs that share part of their genetic sequence. When they find them, they latch on, preventing the messenger RNA from being processed by the protein-making machines known as ribosomes. As such, microRNAs are able to ratchet down a cell's production of a given protein.
Currently, Blelloch and his colleagues are working to replace all four transcription factors with microRNAs and conducting experiments that will reveal the mechanism by which these small molecules are able to induce pluripotency. The team will also be looking to determine which microRNAs might be able to turn adult cells directly into particular adult cell types, by-passing the embryonic stem cell-like stage altogether.
"The goal now is to ensure the safety of induced pluripotent stem cells and to differentiate them into cells that can be used to repair damaged tissue and treat disease," he says.

Dental assessment prior to stem cell transplant: treatment need and barriers to care

Objective To assess the treatment needs of patients undergoing pre-haematopoietic stem cell transplant (HSCT) dental assessment, to collate the examination findings and treatment provided and to define the management issues impacting on care.Design Single centre retrospective analysis.Setting Salaried Primary Care Dental Service, Western General Hospital, Edinburgh, UK.Subjects and methods One hundred and sixteen available charts of patients who attended for pre-transplant dental assessment during April 2004-June 2007 were examined.Results Ninety-four patients, 52 men (55.3%) and 42 women (43.6%), were included. Patients were referred a mean of 31.5 (SD 18.82) days before admission for transplant. Dental assessment occurred, on average, 7.88 days (SD 6.78) following referral. Eighty-eight (93.6%) patients were dentate, while six (6.3%) were edentulous. Eighty-eight (93.6%) patients presented with oral disease; 89 (94.7%) patients received dental care. Issues impacting on care were medical (n = 88, 93.6%), time constraints (n = 73, 77.7%), no GDP (n = 25, 26.7%), dental complexity (n = 5, 5.3%) and anxiety management (n = 1, 1.1%).Conclusion The majority of patients required dental care, most of which, for healthy adults, would normally be completed within a primary care setting. However, the issues surrounding the care of patients destined for HSCT indicate that there is a place for a dedicated dental service as part of the multidisciplinary team.

Durey K, Patterson H, Gordon K.

GPT, Edinburgh Postgraduate Dental Institute, Floor 4, Lauriston Building, Lauriston Place, Edinburgh, EH3 9HA.

Tumor initiating cancer stem cells from human breast cancer cell lines.

Breast cancer is composed of heterogeneous cell populations with different biological properties. The capacity to form tumors resides in a small group of cells termed tumor initiating cells or cancer stem cells. Tumor initiating cells have been identified in a variety of cancers by sorting of subpopulations based on cell surface markers and transplantation into animal models. Tumor initiating cells have the important feature of self renewal, which is a property in common with stem cells. We examined established breast cancer lines for cells with tumor initiating properties. A dye efflux side population in MCF7 and T47D lines expressed markers of breast cancer stem cells. The side population represents a distinct morphologic and functional subpopulation within the human breast cancer cell lines MCF7 and T47D. The side population from human breast cancer cell lines was able to initiate tumors in vivo. The side population cells from human breast cancer cell lines were more resistant to ionizing radiation than the non-side population. We concluded that tumor initiating cells exist in established human breast cancer cell lines.

Han JS, Crowe DL.

University of Illinois Cancer Center, Chicago, IL 60612, USA.

What is the period when embryonic stem cells can produce any type of cell

Totipotent (totally potent) embryonic stem cells are capable of forming every type of body cell. Each totipotent cell could replicate and differentiate and become a human being. All cells within the early embryo are totipotent up until the 16 cell stage or so.

Next are the pluripotent embryonic stem cells which can develop into any of the three major tissue types: endoderm (interior gut lining), mesoderm (muscle, bone, blood), and ectoderm (epidermal tissues and nervous system). Pluripotent stem cells can eventually specialize in any bodily tissue, but they cannot themselves develop into a human being.

How many of you acually know what stem cell research really is?

A. What are human embryonic stem cells? From where do human embryonic stem cells originate?
Embryonic stem cells are stem cells derived from the inner cell mass of an early stage embryo

B. What is the difference between a blastocyst and a fetus?
The blastocyst is an early stage of mammal development early in pregnancy..A fetus is a developing mammal after the embryonic stage and before birth

C. Do you know of other sources for stem cells? Elaborate
Embryonic (explained above), adult stem cells which are found in adult tissues, and cord blood stem cells which are found in the umbilical cord.

D. What are advantages to using adult stem cells?
Advantages= Ability to self-renew indefinitely and generate all the cell types of the organ that they come from,potentially regenerating the entire organ from a few cells.

E. What are the advantages to using adult stem cells? What are the disadvantages to using embryonic stem cells?
Thus far only adult and cord blood stem cells have been successful in treating disease.

I. What are the disadvantages to using adult stem cells?
They are multipotent progenitor cells, meaning while they can create a large number of things.. they are still limited.

G What are their possible uses in medicine?
Cancer, Parkinson's disease, spinal cord injuries, and muscle damage and other conditions

Stem Cell Research- US Patients Battle the FDA Over Use of Their Own Cells

A couple of weeks ago, the American Stem Cell Therapy Association (ASCTA) was formed by a group of doctors not to debate the pros and cons of embryonic stem cell research and adult stem cell research, but to contest the FDA’s position that a person’s own Adult Stem Cells are to be classified as drugs and subject to the same regulations as Viagra, Lipitor and thousands of other chemical concoctions.

The FDA’s stance is that a person’s own stem cells must be tested as a new drug- ie. subject to 7-10 years of clinical trials and testing for each disease/condition it is used for.

As I have argued many times before, this stance is ridiculous and is costing millions of lives while sick Americans wait for the use of their own stem cells which would improve their quality of life.

Well, now a group of patients are now targeting the FDA as well.

And they have issued a press release:

A critical initiative for the ASCTA and the Safe Stem Cells NOW! movement is to bring public awareness to the FDA’s position so consumers, and those who stand to benefit from safe stem cell therapies, have the opportunity to be heard. “We get letters and calls every day from people suffering from a variety of conditions and diseases that have no known cure who are eager to access stem cell therapies.”, Hanson adds. “Many of them are forced to look outside the U.S. for treatment, which involves prohibitive travel and procedure costs.”

Adult Stem Cells Should Be An Option for Patients With No Options

One of those patients is Beverly Lessard, a 71-year-old patient from Florida, who has been diagnosed with end stage emphysema. Her late-stage condition prohibits extensive travel and the estimated cost of $12,000 to $50,000 is unaffordable. “At 71 years of age there is little interest on my part or anyone else’s to opt for lung transplants. I think this is disgraceful for our FDA to prohibit the use of autologous stem cells except in a very narrow concept so that people are forced to seek relief outside the USA,” wrote Lessard.

The FDA Is Not Protecting Us, but Hurting Us

Adult stem cells are ready for early clinical use now and can be processed with the same techniques commonly used in existing in-vitro fertilization labs. “Classifying them as drugs will not add to patient safety, but it will delay treatment to patients who don’t have 1-2 years to wait, let alone 5-7 years,” stated Christopher J. Centeno, M.D., a founding physician member of ASCTA. “ASCTA has established lab guidelines which will allow the safe use of the patient’s own adult stem cells under the supervision of doctors,” continued Dr. Centeno.

Adult Stem Cells Cultured the Same As IVF Cells

Adult stem cells are different from embryonic stem cells. Adult stem cells are found in the human body in various tissues. In order to obtain enough to treat a condition or disease, they often need to be cultured, similar to today’s fertility treatments. Adult stem cells have undergone much more research than embryonic stem cells and thus are closer to real world treatments. These adult stem cells are taken from the patient’s own body (autologous) and ASCTA believes that they are therefore safest for use in treating patients.

About Safe Stem Cells Now!
The Safe Stem Cells NOW! Movement was started by the American Stem Cell Therapy Association and driven by its patient members. The movement’s goal is to inform patients and physicians that their ability to access safe stem cell treatment is being heavily restricted by pharmaceutical industry agendas and by the FDA. For more information, visit http://www.safestemcells.org

I would appreciate it if you could all take some time to sign up for this new organization. Hopefully, we may be able to make some much needed changes and get American patients the help that they need.

Stem cell research bodies unite

Two of the world's leading centres for stem cell research signed an agreement to work more closely together.

Representatives from the Scottish Centre for Regenerative Medicine (SCRM) at the University of Edinburgh and China's National Centre for International Research in Stem Cells (NCIR) gathered in Beijing to seal the "landmark" deal to increase collaboration on stem cell treatments.

The move was welcomed by Scotland's First Minister Alex Salmond, who is nearing the end of a Scottish Government visit to China.

Gene fusion discovery may lead to improved prostate cancer test

NEW YORK (April 9, 2009) -- A newly discovered gene fusion is highly expressed in a subset of prostate cancers, according to a study by researchers at Weill Cornell Medical College. The findings, reported in the April 1 issue of Cancer Research, may lead to more accurate tests for prostate cancer. The gene fusion biomarker is also a different type of fusion than researchers have found in cancer previously and may represent an entirely new mechanism that cancer cells use to outgrow their healthy neighbors.

The SLC45A3-ELK4 gene fusion is detectable at high levels in the urine of some men at risk for prostate cancer. If these data are validated, it may be that in the future men could be tested for prostate cancer through a simple urine test. If the fusion gene is present at a high level, they likely have the disease, and if not, they likely don't have it.

"We think this is going to be a potentially important diagnostic marker in prostate cancer," says senior author Dr. Mark A. Rubin, the Homer T. Hirst Professor of Oncology in Pathology, professor of pathology and laboratory medicine, and vice chair for experimental pathology at Weill Cornell Medical College. "PSA testing is inadequate. PSA detects men with cancer but also many men with benign conditions. As we have seen recently from two major studies on PSA screening, for every 50 men with a positive PSA screening, only one man's life is saved. We urgently need biomarkers to detect clinically significant prostate cancer."

"Our work has a long-term goal of achieving a test that distinguishes clinically significant prostate cancer from indolent disease that does not require additional treatment. With better diagnosis, we will be able to treat cancer patients with individualized therapies -- one of the main goals of the Cancer Center at NewYork-Presbyterian Hospital/Weill Cornell Medical Center," continues Dr. Rubin, who is the Center's associate director of translational research and a pathologist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

Dr. Rubin's team is already working with a company to develop a urine test for prostate cancer using a chromosome-based gene fusion called TMPRSS2-ERG that the team discovered previously while working with members of Dr. Arul Chinnaiyan's research group at the University of Michigan. Dr. Rubin anticipates that the newly discovered SLC45A3-ELK4 gene fusion may be added to that urine test in the future to increase its accuracy and also to potentially help determine the level of response to certain non-surgical systemic treatments. The TMPRSS2-ERG urine test is being evaluated in multiple early clinical trials in the United States and Europe.

Novel Gene Fusion Sheds Light on How Cancer Works

Unlike the gene fusions previously found in cancers, which arise when two chromosomes join together in an abnormal way, the new fusion occurs when the genes are being copied into RNA. The two genes, SLC45A3 and ELK4, reside next to one another on the chromosome in normal and prostate cancer cells. However, when the genes are copied into RNA in the prostate cancer cells, they frequently generate a single RNA message that fuses information from both genes. Ongoing work is exploring the potential biologic implications of this discovery. However, the diagnostic implications are more immediate because these types of genetic chimera occur at significantly higher levels in abnormal tumor cells.

"We think this type of gene fusion might be a common mechanism in cancer," Dr. Rubin says. "This expands our understanding of how tumor cells may hijack androgen-regulated genes with neighboring genes and effectively alter its regulation. This may be a way tumors gain a competitive advantage."

CSHL researchers explain process by which cells 'hide' potentially dangerous DNA segments

The DNA in the 23 pairs of chromosomes in each of the billions of cells of the human body is so tightly packed that it would measure six feet in length if stretched end to end. A genome of this size can squeeze into a cell's tiny nucleus because it is compressed into highly condensed chromatin fibers by proteins called histones.

All chromatin in the cell nucleus represents a massive condensation of the genetic material. But a portion of it might well be called super-condensed; it forms a kind of chromatin called heterochromatin. The genes contained within these portions of the genome are effectively "silenced" because they cannot be accessed by the cell's DNA-activating machinery. These "hidden" parts of the genome also include highly repetitive, gene-poor, regions. Some of these, if unpacked, would set loose DNA sequences that act like parasites – able to jump around to other areas, sometimes randomly, unleashing genetic chaos.

To assemble heterochromatin, numerous molecules participate in an elaborate series of maneuvers that have gradually come to light. "But scientists have been a little hazy on the initial steps and requirements that get this process going," says Professor Leemor Joshua-Tor, Ph.D., of Cold Spring Harbor Laboratory (CSHL). She and her research team have now brought this process into sharper focus by identifying a critical requirement for heterochromatin to be established in the nucleus.

In a report that appears online on April 9th in the journal Molecular Cell, they show that the assembly of heterochromatin depends on the strength with which a protein called Chp1 binds to a specific target site located on a histone protein that has attached to the double helix.

RNAi's role in heterochromatin formation

In a typical chromosome -- roughly the shape of a bow-tie – heterochromatin is concentrated at (and supports the structure of) the centromere, the bow's central "knot." Since centromeres are crucial for genomic integrity, aberrant heterochromatin formation can result in genetic anomalies and diseases such as cancer.

Heterochromatin depends on the density of chemical "marks" that are added to histones at specific locations on their tail ends. These marks consist of methyl groups that get attached to the tail of one of the histones, histone H3, at a specific spot – the ninth residue, which happens to be the amino acid lysine (K). This mark is therefore called H3K9me.

In fission yeast, a model system used for studying heterochromatin mechanisms because of its comparative simplicity, the precise pattern of methylation depends on a process called RNA interference, or RNAi. It involves a host of players: the enzyme that copies DNA into RNA, which is diced into short segments called short interfering RNAs, or siRNAs; a part of the RNAi machinery known as the RITS complex; and various enzymes that are able to alter the configuration of chromatin.

A debate over recruitment

"In trying to understand the interplay between each of these components," explains Joshua-Tor, "there has been a longstanding debate over how the RITS complex initially gets recruited to the regions at the centromere that are destined to become heterochromatin."

At first, scientists thought that the siRNA molecules acted as guides to recruit RITS. After latching on to the chromatin, RITS was in turn thought to recruit the other components: the enzyme that adds the methyl marks; and the protein Chp1, which acts as a molecular "velcro" to keep the RITS complex firmly attached to the methyl-decorated chromatin.

The importance of binding strength

The CSHL team in collaboration with the team of Janet Partridge at St. Jude's Children's Research Hospital, Memphis, has now found that siRNAs cannot do the job of heterochromatin assembly by themselves. Rather, the siRNA-guided interaction relies on the strength with which the velcro-like protein Chp1 binds to methylated chromatin.

"We found that a part of Chp1 known as the chromodomain binds with high affinity (or strength) to methylated chromatin," explains Thomas Schalch, Ph.D., a postdoctoral researcher in the Joshua-Tor lab who led the current study. By teasing apart the origin of this unique affinity, the CSHL team stumbled across Chp1 mutants that would produce siRNAs but could not assemble heterochromatin.

"These results lead us to think that the tight interaction between RITS and the methyl marks is a requirement at least as important as the availability of siRNA," Schalch says.

A crystal structure provides the answer

The team wanted to know the exact points of contact between Chp1 and its target and how these interactions contributed to the strength of binding. For these answers, Schalch and the CSHL team made use of Joshua-Tor's expertise in X-ray crystallography – the science of determining the exact position of atoms and bonds within a molecule by creating a crystal, which is then probed with powerful x-rays.

Disrupting each point of interaction between Chp1 and its target by engineering various mutations into the Chp1 protein decreased the strength of binding to different levels. Even a five-fold decrease in binding strength prevented the mutation-bearing cells from assembling new heterochromatin, even though some of the mutants were able to generate siRNAs.

This work reveals that siRNAs cannot by themselves establish heterochromatin when Chp1's binding to H3K9me – the methylated chromatin – is impaired. Whether this mechanism of heterochromatin assembly discovered in yeast also occurs in mammalian cells is unclear at this point, according to Schalch, as a mammalian equivalent to Chp1 has not been found. "But we've now identified a fingerprint for the high-affinity interaction between a chromatin-binding protein and its 'marked', or methylated, target," says Schalch. "This may help us identify Chp1-like proteins in mammalian cells."

Device Protects Transplanted Pancreatic Cells from the Immune System

LA JOLLA, Calif., April 9, 2009—Scientists at Burnham Institute for Medical Research (Burnham) and the University of California San Diego (UC San Diego) School of Medicine have demonstrated in mice that transplanted pancreatic precursor cells are protected from the immune system when encapsulated in polytetrafluorethylene (PTFE). The study, which suggests a new approach to treating Type 1 diabetes, was published online on April 8 in the journal Transplantation.

The team of scientists showed that after transplantation, the precursor cells mature into functional beta cells that are glucose-responsive and control blood sugar levels. Additionally, the study demonstrated that using precursor cells, instead of more committed beta cells, enhanced the cell transplant’s chances of success.

“The results exceeded our expectations,” said Pamela Itkin-Ansari, Ph.D., assistant adjunct professor at the UC San Diego School of Medicine and Burnham. “We thought that T-cells, although unable to penetrate the device, would cluster around it. But we found no evidence of an active immune response, suggesting that the cells in the device were invisible to the immune system.”

The investigators used two different mouse models in the study. The team transplanted mouse islet cells into other mice to demonstrate that the cells were protected from the immune system when encapsulated in PTFE. Human cells encased in PTFE were then transplanted into immunodeficient mice to study the viability and function of both mature beta cells and precursor cells inside the device. Itkin-Ansari’s team found that by using precursor cells that had not completely differentiated, the transplanted cells could regenerate into fully functional beta cells. This has important implications for how stem cell-derived tissue should be transplanted in the future.

Type 1 diabetes results from an autoimmune response wherein the body attacks and kills insulin producing beta cells in the pancreas. One of the challenges of cell transplantation therapy to treat diabetes is the need for long term immunosuppression, which carries health risks. Transplanting beta cells in a protective device could alleviate the need to use immunosuppressive drugs.

This study was funded by grants from the Juvenile Diabetes Research Foundation, the National Institute of Diabetes and Digestive and Kidney Diseases and the JW Kieckhefer Foundation.

CSHL researchers explain process by which cells 'hide' potentially dangerous DNA segments

The DNA in the 23 pairs of chromosomes in each of the billions of cells of the human body is so tightly packed that it would measure six feet in length if stretched end to end. A genome of this size can squeeze into a cell's tiny nucleus because it is compressed into highly condensed chromatin fibers by proteins called histones.

All chromatin in the cell nucleus represents a massive condensation of the genetic material. But a portion of it might well be called super-condensed; it forms a kind of chromatin called heterochromatin. The genes contained within these portions of the genome are effectively "silenced" because they cannot be accessed by the cell's DNA-activating machinery. These "hidden" parts of the genome also include highly repetitive, gene-poor, regions. Some of these, if unpacked, would set loose DNA sequences that act like parasites – able to jump around to other areas, sometimes randomly, unleashing genetic chaos.

To assemble heterochromatin, numerous molecules participate in an elaborate series of maneuvers that have gradually come to light. "But scientists have been a little hazy on the initial steps and requirements that get this process going," says Professor Leemor Joshua-Tor, Ph.D., of Cold Spring Harbor Laboratory (CSHL). She and her research team have now brought this process into sharper focus by identifying a critical requirement for heterochromatin to be established in the nucleus.

In a report that appears online on April 9th in the journal Molecular Cell, they show that the assembly of heterochromatin depends on the strength with which a protein called Chp1 binds to a specific target site located on a histone protein that has attached to the double helix.

RNAi's role in heterochromatin formation

In a typical chromosome -- roughly the shape of a bow-tie – heterochromatin is concentrated at (and supports the structure of) the centromere, the bow's central "knot." Since centromeres are crucial for genomic integrity, aberrant heterochromatin formation can result in genetic anomalies and diseases such as cancer.

Heterochromatin depends on the density of chemical "marks" that are added to histones at specific locations on their tail ends. These marks consist of methyl groups that get attached to the tail of one of the histones, histone H3, at a specific spot – the ninth residue, which happens to be the amino acid lysine (K). This mark is therefore called H3K9me.

In fission yeast, a model system used for studying heterochromatin mechanisms because of its comparative simplicity, the precise pattern of methylation depends on a process called RNA interference, or RNAi. It involves a host of players: the enzyme that copies DNA into RNA, which is diced into short segments called short interfering RNAs, or siRNAs; a part of the RNAi machinery known as the RITS complex; and various enzymes that are able to alter the configuration of chromatin.

A debate over recruitment

"In trying to understand the interplay between each of these components," explains Joshua-Tor, "there has been a longstanding debate over how the RITS complex initially gets recruited to the regions at the centromere that are destined to become heterochromatin."

At first, scientists thought that the siRNA molecules acted as guides to recruit RITS. After latching on to the chromatin, RITS was in turn thought to recruit the other components: the enzyme that adds the methyl marks; and the protein Chp1, which acts as a molecular "velcro" to keep the RITS complex firmly attached to the methyl-decorated chromatin.

The importance of binding strength

The CSHL team in collaboration with the team of Janet Partridge at St. Jude's Children's Research Hospital, Memphis, has now found that siRNAs cannot do the job of heterochromatin assembly by themselves. Rather, the siRNA-guided interaction relies on the strength with which the velcro-like protein Chp1 binds to methylated chromatin.

"We found that a part of Chp1 known as the chromodomain binds with high affinity (or strength) to methylated chromatin," explains Thomas Schalch, Ph.D., a postdoctoral researcher in the Joshua-Tor lab who led the current study. By teasing apart the origin of this unique affinity, the CSHL team stumbled across Chp1 mutants that would produce siRNAs but could not assemble heterochromatin.

"These results lead us to think that the tight interaction between RITS and the methyl marks is a requirement at least as important as the availability of siRNA," Schalch says.

A crystal structure provides the answer

The team wanted to know the exact points of contact between Chp1 and its target and how these interactions contributed to the strength of binding. For these answers, Schalch and the CSHL team made use of Joshua-Tor's expertise in X-ray crystallography – the science of determining the exact position of atoms and bonds within a molecule by creating a crystal, which is then probed with powerful x-rays.

Disrupting each point of interaction between Chp1 and its target by engineering various mutations into the Chp1 protein decreased the strength of binding to different levels. Even a five-fold decrease in binding strength prevented the mutation-bearing cells from assembling new heterochromatin, even though some of the mutants were able to generate siRNAs.

This work reveals that siRNAs cannot by themselves establish heterochromatin when Chp1's binding to H3K9me – the methylated chromatin – is impaired. Whether this mechanism of heterochromatin assembly discovered in yeast also occurs in mammalian cells is unclear at this point, according to Schalch, as a mammalian equivalent to Chp1 has not been found. "But we've now identified a fingerprint for the high-affinity interaction between a chromatin-binding protein and its 'marked', or methylated, target," says Schalch. "This may help us identify Chp1-like proteins in mammalian cells."

Effective stem cell treatment for strokes has taken a significant step forward today (09 March) as scientists reveal how they have replaced stroke-dam

Hamilton, ON (March 3, 2009) - How messages sent within stem cells through a specific communication pathway can trigger the cells to specialize and become blood cells in humans, has been discovered by scientists of the McMaster Stem Cell and Cancer Research Institute.

The finding, to be published in the March 6 issue of Cell Stem Cell, marks the first time scientists have demonstrated the importance of the pathway, known as the noncanonical Wnt, in inducing blood formation in humans or any other species. The pathway works by organizing the cells so that they can respond to signals for blood development.

Mick Bhatia, director of the McMaster Stem Cell and Cancer Research Institute, is the lead investigator of the study, which involved researchers from McMaster University, Howard Hughes Medical Institute and the Randall T. Moon Institute for Stem Cell and Regenerative Medicine at the University of Washington.

"By directing cell differentiation, this method provides the most efficient way to produce blood cells that we are aware of to date," said Bhatia, a professor in the Department of Biochemistry and Biomedical Sciences at McMaster.

"The work also provides a new way to make blood from human stem cells that could be used for clinical applications to regenerate the immune and blood system in patients, including those with leukemia or undergoing cancer therapies that indirectly destroy the immune and blood system."

Stem cells are the building blocks of every organ and tissue in the body. Through the process of cellular differentiation, moving from a less specialized cell to a more specialize cell, stem cells have the ability to become any type of cell in the body including bone, muscle and blood cells.

Stem cells replace stroke-damaged tissue in rats

Effective stem cell treatment for strokes has taken a significant step forward today (09 March) as scientists reveal how they have replaced stroke-damaged brain tissue in rats.

The team of scientists is funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and led by Dr Mike Modo of the Institute of Psychiatry, King's College London. The work, carried out at the Institute of Psychiatry and University of Nottingham, shows that by inserting tiny scaffolding with stem cells attached, it is possible to fill a hole left by stroke damage with brand new brain tissue within 7 days. The work is published in Biomaterials.

Previous experiments where stem cells have been injected into the void left by stroke damage have had some success in improving outcomes in rats. The problem is that in the damaged area there is no structural support for the stem cells and so they tend to migrate into the surrounding healthy tissues rather than filling up the hole left by the stroke.

Dr Modo said: "We would expect to see a much better improvement in the outcome after a stroke if we can fully replace the lost brain tissue, and that is what we have been able to do with our technique."

Using individual particles of a biodegradable polymer called PLGA that have been loaded with neural stem cells, the team of scientists have filled stroke cavities with stem cells on a ready-made support structure.

Dr Modo continued: "This works really well because the stem cell-loaded PLGA particles can be injected through a very fine needle and then adopt the precise shape of the cavity. In this process the cells fill the cavity and can make connections with other cells, which helps to establish the tissue.

"Over a few days we can see cells migrating along the scaffold particles and forming a primitive brain tissue that interacts with the host brain. Gradually the particles biodegrade leaving more gaps and conduits for tissue, fibres and blood vessels to move into."

The research published today uses an MRI scanner to pinpoint precisely the right place to inject the scaffold-cell structure. MRI is also used to monitor the development of the new brain tissue over time.

The next stage of the research will be to include a factor called VEGF with the particles. VEGF will encourage blood vessels to enter the new tissue.

Professor Douglas Kell, BBSRC Chief Executive said: "Stroke is a leading cause of disability in industrialised countries. It is reassuring to know that the technology for treating stroke by repairing brain damage is getting ever closer to translation into the clinic. This crucial groundwork by Dr Modo and his colleagues will surely be a solid foundation of basic research for much better treatments in the future."

Joe Korner, Director of Communications at The Stroke Association commented: "This research is another step towards using stem cell therapy in treating and reversing the brain damage caused by stroke. It is exciting because researchers have shown they are able to overcome some of the many challenges in translating the potential of using stem cells into reality.

"The potential to reverse the disabling effects of stroke seems to have been proved. However the development of stem cell therapy for stroke survivors is still in the early stages and much more research will be needed before it can be tested in humans or used in practice.

"Every five minutes someone in the UK has a stroke and it is vital that we do all we can to help those affected by stroke."

Protein is key to embryonic stem cell differentiation

LA JOLLA, Calif., March 18, 2009 -- Investigators at Burnham Institute for Medical Research (Burnham) have learned that a protein called Shp2 plays a critical role in the pathways that control decisions for differentiation or self-renewal in both human embryonic stem cells (hESCs) and mouse embryonic stem cells (mESCs).

The research, led by Gen-Sheng Feng, Ph.D., differs with some earlier findings that suggested hESCs and mESCs differentiate as a result of different signaling mechanisms. The discovery that Shp2 has a conserved role between mice and humans suggests an interesting common signaling mechanism between mESCs and hESCs, despite the known distinct signaling paths and biological properties between the two types of pluripotent stem cells. The study was published online in the journal PLoS ONE on March 17, 2009.

Embryonic stem cells (ESCs) are pluripotent cells that can differentiate to become more than 200 different cell types. Because of their plasticity, ESCs have been suggested as potential therapies for numerous diseases and conditions, including neurodegenerative diseases, spinal cord injury and tissue damage. Development of such therapies is largely dependent on fully understanding and controlling the processes that lead to differentiation of hESCs into specialized cell types.

"There are many signaling pathways that help embryonic stem cells decide their fate," said Dr. Feng. "We found that the Shp2 protein acts as a coordinator that fine-tunes the signal strength of multiple pathways and gives us a better understanding of the fundamental signaling methods that determine whether a stem cell's fate will be self-renewal or differentiation."

In the study, the Feng lab created mutant Shp2 mESCs and showed that differentiation was dramatically impaired as the cells self-renewed as stem cells. The researchers also demonstrated small interfering RNAs in hESCs reduce Shp2 expression and subsequent cell differentiation. Feng and colleagues screened chemical libraries and identified a small-molecule inhibitor of Shp2 that, in small doses, partially inhibits differentiation in both mESCs and hESCs. Taken together, these results suggest a conserved role for Shp2 in ESC differentiation and self-renewal in both mice and humans.

"This opens the door for new experimental reagents that will amplify the self-renewal process to create more stem cells for research and potential clinical use in the future," Dr. Feng added. "This research also suggests that comparative analysis of mouse and human embryonic stem cells will provide fundamental insight into the cellular processes that determine 'stemness,' a critical question that remains to be answered in the stem cell biology field."

USC researchers uncover mechanism that regulates movement of blood-forming stem cells in the body

Researchers at the Keck School of Medicine of the University of Southern California (USC) have identified a signaling pathway that helps regulate the movement of blood-forming stem cells in the body—a finding that provides important new insight into how stem cells move around the body and which may lead to improvements in the efficiency of bone marrow transplants.

The study will appear in the journal Nature, and is available online March 25th.

"By identifying the key mechanism by which these stem cells home and engraft to the bone marrow, it may be possible to pharmacologically treat the cells to activate this pathway and thus increase the effectiveness of bone marrow transplants," says lead author Gregor Adams, Ph.D., assistant professor of cell and neurobiology at the Keck School and a researcher at the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC.

Hematopoietic stem cells are blood-forming cells that circulate through the body shifting back and forth between the bloodstream and bone marrow, Adams explains. When patients receive a bone marrow transplant, healthy blood stem cells are injected into their veins. Unless those stem cells can find their way into a specific site known as the stem cell niche, they cannot develop properly to replenish the white cells, red cells and platelets in the patient's blood.

The mechanisms that guide the cells during this migration have not been well understood. However, in this study the researchers found that blood-forming stem cells that lacked a specific signaling molecule, called GalphaS, did not home to or engraft in the bone marrow of adult mice, Adams says.

"Here we show that the GalphaS pathway is a critical intracellular pathway involved in this process," he says. "Currently, large numbers of blood-forming stem cells are required in bone marrow transplantation due to the limited efficiency of the homing process. This study opens up the possibility of treating bone marrow cells with GalphaS pathway activators as a means to increase the effectiveness of bone marrow transplants."

Improving the efficiency with which stem cells colonize the bone marrow following transplantation could have far-reaching implications for disease treatment, says Martin Pera, Ph.D., director of the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC.

"For example, such a discovery might enhance the utility of umbilical cord blood, which contains only limited numbers of stem cells, for the treatment of cancer and blood disorders in children and adults," Pera says.

Adult stem cell injections may reduce pain and improve walking in severe angina patients

Largest CD34+ stem cell study for heart disease

CHICAGO - Preliminary data presented on March 28 as a late-breaking abstract at the American College of Cardiology's 58th annual scientific session from the largest CD34+ adult stem cell study for heart disease has shown the first evidence that delivering a potent form of autologous (from the patient) adult stem cells into the heart muscle of patients with severe angina may result in less pain and improved exercise tolerance.

The six-month, Phase II data were presented by principal investigator Douglas Losordo, M.D., director of the Feinberg Cardiovascular Research Institute and of the Program in Cardiovascular Regenerative Medicine at Northwestern Memorial Hospital. The trial was sponsored by Baxter International Inc.

"The results from this study provide the first evidence that a patient's own stem cells could actually be used as a treatment for their heart disease," said Losordo, who also is the Eileen M. Foell Professor of Heart Research at the Feinberg School. "The study provides potential hope for those patients with currently untreatable angina to be more active with less pain."

"Baxter sponsored this trial in order to continue advancing the science of adult stem cell therapies for cardiovascular disease," said Hartmut J. Ehrlich, MD, vice president of global research and development for Baxter's BioScience business. "While the preliminary results from this early- stage trial seem encouraging, further studies will be necessary to evaluate the effectiveness of this adult stem cell therapy."

Losordo also cautioned that the findings of the 26-site trial, while encouraging, are not yet definitive and require verification in a larger study. Northwestern Memorial Hospital was the lead site of the study.

Trial design

This prospective, randomized, double-blind, placebo-controlled, multi-center study included 167 adult patients who were on maximal medical therapy and were not suitable candidates for conventional procedures to improve blood flow to the heart, such as angioplasty, stents, or coronary artery bypass surgery.

All patients were given a drug to stimulate release of CD34+ adult stem cells from the bone marrow, and these cells were then collected from the bloodstream using a process called apheresis. The CD34+ cells were then separated from the other blood components for use in this investigational therapy using Baxter's ISOLEX 300i Magnetic Cell Selection System, currently approved for use with cancer patients.

The CD34+ adult stem cells were injected into 10 locations in the heart muscle of patients in the treatment group. Patients in the placebo group received saline. A sophisticated electromechanical mapping technology identified where the heart muscle was alive but not functioning, because it was not receiving enough blood supply. This state is called hibernating myocardium.

"Muscle hibernates because it wants to decrease energy consumption to stay alive," Losordo explained. "It's not getting enough oxygenated blood to perform normally, so it shuts down its contractile function."

Results

The autologous stem cell transplant is the first therapy to produce an improvement in patients with severe angina, measured by their ability to walk on a treadmill. Six months after the procedure, the autologous stem cell transplant patients were able to walk longer (average of 60 seconds) on a treadmill than the placebo group. It also took longer until they experienced angina pain on a treadmill compared to the placebo group and, when they felt pain, it went away faster with rest. In addition, they had a reduction of episodes of chest pain compared to the control group.

Stem cell breakthrough: Monitoring the on switch that turns stem cells into muscle

In a genetic engineering breakthrough that could help everyone from bed-ridden patients to elite athletes, a team of American researchers—including 2007 Nobel Prize winner Mario R. Capecchi—have created a "switch" that allows mutations or light signals to be turned on in muscle stem cells to monitor muscle regeneration in a living mammal. For humans, this work could lead to a genetic switch, or drug, that allows people to grow new muscle cells to replace those that are damaged, worn out, or not working for other reasons (e.g., muscular dystrophy). In addition, this same discovery also gives researchers a new tool for the study of difficult-to-treat muscle cancers. The full report containing details of this advance is available online in The FASEB Journal (http://www.fasebj.org).

"We hope that the genetically-engineered mouse models we developed will help scientists and clinicians better understand how to make muscle stem cells regenerate muscle tissue," said Charles Keller, M.D., assistant professor at the University of Texas Health Science Center and a senior researcher involved in the work. "For our own work on childhood muscle cancers, we also hope to understand how tumors start and progress, and to develop therapies that are less toxic than chemotherapy."

The scientists made their discovery by breeding special mice with a specific gene, called "Cre," which, when activated, can trigger mutations in muscle stem cells. This Cre trigger is restricted to muscle stem cells and requires a special drug for it to be activated. In one part of the study, using fluorescent techniques, the researchers were able to visualize stem cells and their derivatives in order to pinpoint exactly where muscle tissue was being made. In another part of the study, the scientists were able to activate tumor-causing mutations in muscle stem cells, providing valuable insights into the origins of muscle tumors, which have been previously elusive.

"This is basic science at its best," said Gerald Weissmann, M.D, Editor-in-Chief of The FASEB Journal. "This study in mice has not only shown us how stem cells turn into muscle in the living body, but brought us closer to the day when we can use stem cells to repair wounded flesh or a maimed physique."

New strategy improves stem cell recruitment, heart function and survival after heart injury

A new study in mice shows that a dual therapy can lead to generation of new blood vessels and improved cardiac function following a heart attack. The research, published by Cell Press in the April 3rd issue of the journal Cell Stem Cell, provides an explanation for the ineffectiveness of current stem-cell-mobilizing therapies and may drive design of future regenerative therapies for the heart.

Stem-cell-based therapies are an attractive option for the treatment of heart damage after a heart attack, also known as myocardial infarction (MI). However, although animal studies using stem cells derived from the bone marrow have elicited some improvement in cardiac function, human trials have not been as successful. "Modern approaches have to focus on the process of cardiac homing to improve the clinical outcome of stem cell therapies," explains senior study author, Dr. Wolfgang-Michael Franz from Ludwig-Maximilians University.

The stromal-cell-derived factor, type I (SDF-1) is the main chemical that guides stem cells to home in on damaged heart tissue. Because SDF-1 is inactivated by CD26/dipeptidylpeptidase IV (DPP-IV), endogenous stem cell localization to the heart is not optimal. The researchers used genetic or pharmacologic inhibitors of CD26/DPP-IV to slow degradation of SDF-1 in mice with surgically induced MI. They also treated the mice with granulocyte colony stimulating factor (GCSF), a commonly used drug that mobilizes multiple stem cell populations from the bone marrow to the blood.

The researchers found that genetic or pharmacologic inhibition of CD26/DPP-IV combined with G-CSF treatment decreased DPP-IV and stabilized activated SDF-1 in the heart, thereby enhancing the recruitment of circulating blood forming precursor cells, or EPCs (endothelial progenitors) to this organ. Further, the combined treatment increased formation of new blood vessels and improved both survival and cardiac function after MI.

The results represent the first experimental evidence that inhibition of DPP-IV combined with G-CSF enhances cardiovascular regeneration. "Our findings may contribute essential new aspects for design of future stem cell trials, since the key issue of all therapeutic stem cell approaches emerges to be the process of cardiac homing," says Dr. Franz. "We propose the use of combined DPP-IV inhibition and G-CSF application as a new therapeutic concept for future stem cell trials."

Cancer stem cells generated by cancer outgrowth

Scientists have discovered that growing mouse skin cells in spheres can lead to generation of cells with properties of cancer stem cells, even without genetic manipulation of stem cell genes. This unexpected finding, published by Cell Press in the April 3rd issue of the journal Cell Stem Cell, provides a potential pathway for generation of cancer stem cells from differentiated cells and may even eventually lead to safer strategies for creation of induced pluripotent stem cells for use in regenerative therapies.

"A hallmark of all solid tumors is the outgrowth of cancer cells into three-dimensional structures," explains senior study author, Dr. Douglas C. Dean, from the University of Louisville Health Sciences Center in Louisville, Kentucky. Dr. Dean and colleagues examined whether abnormal cell configurations might trigger reprogramming of differentiated cells into cells that resembled cancer stem cells.

The researchers observed that mutation of all of the retinoblastoma tumor suppressor gene (RB1) family members, known to be critical for regulating cell-contact inhibition and restricting growth of normal cells into three-dimensional tumor-like structures, led to an outgrowth of cells into spheres that triggered generation of cells similar to cancer stem cells. Surprisingly, the cancer stem cell-like cells expressed key genes expressed in embryonic stem cells and gave rise to a variety of differentiated cells.

Interestingly, cells with only one RB1 mutation remained contact inhibited, but when mechanically scraped off the dish and forced to form spheres, they also exhibited cancer stem-like characteristics. Even cells with intact RB1 genes could be forced to form spheres, suggesting that the reprogramming did not require the loss of RB1. The researchers went on to show that the cancer stem-like cells isolated from the spheres with disrupted RB1 genes formed tumors when injected into mice and differentiated into mature cells in advancing cancers.

These results using cultured cells lead the authors to hypothesize that cancer stem cells may be generated as a direct function of the outgrowth of cells in the animal. "To our knowledge, this is the first example that silenced endogenous embryonic stem cell genes can be spontaneously reactivated in differentiated cells," says Dr. Dean. "We propose that the loss of cell contact inhibition when the RB1 pathway is inhibited leads to outgrowth into sphere-like structures, and these conditions in the advancing cancer trigger reprogramming of differentiated cells to cells with properties of cancer stem cells."

Human ES cells progress slowly in myelin's direction

Scientists from the University of Wisconsin, USA, report in the journal Development (dev.biologists.org) the successful generation from human embryonic stem cells of a type of cell that can make myelin, a finding that opens up new possibilities for both basic and clinical research.

The cells the researchers made are called oligodendrocytes, which are responsible for making myelin in the central nervous system. Myelin forms an insulating sheath that surrounds nerve fibres, both protecting them and speeding up the transmission of nerve impulses. Its loss or damage has serious consequences, as is seen in the condition of multiple sclerosis, because without it nerves lose the ability to transmit impulses to each other and to function properly.

Unlike human embryonic stem (ES) cells, it's relatively easy to persuade mouse ES cells to turn into oligodendrocytes; it's often done by exposing these cells to a protein called Sonic Hedgehog, which produces oligodendrocytes in the spinal cord of developing embryos. Now Su-Chun Zhang and his co-workers show in the May issue of Development (dev.biologists.org) that treating human ES cells with this same protein also turns them into oligodendrocytes – they just take longer to do it, 14 weeks as opposed to the 2 weeks taken by mouse ES cells. They also report another difference between mouse and human ES cells: a growth factor called Fgf2 that promotes oligodendrocyte development in mouse ES cells actually stalls it in human ES cells.

As Dr Zhang reveals, these findings were quite unexpected. 'This was quite a surprise given that this is exactly how we direct mouse ES cells to become oligodendrocytes. But we have discovered an unexpected twist in the cell's response to the same external factor', explained Dr Zhang. 'It nevertheless explains why so many research groups have failed to persuade human neural stem cells to become oligodendrocytes for the past decade.'

As Dr Zhang went on to discuss, these findings are also of clinical importance. 'We are now able to generate a relatively enriched population of oligodendrocyte precursor cells that may be used to repair lost myelin sheaths. These findings also raise awareness of the direct translatability of animal studies to human biology. In this regard, the human oligodendrocytes generated from human ES cells or the generation of disease-induced pluripotent stem cells can provide a useful tool in the future for screening pharmaceuticals directly on human cells.'

Stem cell therapy makes cloudy corneas clear, according to Pitt researchers

PITTSBURGH, April 9 – Stem cells collected from human corneas restore transparency and don't trigger a rejection response when injected into eyes that are scarred and hazy, according to experiments conducted in mice by researchers at the University of Pittsburgh School of Medicine. Their study will be published in the journal Stem Cells and appears online today.

The findings suggest that cell-based therapies might be an effective way to treat human corneal blindness and vision impairment due to the scarring that occurs after infection, trauma and other common eye problems, said senior investigator James L. Funderburgh, Ph.D., associate professor, Department of Ophthalmology. The Pitt corneal stem cells were able to remodel scar-like tissue back to normal.

"Our experiments indicate that after stem cell treatment, mouse eyes that initially had corneal defects looked no different than mouse eyes that had never been damaged," Dr. Funderburgh said.

The ability to grow millions of the cells in the lab could make it possible to create an off-the-shelf product, which would be especially useful in countries that have limited medical and surgical resources but a great burden of eye disease due to infections and trauma.

"Corneal scars are permanent, so the best available solution is corneal transplant," Dr. Funderburgh said. "Transplants have a high success rate, but they don't last forever. The current popularity of LASIK corrective eye surgery is expected to substantially reduce the availability of donor tissue because the procedure alters the cornea in a way that makes it unsuitable for transplantation."

A few years ago, Dr. Funderburgh and other University of Pittsburgh researchers identified stem cells in a layer of the cornea called the stroma, and they recently showed that even after many rounds of expansion in the lab, these cells continued to produce the biochemical components, or matrix, of the cornea. One such protein is called lumican, which plays a critical role in giving the cornea the correct structure to make it transparent.

Mice that lack the ability to produce lumican develop opaque areas of their corneas comparable to the scar tissue that human eyes form in response to trauma and inflammation, Dr. Funderburgh said. But three months after the lumican-deficient mouse eyes were injected with human adult corneal stem cells, transparency was restored.

The cornea and its stromal stem cells themselves appear to be "immune privileged," meaning they don't trigger a significant immune response even when transplanted across species, as in the Pitt experiments.

"Several kinds of experiments indicated that the human cells were alive and making lumican, and that the tissue had rebuilt properly," Dr. Funderburgh noted.

In the next steps, the researchers intend to use the stem cells to treat lab animals that have corneal scars to see if they, too, can be repaired with stem cells. Under the auspices of UPMC Eye Center's recently established Center for Vision Restoration, they plan also to develop the necessary protocols to enable clinical testing of the cells.