More shots with mesenchymal stem cells

Yesterday, I reported on the failure of two late stage trials exploring mesenchymal stem cells to quell the potentally fatal immune response in graft versus host disease. Those trials were led by Osiris, a company in Maryland, which still hopes to look through its data and ongoing trials for signs of efficacy. See Stem-cell drug fails crucial trials

However, they are not the only researchers exploring mesenchymal stem cells: a search on clinicaltrials.gov pulls up 77 studies for a variety of indications. But some scientists are uneasy with the idea of using the cells to quell inflammation, because it’s not clear how they work.

A Karolinska University group published its findings of a 55-person trial in the Lancet, so I asked two of the scientists involved for their thoughts. I reached one, Katarin Le Blanc, in yesterday’s article. This morning another scientist, Olle Ringden, responded. “The findings here will probably preclude mesenchymal stem cells to be used as first-line therapy for acute GVHD.” Ringden, who is working to recruit patients for a similar, double-blind study in Europe, thought that one reason that the Osiris trial did not show efficacy is that the trial included only a few children, and children seem to respond better than adults. He echoedthe thoughts of LeBlanc’s and Pranela Rameshwarof New Jersey Medical School, a scientist uninvolved with either of the studies: “We need to find the optimal way of giving these cells and the optimal conditions. We probably need to find out why mesenchymal stem cells work in some patients and why it doesn’t work in others.”

“The take-home message is that mesenchymal stem cells may be useful in steroid-refractory liver GVHD. In such patients, there was a significantly improved response and also durable complete response, compared to the placebo groups. Mesenchymal stem cells also improved the response rates in patients with steroid-refractory gastrointestinal GVHD. One reason for the poor outcome in this study in contrast to the European trial published in the Lancet may be that there were only few children included in this study (n=28). Children seem to have a better response rate compared to adults.”

Another company is exploring similar stem cells. The small company PluriStem announced this week that it would be starting a second Phase I trial of its product, described as a mesenchymal-like cell derived from placenta. A similar trial is reportedly also underway at Duke. Both trials are for critical limb ischemia, with the idea that these cells can help restore blood flow to jeopardized limbs. The company is also exploring other indications in which inflammation plays a role, including Crohn’s disease and multiple sclerosis.

Stem cell warnings

Not so much a warning, but certainly bad news for Osiris. The mesenchymal stem cell drug Prochymal did not show efficacy in two large controlled study of graft versus host disease. ( Read that story here)

In more alarming news for at least some investors, Reuters is reporting that the US Securities and Exchange Commission has charged company CellCyte Genetics Corp has given false information to investors claiming that its stem cell technology was heading for human trials. Here’s more from Fierce Biotech

More seriously, a group called Bionet is calling for a clamp down on unregulated stem cell treatments, according to the BBC. The coalition of Chinese and European say patients are being subjected to a lot of hype and potential harm when they travel for these expensive treatments.

They are not the first:

See

Stick to the guidelines and fewer get hurt

Offshore stem cell therapies need sensitive regulation

Stem cell researchers face down stem cell tourism

On a philosophically lighter (though perhaps literally heavier note), mice fed the equivalent of the Atkins diet had fewer and less-active bone marrow and peripheral blood endothelial progenitor cells, compared to two other diet regimens. See the report in PNAS.

Here’s other work on how diet affects stem cells.

Transplanted cells detoxify poisoned brain, somewhat

There is some new research just out from StemCells Inc, which is running clinical trials for Batten’s disease, a neuordegenerative disease. Here’s a quick write up from my reading of the paper, a study of a mouse model. Motor coordination symptoms were delayed by a week or so based on a comparison between 14 mice that received transplants and 8 that did not. My initial thoughts are that the length of time of the experiment was too short, and I’m not sure if the magnitude of the observed effect would be clinically meaningful, but it does indicate movement toward ameliorating a serious disease.

Here’s my post from the latest results from StemCells’ Batten’s disease trial indicating that cells survive in human patients for at least a year.

Here’s the mouse research.

Some brains literally poison themselves. In the diseases known as infantile neuronoal ceroid lipofuscinosis or Batten’s disease, brain cells lack enzymes necessary to clear away their byproducts. Clinical symptoms of congenital forms of the disease include seizures, cognitive and motor decline, blindness, and early death. The Palo Alto company StemCells is conducting clinical trials to see whether cell therapy can ameliorate the disease. The rationale is that the functioning enzyme made by transplanted cells can help keep patients’ own cells alive. Work in Cell Stem Cell shows that the transplanted cells do indeed make and secrete the enzyme and that the transplantation delays the loss of motor coordination for a week in a mouse model of the disease.1

Previous, unrelated research had indicated that the transplantation strategy could delay onset of a similar malady called Sandhoff disease for a month and prolong lifespan by six weeks.2 However, this had not been demonstrated for lipofuscinosis nor for the human neural stem cell product the company has developed. A team of scientists led by Nobuko Uchida showed that these cells secreted a functioning lysosomal enzyme palmitoyl protein thioesterase, the enzyme that patients with Batten’s disease lack. Then they transplanted these cells into the brains of immunocompromised mice that were also unable to make this enzyme. When they examined these mice twenty to twenty-seven weeks later, they found that transplanted cells developed into neuronal-like cells in the olfactory bulb, and various types of support cells in other parts of the brain. They remained neural stem cells stem cells in the cortex.

Next, the researchers looked at the amount of lipofuscin, the toxin that builds up in Batten’s patients, in the brains of three mice that received transplants and four that di not. Overall, mice that received transplants had significantly less lipofuscin, 37% less in the cortex, and more than 50% less in the hippocampus.

Thus, the current work shows encouraging proof of principle that transplanted cells can support endogenous ones. According to the paper, evidence from 3,000 mice has not identified any instances of the transplanted cells causing a tumour. The next steps will be to see whether the cells survive long enough and secrete enzyme long enough to have a clinically meaningful effect.

1. Tamaki et al. Neuroprotection of host cells by human central nervous system stem cells in a mouse model of infantile neuronal ceroid lipofuscinosis. Cell Stem Cell 5, 310–319 (2009) DOI 10.1016/j.stem.2009.05.022

2. Lee, J. P. et al. Stem cells act through multiple mechanisms to benefit mice with neurodegenerative metabolic disease. Nature Medicine 13, 439 – 447 (2007)

Halt to clinical trial for simple cysts, not treacherous teratomas

Cross-posted from The Great Beyond

Last week, the US Food and Drug Administration put the brakes on Geron Corp’s clinical trial in spinal cord injury because of just-completed animal studies that raised red flags. The Menlo, California-based biotech company announced Thursday that the animals developed microscopic cysts in the injury site. These lumps, however, did not spread to other parts of the body and none of the animals developed tumours. A second concluded study showed no cysts in spinal cord injured rats, according to a Geron press release.

“I think it provides people with a reasonable explanation,” said Stephen Brozak, an analyst with WBB Securities LLC in Westfield, New Jersey. “Everybody was afraid of the T- word, teratomas, and it clearly wasn’t that.” (Bloomberg)

Analysts rejoiced at the news. Geron shares rose more than 3% yesterday, closing higher than any day since the clinical hold was announced.

Geron is now working with the FDA to relaunch the stalled trials, the company said. No date was set.

by Elie Dolgin

Stem cells, down to one factor

Differentiated human cells have been reprogrammed to an embryonic-like state with the addition of only one gene, rather than the standard four 1. This should advance techniques for the efficient production of high-quality patient-specific stem cells.

The ability to make induced pluripotent stem (iPS) cells using cells from specific patients could enable unprecedented new ways to study disease and also ease the development of cell therapies. However, such applications have been stymied in part because making induced pluripotent stem cells efficiently requires the introduction of pluripotency genes, which are typically inserted at random sites throughout the genome. This unwanted source of variation stymies rigorous comparisons between cells, and could make them behave in unpredictable, dangerous ways if used for cell therapies. Several techniques to make cells without permanent insertion of the genes have been reported, including some that do not use genetic material at all.

See: Human iPS cells with no genetic integration

Virus free pluripotency for human cells

Integration-free iPS cells

Reprogramming to pluripotency without genetic engineering

Generation of human induced pluripotent stem cells by direct delivery of reprogramming proteins

However, researchers are eager for additional, ‘gentler’ ways to reprogram cells, and one possibility would be starting with cells that are more prone to reprogramming. Evidence in mice suggests that the tissue of origin affects how often and how well differentiated cells reprogram.

See: Cell origin and variation in induced pluripotent stem cell lines

Stomach and liver cells reprogrammed

Scholer and colleagues reasoned that neural cells would be a good candidate, since these cells already express high levels of three of the four standard pluripotency factors (Sox2, Klf4 and c-myc). The team had previously shown that this strategy worked in mice. The researchers used viruses to insert copies of the fourth pluripotency factor, Oct4, into the cells. This produced reprogrammed cells that passed all standard tests of pluripotency.

The current study reprogrammed neural stem cells from human fetal tissue. While adult tissues tend to be more difficult to reprogram, and brain biopsies are difficult to obtain, Scholer and colleagues say they are already working out practical solutions. More-accessble cells, such as those found in dental pulp, might also be good candidates.

1. Kim, J.B. Direct reprogramming of human neural stem cells by OCT4. Nature advance online publication, doi:10.1038/nature08436 (28 August 2009)

More information on Russian stem cell IPO

Alexey Bersenev, whom many of you know from his blog Hematopoiesis, had this additional info on the Russian stem cell IPO reported yesterday by Reuters and blogged by me in the previous post. (Thanks Alexey!)

I know Dr. Isaev in person very well. He is a businessmen, but not a scientist. That’s why he has no PubMed record. He also has a medical degree (MD). He is a pioneer of private cord blood baking in Russia. For scientific part of Institute you can look at PubMed for “Kiselev SL” Dr. Kiselev is a scientific director.

The Institute is a publisher of russian scientific journal dedicated to stem cell research and regenerative medicine. The Institute organize conferences for professionals in cord blood banking and also have a research laboratory, dedicated to develop of “cord blood-based cell products” for clinical trials and gene therapy technologies.

I think IPO for his company (aka institute) is a huge leap in commercialization of stem cell and regenerative medicine technologies in Russia and Eastern Europe regions.

Russian stem-cell firm to go public

Moscow’s Human Stem Cell Institute hopes to break the ice in Russia’s frozen IPO market with a $5 million offering, according to an article in Reuter’s.

I’d never heard of this group, which according to Reuters was founded in 2003.

A bit of Googling brought me to this reference, which appears to be a review about cord blood. The last author of the review is A Isaev (Isayev) described as the general manager of the company by Reuters. When I searched PubMed for the authors, I found only four articles by AA Isaev, all written about colon diseases in Russian-language journals.

Its major competitor is a cord-blood banking company called Cryo-Cell. It’s an odd business model, but one that seems to be proliferating. See last year’s run down on cord-blood companies springing up in Asia, as well as a (critical) feature story. Stem cell banking: lifeline or subprime?

First embryonic stem-cell trial placed on hold by FDA

Six months after giving it the green light, the U.S. Food and Drug Administration has told Geron to put plans for a clinical trial in spinal cord injury on hold. The company has differentiated embryonic stem cells into precursors of cells known as oligodendrocytes, which help keep neurons alive. Geron hopes this cell product could promote healing in people who have recently severed their spinal cords.

In a press release, Geron said that the hold was placed after the company submitted data on animal studies done to support delivery of increased doses of its cell product and on animal studies applying the cell product to other neurodegenerative diseases. (See the story from the San Jose Mercury News; here’s the Nature story when trial won approval)

I asked Evan Snyder, who directs the stem cell program at the Burnham Institute and is not privy to the confidential information, to speculate what might have been in the preclinical data that prompted teh FDA’s action. It’s possible that the FDA just wanted more time to review newly submitted data, he said. Or on the other end of the extreme perhaps some sort of tumour or adverse reaction had been observed in the animals. Most likely, he thought, given that the company is trying to make larger doses of the cells, is that undifferentiated or non-neural cells have been observed in the cell product.

Clinical holds are not unusual particularly for innovative therapies. The FDA issued a clinical hold for NeuralStem in February on a trial in Lou Gehrig’s disease (the company uses neural stem cells derived from fetal cells)

At a large FDA advisory committee meeting in April last year, experts discussed the risks and benefits of products derived from embryonic stem cells. They were particularly concerned about uncontrolled cell growth. Even if the cells are not cancerous, tumours in the contained spaces of the brain and spinal cord could be devastating. Committee members were particularly concerned for diseases that are debilitating but not immediately deadly, since adverse events caused by experimental procedures could mean that people with years to live die early or end up suffering more. Patient advocates protested that they should be allowed to decide whether to take that risk.

See previous posts: Overview of FDA meeting (includes links to transcripts)

Nitty-gritty questions for making safe products

NIH chief’s first day: stem cell registry “high priority” but no ETA

Francis Collins, the new director of the US National Institutes of Health, says that he had no timetable for when the NIH will re-establish a registry listing human embryonic stem cell lines eligible for human research funding. He did, however, say that the registry would be a “very high priority.”

Last month the NIH announced guidelines for hESC research that outlined strict informed consent criteria for the donation and use of embryos. Existing, well-studied hES cell lines, many previously eligible for federal funding, do not meet these criteria exactly, and the NIH announced that it would soon establish a working group to ascertain whether these lines were derived with adequate informed consent. However, said Collins, the NIH will not seek out which lines to examine. Instead, researchers must submit applications to the working group that document and explain how the lines meet informed consent standards at the time of derivation. This process, said Collins, will ensure that the lines of the greatest scientific interest are examined first. Until then, some researchers worry that funding for their work is in limbo. (See uncertainty around NIH guidelines)

Read more

Drug screening on cancer stem cells

A recent Cell paper by Priyush Gupta, Rob Weinberg, Eric Lander and other researchers from the Broad and MIT reports a potential way to kill the cancer cells that really matter.

Here is A screen for cancer killers from NatureNews (quotes from University of Toronto’s John Dick, others)

Here is New screening for more potent cancer drugs in the New York Times. (quotes from Stanford’s Mike Clarke, others)

Cancer stem cells are cells capable of growing malignant tumours anew, and there is a surfeit of controversy about whether this is an elite subpopulation or the majority of cells in the tumour. (See Cancer stem cells, becoming common)

The researchers manipulated immortalized cancer stem cells and were able to sort out a subpopulation that resembles cancer stem cells, then they were able to identify drug that selectively kills the cancer stem cells. That’s a big deal, as a growing body of evidence indicates that the cells best able to cause a tumour to regrow are also particularly able to resist cancer drugs. (See Cancer stem cells resemble healthy ones, resist chemotherapy)

Two questions come to mind:

1) How well do these cells represent cancer stem cells? (See Careful assays for cancer stem cells )

2) Will compounds that kill cancer stem cells also kill healthy stem cells? (See How breast cancer resists treatment )

Here’s a nice summary from Jane Visvader, a breast cancer stem cell expert at the The Walter and Eliza Hall Institute of Medical Research.

This is an elegant demonstration of the power of using high throughput screening to target resistant cancer cell subsets. The authors have shown that they can specifically target mesenchymal-like cells in breast tumors, found to be resistant to a standard chemotherapeutic agent (Paclitaxel), using salinomycin.

Here’s this from Piyush Gupta, which addresses whether the cells act like bona fide cancer stem cells

The gist: Cancer stem cells have been difficult to study because they

cannot be maintained as pure populations in culture. Passage through

an EMT has been recently reported (by the Weinberg groups) to induce a

significant increase in the proportion of stem-like epithelial cells.

We show that passage through an EMT also confers increased drug

resistance to cells. Using genetic vectors to induce an EMT, it was

possible to induce a stable increase in the proportion of stem-like

cells. We then performed a chemical screen to find compounds that were

specifically toxic to cells that had passed through an EMT. Compounds

that were identified in this way were then tested the identified

compounds on cancer cell lines that we had not genetically

manipulated, to determine if they acted on bona fide cancer stem cells.

Why the study is of interest:

Cancer stem cells are resistant to many forms of death-inducing

insults. This has suggested that it may be difficult to find therapies

that specifically target CSCs. Our study shows that it is possible to

find agents that selectively kill cancer stem cells and provides a

general method for doing so.

Caveats and further experiments:

Further study will be needed to determine if the chemical we

identified, salinomycin, can be used in patients. In such studies, the

long-term effects on normal stem cell biology will also need to be

evaluated.