A Stem Cell-Based Therapy for Colon Cancer


Colorectal cancer is the third leading cause of death in the Western World. Like many other types of cancer, colorectal cancer spreads and is propagated by cancer stem cells. Therefore, understanding how to inhibit the growth of cancer stem cells provides a key to treating the cancer itself.

By inactivating a gene that drives stem cell renewal in cancer stem cells, scientists and surgeons at the Princess Margaret Cancer Centre in Toronto, Canada, have discovered a promising new approach to treating colorectal cancer.

John Dick, a senior scientist at the Princess Margaret Cancer Centre, said, “This is the first step toward clinically applying the principles of cancer stem cell biology to control cancer growth and advance the development of durable cures.”

In preclinical experiments with laboratory rodents, Dick and his team identified a gene called BMI-1 as a pivotal regulator of colon cancer stem cell proliferation. With this knowledge in hand, Dick’s laboratory dedicated many hours to finding small molecules that disarm BMI-1. Then Dick and his co-workers replicated human colorectal cancer in mice, and used their BMI-1-inhibiting small molecules to treat these cancer-stricken mice.

According to lead author of this work, Antonija Kreso: “Inhibiting a recognized regulator of self-renewal is an effective approach to control tumor growth, providing strong evidence for the clinical relevance of self-renewal as a biological process for therapeutic targeting.”

Dr. Dick explained: “When we blocked the BMI-1 pathway, the stem cells were unable to self-renew, which resulted in long-term and irreversible impairment of tumor growth. In other words, the cancer was permanently shut down.”

The clinical potential of this approach is significant, since it provides a viable treatment that specifically targets colon cancer. About 65% of all colorectal cancers have an activated BMI-1 pathway. Since physicians now have techniques for identifying the presence of BMI-1 and the tools to inhibit it, this strategy could translate into a clinical treatment that might radically transform the treatment of aggressive, advanced colorectal cancers. Such a treatment would be specific, personal, and specific. May the phase 1 trials begin soon!!!

Benefits of stem cells in treating MS declines with donor’s age


MS is a neurodegenerative disease characterized by inflammation and scar-like lesions throughout the central nervous system (CNS). There is no cure and no treatment eases the severe forms of MS. But previous studies on animals have shown that transplantation of mesenchymal stem cells (MSCs) holds promise as a therapy for all forms of MS (see Bai L, et al., Glia 2009 Aug 15;57(11):1192-203). The MSCs migrate to areas of damage, release trophic (cell growth) factors and exert protective effects on nerves and regulatory effects to inhibit T cell proliferation.

Several clinical trials examining the ability of fat-derived MSCs to treat MS patients have been conducted. Unfortunately, most of these studies are rather small and the results are all over the place. One study treated ten patients with MSCs injected intrathecally (just under the meninges that cover the brain and spinal cord) and the results were mixed; 6/10 improved, 3 stayed the same and one deteriorated. Another study treated ten patients with intravenous fat-derived MSCs and the patients showed symptomatic improvement, but when MRIs of the brain were examined, no improvements could be documented. A third study treated 15 people with intrathecal injections and IV administrations of MSCs, and some stabilized. A fourth study only examined 3 patients treated with a mixture of their own fat-derived MSCs and fat-derived MSCs from another person. In all three cases, their MRIs and symptoms improved. A fifth study used umbilical cord MSCs administered intravenously and the patient showed substantial improvement (for review see Tyndall, Pediatric Research 71(4):433-438).

These results are somewhat encouraging, but also somewhat underwhelming and clinical trials go. Why did some work and other not work as well? In order to understand why, researchers must understand the biologic changes and therapeutic effects of older donor stem cells. A new study appearing in the journal STEM CELLS Translational Medicine is the first to demonstrate that adipose-derived MSCs donated by older people are less effective than cells from their younger counterparts.

Fortunately, all the available MS-related clinical trials have confirmed the safety of autologous MSC therapy. As to the efficacy of these cells, however, it is unclear if MSCs derived from older donors have the same therapeutic potential as those from younger ones.

“Aging is known to have a negative impact on the regenerative capacity of most tissues, and human MSCs are susceptible to biologic aging including changes in differentiation potential, proliferation ability and gene expression. These age-related differences may affect the ability of older donor cells to migrate extensively, provide trophic support, persist long-term and promote repair mechanisms,” said Bruce Bunnell, Ph.D., of Tulane University’s Center for Stem Cell Research and Regenerative Medicine. He served as lead author of the study, conducted by a team composed of his colleagues at Tulane.

In their study, Bunnell and his colleagues induced an MS-like disease in laboratory mice called chronic experimental autoimmune encephalomyelitis (EAE). Then they treated them before disease onset with human adipose-derived MSCs derived from younger (less than 35 years) or older (over age 60) donors. The results corroborated previous studies that suggested that older donors are less effective than their younger counterparts.

“We found that, in vitro, the stem cells from the older donors failed to ameliorate the neurodegeneration associated with EAE. Mice treated with older donor cells had increased inflammation of the central nervous system, demyelination leading to an impairment in movement, cognition and other functions dependent on nerves, and a proliferation of splenocytes [white blood cells in the spleen], compared to the mice receiving cells from younger donors,” Dr. Bunnell noted.

In fact, the proliferation of T cells (immune cells that attack the myelin sheath in MS patients) in these mice indicated that older MSCs might actually stimulate the proliferation of the T cells, while younger stem cells inhibit T cell proliferation. T cells are a type of white blood cell in the body’s immune system that help fight off disease and harmful substances. When they attack our own tissues, they can cause diseases like MS.

As such, Dr. Bunnell said, “A decrease in T cell proliferation would result in a decreased number of T cells available to attack the CNS in the mice, which directly supports the results showing that the CNS damage and inflammation is less severe in the young MSC-treated mice than in the old MSC-treated mice.”

“This study in an animal model of MS is the first to demonstrate that fat-derived stem cells from older human donors have less therapeutic effectiveness than cells from young donors,” said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine. “The results point to a potential need to evaluate cell therapy protocols for late-onset multiple sclerosis patients.”

Cardiac Stem Cells Offer New Hope for Treatment of Heart Failure


Scientists from the United Kingdom have, for the first time, highlighted the natural regenerative abilities of a group of stem cells that live in our hearts. This particular study shows that these cells are responsible for repairing and regenerating muscle tissue that has been damaged by a heart attack. Such damage to the heart can lead to heart failure.

There is a robust debate as to the regenerative capacity of cardiac stem cells (CSCs) in the hearts a adult human beings. While many scientists are convinced that CSCs in the hearts of newborns have good regenerative ability, many remain unconvinced that adult CSCs can do similar things (see Zaruba, M.M., et al., Circulation 121, 1992–2000 and Jesty, S.A., et al., Proc. Natl. Acad. Sci. USA 109, 13380–13385). Nevertheless, an earlier paper showed that when introduced into heart muscle after a heart attack, CSCs will regenerate the lost heart muscle and blood vessels lost in the infarct (see Beltrami, A.P., et al., Cell 114, 763–776). Resolving this disagreement requires a different type of experiment.

In this paper, Bernardo Nadal-Ginard and colleagues from the and his collaborators at the Stem Cell and Regenerative Biology Unit at the Liverpool John Moores University in Liverpool and his collaborators from Italy used a different way to affect the heart. When heart attacks are experimentally induced in the heart of rodents, the infarcts are large and they kill off large numbers of CSCs. Therefore, Nadal-Ginard and others induced severe diffuse damage of the heart muscle that also spared the CSCs. They gave the mice a large dose of a drug called isoproterenol, which acts as a “sympathomimetic.” This is confusing science talk that simply means that the drug speeds the heart rate to the point where the heart muscle exhausts itself and then starts to die off. This treatment, however, spares the CSCs (see Ellison, G.M., et al., J. Biol. Chem. 282, 11397–11409).

When the heart muscle was damaged, the CSCs differentiated into heart muscle cells and other heart-specific cells and repaired the damage in the heart. Also, the repairing cells were in the heart and were not the result of bone marrow stem cells that migrated to the bone marrow, thus putting to rest a controversy that has lasted for some years that CSCs are the result of bone marrow stem cells that migrate to the heart.

Elimination of CSCs prevents heart repair after heart damage. If, however, these heart-based stem cells are replaced after damage, the heart repairs itself and the heart recovers its function, anatomical integrity, and cellular structure.

In other experiments, removal of cardiac stem cells (CSCs) and re-injection after a heart attack shows that the CSCs can home in and repair the damaged heart.

c-kit CSCs repair heart

Since Nadal-Ginard showed that CSCs have a capacity to home to the damaged heart, less invasive treatments might be possible and that these treatments might even prevent heart failure after a heart attack in the future.

In a healthy heart, the quantity of CSCs is sufficient to repair heart muscle tissue. However, once the heart is damaged many of the CSCs are also damaged and cannot multiply or produce new muscle tissue. In these cases it could be possible to replace damaged CSCs with new ones that have been grown in the laboratory and administered intravenously.,

These new approaches involved maintaining or increasing the activity of CSCs in order to renew heart muscle and replace old, damaged cells. This new strategy will only require intravenous administration of CSCs and not require open heart procedures that require such a long time to recover.

These findings are very promising. The nest step is a clinical trial, which is due to start early 2014 and is aimed at assessing the safety and effectiveness of CSCs for preventing and treating heart failure in humans.

GERON’S IND FOR SPINAL CORD INJURY PLACED ON HOLD


Geron Corporation has made a cell line called GRNOPC1 from embryonic stem cells. GRNOPC1 is an “oligodendrocyte precursor cell” or OPC line. Before you blow a gasket at the sight of such a long-winded description, just remember that nerves are like wires and wires need insulation.  OPCs are the cells that make the insulation.  During spinal cord injury, the insulation dies off and it causes nerves to malfunction.

In collaboration with Hans Keirstead at UC Irvine, Geron developed a protocol for the administration of GRNOPC1 cells to animals with acute spinal cord injuries. His protocol showed that the OPCs were safe (no tumors were seen, even after one year) and somewhat effective. Some scientists were skeptical, since the mice had somewhat less severe spinal cord injuries.  Nevertheless, Geron was granted an Investigational New Drug Application from the FDA to conduct a Phase I trial with their OPC cell line.

They apparently, however, have bit a bit of a snag. Here is a press release from Geron Corporation.

Geron Corporation today announced that its IND (Investigational New Drug application) for GRNOPC1, a cell therapy for neurologically complete, subacute spinal cord injury, has been placed on clinical hold by the FDA pending the agency’s review of new nonclinical animal study data submitted by the company. A clinical hold is an order that the FDA issues to a sponsor to delay a proposed trial or to suspend an ongoing trial.

Since filing the IND, Geron has been undertaking studies to enable dose escalation of its spinal cord injury product, and has been investigating application of the product to other neurodegenerative diseases. The company has also been performing additional product characterization and conducting further animal studies. Data from this work has been submitted to the FDA. Geron will work closely with the FDA to facilitate their review of the new data and to release the clinical hold. No patients have yet been treated in this study.

From the sound of it, this hold is merely an administrative procedure that the FDA routinely undergoes when presented with new data.  However, if the new data is completely consonant with previous findings, why would there be a hold? We simply do not know at this time.  It is entirely possible that nothing is amiss, and this is merely FDA policy.  However, it is also possible that Geron’s new product does not behave exactly as they thought.

The development of the first cholesterol-lowering drug (lovastatin) experienced a slow-down when a related product being developed in Japan caused cancer in dogs. Roy Vagelos, president of Merck at the time, contacted the FDA and suspended all clinical trials. Further testing by Merck showed that this was an anomaly, and extensive clinical use has vindicated this finding. Maybe this is a similar situation for Geron’s OPC line?  Only time will tell.