A new era for embryonic stem cells

As the new president takes office and the scientific community eagerly awaits the announcement of the reversal of the ban on federal funding of most research involving human embryonic stem cells (hESC’s), there’s news that the FDA has approved the first ever trial of a treatment based on hESC’s for severe spinal cord injury.

This is a very welcome development; for a decade now hopes have been raised about the potential for hESC’s to treat a range of serious illnesses, particularly brain and spinal injuries,  but despite excellent work by organizations such as the Christopher and Dana Reeve Foundation no treatments have yet reached clinical trials in patients.  This is not a criticism of hESC’s, underneath the hype is the reality that hESC research is a very new science. After all the first hESC’s were produced by Professor James Thomson and colleagues at the University of Wisconsin-Madison a mere ten years ago, and a lot of work has been necessary to ensure that hESC therapies are safe and effective enough to justify human trials.

The treatment developed by Geron uses a type of cell known as an oligodendrocyte progenitor cell (OPC) that was derived by growing  hESC’s  under carefully controlled conditions. OPC’s  in their turn develop into oligodendrocytes, cells that forms a sheath around the nerve cells and are vital to the proper function of the nervous system.  In rat studies the scientists at Geron showed that OPC treatment could restore the ability to move after severe spinal injury.  Subsequent safety studies in rodents indicated that the injected cells remained within the nervous system and did not produce teratomas, a type of tumour produced by stem cells that have not been adequately processed to ensure they have differentiated into a more mature cell type suitable for transplantation. An important observation made during Geron’s animal studies of OPC therapy was that the therapy worked when the cells were injected 7 days after injury but not when treatment was delayed until 10 months after injury (1) indication that early treatment was vital, and leading to the decision to treat patients 7-14 days after injury in this phase I clinical trial.

If you take a look through the Geron and Christopher and Dana Reeve Foundation websites you will see that there are many other hESC based treatments under development, and appreciate the undeniable importance of animal research to this work. With a new president who appreciates the importance of hESC research we will no doubt see more announcements of this sort, but it’s also worth remembering that animal research is crucial to other types of stem cell research, including the iPS approach we’ve discussed here and other methods we discussed earlier this week on our sister blog in the UK.

Could this be the dawn of a new era in medicine?

Update 21 February 2011: After being put on hold for over a year due to potential problems with cyst formation identified in an animal study, additional animal studies have proved reassuring and the FDA gave its approval for the trial to go ahead. Geron recently announced the enrollment of  the first patient into their phase I study of hESC based therapy for spinal injury.

Regards

Paul Browne

1) Keirstead H.S. et al. “Human embryonic stem cell-derived oligodendrocyte progenitor cell transplants remyelinate and restore locomotion after spinal cord injury” J Neurosci., Volume 25(19), Pages 4694-4705 (2005) doi:10.1523/JNEUROSCI.0311-05.

2005

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