Happy days are here again for the embryonic stem cell (ESC) research community, or at least they should be. The day after Barack Obama was inaugurated as president in January, the U.S. Food and Drug Administration green-lighted an application from Geron Corporation to pursue the first phase I clinical trial of an ESC-based therapy (in this case, for spinal cord injury).
So scientists at last mostly have what they have been asking for. And the public should now prepare to be disappointed. To address the most obvious one first: practicable ESC-based therapies are years away. The upcoming tests of Geron’s paralysis treatment, for example, will look only at how safely it is tolerated by patients; tests of its effectiveness are further off. The therapeutic cells helped mice to partially recover from spinal injuries, but in humans they might fail to do the same or, worse, might induce tumors. It will take time to find out. New drugs often take five to nine years to progress from phase I testing to market. Moreover, many if not most of those future therapies based on ESC research may not actually involve ESCs. Patients, after all, will not be able to supply embryonic cells directly from their own body. Therapeutic ESCs would either have to come from immunologically matched stockpiles (the equivalent of blood banks) or be cloned for each patient individually. Both solutions would involve technological and legal headaches. Using adult stem cells or others reprogrammed for versatility from a patient’s own tissues may therefore prove much easier. (Adult stem cells are indeed already used to treat some blood-related and orthopedic disorders.)
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