As yet, (reputable) researchers have not yet administered embryo-derived tissues to human beings. For several years, however, Geron has talked about a trial involving volunteers with spinal chord injury. The Nature report says that Geron intends to submit their IND this summer.
I (and others) have previously warned about too hasty a move into human clinical trials. There are several concerns: 1- will embryo-derived tissues develop into cancers? 2- how will we assay this risk preclinically? 3-how will human volunteers be monitored? 4-embryo derived tissues are heterogeneous. What kinds of purity standards should be expected? Each of these questions is incredibly complex, dividing into numerous sub-questions.
Let's hope that researchers avoid some of the mistakes made in the field of gene transfer– and that the FDA plays a more proactive role in establishing appropriate guidelines. One troubling difference between this field and gene transfer is that initial studies of the latter took place in public settings. Expect that embryonic stem cell tissue transplantation studies will largely take place beyond the gaze of the public. (photo credit: uiruriamu 2007)