The regulatory demands for marketing cell-based medicinal products are much more demanding than the demands for other biologics - tough as they are. But switch the cell for the molecules it produces on implantation, and the regulatory burden ought to get lighter. In principle, at least. 

I've been reading a piece in Nature about how research into post-ischaemic cardiac regeneration may be shifting its focus from implanting cells to mimicking the molecular cues for regenerating tissue at the wound site. Can the experiences of cell therapy teach us how to make effective molecular interventions, and easier regulatory paths to the clinic? I consider this question in full here.