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Embryonic stem cells--sources and destinations.

Vats et al. (August 2005 JRSM1) are correct in stating that embryonic stem cells (SCs) represent a unique opportunity to study cellular differentiation processes, and that progress in the related arena of tissue engineering depends on generation of suitable cells and their ability to perform specific biological functions. But, as the authors discussed, social and ethical discord has complicated the availability of human embryonic SCs. In the mouse, they have been produced from single blastomeres obtained from nondestructive biopsy of embryos destined for transfer, or from the isolation of karyotypically normal blastomeres from disaggregated (‘dead’) embryos regarded unsuitable for transfer.2 As neither of these laboratory techniques harms a viable source embryo, application of such methods to human embryos might satisfy some of the objections currently lodged against this research. Indeed, the successful translation of this work to humans could potentiate further advancements in tissue engineering, where preliminary experiments have shown promise for correction of severe organ pathology.3