Are embryonic stem cells really needed for regenerative medicine?

It is estimated that as many as 1 in 3 individuals in the United States might benefit from regenerative medicine therapy. Most regenerative medicine therapies have been postulated to require the use of embryonic stem (ES) cells for optimal effect. Unfortunately, ES cell therapies are currently limited by ethical, political, regulatory, and most importantly biological hurdles. These limitations include the inherent allogenicity of this stem cell source and the accompanying threat of immune rejection. Even with use of the rapidly developing iPS technology, the issues of low efficiency of ES/iPS derivation and the threat of teratoma formation limit ES applications directly in patients. The time and cost of deriving and validating mature, differentiated tissues for clinical use further restricts its use to a small number of well-to-do patients with a limited number of afflictions. Thus, for the foreseeable future, the march of regenerative medicine to the clinic for widespread use will depend upon the development of non-ES cell therapies. Current sources of non-ES cells easily available in large numbers can be found in the bone marrow, adipose tissue and umbilical cord blood. Each of these types of stem cells has already begun to be utilized to treat a variety of diseases.