Meeting the challenges of stem cell therapies

ERIC ROOS provides an insight into this pioneering sector and discusses some of the challenges ahead.

Stem cell research has only recently appeared as a distinct discipline of biological sciences, yet there has been rapid progress towards clinical applications of these cell lines. Commercialisation of this research is already a multimillion dollar industry and many companies are now engaged in development of stem cell therapies for a wide variety of medical conditions. The pace of this growth has been, in no small part, thanks to the lessons learned from the development of other cell-based therapies. These include tissue engineering, which is broadly focussed on artificial skin and repair of joints; immunotherapies, primarily to target cancer cells; and so called “minimal manipulation” techniques for regeneration of structural tissues. While less well known than stem cell therapies, due to their less emotive and ethically challenging nature, all of these techniques are far more advanced from a clinical perspective. Of the three, tissue engineering has enjoyed the most success. However, companies such as Dendreon now have active cellular immunotherapies in the late stages of development and approval, with the first commercial immunotherapy likely to hit the market very soon. In comparison to these relatively mature cell-based therapeutic approaches, development of stem cell therapies is still very much in its infancy. Broadly speaking, these therapies can be divided into two categories based on the type of stem cell they use – pluripotent stem cells or adult stem cells. Pluripotent stem cells can be of either embryonic origin (ESCs), as have been widely publicised, or created by reprogramming of other human cell types, known as induced pluripotent stem cells (iPSCs). Therapies based on generic populations of iPSCs present a promising approach to stem cell therapies, using adult cell lines to create pluripotent cells capable of differentiation into any cell type in the body. However, the first human iPSCs were only produced in 2007 and, while this nascent technology offers huge potential for development of new stem cell therapies, the complex handling requirements for controlled differentiation of pluripotent cells is yet to be fully realised on a commercial scale. As such, the use of both ESCs and iPSCs is still in the early stages of development, with the first human clinical trial using pluripotent stem cells receiving approval from the US Food and Drug Administration in January 2009.

Landmark trial