1. ¹Division of Hematology/Oncology, Children's Hospital, Boston, MA, USA
2. ²Harvard Stem Cell Institute, Cambridge, MA, USA
3. ³Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA

Correspondence: Dr GQ Daley, Division of Hematology/Oncology, Harvard Children's Hospital, Karp Family Research Building, 7214, 4300 Longwood Avenue, Boston, MA 2115, USA. E-mail: george.daley@childrens.harvard.edu

Received 27 January 2006; Revised 3 August 2006; Accepted 4 August 2006.

Abstract

With the isolation of human embryonic stem cells (hESCs) in 1998 came the realization of a long-sought aspiration for an unlimited source of human tissue. The difficulty of differentiating ESCs to pure, clinically exploitable cell populations to treat genetic and degenerative diseases is being solved in part with the help of genetically modified cell lines. With progress in genome editing and somatic cell nuclear transfer, it is theoretically possible to obtain genetically repaired isogenic cells. Moreover, the prospect of being able to select, isolate and expand a single cell to a vast population of cells could achieve a unique level of quality control, until now unattainable in the field of gene therapy. Most of the tools necessary to develop these strategies already exist in the mouse ESC system. We review here the advances accomplished in those fields and present some possible applications to hESC research.