1. ¹Duke-NUS Graduate Medical School, Singapore, Singapore
2. ²Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA

Correspondence: Kam W Leong, Department of Biomedical Engineering, 136 Hudson Hall, Box 90281, Duke University, Durham, North Carolina 27708, USA. E-mail: kam.leong@duke.edu

Received 16 September 2006; Accepted 21 November 2006; Published online 30 January 2007.

Abstract

Stem cells play increasingly prominent roles in tissue engineering and regenerative medicine. Pluripotent embryonic stem (ES) cells theoretically allow every cell type in the body to be regenerated. Adult stem cells have also been identified and isolated from every major tissue and organ, some possessing apparent pluripotency comparable to that of ES cells. However, a major limitation in the translation of stem cell technologies to clinical applications is the supply of cells. Advances in biomaterials engineering and scaffold fabrication enable the development of ex vivo cell expansion systems to address this limitation. Progress in biomaterial design has also allowed directed differentiation of stem cells into specific lineages. In addition to delivering biochemical cues, various technologies have been developed to introduce micro- and nano-scale features onto culture surfaces to enable the study of stem cell responses to topographical cues. Knowledge gained from these studies portends the alteration of stem cell fate in the absence of biological factors, which would be valuable in the engineering of complex organs comprising multiple cell types. Biomaterials may also play an immunoprotective role by minimizing host immunoreactivity toward transplanted cells or engineered grafts.