Cell fusion and stem cells

Differentiation, self-renewal and the ability to readily undergo cell fusion are properties of adult and embryonic stem cells. Spontaneous fusion between stem cells, and fusion of stem cells with various differentiated cell types, has been observed in many in vitro and in vivo contexts. Stem cell fusion is implicated in many crucial functions during normal development and is increasingly being harnessed as a tool for regenerative therapies. Experimentally induced fusion between somatic and stem cells forms the basis for our current understanding of nuclear reprogramming. Additionally, the potential fusion of stem cells with cancer cells may have physiologic contributions to aspects of tumor progression and metastasis. Understanding the mechanisms of stem cell fusion might allow manipulation of these processes to affect tissue regeneration, nuclear reprogramming and cancer chemotherapy. In this chapter we consider the functional consequences of stem cell fusion in development, regeneration and disease and postulate how cell fusion might contribute to the advancement of stem cell therapies in regenerative medicine.