Metamorphosis from bone marrow derived primitive stem cells to functional liver cells.

Both stem cell plasticity and cell fusion have been implicated as physiological responses to tissue injury. It remains the ultimate goal for the future to understand the regulatory control of each during regeneration. In our recent paper by Jang et al. we demonstrate the repair of damaged liver by bone marrow derived stem cells (SCs) in response to microenvironmental cues. Within 48 hrs after transplantation or co-culture, conversion of SCs into liver cells was observed. Fusion was ruled out as a major mechanism of this functional regeneration. Direct differentiation of SCs into liver epithelial cells may be clinically useful. However, if plasticity or fusion results in abnormal genetic changes they could be harmful. Before proceeding with therapeutic applications, the consequences of cellular therapy accompanying both plasticity and fusion must be examined in multiple animal models. Functional repair should also be demonstrated prior to treatment in patients.