Spontaneous fusion of cells between species yields transdifferentiation and retroviral transfer in vivo

SPECIFIC AIMSpontaneous fusion of hematopoietic stem cells with parenchymal cells has recently been observed in certain instances of tissue injury and disease. We asked whether spontaneous fusion could occur under “physiologic” conditions and, if so, whether fused cells could contribute to the normal body plan and whether cell fusion could underlie transfer of retroviruses.PRINCIPAL FINDINGS1. Human cells can spontaneously fuse with porcine cells in vivoIn the course of studying human hematopoietic stem cell engraftment in swine, we asked whether human cells fuse with porcine cells. To address that question, we studied swine in which human hematopoietic stem cells had been injected in utero. Piglets so injected were found to have human cells in the circulation and tissues for more than one year. Peripheral blood leucocytes from piglets with established chimerism for up to one year were incubated with Epstein-Barr Virus (EBV). EBV efficiently immortalizes human B cells, but not porcine B cells because porc...