In view of the origin of extracellular HMGB1 occurring after BMC transplantation into post MI chronic heart failure, there are 4 theoretically possible sources: (i) passive release from dead donor BMCs, (ii) passive release from dead host (endogenous) cells, (iii) active secretion from surviving donor BMCs, and (iv) active secretion from host (endogenous) cells. The gene discussed is HMGB1; the disease is congestive heart failure.