Elutriated stem cells derived from the adult bone marrow differentiate into insulin-producing cells in vivo and reverse chemical diabetes

An ongoing debate surrounds the existence of stem cells in the adult endowed with capacity to differentiate into multiple lineages. We examined the possibility that adult bone marrow cells participate in recovery from chemical diabetes through neogenesis of insulin-producing cells. Small-sized cells negative for lineage markers derived by counterflow centrifugal elutriation from the bone marrow were transplanted into mice made diabetic with streptozotocin and sublethal irradiation. These cells homed efficiently to the injured islets and contributed to tissue revascularization. Islet-homed CD45-negative donor cells identified by sex chromosomes downregulated GFP, expressed PDX-1 and proinsulin, and converted the hormone precursor to insulin. An estimated 7.6% contribution of newly formed insulin-producing cells to islet cellularity increased serum insulin and stabilized glycemic control starting at 5 weeks post-transplant and persisting for 20 weeks. Newly differentiated cells displayed normal diploid genotype and there was no evidence of fusion between the grafted stem cells or their myeloid progeny and injured β-cells. Considering the extensive functional incorporation of insulin-producing donor cells in the injured islets, we conclude that the adult bone marrow contains a subset of small cells endowed with plastic developmental capacity.