OBJECTIVETo study the characteristics of dermal mesenchymal stem cells (DMSC), and explore whether they could enhance hematopoiesis recovery in vivo as well as facilitate proliferation and differentiation of hematopoietic cells in vitro.

METHODSMultipotential stem cells from the murine dermal mesenchyme were dissociated and cultured as donor cells. After 2 approximately 3 passages, the growth status, cell cycle, immunophenotype and morphology of DMSC were analyzed. Hematopoietic cells were plated onto a feeder layer formed by DMSC, cell count and CFU-GM yields were observed dynamically. Female mice received 5 Gy (137)Cs radiation were injected with DMSC cultured for 2 - 3 passages via tail vein. Cell count and CFU-GM yields of the bone marrow were observed regularly. Pathological study of the liver, spleen and bone marrow was done to evaluate hematopoiesis recovery.

RESULTSMurine DMSC are adherent cells with a morphology of fibroblastoid and spindle and multiangle in shape. Immunophenotypes showed that CD(45), CD(34), HL-DR positive DMSC were 1 - 3%, CD(44) and CD(13) positive DMSC 75 approximately 95%. Cell cycle assay demonstrated 83% of DMSC being G(0)/G(1) phase. In vitro, the total cell count and CFU-GM yields in the experimental group were higher than those of the long-term culture bone marrow cells by the third week. The DMSC can sufficiently support the proliferation and differentiation of hematopoietic cells for seven weeks. In vivo, peripheral granulocytic count, cells in the bone marrow of one femoral bone and CFU-GM by the third week in the experimental group were much higher than those of controls. Genetic assay of the murine blood demonstrated Y chromosome.

CONCLUSIONThe DMSC have characteristics of stem cells. DMSC sped up hematopoiesis recovery of irradiated mice. DMSC as a feeder layer can support proliferation and differentiation of hematopoietic cells.