Identification Of Human Mesenchymal Stem Cells In Various Hematopoietic Stages

Purpose:To investigate biological properities of human mesenchymal stem cells (MSCs) in various hematopoietic stages, including adult bone marrow (BM), postnatal umbilical vein (UV), umbilical cord blood (UCB), and dorsal aorta of mid-gestation embryos.Methods: Human MSCs from different developmental stages, including BM, UV, UCB and DA, were isolated and characterized by morphological, immunophynotypical and functional analysis. The differentiation capacities of MSCs from BM, UV and UCB to adipocytes, osteocytes and chondrocytes were compared. Immunoregulatory effect of human BM,UV and UCB derived MSCs were evaluated by T-cell proliferation assay. Finally, the influence of MAPK and PI3K/Akt signaling on osteogenesis and adipogenesis of BM-MSCs were investigated.Results: MSCs were successfully isolated and expanded from adult BM, postnatal UV, UCB and somite-stage AGM region. The MSCs were typically and homogenously spindle-shaped, uniformly expressed CD73, CD105, CD166,CD44,CD29,HLA-ABC, and were capable of generating bone, fat and cartilage in vitro. In comparison, BM-MSCs were best in adipogenesis and inhibiting T lymphocyte proliferation, but UV-MSCs appeared superior in forming cartilage,and UCB-MSCs was better in osteogenesis. During the course of osteogenesis of BM-MSCs, MAPK/ERK and PI3K/Akt were activated in early time points. Specific inhibitor of the two signaling pathway could respectively reduce the formation of bone other than fat in vitro.Conclusions: Authentic MSCs were obtained from adult BM, postnatal UV and UCB, and we successfully isolated clonal MSCs from human AGM region. MSCs from distinct sources differed in differentiation capacities and immunoregulatory abilities. PI3K and MAPK signaling played critical roles in osteogenesis of MSCs.