The Comparison Of The Mesenchymal Stem Cells And Hematopoietic Stem Cells Derived From Human Umbilical Cord Blood And Bone Marrow

To observe the characteristics of the mesenchymal stem cells (MSC) and hematopoietic stem cells (HSC) isolated from umbilical cord blood (UCB) and bone marrow (BM) in vitro, explore their difference and the differentiation of hemetopoietic stem cells to osteoblast. Methods:Mononuclear cells (MNC) and CD34+ selected cells were isolated, purified from umbilical cord blood and bone marrow by density gradient centrifugation and cultured in vitro, SCF and TPO were added to enhance expansion of UCB CD34+ cells. The adherent cells were treated with dexamethasone(Dex), ?-glycerophosphate(GP) and ascorbic acid to induce osteogenic differentiation. Cell morphology was observed by Wright' staining, Alkaline Phospphatase (ALP), osteocalcin (OCN), type I collagen (Col I) expression and calcium deposition were detected, the expression of cell surface antigen was analyzed by flow cytometry. Results:1. Among the 18 UCB samples isolated, only 12 samples were able to generate an adherent layer, but cells are not uniform in morphology, including osteoclast-like cells and fibroblast-like cells. The cells couldn't be passaged over twice. The morphology of these adherent cells had no apparent change when cultured in the osteogenic medium, ALP expression increased, OCN and Col I secreted, but no calcium deposition could be detected by von Kossa staining. CD34+ cells proliferation is high by SCF and TPO activated. CD34+ cells were able to generate very few adherent cells and not proliferate after passage.42. 12 BM samples were isolated. Homogeneous CFU-Fs could be harvest from both MNC and CD34+ cells. MSC proliferated quickly and could be passaged. When cultured in the osteogenic medium, the MSCs became bigger, ALP, OCN and Col I expression were positive, calcium deposition could be observed with von Kossa staining. Conclusions:1. Osteoblast precursor cell is present in CD34+ cells isolated from BM that express low Stro-1. Osteoblast precursor cell is not present in CD34+ cells derived from UCB that express strong Stro-1. There were few adherent cells in UCB CD34+ cells culture in vitro. These demonstrated that the feature of hematopoietic cell (CD34+ cell) obtained from BM and UCB was different.2. The presence of MSC in UCB is still controversial. Our data suggested MSC couldn't be found in UCB.3. Adherent cells could be generated from UCB MNC. The adherent cells can express osteoblast markers (ALP, Col I and OCN) after osteogenic differentiation, although it is osteoclast-like cell in morphology. Our data suggested these cells had acquired some features of osteoblast.