The Tissue Location And Biological Characteristic Of Mesenchymal Stem Cells In Human Placenta

Objective: Mensenchymal stem cells (MSCs) derived from human placenta has been a hot spot in the field on stem cell research. The distribution of MSCs is nonuniform in placenta. How to take tissue materials for obtaining MSCs would influence the cell purification and proliferation in vitro. At present, there is no specific marker for identification of MSCs from adult tissues. The objective of this study is to investigate the distribution of MSCs in human placenta by tissue staining with some general markers, then to verify the biological characteristic by isolating and culturing PMSCs in different group.We expected to provide a basis for further study of MSCs-location in other adult tissues and to establish effective means for obtaining MSCs from placenta.Methods: The fresh tissues were taken in normal placenta during cesarean section without medical indication. According to the central zone(A),the intermediate zone(B),the marginal zone(C), the chorionic plate layer(a),the middle layer(b) and the basal layer(c), the placenta tissues were divided into 9 groups: Aa,Ab,Ac,Ba,Bb,Bc,Ca,Cb,Cc. After that, serial section,immunofluorescence staining and immunohistochemical staining were applied on all groups to study the expression of CD166,CD44,CD29.The distribution of positive expression cells was analysed by HPIAS-1000 colored image analysis system, and the optical density(O.D) values was given to measure the level of expression. All data was analyzed statistically by a SPSS statistical software. At last, PMSCs of each group were isolated and cultured to compare the capability of proliferation. Furthermore, the membrane differentiation antigens of MSCs were detected and the MSCs were induced to differentiate into neuron-like cells,which confirmed that PMSCs should have the potention similar to those of bone marrow mesenchymal stem cells. Results:Distribution of CD166,CD44,CD29 positive cells was mainly concentrated in the area under vascular endothelial cells and in the stroma around the vessel respectively. There were strongly positive cells in the intermediate zone and the middle layer of placenta (Ab)(P<0.05). Only a few positive cells were seen in the marginal zone(C) and the expression of the three antigens was rather weak. The cell proliferation result showed that by the same processing method there were big differences among the groups. The Ab group was comparatively outstanding about the rate of the proliferation. Detection of the surface antigens of MSCs by flow cytometry showed that the culturing cells expressed CD166,CD44,CD29 and CD105, and not expressed CD45,CD34 and HLA-DR.After 24 hours'induction,most of the cells would tend to posses dendron and axon structure as well as express GFAP and NSE as nerou markers.Conclusion: CD166,CD44,CD29-positive cells could be found variously in human placenta, mainly distributed in intermediate zone and the middle layer of placenta (Ab). The proliferation efficiency was positively related to the amount of cells obtained from each group. CD166,CD44,CD29 could be used as reliable indicators of MSCs-location in adult tissues.