OBJECTIVETo explore the biological characteristics of fibroblasts in adult granulation tissue in vitro, including cell viability, CD phenotypic, factor and protein expression, and differentiation, so as to facilitate further research of the role of fibroblasts in early wound healing.

METHODSFibroblasts were isolated from human granulation tissue and cultured by mechanical and enzymatic digestion method. The cell morphology and proliferation were observed under inverted phase contrast microscope. The first and third passages of cells' growth curve were drawn respectively. The surface markers (CD105, CD73, CD90, CD44, CD34, CD45, CD19, CD11b, HLA-DR) of the first and third passage fibroblasts were identified by Flow Cytometry. And the expression of Vimentin, CK19, CD31 and Factor VIII were detected by immunocytochemistry.

RESULTSPrimary cultured fibroblasts were short spindle, polygonal and irregular in shape. The morphology of fibroblasts were uniform by repeatedly passage cultured in vitro and showed spindle-shaped. The proliferative capacity of the fibroblasts were not significantly different, with logarithmic growth phase. From 1 to 4 days, The primary and third passage cells' proliferation was no difference (P > 0.05), After the five days, the proliferative ability of third generation was better than the primary passage (P < 0.01). All fibroblasts highly expressed mesenchymal stem cells' surface markers CD105, CD73, CD90 and CD44, and didnt express hematopoietic stem cells' surface markers CD34, CD45, CD19, CD11b and HLA-DR. The expression of mesenchymal stem cells' surface markers in third generation of cells were increased significantly. Immunocytochemistry showed positive expression of Vimentin, CD31, and negative expression of CK19 and Factor VIII.

CONCLUSIONSFibroblasts in human granulation tissue show the biology characteristics of Mesenchymal Stem Cells. Some biological markers of endothelial cells are expressed in fibroblasts in granulation tissue. The fibroblasts may play an important role during the process of endothelial to mesenchymal transformation in early wound healing.