RESUMO
BACKGROUND: Human skeletal muscle derived myoendothelial cells (MECs) are located in the vascular wall and co-express the markers of muscle stem cells and vascular endothelial cells (CD56+CD34+CD144+CD45-). Studies have shown that MECs are similar to mesenchymal stem cells, express the surface markers of mesenchymal stem cells and have the potential of multidirectional differentiation. OBJECTIVE: To establish an in vitro culture system for human umbilical cord blood CD34+ cells with MECs as trophoblastic layer, and to evaluate the in vitro supporting effect of human skeletal muscle MECs on hematopoietic stem/progenitor cells by measuring the changes in the number, immunophenotype and colony forming ability of CD34+ cells before and after culture. METHODS: There were three groups in the experiment. In experimental group, human umbilical cord blood CD34+ cells were co-cultured with MECs as the nourishing layer; in control group, human umbilical cord blood CD34+ cells were co-cultured with bone marrow mesenchymal stem cells as the nourishing layer; and in blank control group, human umbilical cord blood CD34+ cells were cultured alone without the nourishing layer. The main outcome measures, including the number of human umbilical cord blood CD34+ cells, immunophenotype of blood cells and colony formation ability of hematopoietic stem/progenitor cells were analyzed and compared at 1, 2, and 4 weeks after co-culture. No detection was conducted at 5 weeks due to the lack of survived cells. RESULTS AND CONCLUSION: (1) The number of human umbilical cord blood CD34+ cells increased by MECs as the nourishing layer compared with bone marrow mesenchymal stem cells as the nourishing layer at 1, 2, and 4 weeks; however, there was no significant difference between the two groups (P > 0.05). (2) The cell immunophenotype by flow cytometry analysis indicated that only in the 2nd week, the expression of CD34+CD33- in human umbilical cord blood CD34+ cells in the control group was significantly higher in the experimental group (P 0.05). (3) The colony formation capacity of hematopoietic stem/progenitor cells showed no significant difference between the experimental and control groups at 1, 2, and 4 weeks (P > 0.05). (4) Due to the non-nourishing layer culture system, the number of human umbilical cord blood CD34+ cells decreased significantly in the 1st week, and no cells survived in the 2nd week. Therefore, blood cell immunophenotype and colony analysis could not be performed. (5) To conclude, human skeletal muscle MECs as trophoblasts are the same as human bone marrow mesenchymal stem cells, which have a hematopoietic support in vitro.