Experimental Study In The Differentiation Of Rat Bone Marrow-derived Stem Cells To Mesangial-like Cells

Background and ObjectiveThe normal glomerular capillary is essential to keep efficient ultrafiltration of the plasma, and mesangial cells provide physical support for the glomerular capillary lumen of the kidney. Loss of mesangial cells due to pathologic conditions such as glomerulonephritis and diabetic nephropathy leads to impaired renal function. Recently, great advances have been achieved in the origin of glomerular mesangial cells in rat. Bone marrow mesenchymal stem cells have the potential to differentiate to glomerular mesangial cells. Therefore, Bone marrow mesenchymal stem cells are one of the cell sources for kidney impairment. Under certain conditions, bone marrow-derived cells can differentiate into mesangial-like cells. Based on established research, our study aimed to confirm the potential of bone marrow mesenchymal stem cells differentiation to mesangial cells, and further discover the possible mechanism involved in it.MethodsRat bone marrow stem cells were isolated and cultured in the presence of rat platelet-derived growth factor (PDGF)-BB (200ng/ml) to induce the mesangial cell phenotype. On culture day 7 and thereafter, the cell morphology, mesangial cell-specific markers (α-Actin, Desmin, Thy-1, Myosin and Vimentin), and cell retraction function were examined. To further characterize the cells in the differentiation medium, expression of factor VIII was tested with endothelial cells as the control. Mitogen-activated protein kinase (MAPK) / extracellular regulated protein kinases (ERK) inhibitor (PD98059) was added into the differentiation medium to examine the impact in cell growth and mesangial cell-specific marker genes expression. Results1. After cultivation under the differentiation condition for 7 days, approximately 10% of bone marrow mesenchymal stem cells (0. 1% to 0. 5% of the original bone marrow cells) , attached to collagen type IV coated dishes, expressedα-Actin and Desmin, which highly resembled cultured mesangial cells in rat. The stallete cells in the differentian medium didn't expressed factor VIII , which clearly expressed in rat endothelial cells. PDGF-BB (200ng/ml) induced the expression of mesangial cell-specific marker (α-Actin, Desmin, Thy-1, Myosin and Vimentin) mRNA. The induced cells changed into a wide range of shapes from spindle to stellate and were contracted in response to angiotensin II (10^-7mol/L).2. PDGF-BB(200ng/ml) induced PDGF receptors(including PDGFRαand PDGFRβ) mRNA expression of the mesangial-like cells. Inhibition of MAPK/ERK1/2 phosphorylation by PD98059 (5μmol/L) blocked the expression of mesangial cell-specific marker genes (α-Actin, Desmin, Thy-1 and Myosin) in these cells. The induced cells with PD98059 inhibitor (5μmol/L) kept spindle-shaped morphology, but not stellate shape.ConclusionsThese data indicated that rat bone marrow mesenchymal stem cells can differentiate into mesangial-like cells with PDGF-BB(200ng/ml) induction in vitro, one of the mechanism involved in the differentiation was mediated through MAPK/ERK1/2 signal transduction pathway.