Abstract: Objective To study the feasibility of basic fibroblast growth factor （bFGF）in inducing bone marrow mesenchymal stem cells(BMSCs) to differentiate into cardiomyocyte-like cells in vitro. Methods SD rat BMSCs were isolated and cultured from rat bone marrow, and then induced by bFGF. The cultured cells were observed by a phase-contrast microscope. The immunohistochemical technique and laser scanning confocal microscope (LSCM) were used for examination of the expression of desmin, α-actin and C-TnT. The ultrastructure of induced cells was observed by a transmission electron microscope. GATA4 andα-MHC expressions were detected by relative quantitative RT-PCR after 7, 21, 28 days of induction respectively. Results After primary cells were cultured for 48 hours，most of them became fusiform fibroblast-like shape with two or three processes and a few of them were flat in shape. The morphology of BMSCs induced by bFGF changed obviously. After being induced by bFGF for one week, the cells became larger and most of them became myocyte-like short column in shape or long shuttle-shape while paralleled. After four weeks, most cells became short column-shape and touched with adjacent cells tightly to form myotube-like structure,with apparent directionality of cell arraying. BMSCs induced by bFGF were identified by the positive staining for desmin, α-sarcomeric actin and C-TnT. Of BMSCs, there were more desmin positive and α-actin-positive cells made up higher of all BMSCs than C-TnT-positive cells. Desmin and α-actin-positive cells were about 33.82% and 58.64%, and C-TnT-positive cells were about 28.94%. Desmin(α-actin ) appeared red, and C-TnT was green under a laser scaning confocal microscopy. Their co-expression appeared yellow. Transmission electron microscope showed that the induced cells were rod in shape and the ovoid nuclei were positioned in the center of the cell. lots of mitochondria, rough endoplasmic reticulum, ribosome and paralleled myofilaments were founded in plasm.RT-PCR assessment showed that the differentiated cells began to express GATA-4 from day 7 to day 28 of differentiation and began to express α-myosin heavy china(α-MHC) fro

Key words: Bone marrow mesenchymal stem cell, bFGF, Cardiomyocyte, Differentiation, Rat