Abstract: Objective To explore the effects of insulin-like growth factor binding protein-4 (IGFBP4) on the proliferation and neural differentiation of bone marrow mesenchymal stem cell (BMSC). Methods BMSCs from SD male rats were isolated by the Whole Marrow Adherence Method and identified using immunofluorescence. IGFBP4 expression in the P1, P4, P6, P8 and P10 BMSCs was detected. P4 BMSCs were divided into two groups, and their proliferation activity was detected by CCK8 assay after treatment with or without exogenous IGFBP4. The P4 BMSCs were further divided into three groups to evaluate their potentials of neural differentiation after treatment with NeuroCult medium plus EGF+bFGF or EGF+bFGF+IGFBP4. Neural progenitor cells with neurosphere-like structures were identified by immunostaining of Nestin and Sox-2. The number of the induced neurosphere-like structure was counted and the proliferation of neural progenitor cells was assayed. Results BMSCs from SD rats were successfully cultured, and the cells were positive for CD44, CD90 and CD105. The intensity of IGFBP4 expression was increased after passaging, and IGFBP4 could significantly inhibit BMSCproliferation (P<0.05). BMSCs could be induced to form neural progenitor cells which were immunopositive for Nestin and Sox-2. IGFBP4 promoted the differentiation of BMSCs into neural progenitor stem cells, as manifested by an increased size of neurospheres and increased activity of proliferation (P<0.05). Conclusions IGFBP4 could significantly inhibit the proliferation of BMSCs and promote the differentiation of BMSCs into neural progenitor stem cells.

Key words: insulin-like growth factor binding protein-4 (IGFBP4), bone marrow mesenchymal stem cell(BMSC), neural differentiation