Effect of basic fibroblast growth factor on cultured rat neural stem cell in three-dimensional collagen gel

Objectives: The effect of growth factors on the three-dimensional culture of neural stem cells has not been reported. We studied the effect of basic fibroblast growth factor (bFGF) on cultured rat neural stem cells in a three-dimensional culture. Methods: We cultured rat neural stem cells in collagen gel matrix for three-dimensional culture and examined the effect of bFGF under such culture conditions. Results: After 4 days culture, the cell density in the bFGF treatment roup was 12 times that of the non-treatment group, reaching a significantly high value. In the bFGF treatment group, microtubule associate protein (MAP)-2-positive cell aggregation occurred, although in the bFGF non-treatment group there was no MAP-2-positive cell aggregation and few of the cells were sparsely distributed. Also, in the bFGF treatment group, MAP-2-positive cell aggregation had a luminal structure similar to neural rosettes. There was elongation of MAP-2-positive neurites from the cell aggregation to the circumference in the bFGF treatment group. Discussion: bFGF is known to induce the proliferation, but not the differentiation of neural stem cells in two-dimensional cultures. However, in the three-dimensional culture, bFCF induced both the proliferation and differentiation of neural stem cells. The three-dimensional culture is, therefore, considered a useful method for predicting the response of neural stem cells to cytokines or biologically active substances in vivo.