223 COMPARISON OF NEURAL DIFFERENTIATION BETWEEN RAT AND CAT MESENCHYMAL STEM CELLS UNDER CHALLENGE BY THE SAME NEUROINDUCTION AGENT

Bone marrow-derived mesenchymal stem cells (MSCs) have the potential to differentiate into a variety of cell types, including osteocytes, chondrocytes, and adipocytes. Moreover, MSCs have the capacity to differentiate into neural lineages. The present study aimed to investigate the differences between the expression profiles during neural differentiation of rat and cat MSCs. MSCs in the 4th passage, which were isolated from the femurs and tibias by standard methodology, were used in our study. Culture media was divided into pre-induction medium, which consisted of DMEM-HG, 10% fetal bovine serum, 10 ng mL-1 of basic fibroblast growth factor (bFGF), and 1 mM �-mercaptoethanol, for 24 h, and neuron induction medium, which was composed of DMEM-HG, 2% DMSO, 200 �M BHA, 25 mMKCl, 10 �M forskolin, 5 �g mL-1 insulin-transferrin-sodium selenite, and 20 ng mL-1 bFGF, for 24 h. Thereafter, cell morphology and growth traits were determined by light microscopy imaging and by examining the cell-surface antigen profile and differentiation repertoire by immunocytochemistry, respectively. Regarding the expression of 3 MSC-related surface antigens, rat cells were positive for CD18 and CD44, whereas cat cells expressed CD9 and CD44. Under proneurogenic conditions, rat neuron-like cells progressively increased at 30 min post-induction, peaked at 1 h, and gradually declined after 12 h. At 24 h after neural induction, there were still some neuron-like cells. Meanwhile, cat cells were expressed increasingly during the first hour, peaked at 2 to 3 h, were sustained for 8 h after neural induction, and then gradually declined.A few neuron-like cells remained until 24 h post-induction. In neural differentiation, rat MSCs were positive for �III-tubulin, NF-L, NF-M, NF-H, trkA, and vimentin; cat MSCs were negative for �III-tubulin and NF-H but positive for NF-L, NF-M, trkA, and vimentin. Both MSCs were negative for oligodendrocyte markers. Our results revealed that there is variation in neural differentiation sensitivity due to species type. Rat cells were more sensitive in response to neuroinduction agents, maintained their morphology for a longer time, and expressed relatively mature neuronal markers. On the contrary, the sensitivity of cat cells was weaker, and survival time was shorter compared to that of the rat cells. The cat cells expressed immature neuronal markers. The present data suggest a significant aspect of the culture of MSCs from higher-grade species. This work was supported by KOSEF (Grant ? M10525010001-05N2501-00110).