Yu Xiao-dong, Luo Zhuo-jing, Zhang Lin, Gong Kai
Research Institute of Orthopedic Surgery, Xijing Hospital, Xi'an 710032, China.
Chin Med J (Engl). 2007 Aug 20;120(16):1438-43.
Olfactory ensheathing cells (OECs) can promote many kinds of neuron growth and axonal extension. The aim of the study was to investigate the effects of co-culturing with OECs on neuron apoptosis in vitro.
Apoptosis was induced by treatment of cultured dorsal root ganglion neurons with 1 mmol/L hydrogen peroxide (H(2)O(2)). Cells were randomly arranged into the following treatment groups. In group 1, OECs at different density (10(4)/ml to 8 x 10(5)/ml) were added immediately after H(2)O(2) treatment and cells were co-cultured for 24 hours. In group 2, OECs were added at different time points (0, 4, 8, 12 and 24 hours) after H(2)O(2) treatment. Apoptotic cell death was determined by Hoechst 33258 staining and flow cytometry (FCM). Cell viability was determined by using methyl thiazoleterazolium (MTT) assays.
The results showed in the Hoechest 33258 staining, FCM and MTT that OECs have both the density-dependent protection and time-dependent protection on neuron apoptosis. The apoptosis decreased and the dorsal root ganglion neuron viability increased, when the density of OECs was increased in co-culture groups. But further increasing OEC density above 2 x 10(5)/ml (i.e. 8 x 10(5)/ml) failed to exert additional protection. As the interval between adding H(2)O(2) and adding OECs was increased, the amounts of apoptosis cells were also increased. When OECs were added 24 hours after H(2)O(2), no significant protection was observed.
These results indicated that OECs could protect dorsal root ganglion neurons from apoptosis induced by H(2)O(2) in a density- and time-dependent manner.
嗅鞘细胞（OECs）能够促进多种神经元生长和轴突延伸。本研究旨在探讨与嗅鞘细胞共培养对体外神经元凋亡的影响。
用1 mmol/L过氧化氢（H₂O₂）处理培养的背根神经节神经元以诱导凋亡。细胞被随机分为以下处理组。第1组，在H₂O₂处理后立即加入不同密度（10⁴/ml至8×10⁵/ml）的嗅鞘细胞，并将细胞共培养24小时。第2组，在H₂O₂处理后的不同时间点（0、4、8、12和24小时）加入嗅鞘细胞。通过Hoechst 33258染色和流式细胞术（FCM）测定凋亡细胞死亡情况。使用噻唑蓝（MTT）法测定细胞活力。
Hoechest 33258染色、FCM和MTT结果显示，嗅鞘细胞对神经元凋亡具有密度依赖性保护和时间依赖性保护作用。在共培养组中，随着嗅鞘细胞密度增加，凋亡减少，背根神经节神经元活力增加。但当嗅鞘细胞密度进一步增加至高于2×10⁵/ml（即8×¹⁰⁵/ml）时，未能发挥额外的保护作用。随着加入H₂O₂与加入嗅鞘细胞之间的时间间隔增加，凋亡细胞数量也增加。当在H₂O₂处理24小时后加入嗅鞘细胞时，未观察到明显的保护作用。
这些结果表明，嗅鞘细胞能够以密度和时间依赖性方式保护背根神经节神经元免受H₂O₂诱导的凋亡。
