许旺细胞-海藻酸钠凝胶移植修复大鼠脊髓损伤*

目的：观察许旺细胞-海藻酸钠凝胶移植对大鼠脊髓损伤后细胞凋亡、Bcl-2表达及下肢运动功能恢复的影响。 方法：清洁级SD大鼠随机分为4组：正常对照组、单纯损伤组、许旺细胞组、许旺细胞-海藻酸钠凝胶组。后3组制作脊髓全横断损伤模型。正常对照组、单纯损伤组不进行移植处理，许旺细胞组植入吸附许旺细胞悬液的明胶海绵块、许旺细胞-海藻酸钠凝胶组植入许旺细胞-海藻酸钠凝胶。分别于 12 h，1，3，7，21 d对动物进行BBB评分后处死，取损伤区脊髓节段制成石蜡切片进行TUNEL、Bcl-2染色，观察脊髓内凋亡细胞、Bcl-2细胞的数量及分布变化。 结果：正常对照组仅有少量淡染Bcl-2阳性细胞；单纯损伤组神经元Bcl-2免疫反应阳性细胞表达的高峰在第3天，14 d时Bcl-2免疫反应阳性细胞表达接近正常水平。许旺细胞-海藻酸钠凝胶移植后损伤脊髓细胞Bcl-2免疫反应阳性细胞表达具有显著增高(P < 0.05)，7 d高度表达并持续2周以上。单纯损伤组脊髓内细胞凋亡最多，并于损伤后1，7 d形成两个高峰，多分布于白质中。许旺细胞-海藻酸钠凝胶组BBB评分较单纯损伤组及许旺细胞组明显提高(P < 0.05)。 结论：许旺细胞-海藻酸钠凝胶移植能抑制大鼠脊髓损伤后脊髓细胞凋亡、促进Bcl-2的表达，提高了脊髓运动功能的恢复，但未达到正常水平。 关键词：脊髓损伤；细胞凋亡；许旺细胞；Bcl-2

Schwann cells-alginic acid sodium hydrogel transplantation for repair of spinal cord injury in rats*

OBJECTIVE: To investigate the influences of Schwann cells-alginic acid sodium hydrogel transplantation on cellular apoptosis, Bcl-2 expression, and lower limb locomotor function in a rat model of spinal cord injury. METHODS: SD rats of clean grade were randomly divided into 4 groups: normal control, simple injury, Schwann cells, and Schwann cells-alginic acid sodium hydrogel. Spinal cord transaction model was established in the latter 3 groups. Gelatin sponge blocks containing Schwann cells suspension were transplanted into the Schwann cells group. Schwann cells-alginic acid sodium hydrogel was transplanted into Schwann cells-alginic acid sodium hydrogel group. No treatments were performed in the normal control and simple injury groups. At 12 hours, 1, 3, 7, and 21 days after surgery, animals were assessed using Basso, Beattie and Bresnahan (BBB) locomotor rating scale and were sacrificed. The spinal cord-transected segments were taken to prepare paraffin sections for TUNEL and Bcl-2 staining to quantitate apoptotic cells and Bcl-2 cells in the injured spinal cord and to investigate their distributions. RESULTS: A small number of slightly stained Bcl-2 positive cells were observed in the normal control group. In the simple injury group, Bcl-2 immunoreactive cells peaked at 3 days after surgery, and the expression level was close to normal level at 14 days. Following Schwann cells-alginic acid sodium hydrogel transplantation, Bcl-2 immunoreactive cells in the spinal cord-transected segments were significantly increased till 7 days (P < 0.05) and remained this level for more than 14 days. In the simple injury group, apoptotic cells were most as compared with the remaining 3 groups, and peaked at 1 and 7 days following spinal cord injury, and they were mostly distributed in the white matter. BBB scores were significantly higher in the Schwann cells-alginic acid sodium hydrogel transplantation group than in the simple injury and Schwann cells groups (P < 0.05). CONCLUSION: Schwann cells-alginic acid sodium hydrogel transplantation could inhibit cellular apoptosis and enhance Bcl-2 expression in the spinal cord-transected segments, and thereby promote the recovery of locomotor function after spinal cord injury but did not reach normal levels.