Dental Research Institute, Seoul National University, Seoul, Republic of Korea.
Tissue Eng Part A. 2011 May;17(9-10):1327-40. doi: 10.1089/ten.TEA.2010.0519. Epub 2011 Mar 10.
Electrical stimulation (ES) is a promising technique for axonal regeneration of peripheral nerve injuries. However, long-term, continuous ES in the form of biphasic electric current (BEC) to stimulate axonal regeneration has rarely been attempted and the effects of BEC on Schwann cells are unknown. We hypothesized that long-term, continuous ES would trigger the activation of Schwann cells, and we therefore investigated the effect of BEC on the functional differentiation of primary human mesenchymal stromal cells (hMSCs) into Schwann cells, as well as the activity of primary Schwann cells. Differentiation of hMSCs into Schwann cells was determined by coculture with rat pheochromocytoma cells (PC12 cell line). We also investigated the in vivo effects of long-term ES (4 weeks) on axonal outgrowth of a severed sciatic nerve with a 7-mm gap after retraction of the nerve ends in rats by implanting an electronic device to serve as a neural conduit. PC12 cells cocultured with hMSCs electrically stimulated during culture in Schwann cell differentiation medium (Group I) had longer neurites and a greater percentage of PC12 cells were neurite-sprouting than when cocultured with hMSCs cultured in growth medium (control group) or unstimulated hMSCs in the same culture conditions as used for Group I (Group II). Group I cells showed significant upregulation of Schwann cell-related neurotrophic factors such as nerve growth factor and glial-derived neurotrophic factor compared to Group II cells at both the mRNA and protein levels. Primary Schwann cells responded to continuous BEC with increased proliferation and the induction of nerve growth factor and glial-derived neurotrophic factor, similar to Group I cells, and in addition, induction of brain-derived neurotrophic factor was observed. Immunohistochemical investigation of sciatic nerve regenerates revealed that BEC increased axonal outgrowth significantly. These results demonstrate that BEC enhanced the functional activity of Schwann cells via the induction of neurotrophic factor release and guide-increased axonal outgrowth in vivo. The effectiveness of long-term ES highlights the feasibility of a BEC-based therapeutic device to accelerate nerve regeneration of severed peripheral nerve injuries with a gap.
电刺激（ES）是促进周围神经损伤轴突再生的一种有前途的技术。然而，以双相电流（BEC）形式进行长期连续的 ES 刺激轴突再生的尝试很少，并且 BEC 对施万细胞的影响尚不清楚。我们假设长期连续的 ES 会触发施万细胞的激活，因此我们研究了 BEC 对原代人间充质基质细胞（hMSC）向施万细胞功能分化的影响，以及原代施万细胞的活性。通过与大鼠嗜铬细胞瘤细胞（PC12 细胞系）共培养来确定 hMSC 向施万细胞的分化。我们还研究了在大鼠中通过植入电子装置作为神经导管来缩回神经末端后，长期 ES（4 周）对 7mm 间隙切断的坐骨神经轴突再生的体内影响。在 Schwann 细胞分化培养基中培养的同时进行电刺激的 PC12 细胞与 hMSC 共培养（I 组）比与 hMSC 在生长培养基中培养的共培养（对照组）或在与 I 组相同的培养条件下未刺激的 hMSC 共培养的 PC12 细胞具有更长的神经突和更大比例的 PC12 细胞有神经突发芽。与 II 组细胞相比，I 组细胞在 mRNA 和蛋白质水平上均显示出施万细胞相关神经营养因子（如神经生长因子和胶质源性神经营养因子）的显著上调。与 I 组细胞类似，原代施万细胞对连续 BEC 的反应是增殖增加以及神经生长因子和胶质源性神经营养因子的诱导，此外还观察到脑源性神经营养因子的诱导。坐骨神经再生的免疫组织化学研究表明，BEC 显著增加了轴突的生长。这些结果表明，BEC 通过诱导神经营养因子释放增强了施万细胞的功能活性，并在体内促进了引导性的轴突生长。长期 ES 的有效性突出了基于 BEC 的治疗装置的可行性，该装置可加速有间隙的切断性周围神经损伤的神经再生。
