[免疫抑制药物FK 506对雪旺细胞生长及周围神经轴突再生的刺激作用]

Fansa H, Keilhoff G, Horn T, Altmann S, Wolf G, Schneider W

Klinik für Plastische, Wiederherstellungs- und Handchirurgie, Medizinische Fakultät der Otto-von-Guericke-Universität in Magdeburg.

Handchir Mikrochir Plast Chir. 1999 Sep;31(5):323-9; discussion 330-2. doi: 10.1055/s-1999-13544.

BACKGROUND

Nerve allografts are highly antigenic and, thus, require the continuous use of immunosuppressive drugs. The immunosuppressant Cyclosporine A was used in most studies. More recently, the immunosuppressive effect of FK 506 on peripheral nerve allografts and xenografts has been studied, and the drug has been found to prevent rejection successfully. However, neurotoxic complications have been noted in the central and peripheral nervous system although an increased rate of axonal regeneration has also been shown.

METHODS

Schwann cells were cultured from the sciatic nerve of the rat. The effect of 100 microM FK 506 administered daily on these cultures was assessed over a period of seven days and compared to an untreated control group of cultures. To visualize a direct effect of FK 506 on Schwann cells, the changes in intracellular calcium were recorded using fluorescence imaging of primary rat Schwann cell cultures loaded with Fluo-3. Regeneration of autologous nerve grafts was assessed in a rat model clinically and morphometrically after daily administration of 0.6 mg FK 506/kg body weight.

RESULTS

FK 506 increases the number of Schwann cells in culture significantly compared to the control group, while the fibrocyte population is decreased. FK 506 caused a transient increase of intracellular calcium levels of cultured cells. A significantly higher axon count was observed in the FK 506-treated grafts after two weeks of regeneration compared with controls. Additionally, less myelin debris was evident in the FK 506 treated group after two weeks compared with the control group. Good regeneration was noted in all grafts after six weeks of regeneration.

CONCLUSION

The increased axon counts and decreased myelin debris in the FK 506 grafts after two weeks indicate an accelerated Wallerian degeneration and increased axon sprouting into the graft initially. FK 506 promotes axonal regeneration through binding to FKBP-12, thus activating GAP-43 (growth associated protein) and the TGF beta 1-pathway (transforming growth factor). In addition, the increase of the intracellular calcium may induce Schwann cell proliferation via Calmodulin which in turn promotes axonal regeneration.

背景

神经同种异体移植具有高度抗原性，因此需要持续使用免疫抑制药物。大多数研究使用免疫抑制剂环孢素A。最近，已对FK 506对外周神经同种异体移植和异种移植的免疫抑制作用进行了研究，发现该药物能成功预防排斥反应。然而，尽管也显示出轴突再生率有所提高，但在中枢和外周神经系统中已注意到神经毒性并发症。

方法

从大鼠坐骨神经中培养雪旺细胞。在7天的时间内评估每天给予100微摩尔FK 506对这些培养物的影响，并与未处理的培养物对照组进行比较。为了观察FK 506对雪旺细胞的直接作用，使用加载Fluo-3的原代大鼠雪旺细胞培养物的荧光成像记录细胞内钙的变化。在每天给予0.6毫克FK 506/千克体重后，在大鼠模型中临床和形态计量学评估自体神经移植的再生情况。

结果

与对照组相比，FK 506显著增加了培养物中雪旺细胞的数量，而纤维细胞数量减少。FK 506导致培养细胞的细胞内钙水平短暂升高。再生两周后，与对照组相比，FK 506处理的移植物中观察到明显更高的轴突计数。此外，与对照组相比，两周后FK 506处理组中的髓磷脂碎片明显更少。再生六周后，所有移植物均观察到良好的再生。