Background

Processed nerve allografts are increasingly used in clinical nerve reconstruction with promising results. However, allograft failure has been reported, leading to chronic pain and persistent loss of function. In the present work, we performed a histological and immunohistochemical analysis of two failed allograft reconstructions of a sensory human nerve one year after primary surgery.

Methods

Two patients with a superficial radial nerve injury underwent nerve reconstruction with processed nerve allografts. The clinical follow-up was complicated by severe neuropathic pain and absent sensory reinnervation. Consequently, the failed allografts were excised with subsequent histological and immunohistochemical examinations. For that purpose, the collagen content and neurofilament network as well as the blood and lymphatic vasculature were analysed in the center of the specimens.

Results

Histology revealed increased fibrosis, fatty degeneration, and disorganised proliferation of nerve fibres. Moreover, the microvascular network within the allografts was characterised by increased numbers of microvessels, whereas no difference was found concerning the lymphatic vasculature.

Conclusion

The herein presented histological and immunohistochemical findings indicate that the failure of human allografts is associated with loss of the physiological microvascular architecture. Future studies elucidating the complex interplay of angiogenesis, lymphangiogenesis and axonal regeneration are required to better understand the mechanisms of human allograft failure.

中文翻译：

---

神经内纤维化和微血管结构的丧失——研究失败的人类同种异体神经移植的主要发现

背景

加工过的同种异体神经移植物越来越多地用于临床神经重建，并取得了可喜的成果。然而，据报道，同种异体移植失败，导致慢性疼痛和功能持续丧失。在目前的工作中，我们对初次手术一年后人类感觉神经的两次失败的同种异体移植重建进行了组织学和免疫组织化学分析。

方法

两名患有浅表桡神经损伤的患者接受了处理过的同种异体神经移植的神经重建。临床随访因严重的神经性疼痛和感觉神经支配缺失而变得复杂。因此，通过随后的组织学和免疫组织化学检查切除失败的同种异体移植物。为此，分析了样本中心的胶原含量和神经丝网络以及血液和淋巴管系统。

结果

组织学显示纤维化增加、脂肪变性和神经纤维的无组织增殖。此外，同种异体移植物内的微血管网络的特点是微血管数量增加，而淋巴管系统没有发现差异。

结论

本文提出的组织学和免疫组织化学发现表明，人类同种异体移植物的失败与生理微血管结构的丧失有关。未来的研究需要阐明血管生成、淋巴管生成和轴突再生之间复杂的相互作用，以更好地了解人类同种异体移植失败的机制。