中国神经再生研究(英文版) ›› 2023, Vol. 18 ›› Issue (9): 2082-2088.doi: 10.4103/1673-5374.367848

• 原著:周围神经损伤修复保护与再生 • 上一篇    

保存在体外储存液中大鼠坐骨神经节段的存活率:新电生理和形态学标准评估

  

  • 出版日期:2023-09-15 发布日期:2023-03-07

Survival of rat sciatic nerve segments preserved in storage solutions ex vivo assessed by novel electrophysiological and morphological criteria

Liwen Zhou, Monzer Alatrach, Ted Zhao, Paul Oliphint, George D. Bittner*   

  1. Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
  • Online:2023-09-15 Published:2023-03-07
  • Contact: George D. Bittner, PhD, bittner@austin.utexas.edu.
  • Supported by:
    This work was supported by grants from the Lone Star Paralysis Foundation and NIH R01NS081063 to GDB and Department of Defense award W81XWH-19-2-0054 (to GDB).

摘要:

大多数具有存活细胞的器官或组织异体移植会在体外溶液中储存数小时至数天。异体移植物在移植时宿主血管需要快速再生,以维持供体细胞的功能(例如,心肌收缩,肝脏分泌功能)。相比之下,体外储存的周围神经异体移植不需要再血管化,其在供体许旺细胞的支持下,可以作为支架引导宿主轴突以1-2mm/d的速度生长。使用目前的存储液和方案,供体器官/组织/神经移植物的轴突将在几天内因华勒氏变性而迅速变得不可用。实验研究了几种常见的器官/组织储存液(威斯康星大学冷储存液、Normosol-R、正常生理盐水和乳酸林格)对大鼠坐骨神经体外轴突活力的影响,通过:(1)人工诱导的复合动作电位的传导和(2)轴突和髓鞘形态的新型检测方法进行评估。有活力轴突的周围神经保存在成分、渗透压(250-318mOsm)、温度(4与25°C)和钙含量不同的7种储存液中。有活力轴突的周围神经中的复合动作电位和轴突形态在4°C的无钙低渗稀释(250mOsm)的Normosol-R中达到最好的状态,可保持长达9d。令人惊讶的是,复合动作电位在4℃的威斯康星大学器官保存液和生理盐水中只维持了1-2d,比有活力轴突的周围神经在4℃的稀释的Normosol-R(9d)甚至25℃的稀释的Normosol-R(5d)中维持的时间短得多。周围神经异体移植中存活的轴突对于成功地将受体轴突的近端和远端与供体轴突进行聚乙二醇融合以修复周围神经的节段性缺失至关重要。使用有活力轴突的周围神经进行聚乙二醇融合修复可以防止移植物内部和远端许多轴突的华勒氏变性,并在数周内促进感觉/运动功能和自主行为的良好恢复。这种聚乙二醇融合的有活力轴突的周围神经与所有其他类型的传统供体移植不同,无需组织匹配或免疫抑制就能实现免疫耐受。在储存的有活力轴突的周围神经中保存轴突活力有利于建立有活力轴突的周围神经组织库,以解决目前周围神经移植物短缺的问题。储存的聚乙二醇融合有活力轴突的周围神经也是修复周围神经节段性缺失的有潜力方法。此外,有活力轴突的周围神经储存方案也体外其他类型器官/组织移植的轴突存活提供了有参考价值的储存方案。

https://orcid.org/0000-0002-5610-6264 (George D. Bittner)

Abstract: Most organ or tissue allografts with viable cells are stored in solutions ex vivo for hours to several days. Most allografts then require rapid host revascularization upon transplantation to maintain donor-cell functions (e.g., cardiac muscle contractions, hepatic secretions). In contrast, peripheral nerve allografts stored ex vivo do not require revascularization to act as scaffolds to guide outgrowth by host axons at 1–2 mm/d, likely aided by viable donor Schwann cells. Using current storage solutions and protocols, axons in all these donor organ/tissue/nerve transplants are expected to rapidly become non-viable due to Wallerian degeneration within days. Therefore, ex vivo storage solutions have not been assessed for preserving normal axonal functions, i.e., conducting action potentials or maintaining myelin sheaths. We hypothesized that most or all organ storage solutions would maintain axonal viability. We examined several common organ/tissue storage solutions (University of Wisconsin Cold Storage Solution, Normosol-R, Normal Saline, and Lactated Ringers) for axonal viability in rat sciatic nerves ex vivo as assessed by maintaining: (1) conduction of artificially-induced compound action potentials; and (2) axonal and myelin morphology in a novel assay method. The ten different storage solution conditions for peripheral nerves with viable axons (PNVAs) differed in their solution composition, osmolarity (250–318 mOsm), temperature (4°C vs. 25°C), and presence of calcium. Compound action potentials and axonal morphology in PNVAs were best maintained for up to 9 days ex vivo in calcium-free hypotonic diluted (250 mOsm) Normosol-R (dNR) at 4°C. Surprisingly, compound action potentials were maintained for only 1–2 days in UW and NS at 4°C, a much shorter duration than PNVAs maintained in 4°C dNR (9 days) or even in 25°C dNR (5 days). Viable axons in peripheral nerve allografts are critical for successful polyethylene glycol (PEG)-fusion of viable proximal and distal ends of host axons with viable donor axons to repair segmental-loss peripheral nerve injuries. PEG-fusion repair using PNVAs prevents Wallerian degeneration of many axons within and distal to the graft and results in excellent recovery of sensory/motor functions and voluntary behaviors within weeks. Such PEG-fused PNVAs, unlike all other types of conventional donor transplants, are immune-tolerated without tissue matching or immune suppression. Preserving axonal viability in stored PNVAs would enable the establishment of PNVA tissue banks to address the current shortage of transplantable nerve grafts and the use of stored PEG-fused PNVAs to repair segmental-loss peripheral nerve injuries. Furthermore, PNVA storage solutions may enable the optimization of ex vivo storage solutions to maintain axons in other types of organ/tissue transplants.

Key words: axonal morphometrics, axonal viability, calcium, osmolarity,  , peripheral nerve grafts, peripheral nerve injury, temperature, tissue storage solutions, tonicity, Wallerian degeneration