1Department of Clinical Neurosciences, University of Calgary.
2Hotchkiss Brain Institute, University of Calgary.
J Neurosurg. 2022 Jul 29;138(3):858-867. doi: 10.3171/2022.6.JNS22734. Print 2023 Mar 1.
The objective of this study was to test whether regenerating motor axons from a donor nerve can travel in a retrograde fashion using sensory branches to successfully reinnervate a motor nerve end organ.
This study has two parts. In part I, rats (n = 30) were assigned to one of five groups for obturator nerve (ON)-to-femoral nerve transfer: group 1, ON-to-saphenous nerve (SN) distal stump; group 2, ON-to-SN proximal stump without femoral nerve proper (FNP) injury; group 3, ON-to-SN proximal stump with FNP crush injury; group 4, ON-to-SN proximal stump with FNP transection injury; and group 5, gold standard transfer, ON-to-motor femoral nerve (MFN) branch. At 8 weeks, retrograde labeling was done from the distal MFN, and the spinal cords were examined to assess the degree of obturator motor axon regeneration across the five groups. In part II, only group 4 was examined (n = 8). Through use of immunostaining and optical tissue clearing methods, the nerve transfer networks were cleared and imaged using light-sheet fluorescence microscopy to visualize the regeneration pathways in 2D and 3D models at 2- and 8-week time points.
Proximal FNP transection (group 4) enabled a significantly higher number of retrogradely regenerated motor axons compared with control groups 1-3. Moreover, group 4 had modest, but nonsignificant, superiority of motor neuron counts compared with the positive control group, group 5. Optical tissue clearing demonstrated that the axons traveled in a retrograde fashion from the recipient sensory branch to the FNP mixed stump, then through complex turns, down to distal branches. Immunostaining confirmed the tissue clearing findings and suggested perineurium disruption as a means by which axons could traverse across fascicular boundaries.
Sensory branches can transmit regenerating axons from donor nerves back to main mixed recipient nerves, then distally toward target organs. The extent of retrograde regeneration is markedly influenced by the type and severity of injury sustained by the recipient nerve. Using a sensory branch as a bridge for retrogradely regenerating axons can open new potential horizons in nerve repair surgery for severely injured mixed nerves.
本研究旨在测试供体神经的再生运动轴突是否可以通过感觉分支逆行传播，以成功地重新支配运动神经末梢器官。
本研究分为两部分。在第一部分中，将大鼠（n=30）分为五组进行闭孔神经（ON）-股神经转移：组 1，ON-隐神经（SN）远端残端；组 2，ON-SN 近端残端无股神经干（FNP）损伤；组 3，ON-FNP 挤压伤近端残端；组 4，ON-FNP 切断伤近端残端；组 5，金标准转移，ON-运动股神经（MFN）分支。8 周后，从远端 MFN 进行逆行标记，并检查脊髓以评估 5 组中闭孔运动轴突再生的程度。在第二部分中，仅检查组 4（n=8）。通过使用免疫染色和光学组织透明化方法，清除神经转移网络，并使用光片荧光显微镜对 2 周和 8 周时间点的 2D 和 3D 模型中的再生途径进行成像。
与对照组 1-3 相比，FNP 近端横断（组 4）可使更多逆行再生的运动轴突。此外，与阳性对照组相比，组 4 的运动神经元计数略有但无统计学意义的优势，组 5。光学组织透明化显示，轴突从受体感觉支逆行行进到 FNP 混合残端，然后通过复杂的转弯，向下到达远端分支。免疫染色证实了组织透明化的发现，并表明神经外膜破坏是轴突穿越束状边界的一种方式。
感觉支可以将供体神经的再生轴突逆行传回到主混合受体神经，然后向远端目标器官。逆行再生的程度受受体神经所受损伤的类型和严重程度的显著影响。使用感觉支作为逆行再生轴突的桥梁，可以为严重损伤的混合神经修复手术开辟新的潜在视野。
