Immunofluorescence analyses of anterior cruciate ligament (ACL) allografts following remnant-preserving ACL reconstruction using Achilles tendon allografts have provided evidence for the presence of neural elements. In this study, we aimed to examine the expression of neural elements and quantify the presence of neural cells in ACL remnants and Achilles allografts using nerve growth factor (NGF) therapy after remnant-preserving ACL reconstruction. Experiments were conducted on 5 pairs of rats (approximately 8 weeks old and weighing 320 g at the time of surgery). Longitudinally, split Achilles tendons from the paired rats were freshly frozen and later defrosted with warm saline and allografted onto the right ACL of the other rat that was partially detached at the femoral attachment site. A sham operation was conducted on the left knee to be used as a control. NGF was injected into both knee joints every week for 6 weeks after surgery. The presence of neural cells in the ACL of the sham-operated knee, allografted Achilles tendon, and ACL remnant was examined 6 weeks post-surgery using H and E and immunofluorescent staining. H and E staining did not reveal neural cells in any of the three groups. However, immunofluorescence analysis showed the presence of nestin-positive neural elements in the normal ACL tissues as well as ACL remnants. Additionally, neural elements were examined in 7 of the 8 (87.5%) allograft tissues. Quantitative analysis showed no difference in the number or area of nuclei among the three groups. However, the number and area of neural cells in the Achilles allografts were significantly lower than those in the other two groups (p = 0.000 and p = 0.001, respectively). Our observations indicate that ACL remnants promote the new ingrowth and persistence of neural cells. We suggest that the ingrowth of neural elements can support the persistence and new ingrowth of mechanoreceptors, thereby enhancing the functional stability of knee joints. Moreover, the expression of neural cells in the Achilles allografts was lower than that in normal ACL tissues and ACL remnants in the quantitative evaluation, thereby confirming the essential role of ACL remnants in knee joint functionalization.

中文翻译：

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保留残存的前交叉韧带重建后，使用神经生长因子对大鼠模型中神经元进行定量评估：一项组织学和免疫荧光试验研究。

使用跟腱移植物保留残余物的ACL重建后，对前交叉韧带（ACL）移植物进行的免疫荧光分析为神经元的存在提供了证据。在这项研究中，我们旨在检查神经元的表达并量化保留ACL重建后使用神经生长因子（NGF）治疗的ACL残余物和跟腱中神经细胞的存在。实验是对5对大鼠（约8周大，手术时重320克）进行的。纵向上，将成对大鼠的跟腱分开新鲜冷冻，然后用温盐水解冻，然后同种异体移植到另一只在股骨附着部位分离的大鼠的右ACL。在左膝盖上进行假手术以用作对照。术后6周，每周两次将NGF注入膝关节。假手术膝关节，同种异体跟腱，以及ACL残余物的ACL在手术后6周使用H和E以及免疫荧光染色进行检查。H和E染色在三组中均未显示神经细胞。但是，免疫荧光分析显示正常ACL组织以及ACL残余物中存在Nestin阳性神经元。此外，在8个同种异体移植组织（87.5％）中检查了神经元。定量分析显示，三组之间的核数目或面积没有差异。然而，跟腱移植物中神经细胞的数量和面积显着低于其他两组（分别为p = 0.000和p = 0.001）。我们的观察结果表明，ACL残留物促进了神经细胞的新长入和持久性。我们建议神经元的内生可以支持机械感受器的持久性和新内生，从而增强膝关节的功能稳定性。此外，在定量评估中，跟腱移植物中神经细胞的表达低于正常ACL组织和ACL残余物中的表达，从而证实了ACL残余物在膝关节功能化中的重要作用。我们建议神经元的内生可以支持机械感受器的持久性和新内生，从而增强膝关节的功能稳定性。此外，在定量评估中，跟腱移植物中神经细胞的表达低于正常ACL组织和ACL残余物中的表达，从而证实了ACL残余物在膝关节功能化中的重要作用。我们建议神经元的内生可以支持机械感受器的持久性和新内生，从而增强膝关节的功能稳定性。此外，在定量评估中，跟腱移植物中神经细胞的表达低于正常ACL组织和ACL残余物中的表达，从而证实了ACL残余物在膝关节功能化中的重要作用。