Objective To investigate the effects of removing microglia from spinal cord on nerve repair and functional recovery after spinal cord injury (SCI) in mice. MethodsThirty-nine 6-week-old female C57BL/6 mice were randomly divided into control group (n=12), SCI group (n=12), and PLX3397+SCI group (n=15). The PLX3397+SCI group received continuous feeding of PLX3397, a colony-stimulating factor 1 receptor inhibitor, while the other two groups were fed a standard diet. After 14 days, both the SCI group and the PLX3397+SCI group were tested for ionized calcium binding adapter molecule 1 (Iba1) to confirm that the PLX3397+SCI group had completely depleted the spinal cord microglia. The SCI model was then prepared by clamping the spinal cord in both the SCI group and the PLX3397+SCI group, while the control group underwent laminectomy. Preoperatively and at 1, 3, 7, 14, 21, and 28 days postoperatively, the Basso Mouse Scale (BMS) was used to assess the hind limb function of mice in each group. At 28 days, a footprint test was conducted to observe the gait of the mice. After SCI, spinal cord tissue from the injury site was taken, and Iba1 immunofluorescence staining was performed at 7 days to observe the aggregation and proliferation of microglia in the spinal cord. HE staining was used to observe the formation of glial scars at the injury site at 28 days; glial fibrillary acidic protein (GFAP) immunofluorescence staining was applied to astrocytes to assess the extent of the injured area; neuronal nuclei antigen (NeuN) immunofluorescence staining was used to evaluate neuronal survival. And 5-hydroxytryptamine (5-HT) immunofluorescence staining was performed to assess axonal survival at 60 days. Results All mice survived until the end of the experiment. Immunofluorescence staining revealed that the microglia in the spinal cord of the PLX3397+SCI group decreased by more than 95% compared to the control group after 14 days of continuous feeding with PLX3397 (P<0.05). Compared to the control group, the BMS scores in the PLX3397+SCI group and the SCI group significantly decreased at different time points after SCI (P<0.05). Moreover, the PLX3397+SCI group showed a further decrease in BMS scores compared to the SCI group, and exhibited a dragging gait. The differences between the two groups were significant at 14, 21, and 28 days (P<0.05). HE staining at 28 days revealed that the SCI group had formed a well-defined and dense gliotic scar, while the PLX3397+SCI group also developed a gliotic scar, but with a more blurred and loose boundary. Immunofluorescence staining revealed that the number of microglia near the injury center at 7 days increased in the SCI group than in the control group, but the difference between groups was not significant (P>0.05). In contrast, the PLX3397+SCI group showed a significant reduction in microglia compared to both the control and SCI groups (P<0.05). At 28 days after SCI, the area of spinal cord injury in the PLX3397+SCI group was significantly larger than that in SCI group (P<0.05); the surviving neurons significantly reduced compared with the control group and SCI group (P<0.05). The axonal necrosis and retraction at 60 days after SCI were more obvious. ConclusionThe removal of microglia in the spinal cord aggravate the tissue damage after SCI and affecte the recovery of motor function in mice, suggesting that microglia played a neuroprotective role in SCI.
Objective To evaluate the influencing factors that affect early pain after arthroscopic rotator cuff repair. MethodsA clinical data of 592 patients who met the selection criteria and underwent arthroscopic rotator cuff repair between June 2018 and October 2020 were retrospectively analyzed. There were 239 males and 353 females, with an average age of 58.1 years (range, 32-81 years). Before operation and at 3 days, 6 weeks, and 3 months after operation, the pain degree of patients was evaluated by visual analogue scale (VAS) score; and the patients were divided into no pain or mild pain group and moderate to severe pain group according to the postoperative VAS score. Preoperative and intraoperative related factors were included for univariate analysis, including age, gender, body mass index, preoperative VAS score, history of frozen shoulder, history of hypertension, history of diabetes, history of smoking, affected tendons (supraspinatus, infraspinatus, or subscapularis tendon injury), supraspinatus muscle atrophy, fatty infiltration, operation time, degree of rotator cuff tear, number of anchors, and whether to perform acromioplasty. The influencing factors of postoperative pain were screened; further logistic regression was used to conduct multivariate analysis to screen for risk factors. Results Moderate to severe pain occurred in 440 patients (74.3%) at 3 days after operation, 382 patients (66.2%) at 6 weeks, and 141 patients (23.8%) at 3 months. Multivariate analysis showed that the women, partial-thickness rotator cuff tear, and acromioplasty were risk factors for pain at 3 days after operation (P<0.05); the women, combined with fatty infiltration, partial-thickness rotator cuff tear, and acromioplasty were the risk factors at 6 weeks (P<0.05); and the women, combined with fatty infiltration, and partial-thickness rotator cuff tear were risk factors at 3 months (P<0.05). Conclusion Among patients undergoing arthroscopic rotator cuff repair, women, those with smaller rotator cuff tears, combined with fatty infiltration, and acromioplasty have more severe pain within 3 months after operation, and attention should be paid to postoperative analgesia in these patients management, providing an individualized approach to rehabilitation, and closer follow-up.