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Abstract Background Fibrotic scar formation and inflammation are characteristic pathologies of spinal cord injury (SCI) in the injured core, which has been widely regarded as the main barrier to axonal regeneration resulting in permanent functional recovery failure. Pericytes were shown to be the main source of fibroblasts that form fibrotic scar. However, the mechanism of pericyte-fibroblast transition after SCI remains elusive. Methods Fibrotic scarring and microvessels were assessed using immunofluorescence staining after establishing a crush SCI model. To study the process of pericyte-fibroblast transition, we analyzed pericyte marker and fibroblast marker expression using immunofluorescence. The distribution and cellular origin of platelet-derived growth factor (PDGF)-BB were examined with immunofluorescence. Pericyte-fibroblast transition was detected with immunohistochemistry and Western blot assays after PDGF-BB knockdown and blocking PDGF-BB/PDGFRβ signaling in vitro. Intrathecal injection of imatinib was used to selectively inhibit PDGF-BB/PDGFRβ signaling. The Basso mouse scale score and footprint analysis were performed to assess functional recovery. Subsequently, axonal regeneration, fibrotic scarring, fibroblast population, proliferation and apoptosis of PDGFRβ+ cells, microvessel leakage, and the inflammatory response were assessed with immunofluorescence. Results PDGFRβ+ pericytes detached from the blood vessel wall and transitioned into fibroblasts to form fibrotic scar after SCI. PDGF-BB was mainly distributed in the periphery of the injured core, and microvascular endothelial cells were one of the sources of PDGF-BB in the acute phase. Microvascular endothelial cells induced pericyte-fibroblast transition through the PDGF-BB/PDGFRβ signaling pathway in vitro. Pharmacologically blocking the PDGF-BB/PDGFRβ pathway promoted motor function recovery and axonal regeneration and inhibited fibrotic scar formation. After fibrotic scar formation, blocking the PDGFRβ receptor inhibited proliferation and promoted apoptosis of PDGFRβ+ cells. Imatinib did not alter pericyte coverage on microvessels, while microvessel leakage and inflammation were significantly decreased after imatinib treatment. Conclusions We reveal that the crosstalk between microvascular endothelial cells and pericytes promotes pericyte-fibroblast transition through the PDGF-BB/PDGFRβ signaling pathway. Our finding suggests that blocking the PDGF-BB/PDGFRβ signaling pathway with imatinib contributes to functional recovery, fibrotic scarring, and inflammatory attenuation after SCI and provides a potential target for the treatment of SCI.

IntroductionUnilateral biportal endoscopic (UBE) technique can easily decompress the bony spinal canal and accommodate all open surgical instruments under endoscopic guidance. However, indications and reports of this technique have been limited to degenerative and infectious diseases.MethodsWe used the UBE technique for the decompression and removal of extradural mass lesions in five patients. Under endoscopic guidance, a unilateral approach was used, and decompression and flavectomy were performed. After decompression, removal of the tumor was performed using various forceps. We evaluated the technical process of the procedure, the patient's pre- and postoperative symptoms, and operative radiology and pathologic results.ResultsPostoperative pain and disability improved clinically for all patients. Four patients were confirmed as having an epidural cyst and one patient was diagnosed with hemangioma. During follow-up, no recurrence was observed.ConclusionsWe successfully removed five extradural mass lesions using a biportal endoscopic posterior approach without complications. The biportal endoscopic approach may have advantages, such as minimizing trauma to the normal structures, magnified endoscopic view, and early recovery after the surgery. Biportal endoscopy may be used as an alternative surgical treatment for symptomatic intraspinal extradural benign lesions.

ObjectiveTo assess the learning curve of the unilateral biportal endoscopic (UBE) technique for the treatment of single-level lumbar disc herniation by cumulative summation (CUSUM) method analysis.MethodsA retrospective analysis was conducted to assess 97 patients' general condition, operation time, complications, and curative effect of single segmental UBE surgery performed by a spinal surgeon in his early stage of this technique. The learning curve of operation time was studied using a CUSUM method, and the cut-off point of the learning curve was obtained.ResultsThe operation time was 30 – 241(97.9 ± 34.7) min. The visual analog scale score of lower limb pain decreased from 5.75 ± 0.81 before the operation to 0.39 ± 0.28 at the last follow-up (P < 0.05). The Oswestry disability index score decreased from 66.48 ± 4.43 before the operation to 14.57 ± 3.99 at the last follow-up (P < 0.05). The CUSUM assessment of operation time revealed the learning curve was the highest in 24 cases. In the learning stage (1–24 cases), the operation time was 120.3 ± 43.8 min. In the skilled stage (25–97 cases), the operation time was 90.5 ± 27.8 min.ConclusionsAbout 24 cases of single segmental UBE operation are needed to master the UBE technique.