Combined treatment of spinal cord injury using channeled Porous-GelMA scaffold loaded with genetically engineered MSCs expressing inducible ChABC and constitutive BDNF.

OBJECTIVE: Following spinal cord injury (SCI), glial scarring mediated by chondroitin sulfate proteoglycans (CSPGs), coupled with insufficient neurotrophic support, hinders axonal regeneration. Furthermore, the lack of physical support at the injury site during the acute phase compromises cell survival and engraftment. To overcome these challenges, we developed a three-dimensional channeled porous-GelMA scaffold (CPGS) that provides spatial guidance and structural support. This scaffold is integrated with genetically engineered MSCs designed to continuously release brain-derived neurotrophic factor (BDNF) and inducibly express Chondroitinase ABC (ChABC). This integrated system combines therapeutic factors, stem cells, and tissue engineering to improve the injured microenvironment and promote neural regeneration after SCI.

METHODS: MSCs were genetically engineered for continuous BDNF expression and doxycycline (Dox)-inducible ChABC expression. RT-qPCR and Western blotting were used to validate expression levels. We performed transcriptomic analysis and protein-level verification to assess the activation of key signaling pathways. A porous GelMA-based CPGS, featuring longitudinal guidance cues, was fabricated and characterized for its structure and mechanical properties. BDNF/ChABC-MSCs were then seeded into the CPGS to create an integrated system, which was subsequently evaluated in a rat SCI model.

RESULTS: The BDNF/ChABC-MSCs successfully expressed BDNF and Dox-inducible ChABC, leading to the activation of mTOR, Hedgehog, FAK, and MAPK signaling pathways, as demonstrated by transcriptomic profiling and confirmed at the protein level. The CPGS exhibited longitudinal guidance and favorable mechanical properties. In vivo studies showed that the BDNF/ChABC-MSCs-CPGS system significantly improved BBB scores, markedly reduced lesion size and collagen deposition, decreased CS-56 expression, and increased expression of the axonal regeneration markers, NF-H and GAP43.

CONCLUSION: The BDNF/ChABC-MSCs-CPGS integrated system enhances the SCI lesion microenvironment through structural guidance and biochemical modulation, thereby promoting axonal regeneration and functional recovery. This approach presents a novel strategy for combined tissue engineering and stem cell therapy in SCI treatment.