NanoCRISPR-assisted biomimetic tissue-equivalent patch regenerates the intervertebral disc by inhibiting endothelial-to-mesenchymal transition.

The integrity of the intervertebral disc (IVD), an immune-privileged organ protected by the blood-disc barrier, is compromised following annulus fibrosus (AF) injury. This breach facilitates angiogenesis, immune cell infiltration, and inflammation, accelerating intervertebral disc degeneration (IDD) and resulting in various clinical disorders. Current treatments fail to adequately address biological repair of AF defects and angiogenesis. Single-cell RNA sequencing analyses reveal that vascular endothelial growth factor (VEGF), secreted by IDD-associated fibrochondrocytes, is crucial in promoting angiogenesis by inducing endothelial-to-mesenchymal transition (EndoMT). This study proposes a nano-clustered regularly interspaced short palindromic repeats (CRISPR)-assisted AF patch with an aligned, polydopamine-modified nano-lamellae nanofibrous scaffold that replicates the hierarchical structure of natural AF, providing a conducive microenvironment for AF repair. A zeolitic imidazolate framework-8-based nanoCRISPR system encapsulates the CRISPR/CRISPR-associated protein 9 complex to target and eliminate VEGF-mediated angiogenic factors. In vitro studies demonstrate that the nanoCRISPR-assisted patch can enhance AF cell adhesion and migration, promote extracellular matrix deposition, knock out VEGF expression, and inhibit EndoMT. In vivo studies show its significant efficacy in promoting AF repair, inhibiting abnormal angiogenesis, and delaying IDD progression. This study presents a promising approach for structural and biological AF regeneration, addressing physical and angiogenic barriers in IVD regeneration.