An injectable anti-vascularization functionalized hydrogel for degenerative nucleus pulposus repair

Neovascularization and inflammatory cell invasion within the nucleus pulposus (NP) constitute pivotal pathological changes during the acceleration stage of intervertebral disc degeneration (IDD). Mesenchymal stem cells (MSCs), renowned for their remarkable capacity in intervertebral disc (IVD) regeneration, also exhibit the capability to secrete pro-angiogenic factors, expediting IDD progression under hypoxic conditions. Consequently, we developed a hydrogel comprised of methacrylated hyaluronic acid (HAMA), rat tail collagen I (COL), and MSCs, incorporating the vascular endothelial growth factor receptor (VEGFR) inhibitor cabozantinib (Cabo@HAMA-COL/MSCs hydrogel). This innovative construct aimed to facilitate NP regeneration while mitigating vascularization and inflammation. Our findings revealed that the hydrogel aptly mimicked the mechanical characteristics of NP tissue, exhibiting injectability, low cytotoxicity, and the preservation of the cellular phenotype of NP cells. Co-culturing of MSCs and human umbilical vein endothelial cells (HUVECs) promoted migration, tube formation, and sprouting of HUVECs, which will be inhibited by cabozantinib. In vivo experiments demonstrated that Cabo@HAMA-COL/MSCs hydrogel maintained disc height, protected NP, and alleviated vascularization and inflammation in a puncture-induced rat caudal IDD model. Consequently, our results substantiate that Cabo@HAMA-COL/MSCs hydrogel can prevent IDD degeneration by ameliorating the vascularization-inflammation pathological microenvironment, offering a promising therapeutic strategy for IDD.