Abstract
Background
Intervertebral disc (IVD) degeneration is a major cause of Low back pain (LBP). We have reported an injectable hydrogel (NPgel), which following injection into bovine NP explants, integrates with NP tissue and promotes NP cell differentiation of delivered mesenchymal stem cells (MSCs) without growth factors. Here we investigated the injection of NPgel+MSCs into bovine NP explants under degenerate culture conditions to mimic the in vivo environment of the degenerate IVD.
Methods
hMSCs were incorporated within liquid NPgel and injected into bovine NP explants alongside controls. Explants were cultured for 6 weeks under hypoxia (5%) with ± calcium 5.0mM CaCl2 or IL-1β individually or in combination to mimic the degenerate microenvironment. Cell viability was assessed by caspase 3 immunohistochemistry. Histological and immunohistochemical analysis was performed to investigate altered matrix synthesis and matrix degrading enzyme expression.
Results
CFSe positive hMSCs were identified in all NPgel injected explants and cell viability was maintained. The NPgel integrated with NP tissue and hMSCs produced matrix components: aggrecan, collagen type II and chondroitin sulphate in standard and degenerate culture conditions. Increased cellular immunopositivty for aggrecan and collagen type II as well as decreased cellular immunopositivity for degrading enzyme expression was observed within NP tissue removed from the injection site.
Conclusion
MSCs incorporated within NPgel could be used to regenerate the NP and restore the healthy NP phenotype of degenerate NP cells as a treatment strategy for LBP. We are currently investigating the survival and differentiation capacity of hMSCs delivered via the NPgel into degenerate human NP explants and thus ascertain the future clinical success of this therapy.
Conflicts of Interest: None
Funding: BMRC, MERI Sheffield Hallam University.
