Introduction: Painful intervertebral disc disease (IDD) is a prevalent condition associated with catabolic degenerative changes in the intervertebral disc (IVD). Current treatments provide limited relief, underscoring the need for innovative therapies capable of functioning in the harsh IVD microenvironment. Nasal chondrocytes (NC) have shown promise in adapting to degenerated heterotopic transplantation sites, where they form cartilaginous matrix. This study explores the use of NC-derived 3D spheroids (NCS) for cell-based repair of degenerated IVDs.
Methods: NCS were generated from human or sheep NC and metabolically preconditioned (at reduced glucose and oxygen levels) in medium containing interleukin-1 receptor antagonist (IL-1Ra), to enhance their resilience in target microenvironment low in oxygen and nutrients. Proteomic analysis of preconditioned NCS (pNCS) responses to IDD-mimicking conditions was conducted. pNCS were then injected into: (i) native human or bovine degenerated IVDs ex vivo and (ii) a sheep model of Chondroitinase ABC (ChABC)-induced IDD in vivo. Post-injection pNCS integration and chondroprotective effects in native IVD were assessed.
Results: Compared to non-pNCS, pNCS underwent chromatin changes, increased glycolytic activity, and reduced proliferation, while maintaining the expression of chondroprotective proteins (Aggrecan, Collagen type II, SOX-9). Sustained release of IL-1Ra from pNCS prevented the production of inflammatory mediators in IDD microenvironment. In ex vivo degenerated IVD cultures, pNCS survived, and NC spread into the surrounding NP tissue within 7 days of injection. In a pilot sheep study (n = 2), ChABC caused moderate IDD by 8 weeks, at which point pNCS were injected. Following injection, pNCS/NC localized in the IVD, spread, and survived for at least 2 months.
Conclusion: Following pre-conditioning, NCS were able to adapt to the IDD microenvironment and remained protected from pro-inflammatory insults. NCS survived and integrated into native degenerated IVD tissue in both ex vivo and in vivo models. A larger in vivo study (n = 9 sheep/18 IVDs) is ongoing to further evaluate the safety and efficacy of this approach.