Introduction: Current treatments for painful intervertebral disc (IVD) degeneration provide only limited relief, highlighting the need for new therapies. We have shown that preconditioned nasal chondrocyte-derived spheroids (NCS) survive and integrate into degenerated IVD in ex vivo and in vivo models, showing promise as a cell therapy. To ensure NCS consistency and safety for human use, good manufacturing practice (GMP)-compliant processes and defined quality control (QC) measures must be established to meet clinical standards.
Methods: Human and sheep nasal chondrocytes (NC) were isolated and NCS were fabricated using GMP-compliant materials. Intermediate products (IP) were characterized for inter- and intra-donor variably in size, shape, elastic modulus (MicroTester G2), viability (CellTiter-Glo, Trypan Blue), and key bioactive factors used during NCS fabrication (TGF-b3, IL-1Ra). The final product (FP) included 100 NCS from a single donor in saline. Stability of FP was assessed in terms of size, shape, viability (individual NCS), presence of bioactive factors (storage medium), and injectability. N ³ 5 donors and replicates were used per experiment.
Results: Research-use-only (RUO) materials were successfully replaced with human use (HU) suitable alternatives. TGF-b3 was confirmed as necessary for NCS fabrication, with a washing step efectively removing its residues. Following characterization, product specifications ensuring injectability and funcion of individual NCS were defined as (i) diameter <600µm, (ii) roundness >0.8, (iii) elastic modulus >5 kPa, (iv) cell viability >90%, (v) undetectable TGF-b3, (vi) IL-1Ra >1ng/NCS. Variability in these attributes was not significant. The FP remained stable for at least 24h at 4°C under mild agitation. Consistent results were obtained for human and sheep NCS. Human NC identity was previously confirmed (PMID: 27789021).
Conclusion: We have achieved good reproducibility and consistency in the manufacturing process. Product specifications were defined based on the obtained limits/ranges of critical QC attributes and will be used to establish in-process controls (IPC) and acceptance criteria (AC) for product release to patients. Validation of NCS GMP processes is ongoing in a sheep trial, and the relationship between the intended mode of action and efficacy is under investigation.