A Quality by Design (QbD) Project of Human Dermal Fibroblast and its Therapeutic Effects on Managing Degenerative Intervertebral Disc Fibrosis in Rabbit and Cynomolgus Monkey.

Background: Low back pain (LBP) is the leading cause of disability among the elderly, placing significant social and economic burdens on societies globally. A common cause of chronic LBP is lumbar disc degeneration. Previously, we reported that autologous or allogenic fibroblast injections could treat intervertebral disc degeneration (IVDD) in preclinical studies by maintaining disc height and stability through fibrosis. However, the pathway to successful drug development remains unclear.

Methods: To develop a novel human allogenic fibroblast injection, we launched a quality-by-design (QbD) project focusing on human dermal fibroblasts (HDFs).

Results: We developed a tissue separation process, HDF culture process, and HDF cryopreservation process. The tissue disinfection method used 5% povidone-iodine solution and 75% alcohol for 3-5 min each; the tissue digestion conditions used neutral protease AF followed by overnight soaking plus collagenase NB6 digestion for 2-3 h; the non-animal component medium contained high glucose dulbecco's modified eagle medium (DMEM) + 7.5% human platelet lysate (hPL); A cell density of 14,000-18,000 cells/cm² was used; the cell cryopreservation solution contained 75% CS10 + 10% human serum albumin (HSA) + 15% saline (NaCl). Finally, we explored its therapeutic effects by treating IVDD in rabbits.

Conclusions: The model of lumbar disc degeneration in rabbits was induced by acupuncture, and HDF was injected into the intervertebral disc. The therapeutic effect of HDF was observed by imaging and histopathology at 1, 3, and 6 months after administration. HDF treatment significantly improved the water content of degenerative intervertebral discs and maintained the height and stability of intervertebral discs. Signal pathway analysis in cynomolgus monkeys suggested that the primary mechanism involves promoting disc fibrosis. Therefore, this study demonstrated the feasibility and cost-effectiveness of manufacturing FibroCell^TM, a foreskin-derived human dermal fibroblast injection. FibroCell^TM shows promise as a cell-based therapy for IVDD treatment.