Clinical trials of intervertebral disc regeneration: current status and future developments.

Intervertebral disc (IVD) degeneration (IDD) is considered as one of the major causes for low back pain (LBP). However, conventional surgical approaches for treating LBP do not aim to counter the degeneration. Biological interventions have been investigated with an attempt to regenerate the IVD by restoring its matrices and cell activities. This review summarizes the current clinical trials that explore the efficacy of covering cell-, growth factor-, and small molecule-based approaches. While investigations of growth factor- and small molecule-based therapies are still preliminary, intradiscal delivery of mesenchymal stromal cells has been more widely adopted and shown positive results in addressing the pain and the associated physical disability, albeit to a lower extent than observed in previous animal studies. Strategies that potentiate the endogenous disc progenitors may offer a valid alternative to the exogenous cell transplantation. Identification of the novel biologics to arrest IDD phenotype may potentiate disc repair in future. Large-scale, high-quality long-term trials should be conducted to clarify the safety and efficacy of these therapies.