Juvenile Chondrocytes May Facilitate Disc Repair

Cell transplantation for disc regeneration is a theoretically-attractive alternative to more invasive surgical procedures to treat discogenic pain. Several cell types have been tried in pre-clinical models for this indication, each with relative merits and limitations. Recently, human chondrocytes from prepubertal donors have been shown to be more synthetically active than their adult counterparts and can form scaffold-independent neocartilage in vitro. These features may also be beneficial in the intervertebral discs' challenging environment including high physical pressure and acidity, and low oxygen tension. To test this, we characterized the in vivo disc regeneration potential of juvenile chondrocytes in caudal rat discs. Human juvenile chondrocytes (JCs) were injected into fifteen rats. Fibrin glue without cells served as a control. Tails were imaged with MRI prior to sacrifice and tail discs were processed for histology. MRI data demonstrates that discs injected with fibrin glue alone degenerated over 12 weeks. By contrast, discs injected with JCs maintained their morphology and MRI signal, and displayed a significantly improved MRI index at 12 weeks post-injection. Transplantation of juvenile chondrocytes results in a significant positive outcome compared to that of fibrin glue alone and may provide an ideal allograft for future human studies.