Transplantation of allogenic nucleus pulposus cells attenuates intervertebral disc degeneration by inhibiting apoptosis and increasing migration

Transplantation of nucleus pulposus cells (NPCs) into the intervertebral disc (IVD) has been demonstrated to be an effective treatment of degenerative disc disease (DDD). However, the underlying mechanisms have remained to be sufficiently elucidated. The aim of the present study was to explore the potential cell migration and anti-apoptosis efficacy of NPCs in the treatment of DDD. NPCs cultured from rats expressing green fluorescent protein (GFP-NPCs) were transplanted into the degenerated IVD, and the migration of GFP-NPCs, as well as the degeneration and apoptosis of the IVD were detected to evaluate the therapeutic effect in vivo. In vitro, disc chondrocytes (DCs) and annulus fibrosus cells (AFCs) were co-cultured to explore the underlying mechanism. The results demonstrated that injection of NPCs suppressed DDD by inhibiting apoptosis and increasing extracellular matrix in vivo and in vitro. NPCs migrated into the inner AF in vivo, and NPC migration was observed to be promoted by AFCs and DCs in vitro, particularly by damaged AFCs. These results demonstrated the anti-apoptotic effects and migratory capacity of allogenic NPCs transplanted into the IVD, which evidences the contribution of NPCs to disc regeneration and provide a novel strategy for treating DDD.