Enhancing human nucleus pulposus cells for biological treatment approaches of degenerative intervertebral disc diseases: a systematic review.

Intervertebral disc (IVD) degeneration has been described as an aberrant, cell-mediated, age- and genetics-dependent molecular degeneration process, which can be accelerated by nutritional, mechanical and toxic factors. Collective involvement of these factors can result in structural failures, which are often associated with pain. Current treatment approaches are restricted to symptomatic therapies, not addressing options of restoring structural or biological deterioration of the IVD as the underlying problem. Therapeutic potentials of IVD cell transplantation, biomaterials, inhibiting or activating bioactive factors, including gene-therapeutic approaches, have been shown in vitro or in small animal models. Since human degenerative IVD cells display distinctive features with regard to cell biology and regenerative potential, we attempted a systematic review, investigating the in vitro response of human nucleus pulposus cells to different stimuli. Therefore, we conducted an electronic database search on Medline through July 2011 to identify, compare and discuss publications concerning the effects of cell-cell stimulation, bioactive factors, biomaterials and combinations thereof in terms of cell isolation, proliferation, differentiation and matrix protein synthesis. This survey and discussion might serve as a source for designing future biological treatment strategies for the human IVD.