Multipotential differentiation of human anulus fibrosus cells: an in vitro study.

Background: The existence of fibrocartilage, bone-like tissues, nerves, and blood vessels in the anulus fibrosus during intervertebral disc degeneration has been well documented. Migration of differentiated cells from outside the intervertebral disc has been hypothesized as a possible mechanism for the formation of these tissues. We hypothesized that the normal anulus fibrosus tissue contains multipotent progenitor cells, which are able to differentiate into cartilage and/or fibrocartilage cells, osteoblasts, neurons, and blood vessel cells.