Degenerative disc disease is a major problem, causing billions of dollars in lost work and medication. Patents such as # 6,723,335 cover the use of stem cell injection into the nucleus pulposus of the disc in order to stimulate regeneration. In a recent paper (Yang et al. Mesenchymal Stem Cells Arrest Intervertebral Disc Degeneration Through Chondrocytic Differentiation and Stimulation of Endogenous Cells. Mol Ther 2009 Jul 7) the use of bone marrow stem cell injection into degenerating discs was assessed.
The stem cells used were bone marrow derived mesenchymal stem cells that were autologous to the recipient. Disc degeneration was induced by making a holein the annulus.
After treatment with GFP-mesenchymal stem cells, regeneration of the pulposus was observed based on increased disc space, upregulation of genes encoding for proteoglycans as well as other extracellular matrix components. It was demonstrated that the mesenchymal stem cells differentiated into chondrocyte-like cells, but perhaps more interestingly, the progenitor cells of the nucleus pulposus, called notochordal cells, entered cell cycle and generated extracellualar matrix, thus contributing to the repair process.
These data are interesting because the support what we at StemCellPatents.com are seeing as a recurrent theme, which is that stem cells do not necessarily have to differentiate into new tissue to mediate therapeutic effects, but can do this in many cases simply by producting growth factors that activate resident stem cells. This appears to be the case in critical limb ischemia, where administration of bone marrow stem cells seems to work better in patients that respond to the intramuscular injection by mobilization of bone marrow resident cells.