Although not known for certain, there are separate therapeutic effects from stem cell treatment: 1) Stem cells themselves differentiate into cartilage cells; 2) they exert a paracrine effect on neighboring cells; and 3) they modulate the immune response.

1. After stem cells are injected, they become native tissue through a process of differentiation.  In discs and joints they become cartilage.  Normal cartilage produces collagen and proteoglycans.  These are structural components of both disc and joint.

2. The paracrine effect is a chemical signal made by cells in the body to exert a local effect on other neighboring cells. Stem cells produce this signal which has a positive effect on the native cells. (The native cells are those already present in the degenerative disc or joint). This results in improved function of these native cells which stimulates them to produce new collagen and proteoglycans.

3. The third mechanism is thought to be an anti-inflammatory one. Immune mediators such as tumor necrosis factor and other cytokines, which are pro-inflammatory, are thought to be suppressed.

References:

Stem Cell Basics. In “Stem Cell Information” [stemcells.nih.gov]. Bethesda, MD: National Institutes of Health, U.S. Department of Health and Human Services, 2015 [cited December 13, 2015]

“About stem cells” [www.eurostemcell.org] Edinburgh, Scotland: EuroStemCell, 2015 [cited December 13, 2015]