Tendon tissue is one of many tissue types in mammals that is reluctant to heal completely following injury. Better methods of regeneration are desired, here as elsewhere in the body, and stem cell therapies show a great deal of promise in this regard. The most reliable of current stem cell therapy approaches, those with the greatest expectation of benefits to result for the patient, appear to work largely through a reduction in chronic inflammation. It is interesting to see that hold up in the case of tendons and their supporting stem cell populations.
New research suggests that tendon stem cells (TSCs) may be able to significantly improve tendon healing by regulating inflammation, which contributes to scar-like tendon healing and chronic matrix degradation. This has implications for the treatment of acute tendon injuries and chronic tendon disease. "Inflammation plays a critical role in acute and chronic tendon injuries and healing. Our findings represent an important foundation for the development of a new treatment that would regulate overwhelmed inflammation for tendon ruptures and tears, tendonitis, tendinopathy, and other tendon injuries and diseases."
In their study, the researchers used both in vitro human models and in vivo rat models. In vitro, isolated TSCs were stimulated with proinflammatory cytokines (proteins that can influence interactions between cells), and the expression of genes involved in inflammatory regulation was measured. In vivo, the researchers evaluated inflammatory responses by TSCs, including infiltration of macrophages (white blood cells that consume damaged or dead cells) and expression of anti-/proinflammatory cytokines, at different time points. Connective tissue growth factor (CTGF) was used in both models to stimulate the anti-inflammatory roles of TSCs. The researchers found that CTGF stimulation induced TSCs' production of anti-inflammatory cytokines, consequently leading to improved tendon healing and matrix remodeling. "Many would have predicted that tendon healing is inflammation-linked, but that the anti-inflammatory roles of TSCs could be so potent, and so amplifiable, is a striking finding."