Stem Cell Applications, Tendon and Ligament

Current Treatment Methods

Current therapeutic regimes used to treat ligament/ tendon injury include suturing, grafting, the application of growth factors, and gene transfer/gene therapy. Suturing is necessary for some ligament/ tendon healing because it holds the ruptured ends in close proximity. But the invasive nature of this technique is undesirable, often resulting in more missed work days than a noninvasive, conservative approach. Furthermore, biomechanical outcome is not always improved with suturing (e.g., medial collateral ligaments). Grafting, which is typically used when sutures alone are not a surgical option, removes any irreparable tissue and replaces it with an autograft or allograft. This process is commonly used with torn anterior cruciate ligaments (ACLs), since ligaments inside a synovial capsule heal poorly, if at all. ACL reconstruction techniques with auto—grafts have drawbacks that include additional procedures for tissue harvest and donor site morbidity. Allografts run an increased risk of transmitting diseases, bacterial infections, or immunologically rejecting the transplanted tissue. A different treatment option for ligaments and tendons that will heal entails the use of exogenous growth factors to reduce healing time by augmenting cell migration and proliferation or modulating extracellular matrix components in the injured region. However, full healing capacity or tissue regeneration remains unattainable. Finally, gene therapy relies on viral or nonviral vectors as delivery agents for incorporating foreign DNA into cells to alter protein synthesis or induce expression of therapeutic proteins by the cells. However, healing is a complicated spatial and temporal process that likely cannot be mimicked by one gene during chronic healing. Proper gene delivery of the foreign DNA and the use of viral vectors which pose additional potential health risks, such as mutagenesis, abnormal cell growth, toxicity from overexpression of growth factors, and development of malignancies, likewise create further complications with this procedure. These techniques provide a transient solution to healing, but the long—term success rate is typically lacking. Because of the above limitations to current therapeutic approaches, the use of stem cells has come to the forefront of research.

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