The tendon is a connective tissue between muscle and bone that is relatively acellular and avascular consisting of a hierarchical arrangement of collagen fibre bundles. Tenocytes are the primary cell type within tendon, and they are responsible for the overall maintenance of tendon. Tendons have the role to transmit forces from muscle to bone and protect the surrounding tissues by working as buffers against tension and compression. Tendon injuries are very frequent and affect a wide and heterogeneous population. Over 30 million musculoskeletal injuries occur annually worldwide and nearly half of them involve tendon and ligament injuries. With the increase in life expectancy, it is predicted that tendon injuries will continue to rise, placing an enormous financial strain on healthcare systems.
Firstline therapeutic options differ for chronic and acute tendon injuries. The primary goal of tendinopathy treatment is to reduce pain, mainly through the use of topical or systemic antiinflammatory drugs, whereas surgical techniques aim to repair ruptured tendons. The outcomes of reconstructive surgery differ depending on the type and location of the injury. As tendon healing is slow and leads to fibrotic scarring and adhesions, the natural repair process is not sufficient to functionally repair the injured tissue. Due to this poor healing capacity of native tendons, tissue regeneration after injury remains a formidable challenge. Obviously, better alternative treatment modalities need to be developed.
Cell therapies emerge as interesting alternatives to classical treatments. Currently, commonly utilized seed cells in tendon tissue engineering include tenocytes, fibroblasts and mesenchymal stem cells. Because tendon progenitor/stem cells have to be isolated directly from tendon tissues, there is inevitable donor site morbidity, and hence it is not practical to utilize autologous approach for tendon repair, unless there is a reliable immuno-friendly allogenic source of tenocytes made available to patients. Mesenchymal stem cells are difficult to control their differentiation into specific tissue lineages. Therefore, it will be audacious yet encouraging good attempt to develop an off-the-shelf cell products capable of stimulating tendon regeneration for the treatment of tendon injuries. CBI scientists are working their way to establish GMP quality of tenocyte cell banks and to design reliable, convenient and affordable therapeutic strategies for future tendon repair.