A mini review on the basic knowledge on tendon: revisiting the normal & injured tendon

Tendon is a dense connective tissue that connects muscle to bone. Tendon can adapt to mechanical forces passing across it, through a reciprocal relationship between its cellular components (tenocytes and tenoblasts) and the extracellular matrix (ECM). In early development, the formation of scleraxis-expressing tendon progenitor population in the sclerotome is induced by a fibroblast growth factor signal secreted by the myotome. Tendon injury has been defined as a loss of cells or ECM caused by trauma. It represents a failure of cells and matrix adaptation to mechanical loading. Injury initiates attempts of tendon to repair itself, which has been defined as replacement of damaged or lost cells and ECM by new cells or new matrices. Tendon healing generally consists of four different phases: the inflammatory, proliferation, differentiation and remodelling phases. Clinically, tendons are repaired with a variety of surgical techniques, which show various degrees of success. In order to improve the conventional tendon repair methods, current tendon tissue engineering aims to investigate a repair method which can restore tissue defects with living cells, or cell based therapy. Advances in tissue engineering techniques would potentially yield to a cell-based product that could regenerate functional tendon tissue