Tendon injuries can occur due to sports related incidents, as a result of trauma to overuse or during disease or ageing. Tissue engineering can offer great potential in the treatment of a tendon injury. The preferred cell source is autologous in order to reduce immune response in the treated individual. However, in elderly patients age-related changes in metabolism of the implanted cells may affect results of such therapy. In this study the effect of donor age on synthetic activity of cells used for creation of tendon tissue-engineered constructs was investigated by using label-free proteomic comparison.