New perspectives in rotator cuff tendon regeneration: review of tissue engineered therapies.

Tissue engineering may play a major role in the treatment of rotator cuff tendon lesions through replacement of an injured tendon segment. Tendons have very poor spontaneous regenerative capabilities, and despite intensive remodelling, complete regeneration is never achieved and the strength of tendon and ligaments remains as much as 30% lower than normal even months or years following an acute injury. Tendons seem to be the least complex of the connective tissues with respect to their composition and architecture and this leads to the expectation that they would be more amenable to tissue engineered approaches than other tissues. An accurate literature revision was done in order to know the state of the art of tissue engineering therapies in the field of rotator cuff regeneration. The following techniques of tissue engineering were considered: local injection of stem cells or growth factors, gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons to be further transplanted in the lesion site. So far, few experimental or clinical studies have been done on tendon tissue engineering compared to the extensive work on other tissues of orthopaedic interest, such as bone and cartilage. The existing studies are related to the following tissue engineering methodologies: gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons. In our opinion the previously described literature revision showed the necessity for future studies in this area also because of recent advances in biological and bioactive scaffolds.