AAV-MEDIATED, IN VIVO GENE DELIVERY TO THE ROTATOR CUFF

Tendon injuries present a considerable clinical challenge due to the limited regenerative capacity of tendons. The use of gene transfer to deliver growth factors to sites of tendon damage has been suggested as a promising strategy for improving tendon regeneration. A major issue for this approach is to identify clinically acceptable vectors that can deliver genes to the cells of the tendon, preferably by in vivo delivery. Adeno-associated virus (AAV) has many advantages in this regard, including a favourable safety profile and the ability to sustain long-term transgene expression. Here we explored the use of AAV to deliver marker genes to the supra- and infra-spinatus tendons of the rotator cuff in the rat by injection into the subacromial space. First, we screened various AAV serotypes for their transducing ability towards rat and human tenocytes in vitro . Of the 10 serotypes tested, AAV2.5 and AAV2 exhibited the highest in vitro transduction efficiency in both rat and human tenocytes. Ex vivo transduction of cells within explants of isolated, intact tendon was also demonstrated. Injection of AAV2.5 encoding luciferase into the subacromial space confirmed gene delivery to the infra-, but not supra-, spinatus tendon in vivo with transgene expression persisting for 7 days post -transduction. These data demonstrate the ability of AAV2.5 to deliver genes to the infraspinatus tendon, leading to sustained local expression following in vivo delivery. Our findings suggest that AAV2.5 has several advantages as vector for stimulating tendon regeneration by local, in vivo , gene transfer.