Development of Novel Micro-dystrophins with Enhanced Functionality.

ABSTRACT: Gene therapies using adeno-associated viral (AAV) vectors have advanced into clinical trials for several diseases, including Duchenne muscular dystrophy (DMD). A limitation of AAV is the carrying capacity (?5 kb) available for genes and regulatory cassettes (RCs). These size constraints are problematic for the 2.2-Mb dystrophin gene. We previously designed a variety of miniaturized micro-dystrophins (?Dys) that displayed significant, albeit incomplete, function in striated muscles. To develop ?Dys proteins with improved performance, we explored structural modifications of the dystrophin central rod domain. Eight ?Dys variants were studied that carried unique combinations of between four and six of the 24 spectrin-like repeats present in the full-length protein, as well as various hinge domains. Expression of ?Dys was regulated by a strong but compact muscle-restricted RC (CK8e) or by the ubiquitously active cytomegalovirus (CMV) RC. Vectors were evaluated by intramuscular injection and systemic delivery to dystrophic mdx4cv mice, followed by analysis of skeletal muscle pathophysiology. Two ?Dys designs were identified that led to increased force generation compared with previous ?Dys while also localizing neuronal nitric oxide synthase to the sarcolemma. An AAV vector expressing the smaller of these (?Dys5) from the CK8e RC is currently being evaluated in a DMD clinical trial.

SUBMITTER: Ramos JN 

PROVIDER: S-EPMC6403485 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature