Comparative in vivo characterization of newly discovered myotropic adeno-associated vectors.

BACKGROUND: Adeno-associated virus (AAV)-based gene therapy is a promising strategy to treat muscle diseases. However, this strategy is currently confronted with challenges, including a lack of transduction efficiency across the entire muscular system and toxicity resulting from off-target tissue effects. Recently, novel myotropic AAVs named MyoAAVs and AAVMYOs have been discovered using a directed evolution approach, all separately demonstrating enhanced muscle transduction efficiency and liver de-targeting effects. However, these newly discovered AAV variants have not yet been compared. METHODS: In this study, we performed a comparative analysis of these various AAV9-derived vectors under the same experimental conditions following different injection time points in two distinct mouse strains. RESULTS: We highlight differences in transduction efficiency between AAV9, AAVMYO, MyoAAV2A and MyoAAV4A that depend on age at injection, doses and mouse genetic background. In addition, specific AAV serotypes appeared more potent to transduce skeletal muscles including diaphragm and/or to de-target heart or liver. CONCLUSIONS: Our study provides guidance for researchers aiming to establish proof-of-concept approaches for preventive or curative perspectives in mouse models, to ultimately lead to future clinical trials for muscle disorders.

Synthesis and enzyme-specific activation of carbohydrate-geldanamycin conjugates with potent anticancer activity.

Geldanamycin (GA) is a potent anticancer antibiotic that inhibits Hsp90. Its potential clinical utility is hampered by its severe toxicity. To alleviate this problem, we synthesized a series of carbohydrate-geldanamycin conjugates for enzyme-specific activation to increase tumor selectivity. The conjugation was carried out at the C-17-position of GA. Their anticancer activity was tested in a number of cancer cell lines. The enzyme-specific activation of these conjugates was evaluated with beta-galactosidase and beta-glucosidase. Evidently, glycosylation of C-17-position converted GA to an inactive prodrug before enzyme cleavage. Glucose-GA, as positive control, showed anticancer activity with IC(50) of 70.2-380.9 nM in various cancer cells by beta-glucosidase activation inside of the tumor cells, which was confirmed by 3-fold inhibition using beta-glucosidase specific inhibitor [2,5-dihydroxymethy-3,4-dihydroxypyrrolidine (DMDP)]. Compared to glucose-GA, galactose- and lactose-GA conjugates exhibited much less activity with IC(50) greater than 8000-25 000 nM. However, when galactose- and lactose-GA were incubated with beta-galactosidase in the cells, their anticancer activity was enhanced by 3- to 40-fold. The results suggest that GA can be inactivated by glycosylation of C-17-position and reactivated for anticancer activity by beta-galactosidase. Therefore, galactose-GA can be exploited in antibody-directed enzyme prodrug therapy (ADEPT) with beta-galactosidase for enzyme-specific activation in tumors to increase tumor selectivity.