Large1 gene transfer in older myd mice with severe muscular dystrophy restores muscle function and greatly improves survival

Abstract

Muscular dystrophy is a progressive and ultimately lethal neuromuscular disease. Although gene editing and gene transfer hold great promise as therapies when administered before the onset of severe clinical symptoms, it is unclear whether these strategies can restore muscle function and improve survival in the late stages of muscular dystrophy. Large myd /Large myd ( myd ) mice lack expression of like-acetylglucosaminyltransferase-1 ( Large1 ) and exhibit severe muscle pathophysiology, impaired mobility, and a markedly reduced life span. Here, we show that systemic delivery of AAV2/9 CMV Large1 (AAV Large1 ) in >34-week-old myd mice with advanced disease restores matriglycan expression on dystroglycan, attenuates skeletal muscle pathophysiology, improves motor and respiratory function, and normalizes systemic metabolism, which collectively and markedly extends survival. Our results in a mouse model of muscular dystrophy demonstrate that skeletal muscle function can be restored, illustrating its remarkable plasticity, and that survival can be greatly improved even after the onset of severe muscle pathophysiology.

Verapamil mitigates chloride and calcium bi-channelopathy in a myotonic dystrophy mouse model

“…Mice were acclimated to the system for 2 days, with data collected on day 3. For all 3 days, a single mouse was placed conscious and unrestrained in the WBP chamber and subjected to a 15-minute acclimation period, followed by 10 minutes of data acquisition ( 40 ). Average data from the 10-minute acquisition period were analyzed by 1-way ANOVA with multiple comparisons.…”

Identification of a short, single site matriglycan that maintains neuromuscular function in the mouse

“…The skeletal muscles of 4X mutant mice showed fibers with central nuclei, adipose tissue infiltration, and fibrosis (Fig. 6c), which resembles the muscular phenotypes of the myd mice (45). AAV encoding 4X mutant DG lost its ability to rescue grip strength (Fig.…”

“…The muscle was then passively returned to L o at the same velocity. At 3,15,30,45, and 60 minutes after the ECC protocol, isometric tetanic force was measured. After the analysis of the contractile properties, the muscle was weighed.…”

Deep Mutational Scanning in Disease-related Genes with Saturation Mutagenesis-Reinforced Functional Assays (SMuRF)

“…1a). New drugs 34 , gene therapies 35,36 and cell therapies 37 are being actively developed for dystroglycanopathies related to FKRP or LARGE1, emphasizing the need for improved variant interpretation to facilitate the patient enrollment in these gene-specific trials.…”

“…Among the enzymes, FKRP adds the second ribitol-5-phosphate (Rbo5P) to the Rbo5P tandem 17 while LARGE1 is responsible for adding the repeated disaccharide units of matriglycan 18 . Both enzymes are associated with many rare disease cases, for which novel treatments are being developed vigorously, including new drugs 19 , gene therapies 20,21 and cell therapies 22 . This further emphasizes the need for improved variant interpretation to facilitate the enrollment of more patients in these gene-specific trials.…”