Develop a cellular model of LGMD2B to enable studies of dysferlin’s function and preclinical testing of drug candidates.
We have recently reported the development of “myobundles”, 3D cultures of myogenic progenitor cells derived from human induced pluripotent stem cells (hiPSCs). The myobundles represent the first iPSC-derived human tissue-engineered muscle system that robustly contracts in response to electrical simulation or acetylcholine and contains a pool of functional satellite-like cells. Inside the 3D myobundles, aligned myotubes can be cultured for several weeks during which they acquire a more mature phenotype compared to that achievable in traditional 2D cultures. Using this platform, we have successfully generated functional myobundles from three control dysferlin-positive and three dysferlin-negative (LGMD2B) hiPSC lines provided by Jain foundation. We demonstrated that compared to control myobundles, LGMD2B myobundles exhibit decreased contractile strength, abnormal calcium handling, increased vulnerability to hypoosmotic shock, and altered response to lipid supplementation. We are continuing this work in the myobundle system to understand how dysferlin deficiency alters generation of contractile force, calcium handling, metabolism, mitochondrial function, cellular interactions, and drug response in human skeletal muscle. We expect that these studies will establish a personalized human 3D cell culture platform for testing candidate therapeutics in their ability to normalize injury response and recover muscle contractile function in patients with dysferlin deficiency.