Development of an iPSC-derived cell therapy for Limb-girdle muscular dystrophy type 2A/R1


Pre-Clinical Research

Poster Number: 269


Sunny Sun, PhD, Vita-Therapeutics, Casey Baber, Vita Therapeutics, Andrew Colman, Vita Therapeutics, Oscar Safairad, Vita Therapeutics, Luke Ren, Vita Therapeutics, Amir Saberi, Vita Therapeutics, Sheela Jacob, Vita Therapeutics, Amy Wesa, Vita Therapeutics, Alexandra Capela, Vita Therapeutics, Douglas Falk, Vita Therapeutics, Peter Andersen, Vita Therapeutics

Limb-girdle muscular dystrophy type 2A/R1 (LGMD2A/R1) is a rare form of muscular dystrophy with around 4000 patients in the US and approximately 80-100 new patients identified every year. LGMD2A/R1 is caused by mutations in the CAPN3 gene, which leads to loss of functional calpain-3 protein, resulting in symmetrical muscle wasting of the proximal limb and girdle muscles. There is currently no approved treatment for LGMD2A/R1. Regenerative therapies derived from induced pluripotent stem cells (iPSCs) may provide a promising approach to regenerate muscle mass associated with muscle wasting. Here we describe the pre-clinical development of an iPSC-based autologous therapy for LGMD2A/R1. A CRISPR-based knock-in strategy was developed to replace the endogenous defective CAPN3 gene with a functional version in LGMD2A/R1 patient-derived iPSCs. Using a chemically defined, step-wise myogenic lineage specification protocol, PAX7-expressing myogenic progenitor cells (MPCs) were then generated; upon myogenic fusion induction, these cells formed functional myotubes that produced CAPN3 mRNA and protein. We then transplanted CAPN3 edited LGMD2A/R1 iPSC derived MPCs into the injured TA muscles of NSG mice and demonstrated donor cell-derived muscle regeneration. Furthermore, a subpopulation of transplanted MPCs seeded in the local muscle stem cell niche area under the basal lamina in mice where they adopt a quiescent state and contribute to regeneration upon additional injury, thus providing evidence of a long-term maintenance and regenerative capability. To facilitate in vivo efficacy studies in an animal model of LGMD2A/R1, we generated an immunodeficient calpain-3 null mouse by back-crossing CAPN3KO mice (JAX: CC041-Capn3em10Lutzy/J) with NSG (JAX: NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice. Intramuscular transplantation of CAPN3 edited MPCs into injured muscle of CAPN3KO-NSG mice leads to donor-derived muscle fiber regeneration, supporting the rationale for continued development. Manufacturing of LGMD2A/R1 iPSC-derived MPCs to support IND-studies and first-in-human trials is ongoing with the goal of IND-filing.