Challenge toward gene-therapy using iPS cells for duchenne muscular dystrophy

Abstract

Human artificial chromosomes (HACs) are stable episomal gene vectors that can carry large gene inserts. We have reported complete correction of a genetic deficiency following the transfer of a HAC carrying the genomic dystrophin sequence (DYS-HAC) into induced pluripotent stem (iPS) cells derived from either a Duchenne muscular dystrophy (DMD) model mouse or a human DMD patient. The engineered iPS cells could differentiate in immunodeficient nude mice, and human dystrophin expression was detected in muscle-like tissues. Furthermore, chimeric mice generated from the engineered cells showed tissue-specific expression of dystrophin. Recently, Giulio's group has isolated and characterized a population of blood vessel-associated stem cells, called mesoangioblasts, that can differentiate into multiple mesoderm cell types, including skeletal muscle. The DYS-HAC was transferred to mesoangioblasts from the DMD-model mouse. Thus, when delivered in the arterial circulation, mesoangioblasts crossed the blood vessel wall and participated in skeletal muscle regeneration, ameliorating signs of muscular dystrophy in the DMD model mice. Most recently, the iPS cells from a DMD patient corrected with the DYS-HAC, were successfully differentiated to mesoangioblasts. Therefore, autologous transfer of genetically corrected iPS cells and muscle progenitor cells will be desirable therapeutic cells because immune suppression would not be required.