CRISPR/Cas9 Genome Editing in LGMD2A/R1 Patient-Derived Induced Pluripotent Stem and Skeletal Muscle Progenitor Cells.

Large numbers of Calpain 3 (CAPN3) mutations cause recessive forms of limb-girdle muscular dystrophy (LGMD2A/LGMDR1) with selective atrophy of the proximal limb muscles. We have generated induced pluripotent stem cells (iPSC) from a patient with two mutations in exon 3 and exon 4 at the calpain 3 locus (W130C, 550delA). Two different strategies to rescue these mutations are devised: (i) on the level of LGMD2A-iPSC, we combined CRISPR/Cas9 genome targeting with a FACS and Tet transactivator-based biallelic selection strategy, which resulted in a new functional chimeric exon 3-4 without the two CAPN3 mutations. (ii) On the level of LGMD2A-iPSC-derived CD82+/Pax7+ myogenic progenitor cells, we demonstrate CRISPR/Cas9 mediated rescue of the highly prevalent exon 4 CAPN3 mutation. The first strategy specifically provides isogenic LGMD2A corrected iPSC for disease modelling, and the second strategy can be further elaborated for potential translational approaches.

Unrelated cord blood transplantation can restore hematologic and immunologic functions in patients with Chediak-Higashi syndrome.

CHS is a rare hereditary fatal disease, if not treated. APs occur in 85% of patients and are usually the main cause of mortality, and HSCT from HLA-matched related and unrelated donors is the only effective treatment for CHS and prevents recurrences of APs. We reviewed the records of three patients with CHS who underwent UCBT at KHCC. Records were examined for clinical features at the time of UCBT, conditioning regimens, morbidities, and outcomes. Conditioning comprised BU, cyclophosphamide, horse ATG, and etoposide. All patients tolerated the conditioning well. Two patients are alive, one with mixed and the other with full donor chimerism; hematologic and immunologic defects of CHS have been corrected in both patients. They show no evidence of recurrences of APs and have normal growth and development. In patients with CHS who lack HLA-matched related and unrelated donors, UCBT is a suitable alternative source of stem cells to restore immunologic and hematologic functions and prevent AP relapses, even in mixed chimeric states. Long follow-up and close monitoring are essential to evaluate the long-term benefits of using UCBT in patients with CHS.