Restored expression of dystrophin diminishes Ca2+ influx in DMD muscle in response to electric stimulation.
(a) Representative profiles of the Ca2+ influx pattern in Δ44 and Δ46–47 DMD-Myocytes determined through Fluo-8 intensity in response to electric stimulation. AO88 (+AO)- and control oligonucleotide (+CO)-treated DMD-Myocytes were compared with untreated DMD-Myocytes. Electric pulses were applied to the cells 5 sec after the stationary phase at a constant frequency of 0.2 Hz at 12 V for 1 min. The Ca2+ influx amplitude of AO-treated DMD-Myocytes was lower than that of untreated and + CO myocytes, as indicated by double arrowheads. (b) Quantitative analysis of Fluo-8 intensity amplification in Δ44 and Δ46–47 DMD-Myocytes. Amplification was normalised to that of untreated samples. n = 8, **p < 0.01. (c) Immunocytochemistry of MHC merged with DAPI in Δ44 and Δ46–467 DMD-Myocytes, compared with that of AO- and CO-treated DMD-Myocytes. Scale bar, 200 μm. (d) Quantitative analysis of the differentiation efficiency of two clones each from Δ44 and Δ46–47 DMD-iPStet-MyoD. Percentages of MHC and DAPI double-positive fibres relative to total DAPI-positive cells at day 9 of differentiation. n = 4.