Early pathogenesis of Duchenne muscular dystrophy replicated using stem cells

Duchenne muscular dystrophy (DMD) is a progressive and fatal muscle disease that is linked to a deficiency of dystrophin in muscular cells. The disease is genetic and although its cause has been linked to specific parts of the genetic code, its emergence and development are highly contingent on the background, age and medical history of the patient. This complicates the search for an effective treatment since any pharmacological therapy would need to be specific to each patient. It is costly and difficult to develop effectively, which has caused researchers to turn their focus to the effective suppression of the primary pathology observed in DMD. Some of the approaches that have been taken so far in terms of treatment are mutation-specific exon skipping, gene therapy and cell therapy.

Of these, the exon skipping method seems to show the most promise not only because of its increased efficacy but also because it can be tailored to each patient, which allows for doctors to use personalized medicine. The establishment of human induced pluripotent stem cells (hiPSCs) has lead to a variety of new disease models and is helping researchers uncover more about DMD's pathology. The unlimited proliferation capabilities of hiPSCs allows for the recreation, modeling and study of many diseases such as DMD. Shoji et al. used hiPSCs in their study to develop a new evaluation system to analyze the cellular basis of early DMD pathogenesis by comparing DMD myotubes with the same clone but with truncated dystrophin-expressing DMD myotubes using the exon-skipping method.

To do this, Shoji and his team measured the Ca²⁺ influx in myotypes. They used the Ca²⁺ fluorescent indicator Fluo-8 AM to see the changing levels of calcium ion. Fluo-8^® AM is a revolutionary Ca²⁺ indicator that is marked by increased intensity and more reliable results. Its vibrant bright green color allowed the researchers to establish real time Ca²⁺ imaging. Since Fluo-8 AM shines 2X brighter than previous indicators, it produces robust and easily visible results that allow for the proper tracking of Ca²⁺ flows and influx. What was found in this study was that muscle fibers lacking dystrophin are more susceptible to unregulated Ca²⁺ influx, which leads to the activation of muscle degenerative pathways. Also, it was found that an excessive Ca²⁺ influx is one of the earliest events to occur in intact dystrophin-deficient muscles in response to electric stimuli.

What this all means is that the early pathogenesis of DMD can be replicated using hiPSCs and it also suggests the need to further develop exon-skipping treatment methods because of their independence from genetic variation and ability to counteract the disease's early pathology. The groundbreaking results of this study were made possible by the careful measuring of Ca²⁺. To do this effectively, the researchers relied on the Fluo-8 AM indicator. Because it is not affected by changing temperatures and is available with a variety of Ca²⁺ binding disassociation constants , Fluo-8 AM is a versatile and reliable indicator that delivers robust results that can be depended on. In a study like this where the levels of Ca²⁺ were essential in revealing the results, sharp and accurate readings are a must. With Fluo-8 AM, this is guaranteed and it opens the door for more groundbreaking research into the development and treatment of diseases like DMD.

References

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1. Emi Shoji, Hidetoshi Sakurai, Tokiko Nishino, Tatsutoshi Nakahata, Toshio Heike, Tomonari Awaya, Nobuharu Fujii, Yasuko Manabe, Masafumi Matsuo, Atsuko Sehara-Fujisawa. Early pathogenesis of Duchenne muscular dystrophy modelled in patient-derived human induced pluripotent stem cells. Scientific reports (2015), doi:10.1038/srep12831