|M.Sc Student||Haykin Tatyana|
|Subject||Investigating the molecular, cellular and pathophysiological|
features of induced pluripotent stem cells (iPSC)-
derived cardiomyocytes from SCO2
|Department||Department of Medicine||Supervisor||Professor Emeritus Ofer Binah|
|Full Thesis text|
Human SCO2 gene is one of the genes involved in the assembly of the Cytochrome C Oxidase (COX) protein complex. Mutations in SCO2 affect the heart, the skeletal muscles and the nervous system, leading to hypertrophic cardiomyopathy (HCM), lactic acidosis, encephalopathy, finally resulting in irreversible respiratory dependence and death before the patient reaches 4 years old. This phenotype is caused by COX deficiency, resulting in ATP deficiency.
The main aim of this research was to investigate the possibility of using Induced Pluripotent Stem Cell (iPSC)-derived cardiomyocytes (iPSC-CM) to study the effect of the SCO2 mutation on the heart. Our hypothesis was that the cardiomyocytes derived from iPSCs generated from SCO2-mutated patients will exhibit the molecular, cellular and pathophysiological features of the disease. Our specific aims were (1) Generate and characterise iPSC-derived cardiomyocytes from two SCO2 patients, one homozygous for the G193S mutation, the other heterozygous for the E140K and c.17ins19 mutations (and from healthy individuals as control). (2) Investigate the [Ca2]i transients in the mutated cardiomyocytes under conditions of increased calcium concentration and β-adrenergic stimulation. (3) Investigate the structural changes in the mutated cardiomyocytes.
Our major findings were: (1) All clones used in this study presented normal karyotype, and presented the pluripotency markers typical of iPSC. The clone bearing the G193S mutation and the control clone produced teratomas in a mouse model. Sequencing the DNA of the iPSC confirmed the presence of the mutations. The iPSC spontaneously differentiated into beating cardiomyocytes. The clone bearing the G193S mutation and the control clone exhibited cardiac markers. (2) We did not find differences in Ca2 handling mechanisms between SCO2-mutated induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CM) and control cells. We did not observe the expected behaviour in response to either increased calcium concentration or β-adrenergic stimulation. (3) Intracellular structural changes were found in SCO2-mutated iPSC-CM, similar to the intracellular changes previously described in cells obtained from patients’ heart and muscle. These changes include mitochondrial abnormalities, as well as doubled nuclei and large glycogen masses within the cell. These results indicate that the method of study based on iPSC-CM provides a viable platform for further research of the SCO2 mutations.