Cardiomyocytes cultured on mechanically compliant substrates, but not on conventional culture devices, exhibit prominent mitochondrial dysfunction due to reactive oxygen species and insulin resistance under high glucose

• Published in: PloS one Vol. 13; no. 8; p. e0201891
• Main Authors: Morishima, Masaki, Horikawa, Kazuki, Funaki, Makoto
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23.08.2018; Public Library of Science (PLoS)
• Subjects: Accumulation; Animals; Animals, Newborn; Apoptosis; Attenuation; Biology and Life Sciences; Biomechanical Phenomena; Blood glucose; Cardiomyocytes; Cardiovascular disease; Caspase; Caspase-3; Cell culture; Cell Culture Techniques - instrumentation; Cells, Cultured; Culture Media; Cytoskeleton; Cytoskeleton - metabolism; Cytoskeleton - pathology; Deoxyribonucleic acid; Diabetes; Diabetes mellitus; Disease control; DNA; DNA fragmentation; Elasticity; Engineering and Technology; Fibroblasts; Gels; Glucose; Glucose - metabolism; Health aspects; Heart; Heart cells; Heart Ventricles; Hyperglycemia; In vivo methods and tests; Insulin; Insulin resistance; Insulin Resistance - physiology; Levels; Mechanical properties; Medicine and Health Sciences; Membrane potential; Microenvironments; Mitochondria; Mitochondria - metabolism; Mitochondrial diseases; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - pathology; Neonates; Oxygen; Physical Sciences; Rats, Wistar; Reactive oxygen species; Reactive Oxygen Species - metabolism; Risk factors; Rodents; Signal transduction; Stiffness; Substrates; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0201891

Diabetes causes cardiac dysfunction, and understanding of its mechanism is still incomplete. One reason could be limitations in modeling disease conditions by current in vitro cardiomyocyte culture. Emerging evidence suggests that the mechanical properties of the microenvironment affect cardiomyocyte function. Nevertheless, the impact of high glucose on cardiomyocytes cultured on substrates whose stiffness matches that of the heart (approximately 15 kPa) is untested. To test the hypothesis that cardiomyocytes cultured in microenvironments that mimic the mechanical properties of those for cardiomyocytes in vivo may reproduce the pathophysiology characteristics of diabetic cardiomyocytes ex vivo, such as the morphological appearance, ROS accumulation, mitochondrial dysfunction, apoptosis and insulin-stimulated glucose uptake. Isolated neonatal rat cardiomyocytes were seeded on 15 kPa polyacrylamide (PAA) gels, whose stiffness mimics that of heart tissues, or on glass coverslips, which represent conventional culture devices but are unphysiologically stiff. Cells were then cultured at 5 mM glucose, corresponding to the normal blood glucose level, or at high glucose levels (10 to 25 mM). Cytoskeletal disorganization, ROS accumulation, attenuated mitochondrial membrane potential and attenuated ATP level caused by high glucose and their reversal by a ROS scavenger were prominent in cells on gels, but not in cells on coverslips. The lack of response to ROS scavenging could be attributable to enhanced apoptosis in cells on glass, shown by enhanced DNA fragmentation and higher caspase 3/7 activity in cells on glass coverslips. High-glucose treatment also downregulated GLUT4 expression and attenuated insulin-stimulated glucose uptake only in cells on 15 kPa gels. Our data suggest that a mechanically compliant microenvironment increases the susceptibility of primary cardiomyocytes to elevated glucose levels, which enables these cells to serve as an innovative model for diabetic heart research.