Interstitial Mitochondria Localize to Cellular Membrane Following Transplantation in HL-1 Cardiomyocytes

Katelyn G. Pinti,* Andrya J. Durr, Andrew D. Taylor and John M. Hollander, Department of Exercise Physiology, School of Medicine, West Virginia University, Morgantown, WV 26505

Field (Broad Category): Biology (Health Sciences) 

Student’s Major: Exercise Physiology 

Mitochondrial transplantation has been identified as a therapeutic procedure that provides benefit to ailing heart during ischemia reperfusion. Though the benefit of the procedure is unquestionable, mitochondrial localization during and after transplantation has not been fully elucidated. Few studies suggest that some mitochondria are incorporated into the cell and the mitochondrial network, while others remain in the interstitial space based on immunohistology analysis. This study seeks to understand the localization of mitochondria following transplantation and determine whether mitochondria achieve intracellular localization or remain in the interstitial space using an in vitro model. The knowledge of whether mitochondria are inside of the cells or remaining extracellularly would aid in the identification of the mechanism occurring during transplantation and assist in identifying how they are contributing to functional benefit. Through the use of cell culture, specifically HL-1 immortalized mouse cardiomyocytes, we monitored mitochondrial localization using the MIF NikonA1R confocal microscope for 24 hours post transplantation. Video compilation and Z-stack images reveal that mitochondria appear to be attached to the surface of the cell, particularly in close proximity to the nucleus, but are not incorporated into the cellular space. They further illuminate that mitochondria attached to the surface do not appear to coincide with host cell mitochondrial networks, suggesting that the mechanism of benefit is not dependent on intracellular localization of mitochondria. In summary these data suggest that transplanted mitochondria are not incorporated into cells, but attach to the cellular membrane and remain in the interstitial space. 

Funding: National Heart, Lung, & Blood Institute; Community Foundation for the Ohio Valley Whipkey Trust 

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course