Research Spotlight: Coating Exogenous Mitochondria Prior to Transplantation Improves Uptake and Reduces Toxicity

Kazuhide Hayakawa, PhD, an Assistant Investigator in Radiology at Massachusetts General Hospital and an Assistant Professor of Radiology at Harvard Medical School, is the senior author of a new study in Communications Biology, Mitochondrial surface coating with artificial lipid membrane improves the transfer efficacy..

What question were you investigating with this study?

Emerging findings suggest that exogenous (external) mitochondrial transplantation is promising approach for neuroprotection. However, there are profound limitations in the transfer efficacy as well as concerns about the toxicity of materials produced by naked mitochondria.

What Methods or Approach Did You Use?

We used a modified inverted emulsion method to cover the mitochondrial surface with artificial lipid membranes and found this approach improves transfer efficacy and prevents toxicity.

What Were the Results?

Extracellular mitochondria are present and act as non-cell-autonomous signals to support energetic homeostasis. While mitochondria allograft is a promising approach in rescuing neurons, glia, and vascular cells in central nervous system (CNS) injury and disease, there are profound limitations in cellular uptake of mitochondria and transfer efficacy.

Here, we modified mitochondria by coating them with cationic DOTAP mixed with DOPE via a modified inverted emulsion method to improve mitochondrial transfer and the efficacy. We initially optimized the method using control microbeads and liposomes followed by using mitochondria isolated from intact cerebral cortex of male adult C57BL/6J mice. After the coating process, FACS analysis indicated that approximately 86% of mitochondria were covered by DOTAP/DOPE membrane.

Moreover, the artificial membrane-coated mitochondria (AM-mito) shifted the zeta-potential toward positive surface charge, confirming successful coating of isolated mitochondria. Mitochondrial proteins (TOM40, ATP5a, ACADM, HSP60, COX IV) and membrane potentials were well maintained in AM-mito.

Importantly, the coating improved mitochondrial internalization and neuroprotection in cultured neurons. Furthermore, intravenous infusion of AM-mito immediately after focal cerebral ischemia-reperfusion amplified cerebroprotection in vivo.

What are the Clinical Implications?

Collectively, these findings indicate that mitochondrial surface coating with artificial lipid membrane is feasible and may improve the therapeutic efficacy of mitochondria allograft.

About the Massachusetts General Hospital

Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The Mass General Research Institute conducts the largest hospital-based research program in the nation, with annual research operations of more than $1 billion and comprises more than 9,500 researchers working across more than 30 institutes, centers and departments. In July 2022, Mass General was named #8 in the U.S. News & World Report list of "America’s Best Hospitals." MGH is a founding member of the Mass General Brigham healthcare system.