MitoCatch Delivers Healthy Mitochondria to Specific Cells, Rescuing Dying Neurons

Mitochondrial dysfunction underlies a broad spectrum of currently untreatable diseases, including neurodegenerative disorders, optic nerve atrophy, and heart failure. While transplantation of isolated healthy mitochondria has been proposed as a therapeutic concept, prior approaches lacked the ability to target donor mitochondria to specific disease-affected cell types, limiting both efficiency and clinical relevance. MitoCatch was engineered to solve this fundamental targeting problem.

The research team developed three delivery configurations. MitoCatch-C anchors binders (such as anti-GFP nanobodies) to the surface of target cells so they capture mitochondria displaying a matching ligand (mito-GFP). MitoCatch-M places binders directly on the outer mitochondrial membrane to recognize target-cell-surface proteins. MitoCatch-Bi employs bispecific binders that simultaneously engage both mitochondrial outer membrane proteins and cell-type-specific surface antigens. By engineering binders with varying affinities, the team demonstrated that mitochondrial delivery efficiency can be systematically tuned, offering a potential rheostat for therapeutic dosing.

Efficiency and specificity were rigorously quantified using three metrics: percentage increase in donor-mitochondrion-positive cells (PI), fluorescence ratio increase (FR), and a normalized specificity score (S, ranging 0–1). In induced human neurons (iHNeurons), 91% of anti-GFP-nanobody-displaying cells were GFP-positive versus only 11% of controls (PI=708%, FR=488%, S=0.78). Transmission electron microscopy with miniSOG-labeled mitochondria confirmed genuine internalization, showing transplanted organelles with intact cristae structure inside target neurons. Live imaging demonstrated that transplanted mitochondria move along neurites, undergo fission and fusion with native mitochondria, associate with the endoplasmic reticulum, and traffic at speeds comparable to endogenous mitochondria. Critically, proteomics confirmed selective enrichment of mitochondrial proteins without contamination by lysosomal, ER, or nuclear compartment proteins.

Therapeutic proof-of-concept was demonstrated in two models of optic nerve atrophy. In vitro, neurons derived from a patient harboring an OPA1 mutation (a genetic cause of optic nerve atrophy) showed improved survival when transplanted with healthy mitochondria via MitoCatch. In vivo, intravitreal delivery of MitoCatch-targeted mitochondria in a mouse model of optic nerve injury significantly improved retinal ganglion cell survival. The system also achieved targeted delivery to primary human cardiomyocytes, endothelial cells, immune cells, and multiple retinal cell types, illustrating broad applicability across organs and disease contexts.

The study represents a significant conceptual advance over prior untargeted mitochondrial transplantation attempts, offering cell-type specificity, demonstrated intracellular integration, and functional rescue in both human patient-derived cells and living animals. Remaining questions include long-term persistence of transplanted mitochondria, potential immunogenicity of donor organelles, and the logistical challenge of producing sufficient quantities of purified, functional mitochondria for clinical use.