Mitoprotective therapy prevents rapid, strain-dependent mitochondrial dysfunction after articular cartilage injury

Bartell LR, Fortier LA, Bonassar LJ, Szeto HH, Cohen I, Delco ML · Journal of Orthopaedic Research

Impact triggered mitochondrial depolarization within minutes (34–46% above controls), tightly correlated with local tissue strain (R = 0.68); SS-31 pretreatment kept depolarization and cell death 63-91% lower than untreated impacted cartilage — comparable to unimpacted controls — abolished the strain-depolarization correlation, and preserved cristae structure on electron microscopy.

Population

Explants from the medial femoral condyles of 9 neonatal calves (5 untreated, 4 treated), thousands of cells tracked individually by confocal microscopy

Intervention

SS-31 1 µM in the bath for 30 minutes before a ~1 MPa impact

Comparator

Impacted untreated and unimpacted explants

Limitations

Drug was present before injury — a design no clinical scenario can copy; neonatal bovine explants; a ~1 MPa impact chosen to spread strain rather than to model any injury; Szeto, the inventor and Stealth's founder, is a co-author, and a patent application on SS peptides for osteoarthritis names three of the authors. NIH-funded.