A "Progenitor Cell Ark" hydrogel system for intervertebral disc regeneration via mitochondrial targeting and mitophagy enhancement.

A triple-layered hydrogel microsphere system called a Progenitor Cell Ark delivers nucleus pulposus progenitor cells (NPPCs) together with an SS31-modified Prussian blue nanozyme (SS31-UPN) that targets mitochondria to scavenge ROS and promote mitophagy. In vitro, SS31-UPN protected NPPCs from oxidative damage and restored mitochondrial function, and in severe IVDD rat models the Ark improved disc structure, promoted neo-tissue formation, and restored biomechanical function, outperforming cell or bioscaffold therapy alone.