A microneedle platform Co-encapsulating chondral organoids and PpIX for spatiotemporally orchestrated tumor ablation and osteochondral regeneration

Tumor-derived osteochondral defects (OCDs) pose significant clinical challenges, necessitating integrated strategies for local tumor ablation while preserving the regenerative niche and enabling coordinated cartilage and subchondral bone repair. Herein, we introduce a spatiotemporal microneedle (MN) platform that synergistically combines protoporphyrin IX (PpIX)-mediated sonodynamic therapy (SDT) for precise tumor eradication with chondral organoid (CO)-driven regeneration, leveraging differential mechanical cues for lineage-specific guidance. COs were engineered from bone marrow stem cells (BMSCs) via agarose microwells, yielding uniform aggregates that matured into hyaline-like phenotypes over 30 days and demonstrated superior resilience to oxidative stress compared to monolayer BMSCs, as evidenced by reduced ROS accumulation, preserved proliferation, and modulated inflammatory/antioxidant pathways. MN was fabricated from gelatin methacryloyl (GelMA) in a bilayer architecture: stiff, discrete 10 %GelMA tips to facilitate penetration and promote osteogenesis, and a softer, monolithic 5 %GelMA base to enhance chondrogenesis. PpIX and COs were co-encapsulated for targeted delivery. <i>In vitro</i>, MN(+PpIX) under ultrasound induced robust ROS generation, apoptosis, and proliferation inhibition in giant cell tumor of bone (GCTB) cells via NF-κB modulation. <i>In vivo</i>, in a subcutaneous GCTB xenograft model, MN-mediated SDT significantly reduced tumor volume and enhanced apoptosis. In a rabbit knee OCD model, MN(+PpIX/CO) achieved superior integrated osteochondral repair, with improved bone volume fraction, trabecular thickness, Safranin O/H&E histology, and higher O'Driscoll/ICRS scores compared to controls. Biosafety was confirmed by normal major-organ histology and serum chemistry at 12 weeks. This platform innovatively sequences SDT and regeneration, using stiffness gradients to guide CO fate, offering a minimally invasive solution for tumor-associated OCDs.