Asp6-PSO@MSNs nanoplatform reverses osteoporosis in mice by activating PI3K-Akt for coupled osteogenesis and angiogenesis

Osteoporosis (OP) presents a significant challenge in regenerative medicine, primarily due to the lack of therapeutic strategies that can intelligently respond to the local pathological microenvironment for precise intervention. Current mainstream therapies often fall short in providing spatiotemporally controlled bone regeneration, failing to adequately couple osteogenesis (bone formation) with angiogenesis (blood vessel formation), both critical for bone repair and homeostasis. A key gap exists in developing systems that can specifically target bone lesion sites and release therapeutics in response to disease-specific cues, such as the acidic microenvironment created by osteoclasts.

Researchers engineered a multifunction-integrated, acid-responsive, bone-affinitive nanoplatform, Asp6-PSO@MSNs (APS-M), for spatiotemporally coordinated bone regeneration. Hollow mesoporous silica nanoparticles (MSNs) were designed to encapsulate the osteogenic bioactive Psoralen (PSO). These MSNs were then surface-gated by a bone-targeting peptide, Asp6. This design ensures spatial accumulation at hydroxyapatite-rich lesion sites, with the Asp6 gatekeeper remaining closed at physiological pH. The acidic microenvironment of osteoclasts triggers 'temporal' gate opening for on-demand drug release. The platform's efficacy and mechanism were investigated using transcriptomics and molecular assays in osteoporotic mice.

The nanoplatform demonstrated a dual-mode therapeutic mechanism. It ensured high intracellular Psoralen (PSO) concentration upon release and provided bioactive silicon ions from carrier degradation. These components collectively and robustly activated the PI3K-Akt signaling axis. This activation orchestrated a regenerative microenvironment by coupling osteogenesis, primarily via RUNX2 stabilization, with angiogenesis, through VEGF upregulation. This coordinated action significantly outperformed free drug administration in promoting bone regeneration. The transcriptomics and molecular assays confirmed the upregulation of key osteogenic and angiogenic markers. Importantly, the targeted delivery and acid-responsive release mechanism ensured that therapeutic effects were localized and potent. > APS-M effectively reversed bone loss, restored microarchitecture, and enhanced biomechanical strength in osteoporotic mice, demonstrating its potential for precision osteoporosis management.