Gene-Activating Framework Nucleic Acid-Targeted Upregulating Sirtuin-1 to Modulate Osteoimmune Microenvironment for Diabetic Osteoporosis Therapeutics

Diabetic osteoporosis, a prevalent chronic complication of diabetes, is marked by reduced bone mass, increased bone fragility, and susceptibility to fractures. A significant cause of this condition is the disruption of osteoblastic homeostasis due to prolonged hyperglycemia, which impedes bone regeneration and remodeling. Despite its prevalence, no effective treatments specifically target diabetic osteoporosis. Recently, small-activating RNA (saRNA) therapy has attracted attention for its targeting capacity, high efficacy, and minimal side effects. However, RNA's inherent properties, such as structural instability, susceptibility to degradation, and poor penetration, limit its applications. To address these limitations, a gene-activating tetrahedral framework nucleic acid (tFNA) with sirtuin-1 (SIRT1) gene activation function is developed, termed Tsa. Tsa exhibits an RNA-protecting effect and can effectively penetrate cell membranes to upregulate SIRT1 gene expression. At the histological level, Tsa treatment alleviates diabetic osteoporosis by increasing bone trabecular density and promoting new bone formation. At the cellular level, it switches macrophage polarization toward the anti-inflammatory M2 phenotype while inhibiting the inflammatory M1 phenotype, creating a favorable bone immune microenvironment for osteoblasts. At the genetic level, Tsa activates SIRT1 expression, which deacetylates Acetyl-p65 to block the NF-κB pathway and restore the osteoimmune environment. Overall, this research demonstrates a nanodrug "Tsa", capable of activating SIRT1 and modulating the bone immune environment, thereby showcasing its immense potential for diabetic osteoporosis treatment.