Achyranthes bidentata-functionalized bone organoids enhance bone defect repair

Large bone defects remain difficult to reconstruct because impaired osteogenesis, dysregulated remodeling, and an unfavorable local microenvironment jointly limit durable healing. Here, we developed a translational strategy that integrates Achyranthes bidentata (AB), a traditional osteoactive botanical factor, into a BMSC-derived bone organoid platform to enhance bone regeneration. We first screened AB across a concentration gradient and identified 200 μg/mL as the selected working concentration for promoting BMSC viability, osteogenic differentiation, and matrix mineralization, whereas higher concentrations showed diminished benefit. We then incorporated AB into three-dimensional bone organoid culture to generate AB-bone organoids, which exhibited enhanced viability, increased alkaline phosphatase (ALP) activity and Alizarin Red S (ARS) staining, greater COL-I deposition, and stronger osteogenic marker expression than untreated bone organoids. Functionally, AB-bone organoids outperformed both conventional monolayer BMSCs and untreated organoids, indicating that AB establishes a more potent osteogenic niche within the organoid microenvironment. In a critical-sized calvarial defect model, implantation of AB-bone organoids significantly improved new bone formation, defect bridging, collagen matrix deposition, and osteogenic marker expression compared with untreated organoids or empty defects. As an exploratory clinical extension, we analyzed a retrospective postoperative tibial-fracture cohort and found that systemic oral AB administration was associated with shorter radiographic healing time, higher mRUST scores, lower pain, and better lower-extremity function. Together, this study identifies AB as an organoid-compatible osteoregenerative cue that functionally upgrades bone organoids and supports the translational potential of AB-based organoid engineering for bone repair.