Osteochondral injuries are prevalent and difficult to treat in clinical practice. Traditional tissue engineering typically results in poor integration at the calcified cartilage interlayer, since they cannot address different needs from the cartilage and the supporting subchondral bone. This study presents a hybrid biological scaffold integrating soft and hard components to systematically adopt to osteochondral regeneration. The upper section consists of bioactive hydrogel, kartogenin (KGN), and bone marrow stromal cells (BMSCs), replicating mechanical properties and chondrogenic potential of nature hyaline cartilage. The lower section utilizes a biodegradable metal magnesium (Mg) alloy scaffold with customized porous structure, providing mechanical response comparable to trabecular bone, along with regulated degradation and enhanced angiogenesis and osteogenesis. The bioactive hydrogel is compressed into the pores of Mg scaffold. Notably, the unique combination not only significantly improves mechanical response and fatigue resistance of the cartilage section but also maintains interface stability throughout the repair process. Accordingly, the hybrid scaffold effectively promotes the regeneration of both cartilage and subchondral bone simultaneously by upregulation of osteogenic and chondrogenic specific genes. Overall, this work provides valuable insights for treating osteochondral injuries by material-structure-function integrated strategies.

Osteonecrosis of the femoral head (ONFH) is a common disabling disease. Copper has positive effects on cells that regulate bone metabolism. However, the relationship between copper metabolism (CM) and steroid-induced ONFH (SONFH) remains unclear. The GSE123568 dataset was downloaded from the Gene Expression Omnibus. The differentially expressed CM-related SONFH genes (DE-CMR-SONFHGs) were identified via differential analysis and weighted gene coexpression network analysis (WGCNA). Receiver operating characteristic (ROC) analysis was performed for the predictive accuracy of key genes. Targeting drugs and the copper death-related genes (CDRGs) relevant to key genes were investigated. The bioinformatics results were confirmed via quantitative real-time polymerase chain reaction (qRT–PCR) and Western blot (WB) analysis. Two out of 106 DE-CMR-SONFHGs were identified as key genes (PNP and SLC2A1), which had diagnostic value in distinguishing SONFH from control samples and were related to various immune cell infiltrations. Eleven PMP-targeting drugs and five SLC2A1-targeting drugs were identified. The qRT–PCR, as well as WB, results confirmed the downregulation PNP and SLC2A1 and high expression of the CDRGs DLD, PDHB, and MTF1, which are closely related to these two key genes. In conclusion, PNP and SLC2A1 were identified as key genes related to SONFH and may provide insights for SONFH treatment.

The early treatment of Osteonecrosis of Femoral Head (ONFH) remains a clinical challenge. Conventional Bone Marrow Mesenchymal Stem Cell (BMSC) injection methods often result in unsatisfactory outcomes due to mechanical cell damage, low cell survival and retention rates, inadequate cell matrix accumulation, and poor intercellular interaction. In this study, we employed a novel cell carrier material termed "3D Microscaffold" to deliver BMSCs, addressing these issues and enhancing the therapeutic effects of cell therapy for ONFH. We injected 3D microscaffold loaded with low-dose BMSCs or free high-dose BMSCs into the femoral heads of ONFH rats and assessed therapeutic effects using imaging, serology, histology, and immunohistochemistry. To understand the mechanism of efficacy, we established a co-culture model of human osteoblasts and BMSCs, followed by cell proliferation and activity detection, flow cytometry analysis, Quantitative RT-PCR, and Western blotting. Additionally, RNA sequencing was performed on femoral head tissues. Results showed that the 3D microscaffold with low-dose BMSCs had a therapeutic effect comparable to high-dose free BMSCs. Osteoblasts in the 3D microscaffold group exhibited superior phenotypes compared to the non-3D microscaffold group. Furthermore, we have, for the first time, preliminarily validated that the low-dose BMSCs-loaded 3D microscaffolds may promote the repair of femoral head necrosis through the synergistic action of the MAPK and Hippo signaling pathways.

Osteonecrosis of the Femoral Head (ONFH) is primarily characterized by impaired osteogenesis and insufficient vascularization, leading to progressive structural collapse and limb dysfunction. To develop a targeted strategy for regulating the bone-vascular microenvironment in hip preserving treatment, we integrated a three-dimensionally (3D) printed microporous magnesium alloy scaffold with bone marrow mesenchymal stem cells (BMSCs)-loaded 3D microspheres into a composite regenerative system. We then evaluated its therapeutic efficacy and investigated its underlying mechanisms. In vitro, the composite system demonstrated favorable biocompatibility and promoted osteogenic and angiogenic differentiation. In a steroid-induced rabbit model of femoral head necrosis, micro-CT and histological analysis confirmed the system's significant interventional effect. The magnesium alloy scaffold provided adequate mechanical support and released Mg²⁺ ions to participate in microenvironmental regulation. The BMSCs-loaded 3D microspheres were firmly integrated with the scaffold, which increased BMSCs loading capacity and provided a protective growth environment that shielded cells from mechanical damage. Further experiments indicated that the composite system modulated the interactions among BMSCs, osteoblasts, and vascular endothelial cells. By activating Extracellular Matrix organization, Focal adhesion, and the PI3K-Akt signaling pathways, it regulated the osteoblast and endothelial cell-related bone-vascular microenvironment to promote femoral head repair. This study demonstrates that combining a bioactive magnesium scaffold with BMSCs-loaded microspheres synergistically promotes femoral head repair, highlighting the therapeutic potential of integrating bioactive ion release with cellular paracrine regulation.

Background Early treatment of ONFH (osteonecrosis of the femoral head) has posed a significant challenge for clinicians. Recent attention has been directed towards stem cell therapy, with BMSCs (bone marrow mesenchymal stem cells) emerging as a potential solution for early-stage ONFH due to their unique capabilities. However, traditional cell injection methods have been associated with unsatisfactory results attributed to issues such as mechanical damage during injection, low cell survival rates, limited cell matrix accumulation, and absence of cellular interactions. To address these concerns, this study utilized a novel cell carrier material called 3D-TableTrix Microcarriers capable of loading BMSCs. Methods Through imaging, serological, and histological analyses, low-dose BMSC-loaded Microcarriers were intravenously injected into a rat model of early-stage hormone-induced osteonecrosis of the femoral head. Repair outcomes were compared to those obtained from high-dose BMSC injections to evaluate the efficacy and safety of this improved strategy. Additionally, a co-culture system study was conducted, in which human primary osteoblasts were seeded in the lower layer, while 3D-TableTrix Microcarrier-loaded human BMSCs or monolayer-cultured human BMSCs were seeded in the upper layer. Phenotypic analysis of the co-cultured human osteoblasts focused on comparing the effects of different BMSC cultivation methods. Results The Microcarriers containing low-dose BMSCs demonstrated comparable repair outcomes to high-dose BMSC injections in the rat model of early-stage hormone-induced osteonecrosis of the femoral head, while minimizing the associated risks of high-dose stem cell administration. Furthermore, the co-culture system revealed that the osteoblasts in the 3D group exhibited a superior phenotype compared to the monolayer-cultured group. Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis provided insights into the mechanisms underlying the therapeutic effects of 3D Microcarriers loaded with BMSCs in early-stage hormone-induced osteonecrosis of the femoral head. Conclusions This study confirms that 3D-TableTrix Microcarriers loaded with BMSCs offer a promising cellular therapy for early-stage hormone-induced osteonecrosis of the femoral head, potentially achieving efficient treatment outcomes with minimal cell dosages. The improved strategy addresses challenges associated with traditional cell injection methods and highlights the potential of BMSC-loaded Microcarriers to improve the management of early-stage ONFH.