Endochondral ossification contributes to longitudinal skeletal growth. Osteoblasts, which are bone-forming cells, appear close to terminally differentiated hypertrophic chondrocytes during endochondral ossification. We established mice with conditional knockout (cKO) of Smad4, an essential co-activator for transforming growth factor β family signaling. The mice showed a marked increase in bone volume in the metaphysis as a result of increased bone formation by osteoblasts, in which β-catenin, an effector of canonical Wnt signaling, accumulated. We identified Wnt7b as a factor with increased expression in growth plate cartilage in Smad4 cKO mice. Wnt7b mRNA was expressed in differentiated chondrocytes and suppressed by BMP4 stimulation. Ablation of Wnt7b blunted the increase in bone in adult Smad4 cKO mice and reduced skeletal growth in juvenile mice. Overall, we conclude that Wnt7b is a crucial factor secreted from hypertrophic chondrocytes to initiate endochondral ossification. These results suggest that Smad4-dependent BMP signaling regulates the Wnt7b-β-catenin axis during endochondral ossification.
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http://dx.doi.org/10.1242/dev.201734 | DOI Listing |
Adv Sci (Weinh)
January 2025
Medical 3D Printing Center, Orthopedic Institute, Department of Orthopedic Surgery, The First Affiliated Hospital, School of Basic Medical Sciences, MOE Key Laboratory of Geriatric Diseases and Immunology, Suzhou Medical College, Soochow University, Suzhou, Jiangsu, 215000, China.
Stem cell implantation holds promise for enhancing bone repair, but risks of pathogen transmission and malignant cell transformation should not be ignored. Compared to stem cell implantation, recruitment of endogenous stem cells to injured sites is more critical for in situ bone regeneration. In this study, based on the acidic microenvironment of bone injury, an HG-AA-SDF-1α composite hydrogel with a dual-control intelligent switch function is developed by incorporating stromal cell-derived factor (SDF-1α), arginine carbon dots (Arg-CDs), and calcium ions (Ca) into the oxidized hyaluronic acid/gelatin methacryloyl (HG) hydrogel.
View Article and Find Full Text PDFJ Orthop Translat
January 2025
Musculoskeletal Research Laboratory of Department of Orthopaedics & Traumatology and Innovative Orthopaedic Biomaterial & Drug Translational Research Laboratory, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
The orthopaedic community frequently encounters polytrauma individuals with concomitant traumatic brain injury (TBI) and their fractures demonstrate accelerated fracture union, but the mechanisms remain far from clear. Animal and clinical studies demonstrate robust callus formation at the early healing process and expedited radiographical union. In humans, robust callus formation in TBI occurs independently of fracture fixation methods across multiple fracture sites.
View Article and Find Full Text PDFNuclear morphology, which modulates chromatin architecture, plays a critical role in regulating gene expression and cell functions. While most research has focused on the direct effects of nuclear morphology on cell fate, its impact on the cell secretome and surrounding cells remains largely unexplored, yet is especially crucial for cell-based therapies. In this study, we fabricated implants with a micropillar topography using methacrylated poly(octamethylene citrate)/hydroxyapatite (mPOC/HA) composites to investigate how micropillar-induced nuclear deformation influences cell paracrine signaling for osteogenesis and cranial bone regeneration.
View Article and Find Full Text PDFMater Today Bio
February 2025
Department of Orthopedic Trauma and Microsurgery, Zhongnan Hospital of Wuhan University, Wuhan, 430071, Hubei, China.
Osteomyelitis has gradually become a catastrophic complication in orthopedic surgery due to the formation of bacterial biofilms on the implant surface and surrounding tissue. The therapeutic challenges of antibiotic resistance and poor postoperative osseointegration provide inspiration for the development of bioactive implants. We have strategically designed bioceramic scaffolds modified with (LR) and bacteriophages (phages) to achieve both antibacterial and osteogenic effects.
View Article and Find Full Text PDFMater Today Bio
February 2025
State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, China.
Inspired by the initial mineralization process with bone matrix vesicles (MVs), this study innovatively developed a delivery system to mediate mineralization during bone regeneration. The system comprises nanofibrous chitosan microspheres (NCM) and poly (allylamine hydrochloride)-stabilized amorphous calcium phosphate (PAH-ACP), which is thereafter referred to as NCMP. NCM is synthesized through the thermal induction of chitosan molecular chains, serving as the carrier, while PAH-ACP functions as the mineralization precursor.
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