Related Experiment Video
Updated: Jul 19, 2025
Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation
Published on: May 23, 2025
Platelet factor 4 induces bone loss by inhibiting the integrin α5-FAK-ERK pathway
Wei Li1,2, Qiwei Zhang3,4, Ranli Gu5
1Department of Oral Pathology, Peking University School and Hospital of Stomatology, National Center for Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing Key Laboratory of Digital Stomatology, National Health Commission Key Laboratory of Digital Technology of Stomatology, Peking University, Beijing, China.
Background:
The effect of platelet factor 4 (PF4) on bone marrow mesenchymal stem cells (BMMSCs) and osteoporosis is poorly understood. Therefore, this study aimed to evaluate the effects of PF4-triggered bone destruction in mice and determine the underlying mechanism.
Methods:
First, in vitro cell proliferation and cell cycle of BMMSCs were assessed using a CCK8 assay and flow cytometry, respectively. Osteogenic differentiation was confirmed using staining and quantification of alkaline phosphatase and Alizarin Red S. Next, an osteoporotic mouse model was established by performing bilateral ovariectomy (OVX). Furthermore, the PF4 concentrations were obtained using enzyme-linked immunosorbent assay. The bone microarchitecture of the femur was evaluated using microCT and histological analyses. Finally, the key regulators of osteogenesis and pathways were investigated using quantitative real-time polymerase chain reaction and Western blotting.
Results:
Human PF4 widely and moderately decreased the cell proliferation and osteogenic differentiation ability of BMMSCs. Furthermore, the levels of PF4 in the serum and bone marrow were generally increased, whereas bone microarchitecture deteriorated due to OVX. Moreover, in vivo mouse PF4 supplementation triggered bone deterioration of the femur. In addition, several key regulators of osteogenesis were downregulated, and the integrin α5-focal adhesion kinase-extracellular signal-regulated kinase (ITGA5-FAK-ERK) pathway was inhibited due to PF4 supplementation.
Conclusions:
PF4 may be attributed to OVX-induced bone loss triggered by the suppression of bone formation in vivo and alleviate BMMSC osteogenic differentiation by inhibiting the ITGA5-FAK-ERK pathway.
Insights
Platelet factor 4 (PF4) impairs bone marrow mesenchymal stem cell (BMMSC) differentiation and bone formation. This study reveals PF4 exacerbates osteoporosis by inhibiting the ITGA5-FAK-ERK pathway, contributing to bone loss.
Area of Science:
- Stem Cell Biology
- Bone Biology
- Molecular Biology
Background:
- The role of Platelet Factor 4 (PF4) in bone marrow mesenchymal stem cells (BMMSCs) and osteoporosis remains unclear.
- Understanding PF4's impact is crucial for developing osteoporosis treatments.
Purpose of the Study:
- To investigate the effects of PF4 on BMMSCs and bone destruction in an osteoporosis model.
- To elucidate the underlying molecular mechanisms of PF4-induced bone loss.
Main Methods:
- In vitro assessment of BMMSC proliferation, cell cycle, and osteogenic differentiation.
- Establishment of an ovariectomy (OVX)-induced osteoporotic mouse model.
- Analysis of bone microarchitecture, PF4 levels, gene expression, and protein pathways.
Main Results:
- PF4 reduced BMMSC proliferation and osteogenic differentiation in vitro.
- OVX led to increased PF4 levels and deteriorated bone microarchitecture in vivo.
- PF4 supplementation in mice worsened bone deterioration and inhibited the ITGA5-FAK-ERK pathway.
Conclusions:
- PF4 contributes to OVX-induced bone loss by suppressing bone formation.
- PF4 inhibits BMMSC osteogenic differentiation via the ITGA5-FAK-ERK pathway.
- Targeting the ITGA5-FAK-ERK pathway may offer therapeutic strategies for osteoporosis.
Related Concept Videos
01:22Formation of the Platelet Plug
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
01:17Intracellular Signaling Affects Focal Adhesions
Some...
01:18Structure and Function of Platelets
Platelets are continually replenished, circulating in the bloodstream for 9-12 days before being removed by phagocytes, primarily in the spleen. A microliter of circulating blood contains between 150,000 and 450,000...
01:16Clot Retraction and Fibrinolysis
01:31Osteoclasts in Bone Remodeling
01:20Extrinsic and Intrinsic Pathways of Hemostasis
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which...