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Updated: Jan 15, 2026
In Situ Immunofluorescent Staining of Autophagy in Muscle Stem Cells
Published on: June 12, 2017
Osteoblast dysfunction associated with mitophagy suppression under simulated microgravity
Jindong Xue1, Min Wang1, Songsong Liu1
1College of Intelligent Medicine and Biotechnology, Guilin Medical University, Guilin, 541199, China.
Background:
Bone loss is a significant health concern during spaceflight and mechanical unloading. Simulated microgravity (SMG) disrupts bone homeostasis by inhibiting osteoblast proliferation and differentiation while promoting apoptosis. Although these functional effects have been reported, the underlying mechanisms remain unclear. Mitochondrial quality control, particularly mitophagy involving the PINK1/Parkin pathway, may play a key role. This study aimed to investigate the relationship between osteogenic dysfunction and mitochondrial damage under SMG conditions and preliminarily validate the potential link using the small molecule probe icariin (ICA).
Methods:
An SMG model was established using a rotary cell culture system. Cell proliferation was assessed by CCK-8 assay, apoptosis was analyzed via flow cytometry, and osteogenic differentiation was evaluated by alkaline phosphatase (ALP) and Alizarin Red staining. Expression levels of relevant genes and proteins were measured by qPCR and Western blot. Mitochondrial function was assessed through ATP content, reactive oxygen species (ROS) levels, JC-1 staining for mitochondrial membrane potential, and transmission electron microscopy (TEM) for ultrastructural observation. Additionally, cells were treated with the mitochondrial function-related small molecule icariin (ICA) to observe its regulatory effects on mitophagy markers (PINK1, Parkin, p62, LC3B) expression and osteogenic function.
Results:
SMG significantly inhibited osteoblast proliferation and differentiation and induced apoptosis. These changes were accompanied by impaired mitochondrial function and downregulated expression of mitophagy-related genes. TEM revealed mitochondrial swelling and disrupted cristae structure. Treatment with ICA partially restored mitochondrial function and mitophagy marker expression, along with improved expression of osteogenic markers and cell viability.
Conclusions:
SMG induces osteogenic dysfunction, mitochondrial damage, and downregulation of mitophagy-related gene expression. The results suggest that impaired mitophagy may be a key mechanism underlying unloading-induced bone loss, and ICA, as a small molecule modulator, holds potential as a therapeutic intervention.
Clinical Trial Number:
Not applicable.
Insights
Simulated microgravity impairs bone health by damaging mitochondria and reducing mitophagy. The small molecule icariin shows potential to restore bone cell function and combat bone loss.
Area of Science:
- Cell Biology
- Bone Biology
- Space Medicine
Background:
- Spaceflight and mechanical unloading cause significant bone loss.
- Simulated microgravity (SMG) disrupts bone homeostasis by inhibiting osteoblast function and promoting cell death.
- The precise mechanisms linking SMG to bone loss, particularly involving mitochondrial quality control, are not fully understood.
Purpose of the Study:
- To investigate the link between osteogenic dysfunction and mitochondrial damage under SMG.
- To explore the role of mitophagy in SMG-induced bone loss.
- To evaluate the therapeutic potential of icariin (ICA) in mitigating these effects.
Main Methods:
- Established an SMG model using a rotary cell culture system.
- Assessed osteoblast proliferation, apoptosis, and differentiation.
- Analyzed mitochondrial function (ATP, ROS, membrane potential) and ultrastructure via TEM.
- Measured mitophagy markers (PINK1, Parkin, p62, LC3B) and osteogenic markers.
- Investigated the effects of icariin (ICA) treatment.
Main Results:
- SMG inhibited osteoblast proliferation and differentiation, inducing apoptosis.
- Mitochondrial function was impaired, with downregulated mitophagy markers and structural damage.
- Icariin (ICA) treatment partially restored mitochondrial function, mitophagy, and osteogenic markers, improving cell viability.
Conclusions:
- Impaired mitophagy is a key mechanism in unloading-induced bone loss.
- SMG leads to osteogenic dysfunction and mitochondrial damage.
- Icariin (ICA) shows promise as a therapeutic agent for preventing bone loss.
