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Updated: Jul 16, 2025
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Exosomes derived from LPS-preconditioned bone marrow-derived MSC modulate macrophage plasticity to promote allograft
PeiYao Zhang1, Panfeng Wu1, Umar Zeb Khan1
1Department of Orthopedics, Hand & Microsurgery Surgery, Xiangya Hospital of Central South University, Xiangy Road, Changsha, 410008, Hunan, China.
Objectives:
This study investigated whether exosomes from LPS pretreated bone marrow mesenchymal stem cells (LPS pre-MSCs) could prolong skin graft survival.
Methods:
The exosomes were isolated from the supernatant of MSCs pretreated with LPS. LPS pre-Exo and rapamycin were injected via the tail vein into C57BL/6 mice allografted with BALB/c skin; graft survival was observed and evaluated. The accumulation and polarization of macrophages were examined by immunohistochemistry. The differentiation of macrophages in the spleen was analyzed by flow cytometry. For in vitro, an inflammatory model was established. Specifically, bone marrow-derived macrophages (BMDMs) were isolated and cultured with LPS (100 ng/ml) for 3 h, and were further treated with LPS pre-Exo for 24 h or 48 h. The molecular signaling pathway responsible for modulating inflammation was examined by Western blotting. The expressions of downstream inflammatory cytokines were determined by Elisa, and the polarization of macrophages was analyzed by flow cytometry.
Results:
LPS pre-Exo could better ablate inflammation compared to untreated MSC-derived exosomes (BM-Exo). These loaded factors inhibited the expressions of inflammatory factors via a negative feedback mechanism. In vivo, LPS pre-Exo significantly attenuated inflammatory infiltration, thus improving the survival of allogeneic skin graft. Flow cytometric analysis of BMDMs showed that LPS pre-Exo were involved in the regulation of macrophage polarization and immune homeostasis during inflammation. Further investigation revealed that the NF-κB/NLRP3/procaspase-1/IL-1β signaling pathway played a key role in LPS pre-Exo-mediated regulation of macrophage polarization. Inhibiting NF-κB in BMDMs could abolish the LPS-induced activation of inflammatory pathways and the polarization of M1 macrophages while increasing the proportion of M2 cells.
Conclusion:
LPS pre-Exo are able to switch the polarization of macrophages and enhance the resolution of inflammation. This type of exosomes provides an improved immunotherapeutic potential in prolonging graft survival.
Insights
Exosomes from LPS-treated mesenchymal stem cells (LPS pre-Exo) reduce inflammation and prolong skin graft survival by regulating macrophage polarization. This offers a promising immunotherapeutic strategy for transplantation.
Area of Science:
- Immunology
- Regenerative Medicine
- Cell Biology
Background:
- Allogeneic skin graft survival is often limited by immune rejection and inflammation.
- Mesenchymal stem cells (MSCs) and their derived exosomes show immunomodulatory properties.
- Exosomes from lipopolysaccharide (LPS)-pretreated MSCs (LPS pre-MSCs) may offer enhanced therapeutic benefits.
Purpose of the Study:
- To investigate the efficacy of exosomes derived from LPS-pretreated bone marrow mesenchymal stem cells (LPS pre-Exo) in prolonging skin graft survival.
- To elucidate the underlying mechanisms of LPS pre-Exo in modulating immune responses and inflammation.
Main Methods:
- Exosomes were isolated from LPS-pretreated MSC supernatant.
- In vivo studies involved tail vein injection of LPS pre-Exo into mice with allogeneic skin grafts.
- In vitro studies used bone marrow-derived macrophages (BMDMs) treated with LPS pre-Exo to analyze inflammatory pathways and macrophage polarization via Western blotting, ELISA, and flow cytometry.
Main Results:
- LPS pre-Exo demonstrated superior anti-inflammatory effects compared to untreated exosomes.
- In vivo, LPS pre-Exo significantly reduced inflammatory infiltration and improved allogeneic skin graft survival.
- LPS pre-Exo modulated macrophage polarization, shifting from M1 to M2 phenotypes, via the NF-κB/NLRP3/procaspase-1/IL-1β signaling pathway.
Conclusions:
- LPS pre-Exo effectively promote the resolution of inflammation by reprogramming macrophage polarization.
- These exosomes represent a potent immunotherapeutic agent for enhancing allogeneic skin graft survival.
