Conditioned culture medium of bone marrow mesenchymal stem cells promotes phenotypic transformation of microglia by regulating mitochondrial autophagy

PeerJ. 2024 Jul 4:12:e17664. doi: 10.7717/peerj.17664. eCollection 2024.

Abstract

Objective: To study the mechanism by which conditioned medium of bone marrow mesenchymal stem cells (BMSCs-CM) facilitates the transition of pro-inflammatory polarized microglia to an anti-inflammatory phenotype.

Methods: BV2 cells, a mouse microglia cell line, were transformed into a pro-inflammatory phenotype using lipopolysaccharide. The expression of phenotypic genes in BV2 cells was detected using real-time quantitative PCR (RT-qPCR). Enzyme-linked immunosorbent assay was used to measure inflammatory cytokine levels in BV2 cells co-cultured with BMSCs-CM. The expressions of mitophagy-associated proteins were determined using western blot. The mitochondrial membrane potential and ATP levels in BV2 cells were measured using JC-1 staining and an ATP assay kit, respectively. Additionally, we examined the proliferation, apoptosis, and migration of C8-D1A cells, a mouse astrocyte cell line, co-cultured with BV2 cells.

Results: After co- culture with BMSCs -CM, the mRNA expression of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase significantly decreased in pro-inflammatory BV2 cells, whereas the expression of CD206 and arginase-1 significantly increased. Moreover, TNF-α and interleukin-6 levels significantly decreased, whereas transforming growth factor-β and interleukin-10 levels significantly increased. Furthermore, co-culture with BMSCs-CM increased mitophagy-associated protein expression, ATP levels, mitochondrial and lysosomal co-localization in these cells and decreased reactive oxygen species levels. Importantly, BMSCs-CM reversed the decrease in the proliferation and migration of C8-D1A cells co-cultured with pro-inflammatory BV2 cells and inhibited the apoptosis of C8-D1A cells.

Conclusion: BMSCs-CM may promote the transition of polarized microglia from a pro-inflammatory to an anti-inflammatory phenotype by regulating mitophagy and influences the functional state of astrocytes.

Keywords: Bone marrow mesenchymal stem cells; Conditioned medium; Microglia; Mitochondrial autophagy; Polarization.

MeSH terms

  • Animals
  • Apoptosis
  • Autophagy*
  • Cell Line
  • Cell Proliferation
  • Coculture Techniques*
  • Culture Media, Conditioned / pharmacology
  • Cytokines / metabolism
  • Lipopolysaccharides / pharmacology
  • Mesenchymal Stem Cells* / cytology
  • Mesenchymal Stem Cells* / metabolism
  • Mice
  • Microglia* / metabolism
  • Mitochondria* / metabolism
  • Mitophagy
  • Phenotype

Substances

  • Culture Media, Conditioned
  • Cytokines
  • Lipopolysaccharides

Grants and funding

The authors received no funding for this work.