Proteomic signature of menstrual blood mesenchymal stromal cells and their extracellular vesicles in women with unexplained infertility.

RESEARCH QUESTION: Can the proteome of menstrual blood mesenchymal stromal cells (MenSC), their extracellular vesicles or extracellular-vesicle-depleted supernatant be employed for personalized identification of altered cellular processes in women with unexplained infertility (uIF), enabling their stratification into aetiopathogenetic endotypes?

DESIGN

For MenSC isolation, menstrual blood was collected from 12 fertile healthy volunteers (control group) and eight patients with uIF. MenSC extracellular vesicles were isolated using iodixanol density gradient centrifugation, quantified by flow cytometry and characterized in accordance with the Minimal Information for Studies of Extracellular Vesicles (MISEV) guidelines by transmission electron microscopy, flow cytometry and western blot analysis. Proteomic analysis was undertaken using mass spectrometry and bioinformatic tools.

RESULTS

Mesenchymal marker expression and phenotype of MenSC isolated from the menstrual blood of fertile females and females with uIF did not differ between the groups. MenSC-derived extracellular vesicles were isolated successfully from the conditioned media, and characterized in accordance with the MISEV guidelines. The comprehensive proteomic analysis of MenSC, MenSC extracellular vesicles and extracellular-vesicle-depleted MenSC supernatant showed significant changes in the proteome in all three sample types of uIF, mainly implying compromised cell adhesion, immune response, fibrosis and altered metabolism. These findings were validated by western blot analysis.

CONCLUSIONS

Proteome changes in cell adhesion, immune and inflammatory processes, and protein metabolism were observed in menstrual blood samples of the uIF group. The proteins responsible for these processes may be used as biomarkers to stratify patients into distinct molecular endotypes characterized by altered adhesion, immune response, fibrosis and metabolism, which may lead to the development of personalized treatment approaches for women with uIF.