Extracellular vesicles from bone marrow‐derived mesenchymal stromal cells support ex vivo survival of human antibody secreting cells

Abstract

Extracellular vesicles (EVs) from bone marrow (BM)-derived mesenchymal stromal cells (BM-MSC) are novel mechanisms of cell-cell communication over short and long distances. BM-MSC have been shown to support human antibody secreting cells (ASC) survival ex vivo, but whether the crosstalk between the MSC-ASC interaction can occur via EVs is not known. Thus, we evaluated the role of EVs in ASC survival and IgG secretion. EVs were isolated from irradiated and non-irradiated primary BM-MSC and were quantified. They were further characterized by electron microscopy (EM) and CD63 and CD81 immuno-gold EM staining. Human ASC were isolated via fluorescence-activated cell sorting (FACS) and cultured ex vivo with the EV fractions, the EV-reduced fractions, or conventional media. IgG Elispots were used to measure the survival and functionality of the ASC. Contents of the EV fractions were evaluated by proteomics. We saw that both irradiated and non-irradiated MSC secretome preparations afforded vesicles of a size consistent with EVs. Both preparations appeared comparable in EM morphology and CD63 and CD81 immuno-gold EM. Both irradiated and non-irradiated EV fractions supported ASC function, at 88% and 90%, respectively, by day 3. In contrast, conventional media maintained only 4% ASC survival by day 3. To identify the specific factors that provided in vitro ASC support, we compared proteomes of the irradiated and non-irradiated EV fractions with conventional media. Pathway analysis of these proteins identified factors involved in the vesicle-mediated delivery of integrin signalling proteins. These findings indicate that BM-MSC EVs provide an effective support system for ASC survival and IgG secretion.

Factors of the bone marrow microniche that support human plasma cell survival and immunoglobulin secretion

“…4b ). Our recent studies demonstrate an important role of EVs to mediate ASC survival which may in be in part due to YWHAZ 36 .Therefore, YWHAZ may be transported via EVs or released into the media by our methods of irradiating MSC to generate the secretomes.…”

“…The source of BM-MSC was BMA of healthy donors. Isolation and expansion of MSC were performed as previously described 36 . Briefly, BM mononuclear cells (MNC) were isolated by Ficoll-Hypaque (GE Healthcare) or Lymphocyte Separation Medium (LSM; Cellgro/Corning) density-gradient centrifugation 45 .…”

Challenges in Clinical Development of Mesenchymal Stromal/Stem Cells: Concise Review

“…Other features have been described and are now shared by the scientific community, such as genomic, epigenetic, secretomic, and proteomic profiling . More recently, the release of exosomes, a smaller EV fraction, has been outlined as a relevant biological mechanism in driving tissue regeneration . Although these properties are sufficient for defining a correlation between phenotype and stromal/stem cell functions it still has to be convincingly demonstrated; however, it represents a foundation on which more specific criteria to better identify MSC properties could be developed.…”

Immunoregulatory Effects of Stem Cell-Derived Extracellular Vesicles on Immune Cells

“…Extracellular vesicles (EVs), now identified as a novel apparatus of intercellular communication, did not garner significant attention previously, although they are currently sought after as a topic of research. EVs have a diameter ranging between 50 and 2,000 nm with a bilayer lipid membrane (1) and comprise parental cell-derived active cargos such as lipids (2), proteins (2,3), nucleic acids [(DNAs) (4), mRNA (5,6), microRNAs (miRNAs) (4), non-coding RNAs (7)] and organelles (4,8). Emerging evidence indicates that double-stranded DNA, DNA-binding histones, and certain miRNAs are not associated with small EVs such as exosomes (9).…”