Bovine fetal mesenchymal stem cells exert antiproliferative effect against mastitis causing pathogen Staphylococcus aureus.

Staphylococcus aureus is the most commonly isolated pathogen from clinical bovine mastitis samples and a difficult pathogen to combat. Mesenchymal stem cells (MSC) are multipotent progenitor cells equipped with a variety of factors that inhibit bacterial growth. The aim of the present study was to evaluate the in vitro antibacterial potential against S. aureus of conditioned medium (CM) from MSC derived from fetal bovine bone marrow (BM-MSC) and adipose tissue (AT-MSC). BM-MSC, AT-MSC and fetal fibroblasts (FB) cultures were activated by infection with S. aureus. Bacterial growth was evaluated in presence of CM, concentrated CM (CCM), activated CM (ACM) and concentrated ACM (CACM) from BM-MSC, AT-MSC and FB. Gene expression of ß-defensin 4A (bBD-4A), NK-lysine 1 (NK1), cathelicidin 2 (CATHL2), hepcidin (HEP) and indoleamine 2,3 dioxygenase (IDO) and protein expression of bBD-4A were determined in activated and non-activated cells. The majority of BM-MSC and AT-MSC expressed CD73, Oct4 and Nanog, and were negative for CD34. Growth of S. aureus decreased when it was exposed to CM from BM-MSC, AT-MSC and FB. Moreover, growth of S. aureus in CCM, ACM and CACM was lower compared to controls of CM from BM-MSC and AT-MSC. Activated AT-MSC increased mRNA levels of bBD4A and NK1, and protein levels of bBD4A in CM. Thus, CM from fetal bovine BM-MSC and AT-MSC has the capacity to reduce in average ~30% of S. aureus relative growth under in vitro conditions. The in vitro antibacterial effect of fetal bovine MSC may be mediated by bBD4A and NK1 activity.

Immunomodulatory and immunogenic properties of mesenchymal stem cells derived from bovine fetal bone marrow and adipose tissue.

Little information is currently available on therapeutic features of bovine mesenchymal stem cells (MSCs), despite the development of large animal experimental models including cattle may open alternative strategies for investigating MSC physiology and eventual applications for regenerative therapy. The aim of the present study was to compare in vitro immunomodulatory and immunogenic potentials of bovine fetal MSCs (bfMSCs) derived from bovine fetal bone marrow (BM-MSCs) and adipose tissue (AT-MSCs). Immunomodulatory analyses in bfMSCs were performed by determination of the effect of interferon-γ (IFNγ) on mRNA levels of indoleamine 2, 3-dioxygenase (IDO), transforming growth factor ß1 (TGFß1), prostaglandin E receptor 2 (PTGER2), interleukin-6 and -10 (IL-6 and IL-10), and IDO enzymatic activity. The effect of conditioned medium from IFNγ-stimulated bfMSCs on the proliferation of alloantigen-activated peripheral blood lymphocytes (PBLs) was assessed. Immunogenicity of bfMSCs was determined by quantification of mRNA levels of major histocompatibility complex I and II (MHC-I and -II), CD80 and CD86, and the proportion of cells positive for MHC-I and -II by flowcytometry (FACS) analyses. IFNγ treatment increased IL-6, PTGER2 and IDO gene expression and activity in bfMSCs but did not affect suppressive effect on proliferation of PBLs. Lower proportion of AT-MSCs expressed MHC-I and MHC-II in comparison to BM-MSCs. In conclusion, BM-MSCs and AT-MSCs upregulated expression of immunomodulatory genes in a similar way after IFNγ stimuli. BM-MSCs and AT-MSCs in basal condition and treated with IFNγ displayed similar in vitro immunomodulatory ability. Lower expression of MHC-I and MHC-II suggest that AT-MSCs might be less immunogenic compared to BM-MSCs.