Transforming Growth Factor-β2 Downregulates Major Histocompatibility Complex (MHC) I and MHC II Surface Expression on Equine Bone Marrow-Derived Mesenchymal Stem Cells Without Altering Other Phenotypic Cell Surface Markers.
Authors: Berglund Alix K, Fisher Matthew B, Cameron Kristin A, Poole Emma J, Schnabel Lauren V
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Allogeneic mesenchymal stem cell (MSC) therapy offers considerable potential for treating equine musculoskeletal injuries, yet donor-recipient MHC mismatch poses a significant immunological barrier that can trigger rejection and limit clinical efficacy. Berglund and colleagues investigated whether transforming growth factor-β2 (TGF-β2) could suppress MHC expression on equine bone marrow-derived MSCs, treating cells from 12 horses with TGF-β2 concentrations of 1, 5, or 10 ng/ml and measuring changes in MHC I and II surface expression alongside other phenotypic markers. TGF-β2 treatment successfully reduced both baseline MHC I and II expression and partially blocked interferon-γ-induced upregulation of these molecules; notably, the therapy increased cell yield without affecting morphology, viability, or other surface markers, though the immunosuppressive effect varied substantially between donor animals. Whilst these findings suggest TGF-β2 could enhance allogeneic MSC survival in vivo by reducing immune recognition, the treatment's inability to maintain MHC suppression under inflammatory challenge indicates further refinement is necessary before clinical application. For practitioners considering allogeneic cell therapies, this research highlights both the promise of immune-evasion strategies and the practical reality that individual horse variability and inflammatory conditions may require customised or combination approaches to achieve reliable transplant tolerance.
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Practical Takeaways
- •TGF-β2 pre-treatment of allogeneic MSCs shows potential to reduce immune rejection risk, but donor variability means individual testing may be necessary for clinical application
- •While TGF-β2 reduces baseline MHC expression, it does not fully prevent inflammatory upregulation—additional strategies may be needed to maintain immune-evasive properties in the inflamed injured tissue
- •TGF-β2 treatment increases MSC yield without compromising cell quality, which could improve economic feasibility of therapeutic MSC preparation
Key Findings
- •TGF-β2 treatment reduced MHC I and MHC II surface expression on equine bone marrow-derived MSCs at 1, 5, and 10 ng/ml concentrations
- •TGF-β2 partially blocked IFN-γ-induced upregulation of MHC I and MHC II expression
- •TGF-β2 treatment increased cell yield without altering morphology, viability, or other phenotypic surface markers
- •MHC expression response to TGF-β2 was highly variable and donor-dependent, with variable baseline MHC expression levels