Blood-compatible endometrial mesenchymal stem cells for clinical application

Background & Aim The vascular endothelium is in direct contact with blood and serves as a vital barrier between blood and tissues. Unique to endothelium is their high expression of anti-clotting proteins maintaining blood fluidity and preventing clot formation. Unlike endothelial cells, tissue-resident cells, including most clinically used mesenchymal stem cells (MSCs) are inherently pro-clotting and express proteins such as tissue factor (TF) and collagen-1 triggering clotting on blood contact. Endometrial MSCs (eMSCs) are a unique source of highly proliferative and clonogenic MSCs. This study aims to investigate the blood compatibility profile of eMSCs in pathological environments, simulating inflammation (Infm) and infection (Infn). Methods, Results & Conclusion Human SUSD2+eMSCs were expanded in TGF-βR inhibitor, A8301-containing medium and exposed to TNFα/IFNγ (Infm) or LPS (Infnb) or Poly IC (Infnv). Genes and proteins for haemocompatibility, anti-inflammatory, immunoregulatory, antimicrobial and reparative properties were assessed using RT-PCR, flowcytometry, immunoblotting, ELISA and co-cultured with activated T cells.Resting eMSC/A8301 expressed high SUSD2, CD200, CD274, HLA-ABC, CD46 and CD55, very low TF but no HLA-DR and CD86. These protein levels were maintained under inflammation but TF increased in 60% of the Infm- and InfnbeMSCs. This was associated with a high expression of potent anti-clotting proteins; TM, PGI2, MMP9 and TFPI, and genes; PROS1, tPA, antithrombin-binding HSPGs, CFH, CFI, GAL-1 and MMP1. In addition, InfmeMSCs secreted BAFF, KGF, HGF, PGE2, IDO and VEGF exclusively under inflammatory signals and mitigated T-cell activation by significantly inhibiting their growth and inflammatory cytokines production.InfnbeMSCs secreted potent antimicrobial cytokines such as CCL20, LL37, LEAP2, Chromogranin B, CXCL4, Resistin and Lipocalin. Similarly, InfnveMSCs expressed high levels of interferon-stimulated genes and the antiviral proteins IFITM1/3, OAS1, IFIT1 and MX1. eMSCs/A8301 express surface CD14, CXCR4, TLR2 and intracellular TLR3 but not TLR4 indicating the signalling process in response to gram-positive and negative bacteria and viruses.Our data suggest eMSCs dampen inflammation, fight pathogens, display tissue reparative properties and most importantly may prevent activation of the coagulation cascade when infused suggesting their blood compatibility. eMSCs could be a potentially safer and more efficacious MSC to treat a wide range of diseases via the intravascular route.