Abstract
Background aims. The immunomodulatory and anti-inflammatory effects of mesenchymal stromal cells (MSC) could prove to be a potential therapeutic approach for prolongation of survival of cell xenotransplantation. Adipose (Ad) MSC from genetically modified pigs could be an abundant source of pig donor-specific MSC. Methods. Pig (p) MSC were isolated from adipose tissue of α1,3-galactosyltransferase gene knock-out pigs transgenic for human (h) CD46 (GTKO/hCD46), a potential source of islets. After characterization with differentiation and flow cytometry (FCM), AdMSC were compared with bone marrow (BM) MSC of the same pig and human adipose-derived (hAd) MSC. The modulation of human peripheral blood mononuclear cell (hPBMC) responses to GTKO pig aortic endothelial cells (pAEC) by different MSC was compared by measuring 3H-thymidine uptake. The supernatants from the AdMSC cultures were used to determine the role of soluble factors. Results. GTKO/hCD46 pAdMSC (i) did not express galactose-α1,3-galactose (Gal) but expressed hCD46, (ii) differentiated into chondroblasts, osteocytes and adipocytes, (iii) expressed stem cell markers, (iv) expressed lower levels of Swine Leucocyte Antigen I (SLAI), Swine Leucocyte Antigen II DR (SLAIIDR) and CD80 than pAEC before and after pig interferon (IFN)-γ stimulation. The proliferative responses of hPBMC to GTKO/hCD46 pAdMSC and hAdMSC stimulators were similar, and both were significantly lower than to GTKO pAEC (P < 0.05). The proliferation of hPBMC to GTKO pAEC was equally suppressed by GTKO/hCD46 pAdMSC and hAdMSC (P > 0.05). The supernatant from GTKO/hCD46 pAdMSC did not suppress the human xenoresponse to GTKO pAEC, which was cell–cell contact-dependent. Conclusions. Initial evidence suggests that genetically modified pAdMSC function across the xenogeneic barrier and may have a role in cellular xenotransplantation.
Acknowledgments
The authors thank Drs Agnes Azimzadeh (University of Maryland) and Muhammad Mohiuddin (NHLB1) for providing pig adipose tissue and BM. Studies on xenotransplantation at the Thomas E. Starzl Transplantation Institute of the University of Pittsburgh are supported in part by the Competitive Medical Research Fund of the UPMC Health System, NIH grant number 1U19AI090959-01 and by Sponsored Research Agreements between the University of Pittsburgh and Revivicor Inc., Blacksburg, VA.
Disclosure of conflict of interest: Dr Ayares owns stock in Revivicor Inc. No other author has a conflict of interest.