APCs from vein remnants of CABG patients express antioxidant defense mechanisms, which enable them to resist stress. These properties highlight the potential of APCs in cardiovascular regenerative medicine.

Current vascular replacement grafts used in congenital heart defect corrective surgery have poor longevity and growth potential. Recipient patients often require multiple reoperations. Tissue engineering has the promise to produce a graft with the potential to grow, remodel and repair. Here we aimed at developing an amnion-based scaffold suitable for cardiovascular tissue engineering applications and in vivo usage. The developed human amnion-based scaffold was made by an enzymatic decellularization process followed by freeze-drying as a single or multi-layered structure. These structures were compared to native amnion for seeded cell viability and biomechanical properties then tested for in vivo biocompatibility. Our results demonstrated that while native amnion tissue supported little cell growth, the decellularized-amnion allowed cell engraftment and proliferation cell survival. Additionally, preservation of the scaffold by freeze-drying as a single layer, allowed further improved cell engraftment and cell growth. Multi-layering the freeze-dried amnion-scaffolds resulted in a similar cell growth potential of the single layered construct but superior mechanical strength. The multi-layered construct showed in vitro biocompatibility with endothelial cells, smooth muscle cells, cardiac myocytes, and thymus and cord-blood-derived MSCs. When implanted in a piglet model of left pulmonary artery grafting, the multi-layered construct showed its in vivo suitability and biocompatibility for vascular repair as demonstrated by the development of newly formed endothelium in the intima, a smooth muscle cell-rich medial layer and an adventitia containing new vasa vasorum. endothelial cell layer in the inner side of the graft and a smooth muscle layer in the outer side. In conclusion, our developed amnion-derived scaffold represents an off-the-shelf biocompatible structure that can be seeded with the patient's own MSCs to produce an autologous vascular graft.

Mesenchymal stem cells (MSCs) are attractive tools for regenerative medicine because of their multidifferentiation potential and immunomodulation capacity. In congenital heart defect surgical correction, replacement grafts lacking growth potential are commonly used. Tissue engineering promises to overcome the limitations of these grafts. In this study, we hypothesized that human thymus-derived MSCs are a suitable tool to tissue engineer a living vascular graft with good integration and patency once implanted in vivo. Human thymus-derived MSCs (hT-MSCs) were identified by the expression of MSC markers and mesenchymal differentiation potential. When cultured onto natural scaffold to produce tissue-engineered graft, hT-MSCs exhibited great proliferation potential and the ability to secrete their own extracellular matrix. In addition, when implanted in vivo in a piglet model of left pulmonary grafting, the engineered graft exhibited good integration within the host tissue, indicating potential suitability for corrective cardiovascular surgery. The optimized xeno-free, good manufacturing practices-compliant culture system proved to be optimum for large-scale expansion of hT-MSCs and production of tissue-engineered cardiovascular grafts, without compromising the quality of cells. This study demonstrated the feasibility of engineering clinical-grade living autologous replacement grafts using hT-MSCs and proved the compatibility of these grafts for in vivo implantation in a left pulmonary artery position.