Transplantation of a Tissue-Engineered Human Vascularized Cardiac Muscle

TLDR

Myocardial regeneration strategies have been hampered by a lack of human cardiomyocyte sources and significant donor cell loss after transplantation. The study evaluated whether a three‑dimensional tissue‑engineered human vascularized cardiac muscle could engraft in a rat heart and promote functional vascularization. Human embryonic stem‑cell–derived cardiomyocytes were combined with endothelial cells and fibroblasts, seeded onto biodegradable porous scaffolds, and the resulting triculture constructs were transplanted into the rat heart to form cardiac tissue grafts. The triculture grafts formed stable tissue with both donor and host vasculature, functionally integrated human vessels into the host coronary system, and displayed a significantly higher vessel density (60.3 ± 8 mm⁻³ versus 39.0 ± 14.4 mm⁻³) compared with cardiomyocyte‑only scaffolds.

Abstract

Myocardial regeneration strategies have been hampered by the lack of sources for human cardiomyocytes (CMs) and by the significant donor cell loss following transplantation. We assessed the ability of a three-dimensional tissue-engineered human vascularized cardiac muscle to engraft in the in vivo rat heart and to promote functional vascularization. Human embryonic stem cell-derived CMs alone or with human endothelial cells (human umbilical vein endothelial cells) and embryonic fibroblasts (triculture constructs) were seeded onto biodegradable porous scaffolds. The resulting tissue constructs were transplanted to the in vivo rat heart and formed cardiac tissue grafts. Immunostaining studies for human-specific CD31 and alpha-smooth muscle actin demonstrated the formation of both donor (human) and host (rat)-derived vasculature within the engrafted triculture tissue constructs. Intraventricular injection of fluorescent microspheres or lectin resulted in their incorporation by human-derived vessels, confirming their functional integration with host coronary vasculature. Finally, the number of blood vessels was significantly greater in the triculture tissue constructs (60.3 +/- 8/mm(3), p < 0.05) when compared with scaffolds containing only CMs (39.0 +/- 14.4/mm(3)). In conclusion, a tissue-engineered human vascularized cardiac muscle can be established ex vivo and transplanted in vivo to form stable grafts. By utilizing a multicellular preparation we were able to increase biograft vascularization and to show that the preexisting human vessels can become functional and contribute to tissue perfusion.