Bioartificial heart: a human-sized porcine model--the way ahead.

BACKGROUND: A bioartificial heart is a theoretical alternative to transplantation or mechanical left ventricular support. Native hearts decellularized with preserved architecture and vasculature may provide an acellular tissue platform for organ regeneration. We sought to develop a tissue-engineered whole-heart neoscaffold in human-sized porcine hearts. METHODS: We decellularized porcine hearts (n = 10) by coronary perfusion with ionic detergents in a modified Langendorff circuit. We confirmed decellularization by histology, transmission electron microscopy and fluorescence microscopy, quantified residual DNA by spectrophotometry, and evaluated biomechanical stability with ex-vivo left-ventricular pressure/volume studies, all compared to controls. We then mounted the decellularized porcine hearts in a bioreactor and reseeded them with murine neonatal cardiac cells and human umbilical cord derived endothelial cells (HUVEC) under simulated physiological conditions. RESULTS: Decellularized hearts lacked intracellular components but retained specific collagen fibers, proteoglycan, elastin and mechanical integrity; quantitative DNA analysis demonstrated a significant reduction of DNA compared to controls (82.6±3.2 ng DNA/mg tissue vs. 473.2±13.4 ng DNA/mg tissue, p<0.05). Recellularized porcine whole-heart neoscaffolds demonstrated re-endothelialization of coronary vasculature and measurable intrinsic myocardial electrical activity at 10 days, with perfused organ culture maintained for up to 3 weeks. CONCLUSIONS: Human-sized decellularized porcine hearts provide a promising tissue-engineering platform that may lead to future clinical strategies in the treatment of heart failure.

Reendothelialization of human heart valve neoscaffolds using umbilical cord-derived endothelial cells.

BACKGROUND: Heart valve tissue engineering represents a concept for improving the current methods of valvular heart disease therapy. The aim of this study was to develop tissue engineered heart valves combining human umbilical vein endothelial cells (HUVECs) and decellularized human heart valve matrices. METHODS AND RESULTS: Pulmonary (n=9) and aortic (n=6) human allografts were harvested from explanted hearts from heart transplant recipients and were decellularized using a detergent-based cell extraction method. Analysis of decellularization success was performed with light microscopy, transmission electron microscopy and quantitative analysis of collagen and elastin content. The decellularization method resulted in full removal of native cells while the mechanical stability and the quantitative composition of the neoscaffolds was maintained. The luminal surface of the human matrix could be successfully recellularized with in vitro expanded HUVECs under dynamic flow conditions. The surface appeared as a confluent cell monolayer of positively labeled cells for von Willebrand factor and CD 31, indicating their endothelial nature. CONCLUSIONS: Human heart valves can be decellularized by the described method. Recellularization of the human matrix resulted in the formation of a confluent HUVEC monolayer. The in vitro construction of tissue-engineered heart valves based on decellularized human matrices followed by endothelialization using HUVECs is a feasible and safe method, leading to the development of future clinical strategies in the treatment of heart valve disease.

Development and evaluation of a perfusion decellularization porcine heart model--generation of 3-dimensional myocardial neoscaffolds.

BACKGROUND: Reports about the generation of 3-dimensional neoscaffolds for myocardial tissue engineering are limited. The architecture provided by perfusion decellularization of whole hearts would support the production of human-sized 3-dimensional living tissues from an acellular matrix. The aim of this study was to evaluate the potential of a perfusion decellularization model for whole heart tissue engineering. METHODS AND RESULTS: Hearts were obtained from 12 German Landrace pigs from a selected abattoir. After preparation, the hearts were mounted and perfused on a modified Langendorff decellularization model specifically constructed for this reason. Decellularization was achieved by an ionic detergent-based perfusion protocol. The quality of the decellularization process was quantified by histology and fluorescence microscopy. Data regarding the presence of residual DNA within the decellularized hearts was measured with spectrophotometric quantification and compared to controls. After histological examination, all hearts lacked intracellular components but retained various types of collagen, proteoglycan and elastin. Quantitative DNA analysis demonstrated a significant reduction of DNA in decellularized hearts compared to controls (84.32±3.99 ng DNA/mg tissue vs. 470.13±18.77 ng DNA/mg tissue (P<0.05)). CONCLUSIONS: The modified Langendorff perfusion decellularization model described here is applicable for whole porcine hearts by removing cellular content and DNA. The resulting 3-dimensional matrix provides an interesting tool for further studies in the field of whole heart tissue engineering.