Superior Ventriculo-Arterial Coupling with Decellularized Allografts Compared with Conventional Prostheses

Background To date, no experimental or clinical study provides detailed analysis of vascular impedance changes after total aortic arch replacement. This study investigated ventriculoarterial coupling and vascular impedance after replacement of the aortic arch with conventional prostheses vs. decellularized allografts. Methods After preparing decellularized aortic arch allografts, their mechanical, histological and biochemical properties were evaluated and compared to native aortic arches and conventional prostheses in vitro. In open-chest dogs, total aortic arch replacement was performed with conventional prostheses and compared to decellularized allografts (n = 5/group). Aortic flow and pressure were recorded continuously, left ventricular pressure-volume relations were measured by using a pressure- conductance catheter. From the hemodynamic variables end-systolic elastance (Ees), arterial elastance (Ea) and ventriculoarterial coupling were calculated. Characteristic impedance (Z) was assessed by Fourier analysis. Results While Ees did not differ between the groups and over time (4.1±1.19 vs. 4.58±1.39 mmHg/mL and 3.21±0.97 vs. 3.96±1.16 mmHg/mL), Ea showed a higher increase in the prosthesis group (4.01±0.67 vs. 6.18±0.20 mmHg/mL, P<0.05) in comparison to decellularized allografts (5.03±0.35 vs. 5.99±1.09 mmHg/mL). This led to impaired ventriculoarterial coupling in the prosthesis group, while it remained unchanged in the allograft group (62.5±50.9 vs. 3.9±23.4%). Z showed a strong increasing tendency in the prosthesis group and it was markedly higher after replacement when compared to decellularized allografts (44.6±8.3dyn·sec·cm−5 vs. 32.4±2.0dyn·sec·cm−5, P<0.05). Conclusions Total aortic arch replacement leads to contractility-afterload mismatch by means of increased impedance and invert ventriculoarterial coupling ratio after implantation of conventional prostheses. Implantation of decellularized allografts preserves vascular impedance thereby improving ventriculoarterial mechanoenergetics after aortic arch replacement

Total Aortic Arch Replacement: Superior Ventriculo-Arterial Coupling with Decellularized Allografts Compared with Conventional Prostheses.

BACKGROUND: To date, no experimental or clinical study provides detailed analysis of vascular impedance changes after total aortic arch replacement. This study investigated ventriculoarterial coupling and vascular impedance after replacement of the aortic arch with conventional prostheses vs. decellularized allografts. METHODS: After preparing decellularized aortic arch allografts, their mechanical, histological and biochemical properties were evaluated and compared to native aortic arches and conventional prostheses in vitro. In open-chest dogs, total aortic arch replacement was performed with conventional prostheses and compared to decellularized allografts (n = 5/group). Aortic flow and pressure were recorded continuously, left ventricular pressure-volume relations were measured by using a pressure-conductance catheter. From the hemodynamic variables end-systolic elastance (Ees), arterial elastance (Ea) and ventriculoarterial coupling were calculated. Characteristic impedance (Z) was assessed by Fourier analysis. RESULTS: While Ees did not differ between the groups and over time (4.1+/-1.19 vs. 4.58+/-1.39 mmHg/mL and 3.21+/-0.97 vs. 3.96+/-1.16 mmHg/mL), Ea showed a higher increase in the prosthesis group (4.01+/-0.67 vs. 6.18+/-0.20 mmHg/mL, P<0.05) in comparison to decellularized allografts (5.03+/-0.35 vs. 5.99+/-1.09 mmHg/mL). This led to impaired ventriculoarterial coupling in the prosthesis group, while it remained unchanged in the allograft group (62.5+/-50.9 vs. 3.9+/-23.4%). Z showed a strong increasing tendency in the prosthesis group and it was markedly higher after replacement when compared to decellularized allografts (44.6+/-8.3dyn.sec.cm-5 vs. 32.4+/-2.0dyn.sec.cm-5, P<0.05). CONCLUSIONS: Total aortic arch replacement leads to contractility-afterload mismatch by means of increased impedance and invert ventriculoarterial coupling ratio after implantation of conventional prostheses. Implantation of decellularized allografts preserves vascular impedance thereby improving ventriculoarterial mechanoenergetics after aortic arch replacement

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

Contractility, afterload and ventriculoarterial coupling.

<p>End-systolic elastance (Ees, A), arterial elastance (Ea, B) at baseline and after total aortic arch replacement; and relative changes of ventriculoarterial coupling (VAC, C) in the prosthesis and decellularized allograft groups. All values are given as means ± SEM, *:P<0.05 vs. Baseline</p

ECM composition of aortic arch samples.

<p>HE stain, Masson's Trichrome stain and Movat's Pentachrome stain show complete preservation of the ECM after the decellularization procedure of aortic arch specimens. Bars, 50 µm. Masson's Trichrome stain: cytoplasm (red), collagen (blue), nuclei (dark brown). Movat's Pentachrome stain: nuclei (dark purple to black), elastic fibres (purple to black), collagen (yellow), glycosaminoglycans (green), mucin (blue), cytoplasm (pink to brownish-red).</p

Results of biomechanical measurements.

<p>Left ventricular peak pressure vs. volume. Decellularized hearts showed similar mechanical stability as native hearts with no significant differences in biomechanical behavior. All values are expressed as mean ± SEM.</p

Photomicrographs of unstained tissue samples demonstrating intact coronary vasculature (A, B) with intact third- and fourth-level vessels (A, red arrows).

<p>The extracellular matrix composition of the aortic wall (<b>C</b>) and aortic valve leaflet (<b>D</b>) was preserved after decellularization and showed no remnant nuclear material as demonstrated by hematoxylin and eosin (HE) staining (C, D) and TEM analysis (<b>box in D</b>). Also the aortic valve remained competent after decellularization (<b>E, F</b>).</p

Representative images of a porcine heart before (A) and after (B) decellularization with sodium dodecyl sulfate (SDS).

<p>All structures including the coronary vasculature (B, red arrow) are preserved. Hematoxylin and eosin (HE) staining of ventricular tissue before (C) and after perfusion decellularization (D) showing no remnant nuclear structures after treatment with SDS, with maintained extracellular matrix and coronary vessels (D, black arrow). Scale bars, 200 µm.</p

DNA, collagen and elastin content.

<p>Total DNA content of native aortic arch tissue and decellularized aortic arch allografts (A). Collagen and elastin content of decellularized aortic arch allograft samples compared to that of native aortic arch tissue (B) *:P<0.05 vs. Native aortic arch</p

Images of native (A, C, E, G) and decellularized ventricular tissue (B, D, F, H) stained with DAPI, Masson's Trichrome Stain (Masson), Herovici's Stain (Herovici) and Movat's Pentachrome Stain (Movat) revealed absence of nuclear staining after decellularization (B) and stable preservation of extracellular matrix collagen, elastic fibers including large coronary vessels (D, H, red arrow) after the decellularization procedure.

<p>Scale bars, 200 µm.</p