Allograft Heart Valves: Current Aspects and Future Applications.
Human heart valve allografts continue to represent almost perfect substitutes for heart valves. They have optimal hemodynamic characteristics and are highly resistant to infections. The first clinical use of allograft heart valves was as homovitals being transplanted after antibiotic incubation without any preservation. Since 1968, relatively standardized frozen cryopreservation (SFC) has been employed, including storage in vapor-phase liquid nitrogen. Disadvantages, particularly in pediatric patients, are limited availability due to organ scarcity, inability to grow, degeneration, immune response, and long-term failure. However, in contrast to alternative prosthetic or bioprosthetic heart valve replacements, they represent the best pediatric and juvenile replacement options for the pulmonary valve. Application of multiphoton imaging analysis for three-dimensional visualization of elastin and collagen by induction of autofluorescence without chemical fixation, embedding, and staining has revealed partial destruction of elastic and collagenous matrix in SFC valves. As the overall amount of collagen and elastin remains unchanged, the observed destruction is attributed to freezing-induced extracellular matrix damages due to ice crystal formation during SFC. The objective of this review is an assessment of current allograft preservation methods and the potential of novel preservation techniques to avoid ice formation with accompanied better long-term function.
1 Department of General, Visceral, Thoracic and Vascular Surgery, Frankfurt-Höchst City Hospital , Frankfurt am Main, Germany .
Milan
M
Lisy
1 Department of General, Visceral, Thoracic and Vascular Surgery, Frankfurt-Höchst City Hospital , Frankfurt am Main, Germany .
Guenay
G
Kalender
2 Department of Cell and Tissue Engineering, Fraunhofer Institute for Interfacial Engineering , Stuttgart, Germany .|3 Department of Women's Health, Research Institute for Women's Health, University Tuebingen , Tuebingen, Germany .|4 Cardiovascular Research Laboratories, Department of Medicine/Cardiology, David Geffen School of Medicine , UCLA, Los Angeles, California.
Katja
K
Schenke-Layland
5 Tissue Testing Technologies LLC , North Charleston, South Carolina.|6 Department of Bioengineering, Clemson University , Clemson, South Carolina.|7 Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina , South Carolina.
Kelvin G M
KG
Brockbank
8 Department of Thoracic, Cardiac and Thoracic Vascular Surgery, University Hospital Frankfurt , Frankfurt, Germany .
Anna
A
Biermann
8 Department of Thoracic, Cardiac and Thoracic Vascular Surgery, University Hospital Frankfurt , Frankfurt, Germany .
Ulrich Alfred
UA
Stock
D064591:Allografts / Q000502:physiology*; D000818:Animals; D015925:Cryopreservation; D005615:Freezing; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000502:physiology*; D006801:Humans; D023822:Tissue Engineering
biopreservation; cryopreservation; human tissue; vitrification