Heart Valve Tissue Engineering

Veselý, Ivan

doi:10.1002/9780471740360.ebs1575

Cited by 43 publications

(61 citation statements)

References 58 publications

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“…Daher haben diese Pro thesen eine stark limitierte Haltbarkeit von etwa 5 bis 10 Jahren, was zur Notwen digkeit früher, bei jungen Menschen so gar wiederholter Reoperation führt. Lei der wird besonders im Kindes und Ju gendalter sowie bei Dialysepatienten eine früh einsetzende Verkalkung dieser Klap pen nachgewiesen [5].…”

Section: Klinischer Hintergrundunclassified

“…Abb. 1c) [5], die zwar aufgrund der höheren Bio kompatibilität ebenfalls keiner antiko agulatorischen Therapie bedürfen, je doch nur begrenzt verfügbar sind und fer ner durch immunologische Reaktionen ebenfalls eine limitierte Haltbarkeit be sitzen [5] Die Nutzung der zellfreien biologischen Matrizes für das TE gehört zu den ältesten Methoden [22]. Bereits in den 80er Jahren des letzten Jahrhunderts wurden experi mentell Konzepte erprobt, bei denen die Vorteile einer biologischen Klappenma trix, insbesondere die überragenden hä modynamischen Eigenschaften einer sol chen Matrix, die aus dem nahezu perfek ten dreidimensionalen Klappendesign re sultieren, gezeigt wurden.…”

Section: Klinischer Hintergrundunclassified

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Tissue Engineering von Herzklappen

Akhyari

Minol

Assmann

et al. 2011

Chirurg

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With the introduction of heart valve prostheses cardiac valvular disease has become much more accessible to therapeutic options. However, currently available prostheses display significant limitations, such as limited long-term durability (biological prostheses) and a long-term necessity for anticoagulation therapy. Hence, alternative prosthesis types have been extensively explored in recent years particularly aiming at the development of vital and regenerative prostheses by means of tissue engineering. In the scientific field, different competing concepts have been introduced, including biological or synthetic scaffolds which can be further enhanced by cellular or extracellular components to promote further in vivo development of the prosthesis after implantation. Nowadays, decellularized donor heart valves are among the most advanced prosthesis types experiencing growing clinical attention and widespread use.

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Section: Klinischer Hintergrundunclassified

Tissue Engineering von Herzklappen

Akhyari

Minol

Assmann

et al. 2011

Chirurg

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“…Currently, potential decellularization procedures are evaluated using trial-and-error approaches that involve time consuming and expensive chronic animal studies. 32,34,38,39 As an example, the best scenario one can envisage is a successful reseeding followed by tissue maintenance in the valve implants; however, one might ask what if the reseeded cells in TEHV reduce in numbers or lose functionality. It is thus important to know the intrinsic fatigue mechanism of the acellular valve leaflets in the absence of cell maintenance.…”

Section: Introductionmentioning

confidence: 99%

The Intrinsic Fatigue Mechanism of the Porcine Aortic Valve Extracellular Matrix

Liao

Joyce

Merryman

et al. 2012

Cardiovasc Eng Tech

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Decellularized aortic valves (AV) are promising scaffolds for tissue engineered heart valve (TEHV) application; however, it is not known what the intrinsic fatigue mechanism of the AV extracellular matrix (ECM) is and how this relates to decellularized AV functional limits when tissue remodeling does not take place. In this study, decellularized AVs were subjected to in vitro cardiac exercising and the exercised leaflets were characterized to assess the structural and mechanical alterations. A flow-loop cardiac exerciser was designed to allow for pulsatile flow conditions while maintaining sterility. The acellular valve conduits were sutured into a silicone root with the Valsalva sinus design and subjected to cardiac cycling for 2 weeks (1.0 million cycles) and 4 weeks (2.0 million cycles). Following exercising, thorough structural and mechanical characterizations were then performed. The overall morphology was maintained and the exercised leaflets were able to coapt and support load; however, the leaflets exhibited an unfolded and thinned morphology. The straightening of the locally wavy collagen fiber structure was confirmed by histology and small angle light scattering; the disruption of elastin network was also observed. Biaxial mechanical testing showed that the leaflet extensibility was largely reduced by cardiac exercising. In the absence of cellular maintenance, decellularized leaflets experience structural fatigue due to lack of exogenous stabilizing crosslinks, and the structural disruption is irreversible and cumulative. Although not being a means to predict the durability of the acellular valve implants, this mechanistic study reveals the fatigue pattern of the acellular leaflets and implies the importance of recellularization in developing a TEHV, in which long term durability will likely be better achieved by continual remodeling and repair of the valvular ECM.

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“…Given their long life expectancy and the increased mortality rate (20%) for the case of repeated heart valve substitutions, 25 implant durability represents a major issue for valve replacement in young patients; currently, the main limitation is the inability of the state-of-the-art valve substitutes to adapt and grow.…”

Section: Introductionmentioning

confidence: 99%

A Bioreactor with Compliance Monitoring for Heart Valve Grafts

et al. 2009

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The drawbacks of state-of-the-art heart valve prostheses lead researchers to explore the prospect of using tissue-engineered constructs as possible valve substitutes. It is widely accepted that the mechanical properties of the construct are improved with mechanical stimulation during in vitro growth. We designed a new dynamic bioreactor with the perspective of using decellularized valve homografts as scaffolds in order to produce tissue-engineered valve substitutes. The design guidelines were (a) compatibility with the procedures for the treatment of homografts; (b) delivery of finely controlled pulsatile pressure loads, which induce strain stimuli that may drive cells toward repopulation of and integration with the natural scaffold; and (c) monitoring the construct's biomechanical status through a comprehensive index, i.e., its compliance. The handling needs during the set-up of the homograft and the use of the bioreactor were minimized. The bioreactor and its automated control system underwent tests with a compliant phantom valve. The estimated compliances are in good agreement with the measured ones. Tests were also carried out with porcine aortic samples in order to assess the hydrodynamic and biomechanical reliability. In the future, monitoring the construct's compliance might represent a key factor in controlling the recellularization of the valve homografts, which provides awareness of the construct's biomechanical status by real-time, non-destructive, and non-invasive means.

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Heart Valve Tissue Engineering

Cited by 43 publications

References 58 publications

Tissue Engineering von Herzklappen

Tissue Engineering von Herzklappen

The Intrinsic Fatigue Mechanism of the Porcine Aortic Valve Extracellular Matrix

A Bioreactor with Compliance Monitoring for Heart Valve Grafts

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