Baaijens, F.P.T.

Bouten, C.V.C.

Cox, M.A.J.

Kortsmit, J.

English

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 Tissue engineered heart valves develop native-like collagenarchitectureCitation for published version (APA):Cox, M. A. J., Kortsmit, J., Bouten, C. V. C., & Baaijens, F. P. T. (2008). Tissue engineered heart valves developnative-like collagen architecture. Poster session presented at Mate Poster Award 2008 : 13th Annual PosterContest.Document status and date:Published: 01/01/2008Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 08. Feb. 2024Photograph: Bart van OverbeekeTissue engineered heart valves developnative-like collagen architectureMartijn Cox, Jeroen Kortsmit, Carlijn Bouten, Frank BaaijensEindhoven University of Technology, Department of Biomedical Engineering, The Netherlands/ Biomechanics & Tissue EngineeringIntroductionTo meet in vivo demands, native heart valves have developed an inhomogenous and anisotropic collagennetwork [Fig 1]. Figure 1: The native collagen fiber architecture (left) has parallelbundles running from the commissures (green) towards a more branched circumferential network in the belly (red). Adapted from [1]. This is represented (right) by a narrow fiber distribution (high alignment) in the commissures and a wider distribution in the belly. In tissue engineering we hypothesize that: mimicking hemodynamic loads in a bioreactor will result in native-liketissue development.Although this approach resulted in strong human tissue enineered heart valves (TEHV) [2]  several questionsremain:• Do TEHV develop local native-like fiber architecture?• Can we optimize protocols for this goal?MethodFigure 2: Tissue deformation is induced with a spherical indenter and measured using inverse confocal microscpoy. Digital Image Correlationshows that tissue deforms mainly perpendicular to the main fiber direction. An inverse Finite Element (FEM) analysis is used to estimatefiber distribution and mechanics [3]. ResultsTEHV (n=10) were cultured for 4 weeks using 3 different loading protocols. Indentation tests were performed in the belly and commissure region of each leaflet. In 7 out of 10 valves circumferential alignment (0o) was found in the bellyregion and commissural fiber direction was between 0 and 45o. The exact commissural fiber direction varied betweenprotocols. Figure 3: Top left: loading protocols applied during culture. Top right & bottom row: Estimated fiber distributions demonstrate increasing fiber alginment with increasing load during culture.In 5 out of 10 valves commissural alignment was higher (narrower distribution) than in the belly; the other 5 valves did not reveal differences. Interestingly overall fiber alignment increased with applied load [Fig 3], which is consistent with theoretical predictions [4].Conclusions• Yes, TEHV do develop native-like fiber architecture:– circumferential orientation in belly region (0o)– orientation between 0 and 45o in commissure region• Yes, we can optimize protocols for this goal:– Increased loading leads to increased collagen alignmentReferences[1] Sauren AAHJ: PhD Thesis, 1981[2] Mol A et al.: Circulation 114(I), 2006 [3] Cox MAJ et al,: JBiomech 41(2), 2008[4] Driessen NJB et al.: BMMB 7, 2008-90 -45 0 45 9000.01fiber orientation [deg] fiber volume fraction [-] Abellycommissure-90 -45 0 45 9000.01fiber orientation [deg] fiber volume fraction [-] Bbellycommissure-90 -45 0 45 9000.01fiber orientation [deg] fiber volume fraction [-] Cbellycommissure8 12 16 20 24 2800.020.040.060.080.100.120.140.160.18culture time [days]applied deformation [ml]ACB-90 -60 -30 0 30 60 90fiber angle [deg]fiber volume fraction[-]bellycommissure00+900-900parameter estimationfiberprops.ε1,ε2expFEM

Tissue engineered heart valves develop native-like collagen architecture

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Tissue engineered heart valves develop native-like collagen architecture

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