Thorac Cardiovasc Surg 2013; 61 - P6
DOI: 10.1055/s-0032-1332646

Xenogeneic decellularized heart valve matrices in the sheep model: A histo-morphologic analysis of a nine-month follow up study

Z Jelezneacova 1, S Cebotari 1, I Tudorache 1, T Meyer 1, K Theodoridis 1, AL Wendland 1, 2, T Goecke 1, A Mogaldea 1, KH Waldmann 2, A Haverich 1, A Hilfiker 1
  • 1Medizinische Hochschule Hannover, Klinik für Herz-, Thorax-, Transplantations- und Gefäßchirurgie, LEBAO, Hannover, Germany
  • 2Stiftung Tierärztliche Hochschule Hannover, Hannover, Germany

Objectives: Allogenic decellularized heart valves demonstrate superior durability compared to commercial available bioprostetic grafts. In comparison, xenogenic decellularized grafts, showed severe degeneration in vivo. The aim of our study was the generation of alternative xenogenic decellularized grafts to overcome the limited availability of allogeneic grafts by an improved decellularization protocol.

Methods: Porcine pulmonary heart valves (pPHV) were harvested at the local slaughterhouse and decellularized by a detergent treatment (0.5% SDS/Triton X-100). Upon of verification of complete decellularization the grafts were implanted orthotopically into full grown Merino sheep (n = 3) with a follow up time of nine months. Valve function was assessed by echocardiography after implantation and prior euthanasia. Explanted pPHV were inspected by groß morphology and by histological and immunhistological means in respect to cellular repopulation (DAPI/Phalloidin, H&E and Pentachrome stains), calcification (von Kossa stain) and inflammation (Pappenheim stain, anti-CD45 and anti-CD3 stains).

Results: Implantation and follow-up time was uneventful. Functional analysis revealed no stenosis and no regurgitation and the explant showed no thrombi. Leaflets of two pPHV were tender and shinny, whereas the leaflets of the third pPHV appeared slightly thickened. Evaluation by DAPI/Phalloidin showed an endothelium on the both sides of cusps of all pPHV. H&E and Pentachrome staining demonstrated recellularization of the extracellular matrix (ECM) and a cell migration in the conduit toward the leaflets. In the adventitia a neovessel formation was observed. Despite the presence of CD45 and CD3 positive cells (i.e. lymphocytes and macrophages) in all leaflets, no calcification (von Kossa stain) could be detected.

Conclusion: The positive outcome of this small study encourages the investigation of xenogeneic decellularized heart valve grafts as alternative grafts source to cover the shortage in allogeneic materials. Based on former experiments, we believe that the method of decellularization has a deep impact on the residual immunogenicity.