Collatusso Claudinei, Roderjan João Gabriel, de Noronha Lucia, Klosowski Allyson, Suss Paula Hansen, Guarita-Souza Luiz César, Costa Francisco Diniz Affonso da
Department of Cardiac Surgery, Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Brazil.
Department of Biochemistry, PUCPR, Curitiba, Brazil.
Interact Cardiovasc Thorac Surg. 2019 Aug 1;29(2):302–311. doi: 10.1093/icvts/ivz041. Epub 2019 Mar 8.
Decellularization is an alternative method for processing biological tissues with decreased antigenicity and resistance to calcification. The aim of this study was to characterize the properties of decellularized (dCell) bovine pericardium fixed with 0.1% glutaraldehyde (GA) and to evaluate outcomes of bioprosthetic valves constructed with this tissue when implanted in the mitral position of juvenile sheep.
Bioprosthetic mitral valves were constructed with fresh bovine pericardium fixed in 0.5% GA (control group) or dCell bovine pericardium fixed in 0.1% GA (study group). Before implantation, samples were submitted to histological (haematoxylin-eosin, Movat and 4',6-diamidino-2-phenylindole), biochemical (residual deoxyribonucleic acid and α-gal epitopes) and biomechanical characterization. Valves were implanted (n = 8 in each group) as a mitral valve replacement for 180 days in sheep and explants were re-evaluated histologically and for calcification with radiological studies and calcium content determination.
Unimplanted dCell pericardia exhibited a well-preserved extracellular matrix with absence of cells, a 77% reduction in deoxyribonucleic acid levels and with no detectable α-gal epitopes. When compared to controls, they had lower ultimate tensile strength (7.3 ± 5.4 vs 10.2 ± 3.0 mPa, P = 0.04) and greater percentage elongation in the longitudinal direction (29 ± 6.5% vs 23.8 ± 5.1%, P = 0.02). After 180 days in mitral position, dCell valves showed pliable leaflets without macroscopic signs of calcification. Histologically, dCell leaflets had intact collagen fibres, better tissue remodelling and a significant 89% reduction in calcium content.
This study demonstrates that bioprosthetic valves constructed with dCell bovine pericardium fixed in low GA concentration were resistant to calcification and may thereby improve long-term durability of the tissue.
去细胞化是一种处理生物组织的替代方法，可降低抗原性并提高抗钙化能力。本研究的目的是表征用0.1%戊二醛（GA）固定的去细胞化（dCell）牛心包的特性，并评估用该组织构建的生物瓣膜植入幼年绵羊二尖瓣位置后的效果。
用固定于0.5% GA的新鲜牛心包（对照组）或固定于0.1% GA的dCell牛心包（研究组）构建生物二尖瓣。植入前，对样本进行组织学（苏木精-伊红、Movat和4',6-二脒基-2-苯基吲哚）、生化（残留脱氧核糖核酸和α-半乳糖表位）和生物力学表征。将瓣膜植入绵羊体内（每组n = 8）作为二尖瓣置换物，持续180天，然后对外植体进行组织学重新评估，并通过放射学研究和钙含量测定评估钙化情况。
未植入的dCell心包显示细胞外基质保存良好，无细胞，脱氧核糖核酸水平降低77%，且未检测到α-半乳糖表位。与对照组相比，其极限抗拉强度较低（7.3±5.4 vs 10.2±3.0 mPa，P = 0.04），纵向伸长百分比更高（29±6.5% vs 23.8±5.1%，P = 0.02）。在二尖瓣位置放置180天后，dCell瓣膜的瓣叶柔韧，无宏观钙化迹象。组织学上，dCell瓣叶的胶原纤维完整，组织重塑更好，钙含量显著降低89%。
本研究表明，用低GA浓度固定的dCell牛心包构建的生物瓣膜具有抗钙化能力，从而可能提高组织的长期耐久性。
