Abd-Elfattah A S, Messier R H, Domkowski P W, Jones J L, Aly H M, Crescenzo D G, Wallace R B, Hopkins R A
Department of Surgery, Medical College of Virginia, Richmond.
J Thorac Cardiovasc Surg. 1993 Jun;105(6):1095-105.
Human cardiac valves are increasingly used in the reconstruction of ventricular outflow tracts and offer performance advantages over porcine and mechanical prostheses; the durability of these replacements has been associated with leaflet interstitial cell viability and a presumed sustained function after implantation. Preimplantation tissue preparation entails sequential steps that are potentially cytotoxic and may therefore affect functional cell survival at thaw. We defined the metabolic consequences of each interval using semilunar cusps from 118 porcine valves to model a homograft preparation with 40 minutes of fixed cadaveric (harvest) ischemia. Fifty-eight valves served as controls and were first processed according to standard cryopreservation protocol; nucleosides were extracted at the end of each step to differentiate independent contributions to high-energy phosphate depletion. Sixty simultaneously harvested leaflets were administered the nucleoside transport inhibitor p-nitrobenzy-thionosine (NBMPR) and the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) at procurement, to attempt adenosine salvage and restitution of processing-incurred adenine nucleotide losses. High-performance liquid chromatography was used to compare adenosine triphosphate, diphosphate, and monophosphate and diffusible nucleopurines of the control and EHNA/NBMPR-treated groups. Control results indicate that disruption of the adenosine triphosphate-diphosphate cycle occurs independently with antibiotic disinfection and cryopreservation. However, throughout all preparation steps, adenine nucleotides were maintained at harvest (baseline) concentrations in the EHNA/NBMPR valves. This suggests that salvage therapy may protect a significant number of cells from net high-energy phosphate catabolism. If, with further study, the durability of transplanted valves is concluded to benefit from retained leaflet interstitial cell viability, such enhancement of metabolic tolerance to the obligatory processing may facilitate functional recovery.
人体心脏瓣膜越来越多地用于心室流出道重建，与猪源和机械瓣膜相比具有性能优势；这些置换瓣膜的耐久性与瓣叶间质细胞活力以及植入后假定的持续功能有关。植入前的组织制备需要一系列可能具有细胞毒性的步骤，因此可能会影响解冻时功能细胞的存活。我们使用118个猪瓣膜的半月瓣尖来模拟同种异体移植物制备过程，其中包括40分钟的固定尸体（收获）缺血，以此定义每个阶段的代谢后果。58个瓣膜作为对照，首先按照标准冷冻保存方案进行处理；在每个步骤结束时提取核苷，以区分对高能磷酸耗竭的独立贡献。60个同时收获的瓣叶在获取时给予核苷转运抑制剂对硝基苄硫代肌苷（NBMPR）和腺苷脱氨酶抑制剂赤型-9-(2-羟基-3-壬基)腺嘌呤（EHNA），试图挽救腺苷并恢复处理过程中造成的腺嘌呤核苷酸损失。使用高效液相色谱法比较对照组和EHNA/NBMPR处理组的三磷酸腺苷、二磷酸腺苷、一磷酸腺苷和可扩散核嘌呤。对照结果表明，三磷酸腺苷-二磷酸腺苷循环的破坏在抗生素消毒和冷冻保存过程中独立发生。然而，在所有制备步骤中，EHNA/NBMPR瓣膜中的腺嘌呤核苷酸保持在收获（基线）浓度。这表明挽救疗法可能保护大量细胞免受高能磷酸净分解代谢的影响。如果通过进一步研究得出结论，移植瓣膜的耐久性得益于保留的瓣叶间质细胞活力，那么这种对必要处理的代谢耐受性增强可能有助于功能恢复。
