Pre-implantation viability of cryopreserved valves prepared by the Green Lane Technique
Objective: The importance of a viable donor cell population to the durability and clinical performance of the allografted heart valve is still disputed. The aim of our investigations has been to establish the pre-implantation viability status of the cryopreserved valves currently prepared for use as allografts at Green Lane Hospital and to correlate this with the cellular status of explanted cryopreserved grafts recovered at re-operation.
Methods: Viability was assessed primarily by an autoradiographic assay for the incorporation of glucosamine into proteoglycan matrix and results were compared with cell culture assays and cell ultrastructure. Twenty-six valves were obtained at autopsy and assayed sequentially 1) at collection; 2) after disinfection in antibiotic solution; 3) after thawing following cryopreservation and storage. A second group of 45 similarly disinfected and cryopreserved banked valves considered unsuitable for clinical use was assayed after thawing.
Results: Most of the banked valves showed only sparse radiolabelling confined to the hinge area of the leaflet. By electron microscopy, the unlabelled cells showed severe damage to plasma membranes and cytoplasm. In the autopsy series, valves obtained 24–48 h after donor death were non-viable at collection. Those obtained within 24 h of donor death showed variable extents of radiolabelling, but this declined markedly after 24 h of exposure to antibiotics and progressively still further after 48 h of antibiotic treatment and cryopreservation. Whereas 85% of all valves collected were viable initially, only 15–20% remained viable following disinfection and storage.
Conclusions: The majority, though not all, of the cryopreserved valves prepared at Green Lane Hospital are currently non-viable when implanted. The first 25 explanted cryopreserved valves examined histologically all show some focal fibroblastic growth which may presumably be either donor or recipient in origin. The disinfection and cryopreservation procedures in use at present have additive adverse effects on the cell viability of hypoxically-injured cadaver-derived valves.
KeywordsFormalin Gall Amphotericin Glucosamine Cefoxitin
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