Morphological changes in the musculoelastic layer of the pulmonary artery during storage under moderate hypothermia in a «Сustodiol» solution

A study was conducted on segments of the pulmonary artery retrieved from donors following the confirmation of brain death. The pulmonary artery allograft was preserved in «Custodiol» solution and stored under conditions of moderate hypothermia (+4°C) for up to 60 days. Histological sections 3–6 μm thick were prepared and stained with haematoxylin and eosin, and with the Movat–Russell pentachrome stain. The condition of the muscular-elastic layer of the pulmonary artery wall was assessed.Histological examination showed that after 1–2 days of preservation, the structure of the muscular-elastic layer of the donor pulmonary artery was preserved; by days 3–4, nuclear hyperchromia, oedema of the intercellular matrix and thinning of the internal elastic membrane had appeared. From days 5–6, the first signs of smooth muscle cell death and delamination of the muscular layer were observed. By days 8–10, the disorganisation of the elastic framework, oedema and swelling of the muscular-elastic layer of the pulmonary artery wall had intensified, and clear signs of smooth muscle cell death were evident. By days 16–18, the elastic fibres had become fragmented. By day 30, necrobiotic changes in the cells were increasing, and homogenisation of the internal elastic membrane was observed. By days 50–60, only isolated groups of smooth muscle cells remained; the elastic framework was condensed and fragmented.Consequently, changes in the muscular-elastic layer of the pulmonary artery allograft are characterised by the gradual death of smooth muscle cells, accompanied by oedema and disorganisation of the stroma, against a background of relative preservation of the elastic framework. The structural integrity and viability of the donor pulmonary artery tissue are maintained for up to 6 days of preservation in «Custodiol» solution at +4°C.