Key result
Freezing fresh homograft heart valves in liquid nitrogen preserved fibroblast mitotic activity when pre-stored at +4 °C for up to 6 weeks, with a more rapid decline in viability after 8 weeks.
Why the study?
Does freezing in liquid nitrogen preserve the viability of fresh homograft heart valves?
Does freezing in liquid nitrogen preserve the viability of fresh homograft heart valves?
Freezing in liquid nitrogen can preserve the viability of fresh aortic valve homografts, provided they are not stored at +4 °C for more than 6 weeks prior to freezing.
May inform homograft banking protocols in research; leaves open whether preserved viability improves human outcomes.
A method of long-term storage of fresh homograft heart valves in liquid nitrogen (−195 °C) is described. The object is to preserve them in a viable state with unchanged structure. Five groups of valves were studied. Viability before and after freezing was assessed quantitatively by the use of autoradiography. Mitotic activity of the fibroblasts declined at a very slow rate in groups 1, 2, 3 and 4, in which the valves were stored at +4 °C in a nutrient/antibiotic solution for periods between 24 hours and up to 6 weeks before freezing. The percentage of metabolically active fibroblasts declined more rapidly in valves from group 5, in which the valves had been stored for 8 weeks at +4 °C before freezing.
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Al-Janabi et al. (1974) studied Aortic valve homografts. Freezing in liquid nitrogen (-195 °C) vs. Different pre-freezing storage durations at +4 °C (24 hours to 8 weeks) was evaluated on Viability (mitotic activity of fibroblasts) assessed by autoradiography. Freezing fresh homograft heart valves in liquid nitrogen preserved fibroblast mitotic activity when pre-stored at +4 °C for up to 6 weeks, with a more rapid decline in viability after 8 weeks.
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