A custom preservation solution extends the ex vivo availability of living heart valves for transplantation

Although heart valve transplantation delivers living, growth-capable valves, its clinical implementation is restricted by transplant logistics and donor availability. We developed a preservation solution for the ex vivo storage of living valves that maintains tissue viability for at least 7 weeks.

Porcine pulmonary roots (N = 25) were dissected, treated with a clinically used antibiotic cocktail, and stored in a custom-made preservation solution (Valve Preservation Solution, VPS) or Hanks' Balanced Salt Solution with serum for up to 7 weeks. Tissues were preserved in normothermia (37 °C, 5% CO₂) and hypothermia (4 °C, control group). Tissue preservation was monitored weekly by evaluating viability (AlamarBlue), metabolic activity (media glucose), histologic tissue preservation (hematoxylin and eosin, Movat Pentachrome stain), and valve cell phenotype (immunostaining).

Cold-stored valves (VPS and Hanks' Balanced Salt Solution) demonstrated significantly reduced viability within 1 to 2 weeks ex vivo. In contrast, normothermic storage in VPS preserved leaflet viability for 7 weeks, with consistent glucose metabolism. Immunostaining of normothermic VPS-stored valve leaflets showed a quiescent cell phenotype with little expression of alpha-smooth muscle actin or proliferation markers (relative to baseline), and baseline-level leaflet Vimentin expression. Despite preserved cellular viability, leaflet microarchitectural integrity was only maintained for 3 weeks of ex vivo storage.

Normothermic preservation of living valves can support tissue viability for at least 7 weeks ex vivo. With additional preclinical validation, stored living valves could act as a tissue source for heart valve transplantation, with key advantages in enhanced availability and resource-efficiency.