Due to the shortage of heart grafts, we must improve the quality of graft conservation to increase the pool of donors, in particular by extending the transport time which is currently around 4hours. To do so, we developed a new original preservation solution named LYPS (LYon Preservative Solution), aiming to improved graft protection during preservation.

Our objectives were to evaluate the impact of LYPS during hypothermic perfusion on different cell death pathways and their impact on heart functional recovery.

We used a mimetic cold-ischemia-reperfusion H9C2 cellular model as follows: 20hours of cold preservation, followed by 2hours of warm “reoxygenation” (37°C). In parallel, isolated heart rat graft model was used. Hearts were harvested and submitted to static or dynamic preservation in 3 different solutions (LYPS, Celsior or Plegisol), at deep hypothermia (4°C) and during short (4h) or extended (8h) preservation. Then, cardiac functions were assessed at the time of reperfusion using an ex-vivo retrograde perfusion for 1hour. Cell necrosis, apoptosis, necroptosis and autophagy were evaluated in the two models by flow cytometry and western-blot.

Flow cytometry in vitro results showed that, after cold hypothermia storage (5°C) and reoxygenation, necrosis (Propidium iodide staining) and apoptosis (annexinV: 10% Control, 9% LYPS vs 76% Plegisol, 85% Celsior) were not significantly different between control and LYPS but they were significantly increased with Celsior and Plegisol. The ex vivo results showed that, for usual static storage time (4h) and extended (8h), there was a significant impact of the solution used, with a better recovery with Lyps and Celsior. This was associated with less LC3II, RIPK3 and cleaved caspase 3 protein expression determined by western blot.

In conclusion, our data showed that LYPS could offer a cellular protection allowing good preservation of cardiac cells during 20h where commercial solutions failed. Moreover, LYPS appears to provide functional protection in rat ex vivo model, when preservation time was extended, and when perfusion and midthermia were used.