Engineered Mesenchymal Stromal Cell Therapy during Human Lung Ex Vivo Lung Perfusion is Affected by Lung Acidosis

Purpose Ex Vivo Lung Perfusion (EVLP) is an excellent platform to apply novel therapies for lung repair, perioperative protection and immunomodulation. In our previous large animal EVLP studies, we have combined gene and cell therapies, and used mesenchymal stromal cells genetically engineered to produce anti-inflammatory IL-10 (MSCIL10 cells) for lung protection. We investigated MSCIL10 therapy during EVLP in human rejected lungs as a translational step towards clinical applications. Methods Pairs of human lungs rejected from clinical transplantation (n=4) were split, connected to single-lung EVLP circuits for 12 hours and randomly assigned to control or MSCIL10 groups. 40 × 106 cryopreserved MSCIL10 were administered through the pulmonary artery 1 hour after EVLP start. Perfusate IL-10 levels were measured by ELISA. The effect of the metabolic environment on MSCIL10 cell IL-10 production was studied in vitro by exposing MSCIL10 cells to perfusate samples with varying metabolic conditions, and by selectively altering pH and glucose. Results MSCIL10 cells were rapidly retained in the lung (Fig A) and elevated EVLP perfusate IL-10 levels in minutes (Fig B). In contrast to our previous pig studies, perfusate IL-10 levels declined after 4-6 hours (Fig B) particularly in lungs with low perfusate pH and glucose, and high lactate. Exposing MSCIL10 cells to perfusate samples with poor metabolic conditions in vitro negatively affected IL-10 production. Acidosis profoundly decreased IL-10 production (Fig C) whereas glucose did not have a significant effect (Fig D). Conclusion MSCIL10 therapy rapidly increased perfusate IL-10 levels during human lung EVLP but was negatively affected by acidosis present in damaged lungs. Future studies will determine MSCIL10 effects on lung function and immunomodulation. The results imply that cell-based therapies are affected by target tissue acidosis, and that restoring metabolic conditions may optimize the effect of biologic therapies in damaged lungs.