Machine perfusion is rapidly becoming the standard for graft preservation and provides new opportunities for organ salvage, reconditioning, and repair. Based on their immune-modulatory and regenerating properties,1 arguable mesenchymal stromal cells (MSCs) are the most promising cell therapy for graft repair on the pump, though proof of concept is still lacking.2 Here, we show the feasibility of delivering clinically relevant numbers of human MSCs (hMSCs; 5–10 × 106/kg) during 30-minute hypothermic oxygenated machine perfusion in porcine liver grafts (n = 8; Figure 1). Full methods are described in Supplemental Materials and Methods (SDC, http://links.lww.com/TP/B821). To track the biodistribution of hMSC, cells were genetically labeled with click beetle red luciferase.3 As shown in Figure 2, bioluminescent imaging of both the anterior and posterior side of the liver showed a wide range and patchy distribution of hMSC which retain throughout the liver after 30 minutes of perfusion. No significant difference between arterial (n = 4) or venous infusion (n = 4) was observed. Histological and RNA-expression analysis confirmed the delivery of the hMSC throughout the liver grafts. About 104–105 hMSC were estimated to be still present per kilogram of liver graft. Importantly, the hMSC retained their paracrine activity after infusion. Using both Luminex and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, increasing levels of human-specific interleukin-6 and interleukin-8 released in porcine blood were shown during 4-hour normothermic perfusion. In conclusion, this is the first report showing an effective delivery of hMSC in a liver machine perfusion model. Evidence of paracrine activity of hMSC after delivery indicates regenerative and immune-modulatory effects during normothermic graft perfusion, though this needs further research in a transplantation model.
1. Fouraschen SMG, Hall SRR, de Jonge J, et al. Christ B, Oerlecke J, Stock P. Support of hepatic regeneration by trophic factors from liver-derived mesenchymal stromal/stem cells. In: Animal Models for Stem Cell Therapy. Methods in Molecular Biology (Methods and Protocols). 2014. New York, NY: Springer Science+Business Media89–104
2. Van Raemdonck D, Neyrinck A, Rega F, et al. Machine perfusion in organ transplantation: a tool for ex-vivo graft conditioning with mesenchymal stem cells? Curr Opin Organ Transplant. 2013; 18124–33
3. Hall MP, Woodroofe CC, Wood MG, et al. Click beetle luciferase mutant and near infrared naphthyl-luciferins for improved bioluminescence imaging. Nat Commun. 2018; 91132