Hyperspectral Imaging for Viability Assessment of Human Liver Allografts During Normothermic Machine Perfusion

Abstract

L iver transplantation (LT) is the only curative therapy for patients with end-stage liver disease. In recent decades, LT is characterized by an increasing waiting list mortality due to the lack of donor organs. 1 The utilization of extended criteria donor (ECD) organs has become frequent in order to overcome the severity of organ scarcity. 2 As ECD organs may be associated with an inferior outcome of LT, risk-minimizing strategies are sought after. 3 Normothermic machine perfusion (NMP) is a revived preservation technique nowadays frequently utilized in LT. NMP provides advantages over static cold storage (SCS) due to physiological temperature and organ function, inherent to this preservation method. Furthermore, it enables allograft viability testing before LT. [4][5][6] Commonly assessed viability parameters during liver graft NMP are perfusate lactate, perfusate pH, glucose metabolism, and production and viscosity of bile, as well as arterial inflow. 7-10 Current literature emphasizes perfusate lactate/lactate clearance as essential parameters assessing liver viability during NMP. [5][6][7][8]11 In NMP, hyperlactatemia is predominantly

Normothermic machine perfusion for liver transplantation: current state and future directions

“…Other groups recommend adjusting flow to account for liver volume, requiring 0.1 ml/min/g for hepatic artery and 0.33 ml/min/g for portal vein flows [22]. There are several techniques currently under investigation that may more accurately measure liver perfusion, including hyperspectral imaging and indocyanine green (ICG) clearance; however, none are routinely used in clinical practice [27,28].…”

Viability assessment of the liver during ex-situ machine perfusion prior to transplantation

“…A significantly higher THI was seen in discarded livers compared with transplanted livers end NMP. Kneifel et al also used HIS during NMP at 1, 2 and 4 h of perfusion and showed that StO 2 and THI predicted lactate values at 1 and 2 h of NMP, THI also predicted lactate values at 4 h [55 ▪ ]. Lau et al [56 ▪▪ ] analyzed the indocyanine green (ICG) plasma-disappearance-rate (PDR) and the ICG-perfusion with a near-infrared camera during 7 days of NMP.…”

Normothermic Machine Perfusion Systems: Where Do We Go From Here?

“…66,67 Hyperspectral imaging represents a novel technology of increasing interest for monitoring organ microcirculation, functional biomarkers, water, hemoglobin, or tissue oxygenation. [68][69][70][71] Finally, nontoxic fluorescent dyes offer a means to visualize vasculature and organ function; for example, indocyanine green applied in liver NMP supports the real-time visualization of the intrahepatic biliary tree. 72 Using sensors in direct contact with the organ in question represents another attractive monitoring prospect; for example, implantable oxygen biosensors can monitor tissue oxygen tension, 73 whereas laser-Doppler technology can analyze organ microcirculation.…”

“…The administration of therapies through the perfusate has several benefits that make NMP an attractive therapeutic option, including more efficient delivery, lower doses, and reduced unwanted side effects in nontarget organs. 174 The immunomodulatory properties of mesenchymal stem cells 57–159 and multipotent adult progenitor cells 160–162 have shown beneficial effects during liver, lung, and kidney NMP, presumably due to their immunomodulatory properties, which prompt both anti-inflammatory and regenerative responses. 157,160–162 In human models, initially discarded kidneys 160 and livers 161 treated with multipotent adult progenitor cells or preterm-neonate progenitor cells 162 exhibited improved viability, even meeting established criteria.…”