The “kidney–liver” multiorgan ex vivo perfused model improves the circuit’s biochemical milieu during perfusion compared to the “liver–kidney” counterpart

Addition of a liver to the normothermic perfusion circuit reduces renal pro-inflammatory factors

BACKGROUND

Normothermic machine perfusion (NMP) provides a novel platform to preserve isolated organs in an artificial condition. Our study aimed to explore the interaction between the liver and kidney at an ex vivo organ level by adding a liver to the kidney NMP circuit.

METHODS

Porcine kidney and liver obtained from abattoir were subjected to 9 h NMP after suffering 30-min warm ischemia time and 90-min cold ischemia time. The liver-kidney NMP group (n = 5) and the single-kidney NMP group (n = 5) were designed. During the NMP, perfusion parameters, blood gas analysis, and tissue samples were compared.

RESULTS

The perfusate of both groups remained stable, and continuous urine production was observed during NMP. In the liver-kidney NMP group, the lactate level was low, while blood urea nitrogen increased and glucose levels decreased. After the NMP, the renal tissue in the liver-kidney group exhibited fewer histological changes such as tubular epithelium vacuolization, along with reduced expression of IL-6, IL-8, IL-1β, NLRP3, and GSDMD.

CONCLUSIONS

Our results indicated that the expression of renal pro-inflammatory factors was reduced in the liver-kidney NMP system.

Combined kidney‑liver perfusion enhances the proliferation effects of hypothermic perfusion on liver grafts via upregulation of IL‑6/Stat3 signaling

A limited number of studies have revealed that adding kidneys to liver perfusion may maintain an improved physiological balance; however, the underlying mechanism remains to be elucidated. The preset study confirmed the protective role of this new model and investigated the underlying mechanisms. Methods: A total of 12 rats were randomly assigned into two groups (n=6 for each group): The kidney-liver perfusion (KL) group and liver perfusion (LP) group. Perfusate samples were collected during the perfusion process for the analysis of pH, K+ and liver function. Liver tissues were obtained for the evaluation of adenosine triphosphate (ATP), terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling and immunohistochemistry of Ki67. Cell cycle inhibitors, apoptosis-associated genes and signal transducer and activator of transcription 3 (Stat3) were analyzed using quantitative polymerase chain reaction and western blot analysis. Results: Overall pH and K⁺ values of the KL group were significantly different from the LP group and more stable; aspartate aminotransferase, alanine transaminase and lactate dehydrogenase levels increased progressively over time in the LP group and were significantly different at different time points compared with pre-perfusion levels and the KL group, which suggested the KL group was superior to the LP group. In addition, KL reduced portal vein resistance and was associated with lower ATP consumption compared with the LP group. Furthermore, liver proliferation was upregulated with the upregulation of the interleukin 6 (IL-6)/Stat3 signaling pathway in KL compared with LP. The present study revealed for the first time that KL and hypothermic machine perfusion demonstrated a more proactive repair capability by maintaining liver regeneration via the upregulation of the IL-6/Stat3 signaling pathway.

Normothermic Ex-vivo Liver Perfusion and the Clinical Implications for Liver Transplantation

Despite significant improvements in outcomes after liver transplantation, many patients continue to die on the waiting list, while awaiting an available organ for transplantation. Organ shortage is not only due to an inadequate number of available organs, but also the inability to adequately assess and evaluate these organs prior to transplantation. Over the last few decades, ex-vivo perfusion of the liver has emerged as a useful technique for both improved organ preservation and assessment of organs prior to transplantation. Large animal studies have shown the superiority of ex-vivo perfusion over cold static storage. However, these studies have not, necessarily, been translatable to human livers. Small animal studies have been essential in understanding and improving this technology. Similarly, these results have yet to be translated into clinical use. A few Phase 1 clinical trials have shown promise and confirmed the viability of this technology. However, more robust studies are needed before ex-vivo liver perfusion can be widely accepted as the new clinical standard of organ preservation. Here, we aimed to review all relevant large and small animal research, as well as human liver studies on normothermic ex-vivo perfusion, and to identify areas of deficiency and opportunities for future research endeavors.

Perfusion settings and additives in liver normothermic machine perfusion with red blood cells as oxygen carrier. A systematic review of human and porcine perfusion protocols

Liver machine perfusion (MP) at normothermic temperature (NMP) is a promising way to preserve and evaluate extended criteria donor livers. Currently, no consensus exists in methodology and perfusion protocols. Here, the authors performed a systematic literature search to identify human and porcine studies reporting on liver NMP with red blood cells. A qualitative synthesis was performed concerning technical aspects of MP, fluid composition, gas supply, and liver positioning. Thirty-seven publications including 11 human and 26 porcine studies were considered for qualitative synthesis. Control mode, pressure, flow, perfusate additives, and targeted blood gas parameters varied across human as well as porcine studies. For future analyses, it is advisable to report flow adjusted to liver weight and exact pressure parameters including mean, systolic, and diastolic pressure. Parenteral nutrition and insulin addition was common. Parenteral nutrition included amino acids and/or glucose without lipids. Taurocholic acid derivatives were used as bile flow promoters. However, short-term human NMP without taurocholic acid derivatives seems to be possible. This finding is relevant due to the lack of clinical grade bile salts. Near physiological oxygen tension in the perfusate is doable by adjusting gas flows, while blood gas parameters regulation needs more detailed description.

Surface structural damage study in cortical bone due to medical drilling

A bone's fracture could be produced by an excessive, repetitive, or sudden load. A regular medical practice to heal it is to fix it in two possible ways: external immobilization, using a ferule, or an internal fixation, using a prosthetic device commonly attached to the bone by means of surgical screws. The bone's volume loss due to this drilling modifies its structure either in the presence or absence of a fracture. To observe the bone's surface behavior caused by the drilling effects, a digital holographic interferometer is used to analyze the displacement surface's variations in nonfractured post-mortem porcine femoral bones. Several nondrilled post-mortem bones are compressed and compared to a set of post-mortem bones with a different number of cortical drillings. During each compression test, a series of digital interferometric holograms were recorded using a high-speed CMOS camera. The results are presented as pseudo 3D mesh displacement maps for comparisons in the physiological range of load (30 and 50 lbs) and beyond (100, 200, and 400 lbs). The high resolution of the optical phase gives a better understanding about the bone's microstructural modifications. Finally, a relationship between compression load and bone volume loss due to the drilling was observed. The results prove that digital holographic interferometry is a viable technique to study the conditions that avoid the surgical screw from loosening in medical procedures of this kind.