Yuki Masano

Living donor liver transplantation (LT) and deceased donor split-LT often result in congestion within liver grafts. The regenerative process and function of congested areas, especially graft congestion associated with LT, are not well understood. Therefore, we created new rat models with congested areas in partially resected livers and orthotopically transplanted these livers into syngeneic rats to observe liver regeneration and function in congested areas. This study aimed to compare liver regeneration and the function of congested areas after liver resection and LT, and to explore a new approach to ameliorate the adverse effects of graft congestion. Although the congested areas after liver resection regenerated normally on postoperative day 7, the congested areas after LT had poor regeneration with abscess development on postoperative day 7. Necrotic areas in congested areas were larger after LT than after liver resection on postoperative days 1, 3, and 7 (p < 0.05, p < 0.05, and p < 0.01, respectively). Although congested areas after liver resection did not affect survival, in the LT model, the survival of rats with congested areas was significantly poorer even with larger grafts than that of rats with smaller noncongested grafts (p = 0.04). Hepatocyte growth factor administration improved the survival rate of rats with congested grafts from 41.7% to 100%, improved the regeneration of congested areas, and significantly reduced the size of necrotic areas (p < 0.05). Thus, congested areas in liver grafts may negatively impact recipients. Short-term administration of hepatocyte growth factor may improve postoperative outcomes of recipients with graft congestion and contribute to more effective use of liver grafts (approval number: MedKyo-23137, Institutional Ethics Committee/Kyoto University).

Background.: In some pediatric patients undergoing living-donor liver transplantation, segment IV without the middle hepatic vein can be added to a left lateral segment graft to obtain larger graft volume. Because no clear consensus on this technique exists, this study investigated the effects of congested areas on postoperative outcomes in pediatric patients with biliary atresia undergoing living-donor liver transplantation.Methods.: We retrospectively reviewed data of recipients with biliary atresia aged ≤15 y who had undergone living-donor liver transplantation at Kyoto University Hospital between 2006 and 2021 and with graft-to-recipient weight ratios (GRWR) of ≤2%. Based on the percentage of congested area in the graft, patients were classified into the noncongestion (n = 40; ≤10%) and congestion (n = 13; >10%) groups. To compare the differences between groups with similar nooncongestive GRWRs and investigate the effect of adding congested areas, patients in the noncongestion group with GRWRs of ≤1.5% were categorized into the small noncongestion group (n = 24).Results.: GRWRs and backgrounds were similar between the noncongestion and congestion groups; however, patients in the congestion group demonstrated significantly longer prothrombin times, higher ascites volumes, and longer hospitalization. Further, compared with the small noncongestion group, the congestion group had significantly greater GRWR and similar noncongestive GRWR; however, the congestion group had significantly longer prothrombin time recovery (P = 0.020, postoperative d 14), higher volume of ascites (P < 0.05, consistently), and longer hospitalization (P = 0.045), requiring significantly higher albumin and gamma-globulin transfusion volumes than the small noncongestion group (P = 0.027 andP = 0.0083, respectively). Reoperation for wound dehiscence was significantly more frequent in the congestion group (P = 0.048).Conclusions.: In pediatric liver-transplant recipients, adding a congested segment IV to the left lateral segment to obtain larger graft volume may negatively impact short-term postoperative outcomes.

Yuki Masano, Takashi Ito, Hikaru Aoki, Masaaki Hirata, Shinya Okumura, Takayuki Anazawa, Kazuyuki Nagai, Koichiro Hata, Etsuro Hatano. Korean J Transplant 2022;36:220. https://doi.org/10.4285/ATW2022.F-3568

Objective: Microsurgery using conventional optical microscopes or surgical loupes features a limited field of view and imposes a serious strain on surgeons especially during long surgeries. Here we advocate the micro- and macro-borderless surgery (MMBS) using a novel high-resolution (4K) three-dimensional (3D) video system. This study aimed to confirm the applicability of this concept in several surgical procedures. Methods: We evaluated the possible use and efficacy of MMBS in the following experiments in porcine subjects. Experiment 1 (non-inferiority test) consisted of dissection and anastomosis of carotid artery, portal vein, proper hepatic artery, and pancreatoduodenectomy with surgical loupe versus MMBS. Experiment 2 (feasibility test) consisted of intra-abdominal and intra-thoracic smaller arteries anastomosed by MMBS as a pre-clinical setting. Experiment 3 (challenge on new surgery) consisted of orthotopic liver transplantation of the graft from a donor after circulatory death maintained by machine perfusion. Circulation of the cardiac sheet with a vascular bed in experiment 2 and liver graft during preservation in experiment 3 was evaluated with indocyanine green fluorescence imaging equipped with this system. Results: Every procedure was completed by MMBS. The operator and assistants could share the same field of view in heads-up status. The focal depth was deep enough not to be disturbed by pulsing blood vessels or respiratory movement. The tissue circulation could be evaluated using fluorescence imaging of this system. Conclusions: MMBS using the novel system is applicable to various surgeries and valuable for both fine surgical procedures and high-level surgical education.

Background: We established a completely novel method of auxiliary xenogeneic partial liver transplantation and examined whether liver grafts procured from Syrian hamsters regenerated in nude rats, which were used as in vivo bioreactors.Methods: The hamsters and the rats were all males (n = 10). Partial liver grafts from hamsters were transplanted into nude rats in an auxiliary manner. We evaluated liver graft injury, rejection, and regeneration during 7 days after auxiliary xenogeneic partial liver transplantation.Results: All rats survived until sacrifice on post‐operative day (POD) 1, 3, and 7. HE‐staining showed normal at POD1, mild periportal edema, and slight bile duct and venous endothelial inflammation at POD3, and moderate acute cellular rejection at POD7 without parenchymal necrosis. The liver regeneration rates at POD3 and 7 were 1.54 ± 0.23 and 2.54 ± 0.43, respectively. The Ki‐67 labeling index was also elevated at POD3 (27.5 ± 4.1%). Serum HGF and VEGF were elevated at POD1 and 3. ATP levels of liver grafts recovered at POD7.Conclusions: These results revealed that with appropriate immunosuppressive therapy, partial liver graft regeneration occurred in a xenogeneic animal, which suggests liver grafts regenerated in xenogeneic environments, such as an in vivo bioreactor, have potential to be transplantable liver grafts for humans.