Study about regulation of liver regeneration by modulating portal venous circulation.

肝切除或部分肝移植后，门系统分流组与未分流组相比，肝再生效果较好。上述发现使我们认识到足够的门静脉压力和流量对于获得良好的肝脏再生至关重要。同时，对活体供肝移植（LDLT）的回顾性临床研究表明，门静脉压低于20mmHg是获得较好临床效果和肝脏再生良好的关键因素。下一步，我们在Mie大学医院进行了LDLT的前瞻性临床研究，通过脾切除术、肠系膜下静脉与左肾静脉之间的门静脉系统分流或阻断自发侧支，将门静脉压维持在20mmHg以下，并通过多普勒超声检查确保足够的门静脉流量。结果，受者的存活率显著提高到90%。自2006年以来，京都大学医院在LDLT中应用了改良门静脉循环的策略，并获得了更好的结果（超过90%的受者存活率）。此外，进一步改良，使门静脉压低于17mmHg，即使是接受小尺寸移植物的受者，也能获得更好的结果，其定义为低GRWR（移植物-受者体重比），范围为0.8至0.6。因此，LDLT的GRWR下限可以从0.8移动到0.7，并且可以使用左叶而不是右叶。从右肺叶到左肺叶移植物选择的改变有助于供体手术的安全性。

Excellent liver regeneration after hepatectomy or partial liver transplantation in porcine model was achieved in the group with portosystemic shunt comparing with the group without shunt. The above finding led to the concept that adequate portal venous pressure and flow is essential to obtain good liver regeneration. At the same time, retrospective clinical study for living donor liver transplantation (LDLT) demonstrated that portal venous pressure less than 20mmHg was crucial factor to obtain better clinical outcome with good liver regeneration. At the next step, we performed prospective clinical study of LDLT at Mie University Hospital, in which portal venous pressure was maintained under 20mmHg and sufficient portal venous flow was secured by Doppler ultrasound examination, by means of splenectomy, portosystemic shunt between inferior mesenteric vein and left renal vein, or interception of spontaneous collaterals. As a result, recipient survival was dramatically improved up to 90%. That strategy with modification of portal venous circulation in LDLT had been applied to LDLT at Kyoto University Hospital since 2006, and better outcome (over 90% of recipient survival) has been obtained. In addition, further modification making portal venous pressure less than 17mmHg resulted in better outcome even in recipients receiving small-for-size grafts, defined by low GRWR (graft-recipient weight ratio) ranging from 0.8 to 0.6. As a result, the lowest limit of GRWR in LDLT can be shifted from 0.8 to 0.7, and we can use left lobes rather than right lobes. Changes in graft selection from right lobe to left lobe would contribute to safety of donor operation.