Novel biodegradable magnesium alloy clips compared with titanium clips for hepatectomy in a rat model

Background The use of surgical metal clips is crucial for ligating vessels in various operations. The currently available metal clips have several drawbacks; they are permanent and interfere with imaging techniques such as computed tomography (CT) or magnetic resonance (MR) imaging and carry the potential risk of endo-clip migration. We recently developed a novel magnesium (Mg) alloy for biodegradable clips that reduces artifacts on CT imaging. This study aimed to examine the tolerance, biodegradability, and biocompatibility of the Mg alloy clips compared with those of standard titanium (Ti) clips in hepatectomy. Methods Thirty Wistar rats were divided into two groups based on the clip used (groups A and B). The vascular pedicle, including hepatic artery, portal vein, bile duct, and hepatic vein of the left lateral lobe, was ligated with the Ti clip in group A or the Mg alloy clip in group B, and then the left lateral lobe was removed. The rats were sacrificed at 1, 4, 12, 24, and 36 weeks after surgery. Clinical and histological evaluations were performed. Absorption rate was calculated by measuring the clip volume. Results Although the Mg alloy clips showed biodegradability over time, there were no significant differences in the serum concentration of Mg between the two groups. The remaining volume ratio of Mg alloy clips was 95.5, 94.3, 80.0, 36.2, and 16.7% at 1, 4, 12, 24, and 36 weeks, respectively. No side effects occurred. Most of the microscopic changes were similar in both groups. Conclusions The new biodegradable Mg alloy clips are safe and feasible in vessel ligation for hepatectomy in a rat model and reduce artifacts in CT imaging compared with the standard Ti clips.

Comparative Study of the Liver Anatomy in the Rat, Rabbit, Guinea Pig and Chinchilla

In liver surgical and histological research, small rodents are the most used experimental models. Although the small animals liver is typically lobulated and its macroscopic appearance do not resemble that of the compact human liver, a high degree of lobulation equivalence, allow the use of small rodents in biomedical research. The macroscopic anatomy of the liver of the rat, rabbit, guinea pig and chinchilla was studied from a comparative standpoint. The topography, lobulation and the connection elements of the liver were examined by detailed in situ observation and explanted liver of forty specimens.The rat liver (Hepar) consists of four distinct lobes of different size: the left lateral lobe - LLL (Lobus hepatis sinister lateralis), the median lobe - ML, the right lobe – RL (Lobus hepatis dexter) and the caudate lobe CL (Lobus caudatus). The largest lobe was the median lobe. The rabbit liver consists of five lobes: left lateral lobe - LLL, left medial lobe - LML (Lobus hepatis sinister medialis), right lobe - RL, quadrate lobe – QL (Lobus quadratus) and caudate lobe - CL. The most developed lobe was the left lateral lobe. The caudate lobe had a very narrow attachment on the hilar region. The guinea pig liver show six lobes: left lateral lobe - LLL, left medial lobe - LML, right lateral lobe – RLL (Lobus hepatis dexter lateralis), right medial lobe – RML (Lobus hepatis dexter medialis), quadrate lobe - QL and caudate lobe - CL. The largest lobe of this specie was the left lateral lobe. In chinchilla liver showed four lobes like in the rat. In the rats the most developed hepatic ligament was the falciform ligament (Lig. Falciforme hepatis) which spans from xyphoid process of the sternum and diaphragm to the liver, beginning at the interlobular fissure. The coronary ligament (Lig. Coronarium hepatis) was well developed in all rats. Interlobular ligaments connect the left lateral lobe with the upper caudate lobe. In rabbits, guinea pigs and chinchillas the connection elements were represented by the falciform ligament, coronary ligament, right (Lig.triangulare dextrum) and left triangular ligaments (Lig. Triangulare sinistrum), hepatorenal ligament (Lig.hepatorenale) and hepatoduodenal ligament (Lig. hepatoduodenale) with varying degrees of development.Based on detailed study of the macroscopic anatomy of rat, rabbit, guinea pig and chinchilla a proper experimental model in liver research, could be assessed. In this regard, the vascular anatomy of the liver in the mentioned species is of a great importance and it is subject of another report.

Renoportal Anastomosis in Left Lateral Lobe Living Donor Liver Transplantation: A Pediatric Case

In adult liver transplantation, renoportal anastomosis (RPA) has been introduced as a useful technique for patients with grade 4 portal vein thrombosis and a splenorenal shunt. Here, we report a pediatric case in which RPA allowed a left lateral lobe living donor liver transplantation (LDLT) despite portal vein thrombosis and a large splenorenal shunt. At 36 days old, the patient underwent a Kasai operation for biliary atresia. At 17 months old, she underwent LDLT because of repetitive cholangitis. Pretransplant examinations revealed a large splenorenal shunt and portal vein thrombosis. Simple end-to-end portal reconstruction and clamping of the collateral route after removing the thrombosis were unsuccessful. Thus, RPA was performed using a donor superficial femoral vein as an interpositional graft. The portal vein pressure was 20 mm Hg after arterial reperfusion. Ligation of the splenic artery reduced the portal vein pressure. Although she developed severe acute cellular rejection and chylous ascites, there were no signs of portal vein complications. She was discharged 73 days after transplantation without any signs of renal dysfunction. The patient’s condition was good at her last follow-up, 22 months after transplantation. To our knowledge, this is the youngest case of RPA in pediatric left lateral lobe LDLT. Additionally, this is the first case of RPA with splenic artery ligation and using the donor’s superficial femoral vein as the venous graft for RPA. Although long-term follow-up is necessary, RPA could be a salvage option in LDLT in infants if other methods are unsuccessful.