Vascular Reconstruction with the Cuff Technique in Mouse Orthotopic Liver Transplantation

Summary

This protocol provides technical information for vessel reconstruction using the cuff technique in mouse orthotopic liver transplantation.

Abstract

Mouse orthotopic liver transplantation is an effective methodology for investigating the underlying mechanisms of liver ischemia and reperfusion injury. However, the technical challenges pose a barrier to utilizing this valuable experimental model and passing on these skills to the next generation. The most challenging aspect of this procedure is vascular reconstruction, including the portal vein (PV), infrahepatic inferior vena cava (IHIVC), and suprahepatic inferior vena cava. The use of plastic cuffs, rather than sutures, allows for smoother PV and IHIVC reconstruction. Vessels are reconstructed by attaching a cuff made from an intravenous catheter to the tip of the graft vessel and interposing the cuff into the recipient vessel. The two most crucial aspects are properly visualizing the inner lumen of the vessel and avoiding the use of excessive force. Our aim is to provide a technical overview of vascular reconstructions using the cuff technique in recipient surgery. These technical tips for the cuff technique are expected to help microsurgeons facilitate vascular reconstruction and advance their research.

Introduction

Mouse orthotopic liver transplantation (MOLT) is an effective experimental method first reported in 1991¹. This experimental model, which utilizes genetically modified mice and various research reagents, has played a pivotal role in investigating warm and cold ischemia and reperfusion injuries. However, the model's high technical complexity has hindered the development of basic medicine for liver transplantation². MOLT involves three major steps: (1) retrieval of the liver from the donor mouse, (2) back table surgery, and (3) implantation of the liver into the recipient. Among these recipient procedures, vascular anastomosis poses the greatest challenge. While the suprahepatic inferior vena cava anastomosis is typically completed by hand stitching², the infrahepatic inferior vena cava (IHIVC) and portal vein (PV) can be reconstructed more efficiently using plastic cuffs in place of hand-sewn sutures.

The anhepatic period signifies the interval between the removal of the recipient's native liver and the graft implantation. To ensure consistent results, it is imperative to limit the anhepatic time to less than 20 min. Consequently, studies employing this model have been confined to specific institutions^{3,4,5,6,7,8,9}. Among the various stages of MOLT, achieving smooth PV and IHIVC reconstruction is crucial for minimizing anhepatic time and ensuring successful transplantation.

PV and IVC reconstruction is generally carried out using vascular cuffs since the cuff technique simplifies vascular anastomosis compared to hand-sewn sutures^2,5,8. The technique involved in vascular cuff preparation and secure attachment of the cuff significantly impacts the complexity of recipient vascular reconstruction. Our objective is to provide detailed visual guidance for numerous technical tips related to the cuff method, thereby reducing the learning curve. These video clips will provide a clear understanding of how to attach the cuff to the vessels and reconstruct the PV and IHIVC during recipient surgery.

Protocol

The experimental protocol was approved by the Animal Experimentation Committee at Kyoto University. The study utilized C57BL/6 mice, aged over 10 weeks and weighing between 25 g and 30 g, obtained from a commercial source (see Table of Materials). All animals were anesthetized with 2.5% isoflurane (following institutionally approved protocols), maintained under specific pathogen-free conditions, and all experimental procedures were conducted in compliance with Kyoto University's Regulations on Animal…

Representative Results

PV reconstruction is successful when, upon unclamping the portal vein, there is no tortuosity, and the liver is uniformly perfused. Anhepatic time should be under 20 min, as anhepatic times exceeding 25 min increase the risk of mouse mortality. IHIVC reconstruction is deemed successful if there is no blood regurgitation from the graft. Storing the graft at cold temperatures for 1 h using organ preservation solution results in a serum alanine aminotransferase level of approximately 2,000 U/L at…

Discussion

Learning vascular reconstruction is the most challenging aspect of achieving successful MOLT. The cuff’s quality significantly influences the reconstruction’s difficulty, given the small size of mice⁵. This article provides a detailed protocol for cuff preparation, attachment, and reconstruction.

While there are no major differences from previous reports regarding cuff preparation and connection^2,5, some minor p…

Materials

16 G intravenous catheter	TERUMO	SR-FF2032	IHIVC cuff
20 G intravenous catheter	TERUMO	SR-FF1651	PV cuff
8-0 braid silk	Natsume Seisakusho	CR9-80B2	8-0 silk
Belzer UW Cold Storage Solution	Astellas		Organ preservation fluid
Bulldog clamp	B BRAUN	FB329R	Bulldog clamp
C57BL/6 mice	Oriental Bio Service
Isoflurane inhalation solution	Viatris		Anesthesic
Micro Blunted Tips 0.1 mm x 0.06 mm	F.S.T	11253-20	Straight microforceps
Micro Serrefine Clamp Applicator with Lock	F.S.T	18056-14	Vessel clip applicator
Micro Serrefines	F.S.T	18055-4	Vessel clip
No.11 Spare Blades	FEATHER Safety Razor	11	Blades
Ophthalmic scissor, round handle	B BRAUN	FD103R	Microscissor
Plastic rectangular-shaped container	Daiso		10 cm long, 15 cm wide and 6 cm high
SuperGrip Tips	F.S.T	00649-11	Curved microforceps
SZX7	Olympus	SZX7	Microscope