Basic Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Hepatol. Feb 27, 2022; 14(2): 386-399
Published online Feb 27, 2022. doi: 10.4254/wjh.v14.i2.386
Development of the nervous system in mouse liver
Naoto Koike, Tomomi Tadokoro, Yasuharu Ueno, Satoshi Okamoto, Tatsuya Kobayashi, Soichiro Murata, Hideki Taniguchi
Naoto Koike, Department of Surgery, Seirei Sakura Citizen Hospital, Sakura 285-8765, Chiba, Japan
Naoto Koike, Tomomi Tadokoro, Yasuharu Ueno, Satoshi Okamoto, Tatsuya Kobayashi, Soichiro Murata, Hideki Taniguchi, Department of Regenerative Medicine, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Kanagawa, Japan
Yasuharu Ueno, Hideki Taniguchi, Division of Regenerative Medicine, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
Author contributions: Koike N and Taniguchi H designed and coordinated the study; Koike N, Kobayashi T and Okamoto S performed immunohistochemical study and analyzed data; Tadokoro T and Murata S performed animal experiments; Ueno Y performed genetic analysis; Koike N wrote the manuscript; all authors approved the final version of the article.
Supported by Grant-in-Aid for scientific research (B) from the Ministry of Education, Culture, Sports and Science and Technology of Japan, No. 18H02874 and No. 21H02991.
Institutional animal care and use committee statement: The mice were bred and maintained according to the Yokohama City University institutional guidelines for the use of laboratory animals. All experimental procedures were approved by the institutional review board of the Animal Research Center, Yokohama City University School of Medicine (No. 075).
Conflict-of-interest statement: All authors declare no conflicts of interest.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Naoto Koike, MD, PhD, Chief Doctor, Department of Surgery, Seirei Sakura Citizen Hospital, 2-36-2 Ebaradai, Sakura 285-8765, Chiba, Japan. naotk@sis.seirei.or.jp
Received: July 31, 2021
Peer-review started: July 31, 2021
First decision: September 29, 2021
Revised: October 12, 2021
Accepted: January 19, 2022
Article in press: January 19, 2022
Published online: February 27, 2022
Processing time: 206 Days and 7.8 Hours
ARTICLE HIGHLIGHTS
Research background

The hepatic nervous system plays important roles in organisms. However, the role of the hepatic nervous system in liver development remains unclear.

Research motivation

We previously created functional human micro-hepatic tissue in mice by co-culturing human hepatic endodermal cells with endothelial and mesenchymal cells. However, they lacked Glisson’s sheath [the portal tract (PT)]. The PT consists of branches of the hepatic artery (HA), portal vein, and intrahepatic bile duct (IHBD), collectively called the portal triad, together with autonomic nerves. In-depth studies of both the differentiation and morphogenesis of the liver are prerequisites for in vitro and in vivo reconstitution of hepatic tissue for regenerative medicine.

Research objectives

This study describes morphological and immunohistochemical analyses, mainly focusing on the development of mouse intrahepatic nerve networks.

Research methods

Liver samples from C57BL/6J mice were harvested at different developmental time periods, from embryonic day (E) 10.5 to postnatal day (P) 56. Thin sections of the surface cut through the hepatic hilus were examined using protein gene product 9.5 (PGP9.5) and cytokeratin 19 (CK19) antibodies, markers of nerve fibers (NFs), and biliary epithelial cells. The numbers of NFs and IHBDs were separately counted in a PT around the hepatic hilus (center) and the peripheral area (periphery) of the liver, comparing the average values between the center and the periphery at each developmental stage. NF-IHBD and NF-HA contacts in a PT were also counted, and their relationship was quantified.

Research results

Primitive IHBDs at the center partly acquired CK19 positivity at E16.5. PGP9.5-positive bodies were first observed at this time point, and HAs were first detected at P0 in the periportal tissue of the center. Therefore, primitive PT structures were first constructed at P0 in the center. Along with remodeling of the periportal tissue, the number of CK19-positive IHBDs and PGP9.5-positive NFs gradually increased, and PTs also formed in the periphery until P5. The numbers of NFs and IHBDs were significantly higher in the center than in the periphery from E16.5 to P5. The numbers of NFs and IHBDs reached the adult level at P28, with fewer differences between the center and periphery. NFs were more frequently associated with HAs than IHBDs in PTs at the early phase after birth, after which the number of NF-IHBD contacts gradually increased.

Research conclusions

Mouse hepatic NFs first emerge at the center just before birth and extend toward the periphery. The interaction between NFs and IHBDs or HAs plays important roles in the morphogenesis and stabilization of the PT structure by interaction between NFs, BDs, and HAs.

Research perspectives

Nerve progenitor cells may be an additional cell source, along with hepatic, endothelial, and mesenchymal progenitor cells, when liver organoids are constructed.