Discover the FVB-Abcb4 Knockout Mouse Model: Advancing Intrahepatic Cholestasis Research

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a severe genetic liver disorder that leads to progressive liver damage and often necessitates liver transplantation. To advance research into PFIC3 pathogenesis and potential treatments, the FVB-Abcb4 KO mouse model has emerged as an indispensable tool. This genetically engineered model effectively replicates the pathological features of PFIC3, including hepatomegaly, cholestasis, and fibrosis, providing researchers with a reliable system for studying disease mechanisms and evaluating novel therapeutic approaches.

In this article, we explore the characteristics, advantages, and research applications of the FVB-Abcb4 KO mouse model, demonstrating why it is an optimal choice for cholestasis-related studies. Learn how this model can support breakthroughs in liver disease research and accelerate drug development.

Introduction to Intrahepatic Cholestasis and PFIC

Intrahepatic cholestasis (IHC) is a clinical syndrome caused by defects in bile synthesis, impaired bile secretion, and mechanical or functional obstructions in bile flow within the bile ducts due to liver parenchymal cells and/or intrahepatic bile duct diseases. This results in the leakage of bile components and their accumulation in the bloodstream.^[1] IHC can be caused by a number of conditions, including progressive familial intrahepatic cholestasis (PFIC) and intrahepatic cholestasis of pregnancy (ICP).

Among these, Progressive Familial Intrahepatic Cholestasis (PFIC) is a hereditary form of cholestasis, accounting for approximately 10% to 15% of all neonatal cholestasis cases. PFIC typically manifests as intrahepatic cholestasis in infancy or early childhood and can progress to end-stage liver disease (ESLD), which necessitates liver transplantation or leads to death.^[2] Although the estimated incidence of PFIC is 1 in 50,000 to 100,000 newborns ,it is the underlying cause of nearly all pediatric liver transplant cases, making it a critical research focus.

Figure 1. Etiology, Diagnosis, and Symptoms of Cholestasis. ^[3]

Classification and Symptoms of PFIC

PFIC is classified into six subtypes based on clinical features, laboratory findings, liver histology, and genetic mutations. The most common forms—PFIC1, PFIC2, and PFIC3—are respectively caused by mutations in ATP8B1 (encoding FIC1 protein), ABCB11 (encoding BSEP protein), and ABCB4 (encoding MDR3 protein, referred to as MDR2 in rodents).^[4] PFIC1 and PFIC2 result from impaired bile salt transport, whereas PFIC3 is caused by a phospholipid transport deficiency, leading to reduced phospholipid secretion in bile. All three types share primary clinical symptoms, including cholestatic jaundice and pruritus. As liver fibrosis and cirrhosis progress, most patients eventually require liver transplantation.^[5]

PFIC3 accounts for about one-third of all PFIC cases and typically manifests later in childhood or adolescence compared to PFIC1 and PFIC2.^[6] This delayed onset often leads to diagnostic delays, increasing the risk of liver damage. Additionally, PFIC3 is associated with moderate pruritus, liver tumors, and cholesterol gallstones, resulting in more complications that may progress to ESLD within the first or second decade of life.^[4-6]

Figure 2. Etiology and typical symptoms of the three major PFIC types.^[7]

PFIC3 Mouse Models

PFIC3 is caused by loss-of-function mutations in the ABCB4 gene, leading to dysfunction of the encoded MDR3 protein. This results in impaired phosphatidylcholine (PC) transport, decreased PC levels in bile, increased bile salts concentration, and subsequent cholestasis and hepatocellular injury. Studies have shown that Abcb4 gene knockout (KO) mice —where the murine MDR2 protein is homologous to human MDR3— can exhibit phenotypes similar to human PFIC3. However, disease severity and progression vary among different mouse strain backgrounds. In the commonly used C57BL/6 background, Abcb4-KO mice exhibit a milder pathological phenotype due to lower bile salt toxicityand often require the addition of hydrophobic bile salts to induce a phenotype closer to human PFIC3.^[8-10] In contrast, Abcb4-KO mice on the FVB background can spontaneously reproduce most of the key biomarkers and pathological features of human PFIC3, including hepatosplenomegaly and liver fibrosis, without the need for a special diet. This model exhibits an earlier onset and more severe disease phenotype compared to the same genetic modification on the C57BL/6 background.^[10-11]

Figure 3. Application of Abcb4-KO mice in PFIC3 mechanism research and drug development.^[12]

Cyagen FVB-Abcb4 Knockout Mouse Model

Cyagen has developed the FVB-Abcb4 knockout (KO) mouse model by knocking out the Abcb4 gene in the FVB strain, which can be used for preclinical PFIC3 research. The FVB-Abcb4 KO mice (product number: C001590) completely lacks expression of Abcb4 gene and its encoded MDR2 protein (murine homolog to MDR3), presenting hallmark PFIC3 characteristics including hepatomegaly, elevated liver function damage markers, increased total bilirubin, as well as severe liver histopathological features such as hepatocyte necrosis, inflammatory cell infiltration, connective tissue proliferation, bile duct hyperplasia, and liver fibrosis.

Complete Absence of Abcb4 gene and MDR2 protein expression

Gene and protein expression analysis results show that no expression of the Abcb4 gene was detected in the heart, spleen, and liver of FVB-Abcb4 KO mice, and ABCB4 (MDR2) protein expression was also undetectable in the liver, confirming successful knockout of the gene.

Figure 4. Detection of Abcb4 gene and ABCB4 (MDR2) protein expression in tissues of FVB wild-type mice (WT) and FVB-Abcb4 KO mice.

Significant Hepatomegaly

Compared to wild-type mice, the livers of FVB-Abcb4 KO mice are significantly enlarged.

Figure 5. Comparison of liver morphology between wild-type mice (WT) and FVB-Abcb4 KO mice at 6 weeks of age.

Abnormal liver function markers

Compared to wild-type mice, FVB-Abcb4 KO mice show:

• A significant increase in alanine aminotransferase (ALT) and aspartate aminotransferase (AST), indicating liver parenchymal damage;
• Significantly elevated levels of alkaline phosphatase (ALP) and total bilirubin (T-BIL) suggest the presence of cholestatic jaundice and other related features.

Figure 6. Comparison of liver function markers between wild-type mice (WT) and FVB-Abcb4 KO mice at 6 weeks of age.

Severe Liver Histopathology

H&E staining and Masson staining results show that, compared to wild-type mice, the livers of FVB-Abcb4 KO mice exhibit various symptoms of human PFIC3, including cell necrosis, connective tissue proliferation, inflammatory cell infiltration, increased bile duct proliferation, collagen fiber proliferation and fibrosis, formation of fibrous septa, and fibrous bridging between adjacent portal areas.

Figure 7. Comparison of liver H&E staining, pathological scoring, and Masson staining between wild-type mice and FVB-Abcb4 KO mice.

Summary

The FVB-Abcb4 KO mouse (product number: C001590) is an ideal model for studying progressive familial intrahepatic cholestasis type 3 (PFIC3). The knockout of the Abcb4 gene leads to the loss of MDR2 protein expression in the mice, resulting in significant hepatomegaly and liver function abnormalities, characterized by elevated ALT, AST, ALP, and total bilirubin levels. Additionally, these mice exhibit typical hepatic pathological features, including hepatocyte necrosis, fibrosis, and bile duct hyperplasia, which closely resemble the pathological manifestations in human PFIC3 patients. As a result, FVB-Abcb4 KO mice provide an excellent platform for investigating PFIC3 pathogenesis and advancing drug discovery in cholestasis-related liver diseases.

Cyagen Metabolic Disease Models

Cyagen collaborates extensively with leading pharmaceutical companies, biotechnology firms, and academic research institutions worldwide to develop a comprehensive range of metabolic disease models. Our gene modeling experts have developed disease models related to metabolic conditions such as liver disease, obesity, diabetes, hyperuricemia, and atherosclerosis, accelerating research and drug discovery efforts in these fields.

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References
[1]KuntzM, KuntzHD.Hepatology textbook and atlas.Springer Berlin Heidelberg,2008.Available from: https://link.springer.com/book/10.1007/978-3-540-76839-5
[2]A Siddiqi I, Tadi P. Progressive Familial Intrahepatic Cholestasis. [Updated 2023 Jul 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559317/
[3]Cholelithiasis: What Is It, Causes, Treatment, and More." Osmosis, 6 Sept. 2022, https://www.osmosis.org/answers/cholelithiasis
[4]Srivastava A. Progressive familial intrahepatic cholestasis. J Clin Exp Hepatol. 2014 Mar;4(1):25-36.
[5]Sutton H, Karpen SJ, Kamath BM. Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms. Annu Rev Pathol. 2024 Jan 24;19:319-344.
[6]Orphanet. Mucopolysaccharidosis Type II. Orphanet, n.d. Web. 9 Jan. 2025. https://www.orpha.net/en/disease/detail/79305#:~:text=Prevalence:%201-9%20/%20100,Age%20of%20onset:%20All%20ages
[7]Nayagam JS, Miquel R, Thompson RJ, Joshi D. Genetic cholestasis in children and adults. J Hepatol. 2024 Apr;80(4):670-672.
[8]Smit JJ, Schinkel AH, Oude Elferink RP, Groen AK, Wagenaar E, van Deemter L, Mol CA, Ottenhoff R, van der Lugt NM, van Roon MA, et al. Homozygous disruption of the murine mdr2 P-glycoprotein gene leads to a complete absence of phospholipid from bile and to liver disease. Cell. 1993 Nov 5;75(3):451-62.
[9]Ikenaga N, Liu SB, Sverdlov DY, Yoshida S, Nasser I, Ke Q, Kang PM, Popov Y. A new Mdr2(-/-) mouse model of sclerosing cholangitis with rapid fibrosis progression, early-onset portal hypertension, and liver cancer. Am J Pathol. 2015 Feb;185(2):325-34.
[10]Weber ND, Odriozola L, Martínez-García J, Ferrer V, Douar A, Bénichou B, González-Aseguinolaza G, Smerdou C. Gene therapy for progressive familial intrahepatic cholestasis type 3 in a clinically relevant mouse model. Nat Commun. 2019 Dec 13;10(1):5694.
[11]Aronson SJ, Bakker RS, Shi X, Duijst S, Ten Bloemendaal L, de Waart DR, Verheij J, Ronzitti G, Oude Elferink RP, Beuers U, Paulusma CC, Bosma PJ. Liver-directed gene therapy results in long-term correction of progressive familial intrahepatic cholestasis type 3 in mice.
[12]Wei G, Cao J, Huang P, An P, Badlani D, Vaid KA, Zhao S, Wang DQ, Zhuo J, Yin L, Frassetto A, Markel A, Presnyak V, Gandham S, Hua S, Lukacs C, Finn PF, Giangrande PH, Martini PGV, Popov YV. Synthetic human ABCB4 mRNA therapy rescues severe liver disease phenotype in a BALB/c.Abcb4-/- mouse model of PFIC3. J Hepatol. 2021 Jun;74(6):1416-1428.