Fabricating transplantable, vascularized, and cholangiogenic bioartificial livers via three-dimensional bioprinting: a promising therapeutic strategy for liver failure

The liver (1) is a highly specialized organ with robust regenerative capacity and intricate structure. As a central homeostatic regulator, it orchestrates a myriad of essential physiological processes, including nutrient metabolism, detoxification, protein synthesis, and bile secretion.

Hepatic disorders—encompassing chronic fibrosis, decompensated cirrhosis, viral hepatitis, non-alcoholic fatty liver disease, and hepatocellular carcinoma (HCC) (2)—frequently progress to severe end-stage liver disease such as acute liver failure (ALF), acute-on-chronic liver failure (ACLF), and irreversible hepatic parenchymal damage. These conditions can overwhelm the liver’s limited regenerative potential, leading to progressive organ dysfunction and even death (3). Currently, liver diseases contribute to approximately 2 million deaths globally each year, posing a life-threatening risk to affected individuals and imposing a substantial socioeconomic burden on public health systems worldwide (1).

Liver transplantation (4) remains the gold-standard therapy for patients with acute and chronic liver failure. However, its clinical application is severely hindered by two major problems: shortage of donor organs and a high incidence of acute and chronic post-transplant immune rejection. Conventional hepatocyte transplantation (5), as an alternative cell-based therapy, faces the same limitations; moreover, the sole transplantation of isolated hepatocytes fails to recapitulate the liver’s complex cellular heterogeneity, dynamic intercellular crosstalk, and native microenvironment, resulting in poor long-term therapeutic efficacy.

Thus, developing bioartificial livers to promote hepatic regeneration, restore function, and serve as a viable substitute for liver transplantation has emerged as a pivotal research focus in hepatology, tissue engineering, and regenerative medicine (6). Currently, mainstream experimental models for liver tissue engineering include organoids, cellular spheroids, organ-on-a-chip, microfluidics, and three-dimensional (3D) bioprinting, each with unique advantages and inherent limitations (7).

Liver organoids (8,9) stand out for bridging the gap between two-dimensional (2D) cell cultures and native hepatic tissue. These self-organizing 3D structures recapitulate the delicate architectural and functional interactions between hepatocytes, non-parenchymal cells, and the extracellular matrix (ECM) within the physiological hepatic microenvironment. They can also generate vasculature, bile ducts, functional hepatobiliary connections (10), and key functions.

Cellular spheroids, by contrast, are simple 3D cell aggregates formed by spontaneous cell aggregation, characterized by a relatively homogeneous structure without distinct tissue polarity, limiting their ability to mimic native liver complexity.

Organ-on-a-chip technology enables the precise integration of multiple hepatic cell types, spatial compartmentalization, and control of cell culture parameters; this facilitates efficient nutrient and oxygen transport, mimics native hepatic cell alignment, and supports cell growth in a physiologically optimized microenvironment (11,12).

Microfluidic technology fabricates perfusable, vascularized, and cholangiogenic 3D hepatic models via precise microscale fluid manipulation, enabling continuous on-chip perfusion and overcoming the limitations of static 3D cell cultures, such as nutrient diffusion barriers and hypoxic cores (13,14).

3D bioprinting is a common tissue-engineering technology for fabricating predesigned constructs using cell-laden bioinks. Conventionally employed bioinks for hepatic tissue engineering include natural polymers such as alginate, gelatin, methacrylated gelatin (GelMA), collagen, and organ-specific decellularized ECM (dECM) (15,16). Extrusion-based bioprinting is the most widely utilized due to its high scalability and ease of operation.

Endowed with high precision, spatial controllability, and reproducible complex tissue fabrication, 3D bioprinting enables layer-by-layer deposition of cells and ECM components in a preprogrammed manner. This technology thus allows for the accurate recapitulation of key structural and functional features of the native liver—including vascular networks, biliary systems, and cellular heterogeneity—indispensable for hepatic tissue repair and long-term function.

Despite significant advancements in the development of vascularized and cholangiogenic bioengineered hepatic constructs over the past decade, the in vitro fabrication of a fully functional, transplantable 3D-bioprinted bioartificial liver with integrated and perfusable vasculature and biliary systems remains an unmet challenge in the field. Numerous studies have reported the construction of in vitro bioartificial liver models using diverse bioink formulations and printing strategies, yet few have achieved simultaneous vascular and biliary functional integration suitable for in vivo transplantation.

In our previous work, we developed a 3D-bioprinted bioengineered liver model using HepaRG cells as the hepatic parenchymal component and a gelatin-alginate composite hydrogel as the bioink. Following transplantation into Fah^−/−Rag2^−/− mice—a animal model with hereditary liver dysfunction—this model effectively restored key hepatic functions and significantly improved the survival of mice (17), validating the feasibility of 3D bioprinting for bioartificial liver development.

Coaxial printing, microfluidic techniques, and sacrificial biomaterials are widely employed for vascularization in bioartificial livers. Sacrificial bioinks, which are designed to be degradable under specific culture conditions, can be co-printed with functional cell-laden bioinks via coaxial printing and subsequently degraded during in vitro culture to form hollow vascular architectures (18). In one of our experimental approaches, we integrated coaxial printing to explore vascularization in 3D-bioprinted hepatic constructs, using in vitro-expanded primary hepatocytes (eHep cells) as hepatic parenchymal cells, human umbilical vein endothelial cells (HUVECs) as vascular endothelial cells, and a composite bioink consisting of gelatin, sodium alginate, and liver decellularized ECM (LdECM). This approach successfully yielded artificial vascular networks that were capable of mediating efficient biomolecular exchange with the host vascular system following in vivo transplantation (19).

In another approach, researchers printed HUVEC-laden gelatin sacrificial bioink onto pre-printed, liver lobule-like GelMA hydrogels encapsulating hepatocytes; followed by subsequent degradation of the sacrificial gelatin, HUVECs proliferated on the surface of the hepatocyte layer to form a vascular network, leading to the successful fabrication of an endothelialized liver lobule-like construct (20).

Although recent cutting-edge liver organoid studies have successful advances in cholangiogenesis—with multicellular organoid systems composed of human induced pluripotent stem cell (hiPSC)-derived liver progenitors, cholangiocytes, and mesenchymal cells capable of mimicking the hepatic periportal region and mediating basic bile transport function—the 3D bioprinting of functional, integrated, and scalable biliary duct structures remains an underdeveloped area of research (21).

While Yan and colleagues have utilized self-assembled peptide amphiphiles (PAs) to modulate the structural and biological properties of thiolated-gelatin (Gel-SH) bioinks and promote the formation of functional tubular structures by encapsulated cholangiocytes in 3D hydrogels (22), no studies have reported the successful fabrication of 3D-bioprinted bioartificial livers with integrated and functional biliary duct systems for in vivo bile excretion.

Notably, the integration of both functional vascular and biliary systems is critical for the clinical translation of bioartificial livers: bioartificial livers endowed with both efficient vascular nutrient supply and unobstructed biliary bile excretion capabilities can substantially reduce the incidence of hypoxic necrosis and cholestasis following transplantation, two major causes of graft failure, thereby markedly enhancing post-transplant survival rates and long-term graft function.

Collectively, it is of great significance to fabricate a high-precision, biomimetic, and transplantable bioartificial liver via 3D bioprinting—one that faithfully recapitulates the structural architecture, cellular composition, and physiological function of native liver lobules.

To this end, multi-nozzle 3D bioprinting technology enables the separate and simultaneous deposition of distinct cell-laden bioink formulations, facilitating the precise construction of complex, multicellular, and multicomponent hepatic constructs with spatially defined cell distribution (23).

This leads us to propose that when applying dual-nozzle bioprinting to fabricate multicellular co-culture models in strict accordance with the morphological architecture of native liver lobules, the anatomical and physiological characteristics of hepatic sinusoids, and the physiological cell concentration ratios in liver, the generation of a highly biomimetic, vascularized, cholangiogenic, and transplantable bioartificial liver will be realized (24). Such a bioengineered construct holds great translational potential to address the critical clinical challenge of donor liver scarcity and significantly improve the prognosis of patients with end-stage liver disease, ultimately providing a viable alternative to liver transplantation in the future.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, HepatoBiliary Surgery and Nutrition. The article did not undergo external peer review.

Funding: This work was supported by the Peking Union Medical College Hospital Talent Cultivation Program (Category C) (No. UBJ10452).

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-2026-0170/coif). H.Y. serves as an unpaid editorial board member of HepatoBiliary Surgery and Nutrition. Both authors report that this work was supported by the Peking Union Medical College Hospital Talent Cultivation Program (Category C) (No. UBJ10452). The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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