Biofabrication of synthetic human liver tissue with advanced programmable functions.

Advances in cellular engineering, as well as gene, and cell therapy, may be used to produce human tissues with programmable genetically enhanced functions designed to model and/or treat specific diseases. Fabrication of synthetic human liver tissue with these programmable functions has not been described. By generating human iPSCs with target gene expression controlled by a guide RNA-directed CRISPR-Cas9 synergistic-activation-mediator, we produced synthetic human liver tissues with programmable functions.

Assembly and Function of a Bioengineered Human Liver for Transplantation Generated Solely from Induced Pluripotent Stem Cells.

The availability of an autologous transplantable auxiliary liver would dramatically affect the treatment of liver disease. Assembly and function in vivo of a bioengineered human liver derived from induced pluripotent stem cells (iPSCs) has not been previously described. By improving methods for liver decellularization, recellularization, and differentiation of different liver cellular lineages of human iPSCs in an organ-like environment, we generated functional engineered human mini livers and performed transplantation in a rat model.

Cellular Location of HNF4α is Linked With Terminal Liver Failure in Humans.

Hepatocyte nuclear factor 4 alpha (HNF4α) is a transcription factor that plays a critical role in hepatocyte function, and HNF4α-based reprogramming corrects terminal liver failure in rats with chronic liver disease. In the livers of patients with advanced cirrhosis, HNF4α RNA expression levels decrease as hepatic function deteriorates, and protein expression is found in the cytoplasm. These findings could explain impaired hepatic function in patients with degenerative liver disease.

[Emergence of 3D human fatty liver models engineered in the laboratory].

Organoids offer an elegant approach to model human diseases and test new drugs. Nonalcoholic fatty liver disease (NAFLD) whose incidence has dramatically increased in recent years with the rise of obesity, is defined by triglyceride accumulation in hepatocytes, inflammation, liver injury, and progression to fibrosis. There is currently no approved therapy but many pathways are being explored.

Generation of Human Fatty Livers Using Custom-Engineered Induced Pluripotent Stem Cells with Modifiable SIRT1 Metabolism.

The mechanisms by which steatosis of the liver progresses to non-alcoholic steatohepatitis and end-stage liver disease remain elusive. Metabolic derangements in hepatocytes controlled by SIRT1 play a role in the development of fatty liver in inbred animals. The ability to perform similar studies using human tissue has been limited by the genetic variability in man.

Guide to the Assessment of Mature Liver Gene Expression in Stem Cell-Derived Hepatocytes.

Differentiation of stem cells to hepatocyte-like cells (HLCs) holds great promise for basic research, drug and toxicological investigations, and clinical applications. There are currently no protocols for the production of HLCs from stem cells, such as embryonic stem cells or induced pluripotent stem cells, that produce fully mature hepatocytes with a wide range of mature hepatic functions. This report describes a standard method to assess the maturation of stem cell-derived HLCs with a moderately high-throughput format, by analysing liver gene expression by quantitative RT-qPCR.

Induced Pluripotent Stem Cell-Derived Endothelial Cells: Overview, Current Advances, Applications, and Future Directions.

Endothelial cells are prevalent in our bodies and serve multiple functions. By lining the vasculature, they provide a barrier to tissues and facilitate the transport of molecules and cells. They also maintain hemostasis and modulate blood flow by reacting to chemokines and releasing signal molecules.

Liver-enriched transcription factor expression relates to chronic hepatic failure in humans.

The mechanisms by which the liver fails in end-stage liver disease remain elusive. Disruption of the transcription factor network in hepatocytes has been suggested to mediate terminal liver failure in animals. However, this hypothesis remains unexplored in human subjects.

Understanding Liver Regeneration: From Mechanisms to Regenerative Medicine.

Liver regeneration is a complex and unique process. When two-thirds of a mouse liver is removed, the remaining liver recovers its initial weight in approximately 10 days. The understanding of the mechanisms responsible for liver regeneration may help patients needing large liver resections or transplantation and may be applied to the field of regenerative medicine.

Microenvironment of a tumor-organoid system enhances hepatocellular carcinoma malignancy-related hallmarks.

Organ-like microenviroment and 3-dimensional (3D) cell culture conformations have been suggested as promising approaches to mimic in a micro-scale a whole organ cellular functions and interactions present in vivo. We have used this approach to examine biologic features of hepatocellular carcinoma (HCC) cells. In this study, we demonstrate that hepatocellular carcinoma (HCC) cells, fibroblasts, endothelial cells and extracellular matrix can generate organoid-like spheroids that enhanced numerous features of human HCC observed in vivo.

Current strategies to generate mature human induced pluripotent stem cells derived cholangiocytes and future applications.

Stem cell research has significantly evolved over the last few years, allowing the differentiation of pluripotent cells into almost any kind of lineage possible. Studies that focus on the liver have considerably taken a leap into this novel technology, and hepatocyte-like cells are being generated that are close to resembling actual hepatocytes both genotypically and phenotypically. The potential of this extends from disease models to bioengineering, and even also innovative therapies for end-stage liver disease.

Regeneration and Cell Recruitment in an Improved Heterotopic Auxiliary Partial Liver Transplantation Model in the Rat.

Background: Auxiliary partial liver transplantation (APLT) in humans is a therapeutic modality used especially to treat liver failure in children or congenital metabolic disease. Animal models of APLT have helped to explore therapeutic options. Though many groups have suggested improvements, standardizing the surgical procedure has been challenging.

SIRT1 Disruption in Human Fetal Hepatocytes Leads to Increased Accumulation of Glucose and Lipids.

There are unprecedented epidemics of obesity, such as type II diabetes and non-alcoholic fatty liver diseases (NAFLD) in developed countries. A concerning percentage of American children are being affected by obesity and NAFLD. Studies have suggested that the maternal environment in utero might play a role in the development of these diseases later in life.

From hacking the human genome to editing organs.

In the recent decades, human genome engineering has been one of the major interesting research subjects, essentially because it raises new possibilities for personalized medicine and biotechnologies. With the development of engineered nucleases such as the Zinc Finger Nucleases (ZFNs), the Transcription activator-like effector nucleases (TALENs) and more recently the Clustered Regularly Interspaced short Palindromic Repeats (CRISPR), the field of human genome edition has evolved very rapidly. Every new genetic tool is broadening the scope of applications on human tissues, even before we can completely master each of these tools.

EGFR: A Master Piece in G1/S Phase Transition of Liver Regeneration.

Unraveling the molecular clues of liver proliferation has become conceivable thanks to the model of two-third hepatectomy. The synchronicity and the well-scheduled aspect of this process allow scientists to slowly decipher this mystery. During this phenomenon, quiescent hepatocytes of the remnant lobes are able to reenter into the cell cycle initiating the G1-S progression synchronously before completing the cell cycle.

Increased susceptibility to liver fibrosis with age is correlated with an altered inflammatory response.

It has been suggested that increasing age is correlated with an acceleration of the progression of liver fibrosis induced by various agents, such as hepatitis C virus or chronic alcohol consumption. However, the cellular and molecular changes underlying this predisposition are not entirely understood. In the context of an aging population, it becomes challenging to decipher the mechanisms responsible for this higher susceptibility of older individuals to this acquired liver disorder.

GH receptor plays a major role in liver regeneration through the control of EGFR and ERK1/2 activation.

GH is a pleiotropic hormone that plays a major role in proliferation, differentiation, and metabolism via its specific receptor. It has been previously suggested that GH signaling pathways are required for normal liver regeneration but the molecular mechanisms involved have yet to be determined. The aim of this study was to identify the mechanisms by which GH controls liver regeneration.