Human Liver Function Research Articles

Characterization and genome sequence of N,N-dimethylformamide degradation in Paracoccus sulfuroxidans DM175A1-1 isolated from activated sludge of wastewater.

N,N-dimethylformamide (DMF) is an organic solvent with stable chemical properties and high boiling point. Based on its good solubility, DMF is widely used in synthetic textile, leather, electronics, pharmaceutical and pesticide industries. However, the DMF pollutes the environment and does harm to human liver function, kidney function, and nerve function. Herein, an efficient DMF-degrading strain, DM175A1-1, was isolated and identified as Paracoccus sulfuroxidans. This strain can use DMF as the sole source of carbon and nitrogen. Whole-genome sequencing of strain DM175A1-1 revealed that it has a 3.99-Mbp chromosome a 120-kbp plasmid1 and a 40-kbp plasmid2. The chromosome specifically harbors the dmfA1 and dmfA2 essential for the initial steps of DMF degradation. And it also carries the some part of genes facilitating subsequent methylotrophic metabolism and glutathione-dependent pathway. Through further DMF tolerance degradation experiments, DM175A1-1 can tolerate DMF concentrations up to 10,000 mg/L, whereas the majority of Paracoccus strains could only show degradation activity below 1,000 mg/L. And the efficiency of organic nitrogen conversion to NH3-N in DMF can reach 99.0% when the hydraulic retention time (HRT) is controlled at 5 days. Meanwhile, it showed a significant degradation effect at a pharmaceutical enterprise in Zhejiang Province with high concentration of DMF wastewater. This study provides a new strain Paracoccus sulfuroxidans DM175A1-1 which shows a significant influence on DMF degradation, and reveals the characterization on its DMF degradation. It lays the foundation for the application of biological method in the efficient degradation of DMF in industrial wastewater.

Effects of Selenium and Cadmium on Human Liver and Kidney Functions in Exposed Black Shale Areas.

Animal experiments suggest that selenium (Se) may alleviate cadmium (Cd) toxicity in animal liver and kidneys, but its effect on human liver and kidneys remains uncertain. In China, areas with black shale have shown elevated levels of Se and Cd. According to the USEPA (U.S. Environmental Protection Agency) evaluation method, the soil and rice in these areas pose significant risks. In black shale regions such as Enshi and Zhuxi County, residents who long-term consume local rice may surpass safe Se and Cd intake levels. Significantly high median blood Se (B-Se) and urine selenium (U-Se) levels were detected in these areas, measuring 416.977μg/L and 352.690μg/L and 104.527μg/L and 51.820μg/L, respectively. Additionally, the median blood Cd (B-Cd) and urine Cd (U-Cd) levels were markedly elevated at 4.821μg/L and 3.848μg/L and at 7.750μg/L and 7.050μg/L, respectively, indicating substantial Cd exposure. Nevertheless, sensitive liver and kidney biomarkers in these groups fall within healthy reference ranges, suggesting a potential antagonistic effect of Se on Cd in the human body. Therefore, the USEPA method may not accurately assess Cd risk in exposed black shale areas. However, within the healthy ranges, residents in the Enshi study area had significantly greater median levels of serum creatinine and cystatin C, measuring 67.3μmol/L and 0.92mg/L, respectively, than those in Zhuxi did (53.6μmol/L and 0.86mg/L). In cases of excessive Se and Cd exposure, high Se and Cd levels impact the filtration function of the human kidney to some extent.

PFHxS Exposure and the Risk of Non-Alcoholic Fatty Liver Disease.

Perfluorohexanesulfonic acid (PFHxS) is a highly prevalent environmental pollutant, often considered to be less toxic than other poly- and perfluoroalkyl substances (PFASs). Despite its relatively lower environmental impact compared to other PFASs, several studies have suggested that exposure to PFHxS may be associated with disruptions of liver function in humans. Nevertheless, the precise pathomechanisms underlying PFHxS-induced non-alcoholic fatty liver disease (NAFLD) remain relatively unclear. Therefore, this study applied our previously published transcriptome dataset to explore the effects of PFHxS exposure on the susceptibility to NAFLD and to identify potential mechanisms responsible for PFHxS-induced NAFLD through transcriptomic analysis conducted on zebrafish embryos. Results showed that exposure to PFHxS markedly aggravated hepatic symptoms resembling NAFLD and other metabolic syndromes (MetS) in fish. Transcriptomic analysis unveiled 17 genes consistently observed in both NAFLD and insulin resistance (IR), along with an additional 28 genes identified in both the adipocytokine signaling pathway and IR. These shared genes were also found within the NAFLD dataset, suggesting that hepatic IR may play a prominent role in the development of PFHxS-induced NAFLD. In conclusion, our study suggests that environmental exposure to PFHxS could be a potential risk factor for the development of NAFLD, challenging the earlier notion of PFHxS being safer as previously claimed.

Associations between inhalation of typical volatile and semi-volatile organic compounds in e-waste dismantling workers with liver function damage

Studies in cell culture and animal models suggest hepatotoxicity of some volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), however, their effects in human populations under real exposure conditions have never been clarified. In this cross-sectional study, 224 participants, 38 e-waste dismantling workers and 186 subjects residing near to the dismantling sites in southern China, were evaluated for personal inhalational exposure to 72 VOCs and 91 SVOCs according to site-specific atmospheric chemical concentrations and personal exposure time. Additionally, their serum samples were subjected to liver function tests (LFTs), including total protein (TP), albumin (ALB), globulin (GLB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and bilirubin. Linear regression analysis of the VOC/SVOC levels against the LFTs results indicated that VOC exposure was negatively associated with the TP, ALB, GLB levels (indicating liver-specific protein synthesis functions), while positively associated with AST, ALT, GGT activities (marking liver damage). Somehow, SVOC exposure appeared to be positively associated with not only AST and ALT but also TP and ALB. These findings were supported by the quantile g-computation analysis and confirmed in the Bayesian kernel machine regression model. This study indicates that simultaneous inhalation of VOCs and SVOCs may impair human liver functions.

Higher urinary glyphosate exposure is associated with increased risk of liver dysfunction in adults: An analysis of NHANES, 2013-2016.

Glyphosate (GLY) exposure, both exogenous and endogenous, is a global concern. Multiple studies of model systems in vitro and in vivo have demonstrated the potential toxic effects of GLY exposure on human organs, particularly the liver and renal system. However, there is currently limited epidemiological evidence establishing a link between GLY exposure and hepatorenal function in the general population. In this study, a multivariable linear regression model and forest plots were employed to evaluate the connection between urinary GLY and biomarkers of hepatorenal function in 2241 participants from the National Health and Nutrition Examination Survey 2013-2016. Additionally, subgroup analyses were conducted based on age, gender, race, BMI, and chronic kidney disease (CKD). Alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), AST/ALT and fibrosis 4 score (FIB-4) all increased with elevated urinary GLY concentrations after adjusting for potential confounders, while albumin (ALB) exhibited the opposite trend, particularly among younger, female, non-Hispanic white, overweight, and CKD participants. Furthermore, individuals in the third tertile had a greater risk of liver dysfunction than those in the first tertile after categorizing urinary GLY concentrations. However, our study showed no proof that GLY exposure affects the ratio of urine albumin to creatinine (ACR) or serum creatinine levels. Overall, these results imply that GLY exposure may have adverse effects on human liver function.

ICG clearance test based on photoacoustic imaging for assessment of human liver function reserve: An initial clinical study

Liver function reserve (LFR) plays an extensive and important role in patients with liver disease. Indocyanine green (ICG) clearance test is the standard diagnostic approach for LFR evaluation which was performed by spectrophotometry or pulse dye densitometry (PDD). Spectrophotometry is the gold standard, it's invasive and not real-time. PDD is non-invasive, but accuracy of PDD is controversial. Taken spectrophotometry as the reference standard, this study investigated the accuracy of photoacoustic imaging (PAI) method for LFR assessment and compared to PDD in healthy volunteers. The results demonstrated a strong correlation between PAI method and spectrophotometry (r = 0.9649, p < 0.0001). No significant difference was shown in ICG clearance between PAI and spectrophotometry method (rate constant k1 vs. k2, 0.001158 +−0.00042 vs. 0.001491 +- 0.00045, p = 0.0727; half-life t1 vs. t2, 601.2 s vs. 474.4 s, p = 0.1450). These results indicated that PAI may be valuable as a noninvasive, accurate diagnostic tool for LFR assessment in human.

Three-Dimensional Cell Co-Culture Liver Models and Their Applications in Pharmaceutical Research.

As the primary site for the biotransformation of drugs, the liver is the most focused on organ type in pharmaceutical research. However, despite being widely used in pharmaceutical research, animal models have inherent species differences, while two-dimensional (2D) liver cell monocultures or co-cultures and three-dimensional (3D) liver cell monoculture in vitro liver models do not sufficiently represent the complexity of the human liver's structure and function, making the evaluation results from these tools less reliable. Therefore, there is a pressing need to develop more representative in vitro liver models for pharmaceutical research. Fortunately, an exciting new development in recent years has been the emergence of 3D liver cell co-culture models. These models hold great promise as in vitro pharmaceutical research tools, because they can reproduce liver structure and function more practically. This review begins by explaining the structure and main cell composition of the liver, before introducing the potential advantages of 3D cell co-culture liver models for pharmaceutical research. We also discuss the main sources of hepatocytes and the 3D cell co-culture methods used in constructing these models. In addition, we explore the applications of 3D cell co-culture liver models with different functional states and suggest prospects for their further development.

Mathematical models for biomarker calculation of drug-induced liver injury in humans and experimental models based on gadoxetate enhanced magnetic resonance imaging.

Drug induced liver injury (DILI) is a major concern when developing new drugs. A promising biomarker for DILI is the hepatic uptake rate of the contrast agent gadoxetate. This rate can be estimated using a novel approach combining magnetic resonance imaging and mathematical modeling. However, previous work has used different mathematical models to describe liver function in humans or rats, and no comparative study has assessed which model is most optimal to use, or focused on possible translatability between the two species. Our aim was therefore to do a comparison and assessment of models for DILI biomarker assessment, and to develop a conceptual basis for a translational framework between the species. We first established which of the available pharmacokinetic models to use by identifying the most simple and identifiable model that can describe data from both human and rats. We then developed an extension of this model for how to estimate the effects of a hepatotoxic drug in rats. Finally, we illustrated how such a framework could be useful for drug dosage selection, and how it potentially can be applied in personalized treatments designed to avoid DILI. Our analysis provides clear guidelines of which mathematical model to use for model-based assessment of biomarkers for liver function, and it also suggests a hypothetical path to a translational framework for DILI.

Environment-wide association study of elevated liver enzymes: results from the Korean National Environmental Health Survey 2018-2022.

Environmental exposure is characterized by low concentration, chronic, and complex exposure. Traditional epidemiological studies show limitations in reflecting these characteristics since they usually focus on a single or very limited number of exposure factors at a time. In this study, we adopted the methodology of environment-wide association study (EWAS) to figure out the association of human liver function with various environmentally hazardous substances. We analyzed 2,961 participants from the Korean National Environmental Health Survey Cycle 4 (2018-2020). Using generalized linear model (GLM) analysis, we analyzed the association of 72 variables with 3 liver function indices (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and gamma glutamyl transferase [GGT]). Finally, we visualized our results with Manhattan plot. In GLM analysis, perfluorooctanesulfonate were positively associated with ALT (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.39-3.46; p adjusted = 0.0147) and perfluorodecanoic acid showed positive association with GGT (OR: 2.73; 95% CI: 1.36-5.5; p adjusted = 0.0256). Plasma mercury showed positive association with GGT (OR: 1.45; 95% CI: 1.14-1.84; p adjusted = 0.0315). Using a plastic container while keeping food in the refrigerator was associated with elevated GGT compared to using a glass container (OR: 1.51; 95% CI: 1.16-1.95; p adjusted = 0.0153). 2-ethyl-5-oxohexyl phthalate, showed a negative trend with all 3 indices, with AST (OR: 0.54; 95% CI: 0.39-0.73; p adjusted = 0.00357), ALT (OR: 0.5; 95% CI: 0.34-0.75; p adjusted = 0.036), GGT (OR: 0.55; 95% CI: 0.4-0.76; p adjusted = 0.00697). Bisphenol S and frequent use of sunblock cream showed negative association with ALT (OR: 0.77; 95% CI: 0.66-0.89), and GGT (OR: 0.25; 95% CI: 0.11-0.55), respectively. We conducted an exploratory study on environmental exposure and human liver function. By using EWAS methodology, we identified 7 factors that could have potential association with liver function.

2D and 3D liver models

2D and 3D liver models

The Potential Effect of Henna (Stone Dye) Extract Paraphenylenediamine on Human Blood Cells, Liver and Renal Function

Some of the dyes that are used for coloring hair and skin contain a chemical compound called paraphenylenediamine (PPD), which is potentially toxic. The study comprised 50 adult Sudanese women who were selected by stratified random sampling and working as henna artist. Urine samples were taken for detection of PPD while blood samples were taken for investigating kidney and liver functions by measuring its relevant hematological indices. In other hand Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC) were used to detection of PPD in black henna (stone dye) samples and urine. The PPD was detected in the urine of all women who used the black henna its concentration varied according to duration of exposure being significantly higher in those with &gt;10 years of exposure (p≤0.01). Similarly significant changes in liver function, kidney function and hematological indices were found in the group of women who used natural henna. This study concluded that natural henna is safe to use, while Black dye is potentially hazardous. It contains the high concentration of PPD, is the one most commonly associated with adverse effects.

Pregnancy and weaning regulate human maternal liver size and function

During pregnancy, the rodent liver undergoes hepatocyte proliferation and increases in size, followed by weaning-induced involution via hepatocyte cell death and stromal remodeling, creating a prometastatic niche. These data suggest a mechanism for increased liver metastasis in breast cancer patients with recent childbirth. It is unknown whether the human liver changes in size and function during pregnancy and weaning. In this study, abdominal imaging was obtained in healthy women at early and late pregnancy and postwean. During pregnancy time points, glucose production and utilization and circulating bile acids were measured. Independently of weight gain, most women's livers increased in size with pregnancy, then returned to baseline postwean. Putative roles for bile acids in liver growth and regression were observed. Together, the data support the hypothesis that the human liver is regulated by reproductive state with growth during pregnancy and volume loss postwean. These findings have implications for sex-specific liver diseases and for breast cancer outcomes.

Engineering Modular 3D Liver Culture Microenvironments In Vitro to Parse the Interplay between Biophysical and Biochemical Microenvironment Cues on Hepatic Phenotypes.

In vitro models of human liver functions are used across a diverse range of applications in preclinical drug development and disease modeling, with particular increasing interest in models that capture facets of liver inflammatory status. This study investigates how the interplay between biophysical and biochemical microenvironment cues influence phenotypic responses, including inflammation signatures, of primary human hepatocytes (PHH) cultured in a commercially available perfused bioreactor. A 3D printing-based alginate microwell system was designed to form thousands of hepatic spheroids in a scalable manner as a comparator 3D culture modality to the bioreactor. Soft, synthetic extracellular matrix (ECM) hydrogel scaffolds with biophysical properties mimicking features of liver were engineered to replace polystyrene scaffolds, and the biochemical microenvironment was modulated with a defined set of growth factors and signaling modulators. The supplemented media significantly increased tissue density, albumin secretion, and CYP3A4 activity but also upregulated inflammatory markers. Basal inflammatory markers were lower for cells maintained in ECM hydrogel scaffolds or spheroid formats than polystyrene scaffolds, while hydrogel scaffolds exhibited the most sensitive response to inflammation as assessed by multiplexed cytokine and RNA-seq analyses. Together, these engineered 3D liver microenvironments provide insights for probing human liver functions and inflammatory response in vitro.

Using a Human Liver Tissue Equivalent (hLTE) Platform to Define the Functional Impact of Liver-Directed AAV Gene Therapy

Clinical trials employing AAV vectors for hemophilia A have been hindered by unanticipated immunological and/or inflammatory responses in some of the patients. Also, these trials have often yielded lower levels of transgene expression than were expected based upon preclinical studies, highlighting the poor correlation between the transduction efficiency observed in traditional 2D cultures of primary cells in vitro, and that observed in those same cell types in vivo. It has been also recognized that there are marked species-specific differences in AAV-vector tropism, raising the critical question of the accuracy with which various animal models will likely predict tropism/vector transduction efficiency, and eventual treatment success in humans. Human liver tissue equivalents (hLTEs) are comprised of major cell types in the liver in physiologically relevant frequencies and possess the ability to recapitulate the biology and function of native human liver. Here, we hypothesize that hLTEs can be used as a better model to predict the efficacy and safety of AAV gene therapy in humans. We fabricated hLTEs using 75% hepatocytes, 10% stellate cells, 10% Kupffer cells, and 5% liver sinusoid-derived endothelial cells in 96-well Elplasia plates with 79 microwells per well. hLTEs were transduced at an MOI of 10 5vg/cell, on the day of fabrication, with the clinically relevant serotypes AAV5 (hLTE-5) or AAV3b (hLTE-3b), both encoding a GFP reporter. After 4 days of self-aggregation, live/dead assay was performed to confirm viability. Non-transduced hLTEs served as negative controls (hLTE(-)), and hLTEs exposed to 20 mM acetaminophen were used as positive controls for liver inflammation/damage. Incucyte® Live-Cell Imaging system was used to track the aggregation and GFP expression of hLTEs. Over the course of the next 5 days, media was collected to determine hepatic functionality, RNA was isolated to assess dysregulation of genes involved in inflammation and fibrosis, DNA was isolated to determine whether AAV vectors integrate into the genome of human hepatocytes and, if so, to define the frequency at which this occurs and the genomic loci of integration, and hLTEs were fixed and processed at appropriate times for histological analyses and transmission electron microscopy (TEM). TEM analysis revealed that all groups exhibited microvilli and bile-canaliculus-like structures, demonstrating the formation of a rudimentary biliary system and, more importantly, proving that hLTEs resemble native liver structure. Incucyte® imaging showed that AAV5 and AAV3b transduction impaired formation of hLTEs (57.57 ± 2.42 and 24.57 ± 4.01 spheroids/well, respectively) in comparison with hLTE(-) (74.86 ± 3.8 spheroids/well). Quantification of GFP expression demonstrated that AAV5 yielded the most efficient transduction of hLTEs (fold change in GFP expression compared to control: 2.73 ± 0.09 and 1.19 ± 0.03 for hLTE-5 and hLTE-3b, respectively). Chromogenic assays showed decreased urea production in cell culture supernatants of AAV transduced groups compared to the non-transduced hLTEs on days 6 and 10 of culture, demonstrating decreased hepatocyte functionality. However, ALT and AST levels were similar in all groups. On day 10, hLTEs were either used for RNA isolation or fixed in 4% PFA and processed for histology. Masson's Trichrome and Alcian Blue/Sirius Red staining was performed to detect fibrosis, which was then quantified using ImageJ. These analyses showed no significant increase in fibrosis in either hLTE-5 or hLTE-3b compared to hLTE(-). Nevertheless, RT 2 PCR Array for Human Fibrosis detected dysregulation of several genes involved in fibrosis/inflammation in both hLTE-5 and hLTE-3b (16/84 and 26/84, respectively). In conclusion, data collected thus far show successful recapitulation of native liver biology and demonstrate that AAV5 transduces hLTEs more efficiently than AAV3b. However, impaired self-aggregation and decreased hepatocyte functionality was observed in both AAV-transduced groups. Studies to address the incidence and location(s) of AAV integration are ongoing. We have thus shown that the hLTE system can provide critical new knowledge regarding the efficacy and safety of AAV gene therapy in the human liver. DisclosuresNo relevant conflicts of interest to declare.

Множинні ефекти хронічного низькодозового впливу кадмію на печінку, остеогенез та гемопоез тварин і людини

Cadmium salts are among the TOP-20 of the most dangerous compounds for animals in terms of toxicity. At the same time, today there is a paradigm shift in the studies of cadmium effects: in contrast to the acute effects of intoxication, more importance and practical relevance is attained by studying the continued chronic exposure to small cadmium doses (Chronic Low Cd Exposure) which can take place in real environmental conditions of industrially polluted regions and already impacts about 10% of the world population. While the early changes in kidneys and marker parameters of the urinary system under the action of cadmium are being studied quite actively, cadmium effects on other organs and systems in the body are insufficiently investigated. The purpose of the study was to analyse the multiple effects of cadmium on liver function, osteogenesis, haematopoiesis, and haemostasis in animals and humans. Protective mechanisms that reduce cadmium accumulation in hepatocytes compared to renal cells, in particular, the role of cellular transporters of biogenic metal ions (Fe2+, Zn2+, Mn2+, Cu2+), are systematized. Results and discussion. Cadmium mostly uses divalent metal transporter 1 and Zrt/Irt-like transporters, such as ZIP8 and ZIP14. Given the role of liver in the chelation and deposition of cadmium in the form of complexes with metallothioneins and glutathione, the significant potential of chelating and antioxidant hepatoprotectants to reduce negative effects is suggested. The role of exogenous chemical chelators and antioxidants in detoxifying cadmium is supported by the studies of other cadmium-binding molecules (glutathione, polyphenols, anthocyanins). Both direct effects of cadmium on the osteogenesis and calcium metabolism, and indirect effects on osteoblasts and osteoclasts are considered. In particular, current data on cadmium role in the development of endemic disease Itai-Itai in Japan is discussed. Notably, cadmium effect in children has a special hazards and long-term consequences. Data on cadmium role in interfering Ca2+ metabolism, particularly its effects on epithelial calcium channels (TRPV5) and Na-phosphate co-transporters (SLC34A1) are summarized. Conclusion. Current data suggest that chronic effects of cadmium in ultra-low concentrations upon the osteogenesis are even more evident than in renal system. A review of current data on cadmium effects upon the hematopoietic system in animal models is presented. The earliest studies found relation between cadmium and haemoglobin decrease, which could be mediated by interfering with intracellular Fe traffic, and effects on erythropoietin synthesis. Cadmium affected haemostasis and increased platelet aggregation. Animal studies suggest that chronic cadmium toxicity leads to hypercoagulation and increases the risks of thrombosis. Based on the summarized data, it is concluded that the investigating cadmium effects on hematopoiesis and hemostasis is a promising area for further studies of chronic low-dose cadmium exposure

The future of liver transplantation: Ex-vivo machine perfusion

Long-term preservation of liver grafts outside of the body (ex vivo) may enable treatment, repair, assessment of poor-quality livers currently declined for transplantation and regeneration of partial livers, thereby mitigating global donated liver shortage. The challenge, however, is to keep injured or resected human livers viable for multiple days, a time window necessary for expanded therapeutic interventions. Here, we present a liver perfusion technology that maintains ex vivo human liver function for seven days. The perfusion apparatus was engineered recapitulating core endocrine, renal, pulmonary, cardiac, diaphragmatic, and other physiologic functions for the liver, which are prerequisite for successful long-term liver preservation. The machine was developed in a stepwise fashion using swine livers and eventually tested in injured human livers declined for transplantation and in partial livers from patients, who have undergone formal hepatectomy. Perfused human livers, discarded for poor quality and predicted failure after transplantation, as well as the partial livers unveiled preserved function during ex vivo machine perfusion, as indicated by bile production, synthesis of coagulation factors and maintained cellular energy, among many others. Histological examinations of serial biopsies confirmed an intact liver structure at day seven. This data demonstrates, first, that injured human livers may recover from lethal injury and maintain function for one week outside of the body and second, that the availability of this machine perfusion system may provide an important tool for assessment of liver quality, to induce liver regeneration in partial livers, and to perform therapeutic interventions prior to transplantation.

Hepatocyte size fractionation allows dissection of human liver zonation.

Human hepatocytes show marked differences in cell size, gene expression, and function throughout the liver lobules, an arrangement termed liver zonation. However, it is not clear if these zonal size differences, and the associated phenotypic differences, are retained in isolated human hepatocytes, the "gold standard" for in vitro studies of human liver function. Here, we therefore explored size differences among isolated human hepatocytes and investigated whether separation by size can be used to study liver zonation in vitro. We used counterflow centrifugal elutriation to separate cells into different size fractions and analyzed them with label-free quantitative proteomics, which revealed an enrichment of 151 and 758 proteins (out of 5163) in small and large hepatocytes, respectively. Further analysis showed that protein abundances in different hepatocyte size fractions recapitulated the in vivo expression patterns of previously described zonal markers and biological processes. We also found that the expression of zone-specific cytochrome P450 enzymes correlated with their metabolic activity in the different fractions. In summary, our results show that differences in hepatocyte size matches zonal expression patterns, and that our size fractionation approach can be used to study zone-specific liver functions in vitro.

Reply to "Discussion of 'Whey protein supplementation and its potentially adverse effects on health: a systematic review' - Unsubstantiated claims of adverse effects of whey protein supplementation on human kidney and liver function".

Reply to "Discussion of 'Whey protein supplementation and its potentially adverse effects on health: a systematic review' - Unsubstantiated claims of adverse effects of whey protein supplementation on human kidney and liver function".

Discussion of "Whey protein supplementation and its potentially adverse effects on health: a systematic review" - Unsubstantiated claims of adverse effects of whey protein supplementation on human kidney and liver function.

Discussion of "Whey protein supplementation and its potentially adverse effects on health: a systematic review" - Unsubstantiated claims of adverse effects of whey protein supplementation on human kidney and liver function.

An in vitro 3D Model of Functional Human Liver Organoids

Introduction: The development of adequate model systems to investigate human liver function and metabolism in health and disease has proved challenging. Three-dimensional (3D) liver tissues reconstituted from liver cells, termed liver organoids, have enormous potential for investigating aspects of liver disorders and drug toxicity. The aim of our study is by integration of multiple novel surgical techniques, engineering of growth factors and morphogens bound to extracellular matrix, direct cell reprogramming to produce functional 3D liver organoids. Methods: Tissue from 20 liver resections were used for hepatocyte isolations. Tissue underwent a two-step EDTA/collagenase digestion. Cell viability was determined by ATP luminescence and 7AAD. qPCR, FACS, Western blot, imunofluorescence analysis and biochemical assays were undertaken to ascertain cellular phenotype and function in 3D cultures. Additionally, liver development-associated signaling pathways were tested. Results: We demonstrate that there is direct correlation between liver status, the number and viability of isolated hepatocytes and their functional properties in 2D and 3D environment. FACS analysis indicated that prolonged cultivation in 2D leads to changes in cell populations. We also generated functional liver 3D organoids that maintained viability up to three weeks, produced albumin and expressed liver specific genes HNF4, CK19, AAT, CYP3A4. Conclusions: We have successfully established a method for the culture of human liver organoids in novel engineered 3D environments that can be used for biomarker discovery, drug toxicity studies and liver transplantation.