An All-Human Hepatic Culture System for Drug Development Applications

Finding a long-term, human-relevant culture model for primary human hepatocytes (PHHs) for pharmacological and toxicological studies remains a challenge. Current in vitro model platforms are often inconvenient and complex, lack phenotypic stability over time, and do not support multiple PHH lots, lacking experimental reproducibility and flexibility. Here, we provide a detailed protocol for the thawing, plating, and maintenance of an all-human 2D+ hepatic system (TV2D+), which takes advantage of standard two-dimensional (2D) culture techniques and equipment while maintaining the longevity and phenotypic stability over time that typically accompany more complex three-dimensional (3D) systems. The results show attachment and percent plateability in TV2D+ as a function of PHH seeding density, as well as stable functionality for at least 2 weeks in culture. A range of PHH seeding densities are assessed to achieve a successful long-term culture. When established properly, the PHHs in TV2D+ organize into hepatocyte colonies, express a hepatic-specific marker, and maintain viability, architectural integrity, and physiologically relevant levels of albumin and urea. This unique combination of attributes makes the TV2D+ system a suitable hepatic model for a variety of pharmacological and toxicological applications.

Increasing the availability of quality human tissue for research

Advances in 3D and other in vitro tissue model platforms have led to fundamental improvements in research on human disease, development of novel therapies, and safety testing. In addition, histological and cellular investigations of human tissues continue to serve as keystones in understanding disease and health processes. In recognition of the importance of human tissues in research, the Physicians Committee for Responsible Medicine held a workshop. Working closely with key stakeholders from the research community, regulatory agencies, and organ procurement organizations, the goal was to explore, understand, and address the barriers to increased use of human organs, tissues, and cells in research. Workshop participants were tasked with identifying the challenges of accessing and qualifying tissues for research purposes and creating a strategy to help meet the needs of the research communities to increase the availability and quality of human tissues in biomedical and translational research. Break-out groups identified significant challenges in the areas of policy, scientific development, and public engagement with respect to the provision and application of tissues and cells for scientific advancement. Following working group recommendations, stakeholders concluded that there is a need to facilitate the availability and quality of human tissues for the research community, as well as provide a framework for education of the public, medical professionals, and researchers to foster donation and utilization for research in place of animal models. The success of these new initiatives will facilitate greater access to high-quality human tissues for biomedical and translational research and help ensure the transition away from the dependence on animal models.

Primary Alcohol-Activated Human and Mouse Hepatic Stellate Cells Share Similarities in Gene-Expression Profiles

Alcoholic liver disease (ALD) is a leading cause of cirrhosis in the United States, which is characterized by extensive deposition of extracellular matrix proteins and formation of a fibrous scar. Hepatic stellate cells (HSCs) are the major source of collagen type 1 producing myofibroblasts in ALD fibrosis. However, the mechanism of alcohol-induced activation of human and mouse HSCs is not fully understood. We compared the gene-expression profiles of primary cultured human HSCs (hHSCs) isolated from patients with ALD (n = 3) or without underlying liver disease (n = 4) using RNA-sequencing analysis. Furthermore, the gene-expression profile of ALD hHSCs was compared with that of alcohol-activated mHSCs (isolated from intragastric alcohol-fed mice) or CCl₄-activated mouse HSCs (mHSCs). Comparative transcriptome analysis revealed that ALD hHSCs, in addition to alcohol-activated and CCl₄-activated mHSCs, share the expression of common HSC activation (Col1a1 [collagen type I alpha 1 chain], Acta1 [actin alpha 1, skeletal muscle], PAI1 [plasminogen activator inhibitor-1], TIMP1 [tissue inhibitor of metalloproteinase 1], and LOXL2 [lysyl oxidase homolog 2]), indicating that a common mechanism underlies the activation of human and mouse HSCs. Furthermore, alcohol-activated mHSCs most closely recapitulate the gene-expression profile of ALD hHSCs. We identified the genes that are similarly and uniquely up-regulated in primary cultured alcohol-activated hHSCs and freshly isolated mHSCs, which include CSF1R (macrophage colony-stimulating factor 1 receptor), PLEK (pleckstrin), LAPTM5 (lysosmal-associated transmembrane protein 5), CD74 (class I transactivator, the invariant chain), CD53, MMP9 (matrix metallopeptidase 9), CD14, CTSS (cathepsin S), TYROBP (TYRO protein tyrosine kinase-binding protein), and ITGB2 (integrin beta-2), and other genes (compared with CCl₄-activated mHSCs). Conclusion: We identified genes in alcohol-activated mHSCs from intragastric alcohol-fed mice that are largely consistent with the gene-expression profile of primary cultured hHSCs from patients with ALD. These genes are unique to alcohol-induced HSC activation in two species, and therefore may become targets or readout for antifibrotic therapy in experimental models of ALD.

A population of selected renal cells augments renal function and extends survival in the ZSF1 model of progressive diabetic nephropathy

New treatment paradigms that slow or reverse progression of chronic kidney disease (CKD) are needed to relieve significant patient and healthcare burdens. We have shown that a population of selected renal cells (SRCs) stabilized disease progression in a mass reduction model of CKD. Here, we further define the cellular composition of SRCs and apply this novel therapeutic approach to the ZSF1 rat, a model of severe progressive nephropathy secondary to diabetes, obesity, dyslipidemia, and hypertension. Injection of syngeneic SRCs into the ZSF1 renal cortex elicited a regenerative response that significantly improved survival and stabilized disease progression to renal structure and function beyond 1 year posttreatment. Functional improvements included normalization of multiple nephron structures and functions including glomerular filtration, tubular protein handling, electrolyte balance, and the ability to concentrate urine. Improvements to blood pressure, including reduced levels of circulating renin, were also observed. These functional improvements following SRC treatment were accompanied by significant reductions in glomerular sclerosis, tubular degeneration, and interstitial inflammation and fibrosis. Collectively, these data support the utility of a novel renal cell-based approach for slowing renal disease progression associated with diabetic nephropathy in the setting of metabolic syndrome, one of the most common causes of end-stage renal disease.

Inhibition of trypsin and thrombin by amino(4-amidinophenyl)methanephosphonate diphenyl ester derivatives: X-ray structures and molecular models

X-ray structures of trypsin from bovine pancreas inactivated by diphenyl [N-(benzyloxycarbonyl)amino](4-amidinophenyl)methanephosphonate [Z-(4-AmPhGly)P(OPh)2] were determined at 113 and 293 K to 1.8 angstrom resolution and refined to R factors of 0.211 (113 K) and 0. 178 (293 K). The structures reveal a tetrahedral phosphorus covalently bonded to the O gamma of the active site serine. Covalent bond formation is accompanied by the loss of both phenoxy groups. The D-stereoisomer of Z-(4-AmPhGly)P-(OPh)2 is not observed in the complex. The L-stereoisomer of the inhibitor forms contacts with several residues in the trypsin active site. One of the phosphonate oxygens is inserted into the oxyanion hole and forms hydrogen bonds to the amides of Gly193, Asp194, and Ser195. The second phosphonate oxygen forms hydrogen bonds to N epsilon 2 of His 57. The p-amidinophenylglycine moiety binds into the trypsin primary specificity pocket, interacting with Asp189. The amide forms a hydrogen bond to the carbonyl oxygen atom of Ser214. The inhibitor moiety, from the 113 K structure of trypsin inactivated by the reaction product of Z-(4-AmPhGly)P(OPh)2, was docked into human thrombin [Bode, W., Mayr, I., Baumann, U., Huber, R., Stone, S. R., & Hofsteenge, J. (1989) EMBO J. 8, 3467-3475] and energy minimized. The inhibitor fits well into the thrombin active site, forming favorable contacts similar to those in the trypsin complex with no bad contacts.