Distinct Iron Deposition Profiles of Liver Zones in Various Models with Iron Homeostasis Disorders

Single Cell Gene Expression Analysis in a 3D Microtissue Liver Model Reveals Cell Type-Specific Responses to Pro-Fibrotic TGF-β1 Stimulation

3D cell culture systems are widely used to study disease mechanisms and therapeutic interventions. Multicellular liver microtissues (MTs) comprising HepaRG, hTERT-HSC and THP-1 maintain multicellular interactions and physiological properties required to mimic liver fibrosis. However, the inherent complexity of multicellular 3D-systems often hinders the discrimination of cell type specific responses. Here, we aimed at applying single cell sequencing (scRNA-seq) to discern the molecular responses of cells involved in the development of fibrosis elicited by TGF-β1. To obtain single cell suspensions from the MTs, an enzymatic dissociation method was optimized. Isolated cells showed good viability, could be re-plated and cultured in 2D, and expressed specific markers determined by scRNA-seq, qRT-PCR, ELISA and immunostaining. The three cell populations were successfully clustered using supervised and unsupervised methods based on scRNA-seq data. TGF-β1 led to a fibrotic phenotype in the MTs, detected as decreased albumin and increased αSMA expression. Cell-type specific responses to the treatment were identified for each of the three cell types. They included HepaRG damage characterized by a decrease in cellular metabolism, prototypical inflammatory responses in THP-1s and extracellular matrix remodeling in hTERT-HSCs. Furthermore, we identified novel cell-specific putative fibrosis markers in hTERT-HSC (COL15A1), and THP-1 (ALOX5AP and LAPTM5).

Liver Iron Retention Estimated from Utilization of Oral and Intravenous Radioiron in Various Anemias and Hemochromatosis in Humans

Patients with hereditary hemochromatosis and non-transfusion-dependent hereditary anemia develop predominantly liver iron-overload. We present a unique method allowing quantification of liver iron retention in humans during first-pass of ⁵⁹Fe-labeled iron through the portal system, using standard ferrokinetic techniques measuring red cell iron uptake after oral and intravenous ⁵⁹Fe administration. We present data from patients with iron deficiency (ID; N = 47), hereditary hemochromatosis (HH; N = 121) and non-transfusion-dependent hereditary anemia (HA; N = 40). Mean mucosal iron uptake and mucosal iron transfer (±SD) were elevated in patients with HH (59 ± 18%, 80 ± 15% respectively), HA (65 ± 17%, 74 ± 18%) and ID (84 ± 14%, 94 ± 6%) compared to healthy controls (43 ± 19%, 64 ± 18%) (p < 0.05) resulting in increased iron retention after 14 days compared to healthy controls in all groups (p < 0.01). The fraction of retained iron utilized for red cell production was 0.37 ± 0.17 in untreated HA, 0.55 ± 0.20 in untreated HH and 0.99 ± 0.22 in ID (p < 0.01). Interestingly, compared to red blood cell iron utilization after oral iron administration, red blood cell iron utilization was higher after injection of transferrin-bound iron in HA and HH. Liver iron retention was considerably higher in HH and HA compared to ID. We hypothesize that albumin serves as a scavenger of absorbed Fe(II) for delivering albumin-bound Fe(III) to hepatocytes.

Carbon black-induced detrimental effect on osteoblasts at low concentrations: Remarkably compromised differentiation without significant cytotoxicity

Due to similar aerodynamic and micro-nano sized properties between airborne particles and synthetic nanoparticles, a large number of studies have been conducted using carbon-based particles, such as carbon black (CB), carbon nanotubes and graphite, in order to achieve deeper understandings of their adverse effects on human health. It has been reported that particulate matters can aggravate morbidity of patients suffering from bone and joint diseases, e.g. arthritis. However, the molecular mechanism is still elusive thus far. Under this context, we employed two cell lines of osteoblasts, MC3T3-E1 and MG-63, upon exposure to 4 different CB samples with differential physicochemical properties in research of mechanistic insights. Our results indicated that the carbon/oxygen ratio differed in these 4 CB materials showing the order: SB4A < Printex U < C1864 < C824455. In stark contrast, their cytotoxicity and capacity to trigger reactive oxygen species (ROS) in MC3T3-E1 and MG-63 cells closely correlated to oxygen content, revealing the reverse order: SB4A < Printex U < C1864 < C824455. It would be reasonable to speculate that ROS production was a predominant cause of CB cytotoxicity, which strongly relied on the oxygen content of CB. Our study further manifested that all CB samples even at low concentrations significantly inhibited osteoblast differentiation, as reflected by remarkably reduced activity of alkaline phosphatase (ALP) and compromised expression of the differentiation-related genes. And the inhibition on osteoblast differentiation also closely correlated to oxygen content of CB samples. Taken together, our combined data recognized oxygen-associated toxicity towards osteoblasts for CBs. More importantly, we uncovered a new adverse effect of CB exposure: suppression on osteoblast differentiation, which has been overlooked in the past.