Characterization of isolated liver sinusoidal endothelial cells for liver bioengineering

Background

The liver sinusoidal capillaries play a pivotal role in liver regeneration, suggesting they may be beneficial in liver bioengineering. This study isolated mouse liver sinusoidal endothelial cells (LSECs) and determined their ability to form capillary networks in vitro and in vivo for liver tissue engineering purposes.

Methods and results

In vitro LSECs were isolated from adult C57BL/6 mouse livers. Immunofluorescence labelling indicated they were LYVE-1⁺/CD32b⁺/FactorVIII⁺/CD31^?. Scanning electron microscopy of LSECs revealed the presence of characteristic sieve plates at 2 days. LSECs formed tubes and sprouts in the tubulogenesis assay, similar to human microvascular endothelial cells (HMEC); and formed capillaries with lumens when implanted in a porous collagen scaffold in vitro. LSECs were able to form spheroids, and in the spheroid gel sandwich assay produced significantly increased numbers (p?=?0.0011) of capillary-like sprouts at 24 h compared to HMEC spheroids. Supernatant from LSEC spheroids demonstrated significantly greater levels of vascular endothelial growth factor-A and C (VEGF-A, VEGF-C) and hepatocyte growth factor (HGF) compared to LSEC monolayers (p?=?0.0167; p?=?0.0017; and p?<?0.0001, respectively), at 2 days, which was maintained to 4 days for HGF (p?=?0.0017) and VEGF-A (p?=?0.0051). In vivo isolated mouse LSECs were prepared as single cell suspensions of 500,000 cells, or as spheroids of 5000 cells (100 spheroids) and implanted in SCID mouse bilateral vascularized tissue engineering chambers for 2 weeks. Immunohistochemistry identified implanted LSECs forming LYVE-1⁺/CD31^? vessels. In LSEC implanted constructs, overall lymphatic vessel growth was increased (not significantly), whilst host-derived CD31⁺ blood vessel growth increased significantly (p?=?0.0127) compared to non-implanted controls. LSEC labelled with the fluorescent tag DiI prior to implantation formed capillaries in vivo and maintained LYVE-1 and CD32b markers to 2 weeks.

Conclusion

Isolated mouse LSECs express a panel of vascular-related cell markers and demonstrate substantial vascular capillary-forming ability in vitro and in vivo. Their production of liver growth factors VEGF-A, VEGF-C and HGF enable these cells to exert a growth stimulus post-transplantation on the in vivo host-derived capillary bed, reinforcing their pro-regenerative capabilities for liver tissue engineering studies.

     

A monokine regulates colony-stimulating activity production by vascular endothelial cells

Human umbilical vein endothelial cells were cultured in supernatants of peripheral blood monocytes that had been cultured for 3 days with and without lactoferrin. Colony-stimulating activity (CSA) was measured in supernatants of the endothelial cell cultures and appropriate control cultures using normal, T-lymphocyte-depleted, phagocyte-depleted, low- density bone marrow cells in colony growth (CFU-GM) assays. Monocyte- conditioned medium contained a nondialyzable, heat labile factor that enhanced 4-15--fold the production of CSA by endothelial cells. The addition of lactoferrin to monocyte cultures reduced the activity of this monokine by 69%. Lactoferrin did not inhibit CSA production by monokine-stimulated endothelial cells. Therefore, vascular endothelial cells are potent sources of CSA, the production of CSA by these cells is regulated by a stimulatory monokine, and the production and/or release of the monokine is inhibited by lactoferrin, a neutrophil- derived putative feedback inhibitor of granulopoiesis. Inasmuch as a similar monokine is known to stimulate CSA production by fibroblasts and T lymphocytes, we suggest that mononuclear phagocytes play a pivotal role in the regulation of granulopoiesis by recruiting a variety of cell types to produce CSA.     

The Effect of a Low Fructose and Low Glycemic Index/Load (FRAGILE) Dietary Intervention on Indices of Liver Function,Cardiometabolic Risk Factors,and Body Composition in Children and Adolescents With Nonalcoholic Fatty Liver Disease (NAFLD)

Background: Nonalcoholic fatty liver disease (NAFLD) is a common liver disease in obese children. Diets high in added fructose (high fructose corn syrup; HFCS) and glycemic index (GI)/glycemic load (GL) are associated with increased risk of NAFLD. Lifestyle modification is the main treatment, but no guidelines regarding specific dietary interventions for childhood NAFLD exist. We hypothesized that reductions in dietary fructose (total, free, and HFCS)/GI/GL over 6 months would result in improvements in body composition and markers of liver dysfunction and cardiometabolic risk in childhood NAFLD. Methods: Children and adolescents with NAFLD (n = 12) and healthy controls (n = 14) 7–18 years were studied at baseline and 3 and 6 months post–dietary intervention. Plasma markers of liver dysfunction (ALT, AST, γGT), cardiometabolic risk (TG, total cholesterol, LDL‐HDL cholesterol, Apo‐B100, Apo‐B48, Apo‐CIII, insulin, homeostasis model of assessment of insulin resistance [HOMA‐IR]), inflammation (TNF‐α, IL‐6, IL‐10), anthropometric, and blood pressure (BP) were studied using validated methodologies. Results: Significant reductions in systolic BP (SBP), percentage body fat (BF), and plasma concentrations of ALT (P = .04), Apo‐B100 (P < .001), and HOMA‐IR were observed in children with NAFLD at 3 and 6 months (P < .05). Dietary reductions in total/free fructose/HFCS and GL were related to reductions in SBP (P = .01), ALT (P = .004), HOMA‐IR (P = .03), and percentage BF in children with NAFLD. Reductions in dietary GI were associated with reduced plasma Apo‐B100 (P = .02) in both groups. With the exception of Apo‐B100, no changes in laboratory variables were observed in the control group. Conclusion: Modest reductions in fructose (total/free, HFCS) and GI/GL intake result in improvements of plasma markers of liver dysfunction and cardiometabolic risk in childhood NAFLD.