Wharton's Jelly mesenchymal stem cell-derived extracellular vesicles induce liver fibrosis-resolving phenotype in alternatively activated macrophages.

The potential of extracellular vesicles (EVs) isolated from mesenchymal stromal cells in guiding macrophages toward anti-inflammatory immunophenotypes, has been reported in several studies. In our study, we provided experimental evidence of a distinctive effect played by Wharton Jelly mesenchymal stromal cell-derived EVs (WJ-EVs) on human macrophages. We particularly analyzed their anti-inflammatory effects on macrophages by evaluating their interactions with stellate cells, and their protective role in liver fibrosis. A three-step gradient method was used to isolate monocytes from umbilical cord blood (UCB). Two subpopulations of WJ-EVs were isolated by high-speed (20,000 g) and differential ultracentrifugation (110,000 g). Further to their characterization, they were designated as EV20K and EV110K and incubated at different concentrations with UCB-derived monocytes for 7 days. Their anti-fibrotic effect was assessed by studying the differentiation and functional levels of generated macrophages and their potential to modulate the survival and activity of LX2 stellate cells. The EV20K triggers the polarization of UCB-derived monocytes towards a peculiar M2-like functional phenotype more effectively than the M-CSF positive control. The EV20K treated macrophages were characterized by a higher expression of scavenger receptors, increased phagocytic capacity and production level of interleukin-10 and transforming growth factor-ß. Conditioned medium from those polarized macrophages attenuated the proliferation, contractility and activation of LX2 stellate cells. Our data show that EV20K derived from WJ-MSCs induces activated macrophages to suppress immune responses and potentially play a protective role in the pathogenesis of liver fibrosis by directly inhibiting HSC's activation.

Rat liver extracellular matrix and perfusion bioreactor culture promote human amnion epithelial cell differentiation towards hepatocyte-like cells.

Congenital and chronic liver diseases have a substantial health burden worldwide. The most effective treatment available for these patients is whole organ transplantation; however, due to the severely limited supply of donor livers and the side effects associated with the immunosuppressive regimen required to accept allograft, the mortality rate in patients with end-stage liver disease is annually rising. Stem cell-based therapy aims to provide alternative treatments by either cell transplantation or bioengineered construct transplantation. Human amnion epithelial cells (AEC) are a widely available, ethically neutral source of cells with the plasticity and potential of multipotent stem cells and immunomodulatory properties of perinatal cells. AEC have been proven to be able to achieve functional improvement towards hepatocyte-like cells, capable of rescuing animals with metabolic disorders; however, they showed limited metabolic activities in vitro. Decellularised extracellular matrix (ECM) scaffolds have gained recognition as adjunct biological support. Decellularised scaffolds maintain native ECM components and the 3D architecture instrumental of the organ, necessary to support cells' maturation and function. We combined ECM-scaffold technology with primary human AEC, which we demonstrated being equipped with essential ECM-adhesion proteins, and evaluated the effects on AEC differentiation into functional hepatocyte-like cells (HLC). This novel approach included the use of a custom 4D bioreactor to provide constant oxygenation and media perfusion to cells in 3D cultures over time. We successfully generated HLC positive for hepatic markers such as ALB, CYP3A4 and CK18. AEC-derived HLC displayed early signs of hepatocyte phenotype, secreted albumin and urea, and expressed Phase-1 and -2 enzymes. The combination of liver-specific ECM and bioreactor provides a system able to aid differentiation into HLC, indicating that the innovative perfusion ECM-scaffold technology may support the functional improvement of multipotent and pluripotent stem cells, with important repercussions in the bioengineering of constructs for transplantation.