Urinary Bladder Tissue Engineering Using Natural Scaffolds in a Porcine Model: Role of Toll-Like Receptors and Impact of Biomimetic Molecules

Abstract

Introduction: Natural scaffolds have been shown to induce T helper 2 (TH2)-specific immune responses in host tissues; however, the precise mechanisms that underlie this immune response are unknown. Using a porcine animal model, we evaluated the role of Toll-like receptors (TLRs) and matrix remodelling in the implantation of bladder acellular matrix (ACM) grafts and ACMs fortified with biomimetic materials. Materials and Methods: Bladders were decellularized with detergent and treated in 3 different ways prior to implantation: ACM alone, hyaluronic acid (HA)-ACM and HA-vascular endothelial growth factor (VEGF)-ACM. Animals were sacrificed at 4 or 10 weeks post-implantation and total gene expressions for TH2 (IL-4), TH1 (IFN-γ), TLR2, TLR4, and TGF-β1 were analyzed using real-time RT-PCR. Using histology (H&E and Masson’s trichrome) and immunohistochemistry (uroplakin, α-smooth muscle actin, CD31 and factor VIII) the regenerative capacity was correlated with the gene expression of different proteins. Results: IL-4, TLR2, and TLR4 gene expression were markedly decreased at 4 and 10 weeks in both the HA-ACM group and the HA-VEGF-ACM group compared to ACM alone. IFN-γ expression was negligible in all groups and time periods. TGF-β1 expression was highest in the HA- and VEGF-treated grafts. Recellularization was inversely proportional to TLR and TH2 expression but proportional to TGF-β1. Conclusion: ACM alone grafts demonstrated stronger TLR4 expression which may promote a distinct TH2 immune response and a reduced regenerative capacity in grafts. Treatment of grafts with HA and VEGF may help regulate host immune responses by reducing TLR4 and IL-4 and increasing TGF-β1.

Histological changes induced by Polyglycolic-Acid (PGA) scaffolds seeded with autologous adipose or muscle-derived stem cells when implanted on rabbit bladder

“…When these matrixes were treated with hyaluronic acid or vascular endothelium growth factor (VEGF), the lymphocytes migration was reduced and the TGF β-1 production was increased. 10,11 Several cell sources have been used for cell therapy, including adult stem cells, embryonic stem cells, induced pluripotent stem cells, etc. Studies have shown that ADSCs and MDSCs stimulate pro-angiogenic cytokines such as hepatocytic growth factor (HGF), TGF-β, VEGF, fibroblastic growth factor type 2, angiopoietin-1, placenta growth factor, and play an essential part in the antifibrosis effect.…”

The Immunopathology of Sepsis: Pathogen Recognition, Systemic Inflammation, the Compensatory Anti‐Inflammatory Response, and Regulatory T Cells

“…After mapping of the gene sequences for human and murine PRRs, exploration of the genomic sequence of other species has allowed the identification of homologs of the majority of TLRs in dogs, cats, cattle, sheep, goats, horses, and pigs . Other PRRs have also been identified in these species, although less is known about them than the TLRs (Table ).…”

Sustained release of VEGF from PLGA nanoparticles embedded thermo-sensitive hydrogel in full-thickness porcine bladder acellular matrix

“…It is produced by extracting the cells and soluble matrix components from the extracellular matrix, and so it has almost all the properties of a normal bladder, and maintains a low potential for inflammatory attack on the graft because most of the antigenic proteins are extracted from the bladder tissue. The long-term follow-up of vascular acellular matrix allografts has demonstrated their biocompatibility [3-5]. …”