Synergy of Hydeal-D® and Hyaluronic Acid for Protecting and Restoring Urothelium: In Vitro Characterization

Abstract

Interstitial cystitis (IC) or painful bladder syndrome is a chronic dysfunction due to an inflammatory condition, characterized by bladder pain and urinary frequency. Currently, no gold standard therapy is available since IC does not respond to conventional ones. Given these premises, the aim of this work was the in vitro characterization of biological properties (mucoadhesion and anti-inflammatory activity) of a commercial product (HydealCyst–HydC) based on hyaluronic acid (HA) and the benzyl ester of HA (Hydeal-D®) intended for bladder instillation to restore and/or protect the urothelial layer of glycosamino glycans (GAGs). The in vitro characterization demonstrated that an interaction product is formed between HA and Hydeal-D® that has a role in the rheological behavior and mucoadhesive properties. HA was identified as a key component to form the mucoadhesive joint, while the interaction of HA with Hydeal-D® improved polysaccharide stability and prolonged the activity ex vivo. Moreover, HydC is cytocompatible with urothelial cells (HTB-4) and possesses an anti-inflammatory effect towards these cells by decreasing the secretion of IL-6 and IL-8, which were both increased in patients with IC, and by increasing the secretion of sulfated GAGs. These two findings, along with the resilience properties of the formulation due to mucoadhesion, suggest the active role of HydC in protecting and restoring urothelium homeostasis.

The Model of Interstitial Cystitis for Evaluating New Molecular Strategies of Interstitial Regeneration in Humans

“…Different descriptions of the sensation include 'pressure', 'burning', 'sharp', and 'discomfort' [2,5,7]. Due to multifactorial etiology, numerous hypotheses have been proposed, such as urinary tract infection, surgery, or viral illness, although the most recognized is a progressive weakening of the bladder wall lining, consisting of glycosaminoglycans such as hyaluronic acid, chondroitin sulphate, heparan sulphate, and dermatan sulphate [12]. Biopsies analysis shows increased urothelial permeability due to diminished GAG levels and ultrastructural abnormalities characterized by a loss of tight junctions and adhesive junction proteins [10].…”

“…Biopsies analysis shows increased urothelial permeability due to diminished GAG levels and ultrastructural abnormalities characterized by a loss of tight junctions and adhesive junction proteins [10]. If a physiological situation occurs, GAGs cover the urothelium and play a crucial role in protecting the bladder and preventing the adhesion of pathogenic bacteria to it [12]. Unlike this, the damaged protective layer lets in the infiltration of harmful urine components with inflammatory action into the underlying layer, resulting in the consequent activation of mast cells [13] and the overexpression of angiogenic factors, such as vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) in the submucosa [14].…”

“…HA is a nonsulfated mucopolysaccharide based on two sugars, D-glucuronic acid and N-acetyl-D-glucosamine, bonded with alternating β-1,4 and β-1,3 glycosidic bonds [43]. It exists in the form of many different molecular weights (MWs), with a variable half-life and is characterized by interesting viscoelastic and rheological behavior due to its polymeric and polyelectrolyte properties [12,44,45]. HA is a component of numerous fluids and biological tissues, where it is involved in either structural or biological processes such as pathogen/viral defense, coagulation, inflammation, wound healing, cell proliferation, cell adhesion, cell migration, morphogenesis, tissue integrity, tissue flexibility, and lubrication [12,[44][45][46].…”

“…It exists in the form of many different molecular weights (MWs), with a variable half-life and is characterized by interesting viscoelastic and rheological behavior due to its polymeric and polyelectrolyte properties [12,44,45]. HA is a component of numerous fluids and biological tissues, where it is involved in either structural or biological processes such as pathogen/viral defense, coagulation, inflammation, wound healing, cell proliferation, cell adhesion, cell migration, morphogenesis, tissue integrity, tissue flexibility, and lubrication [12,[44][45][46]. HA, as described before, is an important component of the GAG layer that increases in the urine of patients with BPS, thus demonstrating a disruption of the GAG barrier at the bladder level [47].…”

“…When this barrier decreases or becomes absent, it allows for the diffusion of urinary potassium ions into the bladder wall, resulting in the stimulation of C-type nerve fibers, as already described. Moreover, HA enhances the secretion of enzymes, leading to increased GAGs production, and it is able to alter epithelial permeability stimulating of the expression of tight junction proteins [12]. The immunomodulatory effect of HA is well known and described [48]: HA fragments use both Toll-like receptor (TLR) 4 and TLR2 as well as CD44 to stimulate inflammatory genes in inflammatory cells.…”