Development of an implantable three-dimensional model of a functional pathogenic multispecies biofilm to study infected wounds

Non Clinical Model to Assess the Mechanism of Action of a Combined Hyaluronic Acid, Chondroitin Sulfate and Calcium Chloride: HA+CS+CaCl2 Solution on a 3D Human Reconstructed Bladder Epithelium

Purpose

Medical Device Regulation (EU) 2017/745 requires the principal mode of action (MoA) to be demonstrated by experimental data. The MoA of Ialuril® Prefill (combined as HA+CS+CaCl2: sodium hyaluronate 1.6%, sodium chondroitin sulphate 2% w/v and calcium chloride 0.87%) Class III medical device, indicated for intravesical instillation to reduce urinary tract infections, has been evaluated on a 3D reconstructed human bladder epithelium (HBE).

Methods

Three experimental designs; i) E. coli strain selection (DSM 103538, DSM 1103) to investigate the HA+CS+CaCl2 properties in modifying bacterial growth in liquid broth (CFU 4h and 24h) at 80%, 50% and 25% concentrations; ii) evaluation of film forming properties on HBE after 15 min exposure by quantifying caffeine permeation across the epithelium; iii) capacity to counteract E. coli adhesion and biofilm formation on colonized HBE by viable counts and ultrastructural analysis by scanning electron microscopy (SEM) using ciprofloxacin as the reference antimicrobial molecule.

Results

No significant differences were observed in bacterial viability for both the E. coli strains. HA+CS+CaCl2 reduced caffeine permeation of 51.7% and 38.1% at 1h and 2h, respectively and determined a significant decrease in caffeine permeation rate at both timepoints supporting HA+CS+CaCl2 capacity to firmly adhere to the bladder epithelium creating a physical barrier on the surface. The viable counts in HBE treated tissues then infected with E. coli resulted not different from the negative control suggesting that the device did not inhibit E. coli growth. SEM images showed homogenous product distribution over the HBE surface and confirmed the capacity of HA+CS+CaCl2 to adhere to the bladder epithelium, counteracting biofilm formation.

Conclusion

The results support the capacity of HA+CS+CaCl2 to counteract bacterial invasion by using a physico-mechanical mode of action: this medical device represents a valid alternative to antibiotics in the treatment of recurrent UTIs.

Overview of the effects and mechanisms of NO and its donors on biofilms

Microbial biofilm is undoubtedly a challenging problem in the food industry. It is closely associated with human health and life, being difficult to remove and antibiotic resistance. Therefore, an alternate method to solve these problems is needed. Nitric oxide (NO) as an antimicrobial agent, has shown great potential to disrupt biofilms. However, the extremely short half-life of NO in vivo (2 s) has facilitated the development of relatively more stable NO donors. Recent studies reported that NO could permeate biofilms, causing damage to cellular biomacromolecules, inducing biofilm dispersion by quorum sensing (QS) pathway and reducing intracellular bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) levels, and significantly improving the bactericidal effect without drug resistance. In this review, biofilm hazards and formation processes are presented, and the characteristics and inhibitory effects of NO donors are carefully discussed, with an emphasis on the possible mechanisms of NO resistance to biofilms and some advanced approaches concerning the remediation of NO donor deficiencies. Moreover, the future perspectives, challenges, and limitations of NO donors were summarized comprehensively. On the whole, this review aims to provide the application prospects of NO and its donors in the food industry and to make reliable choices based on these available research results.