Human amniotic membrane (hAM) is the innermost layer of fetal membranes, which surrounds the developing fetus and forms the amniotic cavity. hAM and hAM-derived cells possess many properties that make them suitable for use in regenerative medicine, such as low immunogenicity, promotion of epithelization, anti-inflammatory properties, angiogenic and antiangiogenic properties, antifibrotic properties, antimicrobial properties, and anticancer properties. Many pathological conditions of the urinary tract lead to organ damage or complete loss of function. Consequently, the reconstruction or replacement of damaged organs is needed, which makes searching for new approaches in regenerative and reconstructive urology a necessity. The use of hAM for treating defects in kidneys, ureters, urinary bladder, and urethra was tested in vitro in cell cultures and in vivo in mice, rats, rabbits, cats, dogs, and also in humans. These studies confirmed the advantages and the potential of hAM for use in regenerative and reconstructive urology as stated above. However, they also pointed out a few concerns we have to take into consideration. These are (1) the lack of a standardized protocol in hAM preparation and storage, (2) the heterogeneity of hAM, and especially (3) low mechanical strength of hAM. Before any wider use of hAM for treating urological defects, the protocols for preparation and storage will need to be standardized, followed by more studies on larger animals and clinical trials, which will altogether extensively assess the potential of hAM use in urological patients.

Urinary tract infections are among the most common bacterial infections in humans. Moreover, they are highly recurrent and increasingly often resistant to antibiotics. The antimicrobial properties of the amniotic membrane (AM), the innermost layer of fetal membranes, have been briefly reported in the literature, however, the results of published studies are often inconsistent and unclear; moreover, its effect on uropathogenic bacteria has not yet been investigated. Further, there is no data in the literature about the effect of AM preparation and storage on its antimicrobial properties. To examine the impact of several preparation procedures on the antimicrobial properties of AM, we prepared patches and homogenates of fresh (fAM) and cryopreserved (cAM) human AM and tested them on 14 selected Gram-positive and Gram-negative uropathogenic bacteria. By employing novel antimicrobial efficiency assays we showed that fAM and cAM homogenates have broad-spectrum antimicrobial activity against all here tested uropathogenic bacteria, except for Serratia marcescens. Moreover, they had a potent effect also on the multiple-resistant clinical strains of uropathogenic Escherichia coli. Interestingly, the patches of fAM and cAM had no antimicrobial effect on any of the tested strains. We therefore prepared and stored AM patches according to the standard procedure for clinical use in ophthalmology, which includes the cryopreservation of antibiotic-treated AM, and performed antimicrobial efficiency assays. Our findings suggest that the ultrastructure of AM patches could enable the retention of added antibiotics. In addition, we also prepared gentamicin-resistant uropathogenic E. coli strains, which confirmed that the antimicrobial effect of antibiotic-treated AM patches can be attributed to the antibiotic alone. To summarize, here we describe novel protocols for preparation and storage of AM to ensure the preservation of its antimicrobial factors. Moreover, we describe the mechanism of AM retention of antibiotics, based on which the AM could potentially be used as a drug delivery vehicle in future clinically applicable approaches.

Urinary tract infections (UTIs) represent a serious global health issue, especially due to emerging multidrug-resistant UTI-causing bacteria. Recently, we showed that the human amniotic membrane (hAM) could be a candidate for treatments and prevention of UPEC and Staphylococcus aureus infections. However, its role against multidrug-resistant bacteria, namely methicillin-resistant S. aureus (MRSA), extended-spectrum beta-lactamases (ESBL) producing Escherichia coli and Klebsiella pneumoniae, vancomycin-resistant Enterococci (VRE), carbapenem-resistant Acinetobacter baumannii, and Pseudomonas aeruginosa has not yet been thoroughly explored. Here, we demonstrate for the first time that the hAM homogenate had antibacterial activity against 7 out of 11 tested multidrug-resistant strains, the greatest effect was on MRSA. Using novel approaches, its activity against MRSA was further evaluated in a complex microenvironment of normal and cancerous urinary bladder urothelia. Even short-term incubation in hAM homogenate significantly decreased the number of bacteria in MRSA-infected urothelial models, while it did not affect the viability, number, and ultrastructure of urothelial cells. The hAM patches had no antibacterial activity against any of the tested strains, which further exposes the importance of the hAM preparation. Our study substantially contributes to basic knowledge on the antibacterial activity of hAM and reveals its potential to be used as an antibacterial agent against multidrug-resistant bacteria.

The tumour microenvironment, which is comprised of various cell types and the extracellular matrix, substantially impacts tumour initiation, progression, and metastasis. Mesenchymal stem/stromal cells (MSCs) are one of the key stromal cells in the tumour microenvironment, and their interaction with cancer cells results in the transformation of naïve MSCs to tumour-associated MSCs. The latter has an important impact on tumour growth and progression. Recently, it has been shown that they can also contribute to the development of chemoresistance in cancer cells. This review provides an overview of 42 studies published between 1 January 2001 and 1 January 2022 that examined the effect of MSCs on the susceptibility of cancer cells to chemotherapeutics. The studies showed that MSCs affect various signalling pathways in cancer cells, leading to protection against chemotherapy-induced damage. Promising results emerged from the use of inhibitors of various signalling pathways that are affected in cancer cells due to interactions with MSCs in the tumour microenvironment. These studies present a good starting point for the investigation of novel treatment approaches and demonstrate the importance of targeting the stroma in the tumour microenvironment to improve treatment outcomes.

NLRP3 is a pattern recognition receptor forming an inflammasome in response to diverse pathogen and self-derived triggers, but molecular insights on NLRP3 activation are still lacking. Here, we drive ectopic NLRP3 to different subcellular locations in NLRP3-deficient macrophages to map the spatial activation profile of NLRP3, and find that NLRP3 variants enriched at the organellar membranes respond to canonical triggers similarly to wild-type NLRP3; however, unlike wild-type, these NLRP3 variants can be activated even in the absence of the polybasic phospholipid-binding segment. Mechanistically, membrane or protein scaffolds mediate NLRP3 clustering, which leads to the unfastening of the inactive NACHT domain conformation preceding the activated NLRP3 oligomer formation. Our data thus suggest that scaffold-promoted clustering is an important step in NLRP3 activation, enabling NLRP3 to sense distinct activator-induced cellular anomalies exhibited via lipid or protein assemblies, thereby establishing NLRP3 as the master sensor of perturbations in cell homeostasis.

Purpose: Due to the emergence and spread of bacterial strains resistant to antibiotics, the development of new antimicrobials is imperative. The antimicrobial effect of the amniotic membrane (AM) has been explored to a limited extent so far. Materials and methods: We collected 12 biological samples of AM homogenates and tested their antimicrobial effect on 4 pathogens, including the clinical strain of uropathogenic Escherichia coli (UPEC), the wild-type strain of Staphylococcus aureus, and the wild-type strain and a clinical strain of Serratia marcescens. To quantify the antibacterial effect of AM, we monitored the effect of AM homogenate on bacterial growth using plate count method and agar diffusion method. Additionally, minimal inhibitory concentrations (MICs) for AM homogenate dilutions were determined and S. marcescens growth in AM homogenate alone was evaluated. Results: Our results demonstrated that AM homogenate had a bacteriostatic effect on studied UPEC and S. aureus. Interestingly, when used in lower concentrations, the AM homogenate had a bactericidal effect on both strains. In contrast, S. marcescens was completely resistant to the growth-inhibitory substances of AM homogenate. Its growth was slightly accelerated in liquid culture medium in the presence of AM homogenate and the strain was able to grow in undiluted, 2-fold and 4-fold diluted AM homogenate. Conclusion: Obtained results illustrated that AM homogenate could be a candidate for treatments and prevention of UPEC and S. aureus infections, but not that of S. marcescens, whose growth is enhanced by AM homogenate. Moreover, the established liquid culture medium assay can be used as a time- and cost-effective method for a personalized evaluation of drug effect on the growth of chosen bacterial strains with parallel testing of resistance or susceptibility to multiple drugs. The susceptibility of bacteria to AM homogenate in solid and liquid culture media is encouraging for its use in biomedical applications.