Host-microbe interactions in the intestine play a significant role in health and disease. Novel scaffolds for host cells, capable of potentially supporting these intricate interactions, are necessary to improve our current systems for mimicking host-microbiota interplay in vitro/ex vivo. In this research paper, we study the application of gelatin methacrylamide (GelMA) as scaffold material for intestinal epithelial cells in terms of permeability, mechanical strength, and biocompatibility. We investigated whether the degree of substitution (DS) of GelMA influences the permeability and found that both high and low DS GelMA show sufficient permeability of biorelevant transport markers. Additionally, we researched epithelial cell adherence and viability, as well as mechanical characteristics of different concentrations of GelMA. All concentrations of hydrogel show long-term biocompatibility for the mono- and co-cultures, despite the goblet-like cells (LS174T) showing lower performance than enterocyte-like cells (Caco-2). The mechanical strength of all hydrogel concentrations was in a physiologically relevant range to be used as scaffold material for intestinal cells. Lastly, we examined the effect of the two sterilization methods, ethylene oxide (EO) and 70% ethanol followed by UVC (EtOH/UVC). We found that the impact of the two methods on the mechanical characteristics was minimal, and we did not find a significant effect between the two methods on cell viability and confluency of Caco-2 cells seeded on the GelMA hydrogels. Based on these results, we conclude that GelMA is a suitable material as a scaffold for intestinal cell types in terms of permeability, mechanical strength and biocompatibility. These findings contribute to the growing field of in vitro modeling of the gut and moves the field further to ensuring more translatable research on host-microbe interactions.

The skin plays a vital role in protection, hydration, and thermoregulation; however, its integrity can be compromised by injury. Jellyfish skin polysaccharides (JSP), extracted from Rhizostoma pulmo, have shown promise in promoting wound healing by enhancing cell migration and offering protection against oxidative stress. This study investigates the effect of JSP incorporation into wound dressings based on acrylate-endcapped urethane-based precursor (AUP); which are already known for their favorable swelling capacity and mechanical strength. AUP+JSP composites were processed into both hydrogel sheets and electrospun fibers (ESFs) and characterized in terms of morphological, mechanical, physicochemical, and biological properties. JSP incorporation preserved the UV-crosslinking capability of AUP, as well as the mechanical and swelling properties of the resulting hydrogels. Notably, JSP addition induced a unique branched and homogeneous 3D architecture in the ESFs, characterized by raised fiber structures interrupting the otherwise typical flat fibrous network. Biological evaluations on murine fibroblasts included cytocompatibility assays, assessments of oxidative stress resistance, and in vitro scratch assays. The results confirmed the biocompatibility of the AUP+JSP formulations and demonstrated significantly enhanced scratch closure in JSP-containing dressings, particularly in the ESFs. These findings support the potential of JSP-functionalized hydrogel sheets and electrospun fibers as advanced wound dressing platforms.

Melt electrowriting (MEW) is an additive manufacturing technique that harnesses electro-hydrodynamic phenomena to produce 3D-printed fibres with diameters on the scale of 10s of microns. The ability to print at this small scale provides opportunities to create structures with incredibly fine resolution and highly defined morphology. The current gold standard material for MEW is poly(ϵ-caprolactone) (PCL), a polymer with excellent biocompatibility but lacking in chemical groups that can allow intrinsic additional functionality. To provide this functionality while maintaining PCL's positive attributes, blending was performed with a Poly(Ethylene Glycol) (PEG)-based Acrylate endcapped Urethane-based Precursor (AUP). AUPs are a group of polymers, built on a backbone of existing polymers, which introduce additional functionality by the addition of one or more acrylate groups that terminate the polymer chain of a backbone polymer. By blending with a 20kDa AUP-PEG in small amounts, it is shown that MEW attributes are preserved, producing high-quality meshes. Blends were produced in various PCL:AUP weight ratios (100:0, 90:10 and 0:100) and processed into both solvent-cast films and MEW meshes that were used to characterise the properties of the blends. It was found that the addition of AUP-PEG to PCL significantly increases the hydrophilicity of structures produced with these polymers, and adds swelling capability compared to the non-swelling PCL. The developed blend (90:10) is shown to be processable using MEW, and the quality of manufactured scaffolds is evaluated against pure PCL scaffolds by performing scanning electron microscopy image analysis, with the quality of the novel MEW blend scaffolds showing comparable quality to that of pure PCL. The presence of the functionalisable AUP material on the surface of the developed scaffolds is also confirmed using fluorescence labelling of the acrylate groups. Biocompatibility of the MEW-processable blend was confirmed through a cell viability study, which found a high degree of cytocompatibility.

Long-term drug evaluation heavily relies upon rodent models. Drug discovery methods to reduce animal models in oncology may include three-dimensional (3D) cellular systems that take into account tumor microenvironment (TME) cell types and biomechanical properties. In this study we reconstructed a 3D tumor using an elastic polymer (acrylate-endcapped urethane-based poly(ethylene glycol) (AUPPEG)) with clinical relevant stiffness. Single cell suspensions from low-grade serous ovarian cancer (LGSOC) patient-derived early passage cultures of cancer cells and cancer-associated fibroblasts (CAF) embedded in a collagen gel were introduced to the AUPPEG scaffold. After self-organization in to a 3D tumor, this model was evaluated by a long-term (> 40 days) exposure to a drug combination of MEK and HSP90 inhibitors. The drug-response results from this long-term in vitro model are compared with drug responses in an orthotopic LGSOC xenograft mouse model. The in vitro 3D scaffold LGSOC model mimics the growth ratio and spatial organization of the LGSOC. The AUPPEG scaffold approach allows to test new targeted treatments and monitor long-term drug responses. The results correlate with those of the orthotopic LGSOC xenograft mouse model. The mechanically-tunable scaffolds colonized by a three-dimensional LGSOC allow long-term drug evaluation and can be considered as a valid alternative to reduce, replace and refine animal models in drug discovery.

Cell therapies such as adoptive T cell transfer require ex vivo modification of cells with exogenous cargo to modulate their phenotype (e.g., to express a synthetic antigen receptor) for optimal therapeutic efficacy upon reinfusion in a patient. Several studies have shown superior anti-tumor activity of minimally differentiated T cell subsets over their activated counterparts. Therefore, developing techniques for safe and efficient manipulation of these quiescent cells is important for both clinical applications and fundamental studies of T cell biology. Photoporation with photothermal electrospun nanofibers (PEN) is an efficient and minimally perturbing nonviral intracellular delivery technique for activated and expanded T cells. However, the technique has not yet been applied to unstimulated T cells. Here, we investigated the potential of PEN photoporation for delivery of macromolecules into these cells. First, we confirmed with inductively coupled plasma tandem mass spectrometry that there was no significant iron release from fibers after laser activation of PEN substrates for laser fluences up to 0.36 J/cm2. Next, we demonstrated successful intracellular delivery of 150 kDa FITC-dextran as model macromolecule in resting and pre-activated lymphocytes with 55-60 % delivery efficiency. By analyzing metabolic activity, activation surface marker presentation and extracellular cytokine release, we found that PEN treatment had no effect on cell proliferation and limited impact on T cell activation propensity for all tested irradiation energies. Thus, our findings show that PEN photoporation holds promise as a safe and efficient delivery strategy, paving the way for its use in genetic modification of minimally differentiated T cells.

Most commercial dressings with moderate to high exudate uptake capacities are mechanically weaker and/or require a secondary dressing. The current research article focuses on the development of hydrogel-based wound dressings combining mechanical strength with high exudate absorption capacities using acrylate-endcapped urethane-based precursors (AUPs). AUPs with varying poly(ethylene glycol) backbone molar masses (10 and 20 kg mol-1 ) and endcap chemistries are successfully synthesized in toluene, subsequently processed into UV-cured hydrogel sheets and are benchmarked against several commercial wound dressings (Hydrosorb, Kaltostat, and Mepilex Ag). The AUP materials show high gel fractions (>90%) together with strong swelling degrees in water, phosphate buffered saline and simulated wound fluid (12.7-19.6 g g-1 ), as well as tunable mechanical properties (e.g., Young's modulus: 0.026-0.061 MPa). The AUPs have significantly (p < 0.05) higher swelling degrees than the tested commercial dressings, while also being mechanically resistant. The elasticity of the synthesized materials leads to an increased resistance against fatigue. The di- and hexa-acrylated AUPs show excellent in vitro biocompatibility against human foreskin fibroblasts, as evidenced by indirect MTS assays and live/dead cell assays. In conclusion, the processed AUP materials demonstrate high potential for wound healing application and can even compete with commercially available dressings.

Abstract Background Nowadays, a wide range of wound dressings is already commercially available. The selection of the dressing is of paramount importance as inappropriate wound management and dressing selection can delay the wound healing process. Not only can this be distressing for the patient, but it can also contribute to complications such as maceration and subsequent infection. Many researchers are targeting the design of dressings with superior properties over existing commercial dressings. However, reported results in the state-of-the-art are rarely benchmarked against commercial dressings. The aim of this study was to determine several characteristics of a large variety of the most frequently used commercial wound dressings, providing an overview for both practitioners and researchers. Methods For this comparative study, 11 frequently used commercial wound dressings were selected, representing the different types. The morphology was studied using scanning electron microscopy. The dressings were characterized in terms of swelling capacity (water, phosphate buffered saline and simulated wound fluid), moisture vapour transmission rate (MVTR) and moisture uptake capacity (via dynamic vapour sorption) as well as mechanical properties using tensile testing and texturometry. Results The selected dressings showed distinctive morphological differences (fibrous, porous and/or gel) which was reflected in the different properties. Indeed, the swelling capacities ranged between 1.5 and 23.2 g/g (water), 2.1 and 17.6 g/g (phosphate buffered saline) or 2.9 and 20.8 g/g (simulated wound fluid). The swelling capacity of the dressings in water increased even further upon freeze-drying, due to the formation of pores. The MVTR values varied between 40 and 930 g/m2/24 h. The maximal moisture uptake capacity varied between 5.8% and 105.7% at 95% relative humidity. Some commercial dressings exhibited a superior mechanical strength, due to either being hydrophobic or multi-layered. Conclusions The present work not only offers insight into a valuable toolbox of suitable wound dressing characterization techniques, but also provides an extensive landscaping of commercial dressings along with their physico-chemical properties, obtained through reproducible experimental protocols. Furthermore, it ensures appropriate benchmark values for commercial dressings in all forthcoming studies and could aid researchers with the development of novel modern wound dressings. The tested dressings either exhibited a high strength or a high swelling capacity, suggesting that there is still a strong potential in the wound dressings market for dressings that possess both.

Malodorous wounds have a detrimental effect on the patient's well-being. A dressing combining the properties of hydrogels and activated carbon (AC) would be beneficial for the treatment of these wounds, controlling wound exudate while adsorbing malodor-causing compounds. The present work involves the use of acrylate-endcapped, urethane-based precursors (AUPs) and methacrylated alginate (AlgMOD). AUPs are synthesized with a varying poly(ethylene glycol) backbone molar mass (2-20 kg mol(-1)) to tune mechanical and swelling properties, whereas methacrylated alginate, known for its hemostatic properties, enables chemical cross-linking. Blends of AUP and AlgMOD with AC are processed into hydrogel sheets and electrospun membranes. The results indicate tunable mechanical (Young's moduli 0.03-0.63 MPa) and swelling properties (2.2-34.9 g(water) ghydrogel-1) along with high gel fractions (>85%). The sheets are compared with commercial odor-adsorbing dressings (Carbonet and Carboflex), enabling benchmarking. AUP sheets (8 and 10 kg mo(-1)) containing 0.5% w/w AC show strong adsorption (>90% after 24 h) of crystal violet. The obtained (core-shell AlgMOD/AUP) fibers are visualized using scanning and transmission electron microscopy. Indirect cell tests reveal the developed materials to be biocompatible. In conclusion, a hydrogel-based odor-adsorbing wound dressing is successfully synthesized and holds promise for malodorous wound healing.

Improving wound healing by developing innovative dressing materials has been an important focus over the past few years in the biomedical field. In this regard, the current study focuses on developing new dressings based on acrylate-endcapped urethane-based polymers (AUPs). The materials have been processed into films and electrospun mats. Exudate uptake capacity, mechanical properties and fiber morphology were evaluated herein. The results showed superior uptake capacity of both films and mats when compared to Aquacel®Ag, Exufiber® and Help®. Addition of a high molar mass poly(ethylene glycol) to the AUP polymers benefits both the film and electrospun dressings in terms of flexibility and elongation. An in vivo study was conducted to assess the wound healing properties of these dressings on an acute wound model induced to rats. A macroscopic evaluation indicated that wound contraction and wound fraction percentages were improved significantly in case of the AUP-materials when compared to both the positive (Aquacel®Ag) and negative (Exufiber® and Help®) controls. A histopathological assay, to underline the changes noticed on a macroscopical level, was also performed. The data obtained proved that the developed dressings are beneficial towards tissue regeneration and accelerated wound healing. These findings offer a practical yet adequate strategy for the fabrication of acrylate-endcapped urethane-based materials for wound healing applications.

In Belgium, around 120 000 people suffer from burns yearly. Burns still remain a major clinical challenge, mainly due to bacterial infection. Nowadays, infections are diagnosed by removing the wound dressing followed by wound sampling and sample analysis. In situ detection of infection by means of a color signal can alert health care staff in an early state and improve clinical outcomes. In the current work, different acrylate endcapped urethane based precursors (AUP) were combined with diagnostic compounds. AUP with a poly(ethylene glycol) backbone molar mass of 20 kg/mol (AUP20k) was combined with three cross-linkers (pentaerythritol tetraacrylate, ethylene glycol diacrylate and AUP2k) in different double bond ratios (1:1 and 1:4). AUP20k hydrogels with the crosslinker AUP2k in a 1:1 double bond ratio revealed to have the most optimal mechanical and swelling properties. These had an absorption capacity of 32±1.6 times its own weight and a gel fraction of 80.2±4.1%. Moreover, their compressive modulus in dry and wet state was 52.4±1.0 kPa and 35.7±3.0 kPa respectively. Subsequently, the potential of Ellman’s reagent and bacteria-responsive liposomes to induce a color signal upon bacterial infection was investigated. Both the Ellman’s reagent and the bacteria-responsive phospholipid liposomes with the self-quenching dye 5(6)carboxyfluorescein were successfully incorporated in the hydrogels. Especially the latter showed great diagnostic potential as a fluorescent yellow signal of the hydrogel was demonstrated and quantified by colorimetry upon simulation of infection. Hydrogel wound dressings with a controlled diagnostic potential can thus early identify infections and better control the healing of burn wounds.

Wound dressings under the form of films constituted of modified alginate (methacrylated alginate - AlgMA) versus a gelatine derivative containing norbornene functionalities (GelNB) are developed and evaluated for their moisturizing effects, followed by further in vivo testing to assay their wound healing potential. The gel fraction results shows that AlgMA and GelNB films displayed a high crosslinking efficiency while the swelling assay reveals a stronger water uptake capacity for AlgMA films compared to GelNB and to commercial dressing AquacelAg, used as positive control. Referring to the in vivo wound healing effect, the GelNB films not only exhibit proper healing properties, yet is higher to the AquacelAg, while the AlgMA films exhibit similar wound healing effect as the positive control. On a microscopic level, the healing phases (from inflammation to proliferation and contraction) are present for both materials, yet at a faster rate for the GelNB films, which is in line with the macroscopic findings. These results provide data which support that GelNB films outperform AlgMA films, but both can be used for wound healing applications.