Silk fibroin is a promising biomaterial for tissue engineering due to its valuable mechanical and biological properties. However, being a natural product and a protein, it lacks the processability and uniform quality of an advanced synthetic material. Here we propose a way to overcome this contradiction using novel fibroin photocrosslinkable derivative (FBMA). FBMA was synthesized by methacrylation of native fibroin nucleophilic side groups. It was dissolved in either formic acid (FA) or hexafluoroisopropanol (HFIP), and the obtained solutions were photocrosslinked into hydrogel scaffolds of various structural forms including films, micropatterns, pads and macroporous sponges. UV-exposition of dry FBMA films through a photomask created complex microscaled patterns of the polymer. The nature of the solvent affected the properties of resulting hydrogels. When HFIP was used as the solvent, the resulting hydrogels had a storage modulus ∼4 times higher than that of hydrogels fabricated using FA and ∼20 times higher compared to the reference hydrogel obtained from pristine fibroin. Both FBMA-based hydrogels were biocompatible and supported fibroblast adhesion and growth in vitro. Cells cultivated on FBMA scaffolds produced with HFIP exhibited more spread phenotype at 4 and 24 h of cultivation, consistent with increased stiffness of the hydrogel. Hence, FBMA is an attractive material for fabrication of micropatterned scaffolds of centimeterscale size with minutely tunable physico-chemical properties via convenient and reproducible technological processes, applicable for rapid prototyping.
Chronic infections are associated with the formation of non-attached biofilm-like aggregates. In vitro models of surface-attached biofilms do not always accurately mimic these processes. Here, we tested a new approach to create in vitro non-attached bacterial aggregates using the principle of magnetic levitation of biological objects placed into a magnetic field gradient. Bacteria grown under magnetic levitation conditions formed non-attached aggregates that were studied with CLSM and SEM and characterized quantitatively. Non-attached aggregates consisted of bacteria submerged into an extracellular matrix and demonstrated features characteristic of biofilms, such as polymeric matrix that binds Ruby Red and Congo red dyes, prerequisite of bacterial growth, and increased resistance to gentamicin. Three quantitative methods were explored to characterize strain-specific potential to form non-attached aggregates: geometric sizes, relative quantities of aggregated and free-swimming bacteria, and Congo red binding. A comparison of three E. coli strains demonstrated that the strain weakly forming non-attached aggregates differed from strains that formed aggregates based on all three parameters (p<0.05). Further, we characterized biofilm formation on plastic and agar surfaces by these strains and found that good biofilm formation ability does not necessarily indicate good non-attached aggregate formation ability, and vice versa. The model and quantitative methods can be applied for in vitro studies of non-attached aggregates and modeling bacterial behavior in chronic infections, as it is important to increase understanding of the role that non-attached bacterial aggregates play in the pathogenesis of chronic diseases. Importance paragraph An increasing amount of evidence indicates that chronic infections are associated with non-attached biofilm-like aggregates formed by pathogenic bacteria. These aggregates differ from biofilms because they form under low-shear conditions within the volume of biological fluids and they do not attach to surfaces. Here, we describe an in vitro model that provides non-attached aggregate formation within the liquid volume due to magnetic levitation. Using this model, we demonstrated that despite morphological and functional similarities of non-attached aggregates and biofilms, strains that exhibit good biofilm formation might exhibit poor non-attached aggregate formation, suggesting that mechanisms underlying the formation of biofilms and non-attached aggregates are not identical. The magnetic levitation approach can be useful for in vitro studies of non-attached aggregate formation and simulation of bacterial behavior in chronic infections.
Despite decades of research, the goal of achieving scarless wound healing remains elusive. One of the approaches, treatment with polymeric microcarriers, was shown to promote tissue regeneration in various in vitro models of wound healing. The in vivo effects of such an approach are attributed to transferred cells with polymeric microparticles functioning merely as inert scaffolds. We aimed to establish a bioactive biopolymer carrier that would promote would healing and inhibit scar formation in the murine model of deep skin wounds. Here we characterize two candidate types of microparticles based on fibroin/gelatin or spidroin and show that both types increase re-epithelialization rate and inhibit scar formation during skin wound healing. Interestingly, the effects of these microparticles on inflammatory gene expression and cytokine production by macrophages, fibroblasts, and keratinocytes are distinct. Both types of microparticles, as well as their soluble derivatives, fibroin and spidroin, significantly reduced the expression of profibrotic factors Fgf2 and Ctgf in mouse embryonic fibroblasts. However, only fibroin/gelatin microparticles induced transient inflammatory gene expression and cytokine production leading to an influx of inflammatory Ly6C+ myeloid cells to the injection site. The ability of microparticle carriers of equal proregenerative potential to induce inflammatory response may allow their subsequent adaptation to treatment of wounds with different bioburden and fibrotic content.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.