Bacterial nanocellulose (BNC) and two BNC-based composites with carboxymethyl cellulose or hydroxyethyl cellulose (BNC-CMC or BNC-HEC, respectively), were produced in situ by Komagataeibacter xylinus E25 under stationary conditions and plasticized with glycerol (ex situ modification). The BNC-CMC composite had the loosest structure (visible in SEM images) and was less crystalline (CI of 88.6%) than BNC (CI of 92.9%) and BNC-HEC (CI of 90.4%). Cellulose fibers synthesized by K. xylinus E25 in the presence of HEC were thinner in comparison to the fibers of control BNC while there was no difference in the fibers width between the BNC-CMC and control BNC. The glycerol-plasticized BNC, BNC-CMC and BNC-HEC membranes were flexible after drying, and absorbed high amounts of artificial exudate and water after rehydration. BNC-CMC treated with 2.5% v/v aqueous glycerol was characterized by the greatest free swell absorptive capacity (up to 19 g artificial exudate/g dry weight in 24 h) while the highest rehydration capacity (around 96% of the initial water content) was observed in case of BNC-CMC plasticized with 10% v/v glycerol and dehydrated. The in situ and ex situ modifications of BNC affected also the tensile strength. The highest values of tensile strength at break (around 152.2 N) and Young's modulus (around 290.3 MPa) were observed in case of the BNC-CMC composite plasticized with 2.5% v/v glycerol. The impact of plasticized BNC, BNC-CMC and BNC-HEC on the viability of HaCaT keratinocytes was also studied and found to be positive at glycerol concentrations up to 2.5% (v/v) that suggests their potential utility as wound dressings.
ATP, ADP, UTP, and UDP acting as ligands of specific P2Y receptors activate intracellular signaling cascades to regulate a variety of cellular processes, including proliferation, migration, differentiation, and cell death. Contrary to a widely held opinion, we show here that nucleoside 5′-Omonophosphorothioate analogs, containing a sulfur atom in a place of one nonbridging oxygen atom in a phosphate group, act as ligands for selected P2Y subtypes. We pay particular attention to the unique activity of thymidine 5′-Omonophosphorothioate (TMPS) which acts as a specific partial agonist of the P2Y6 receptor (P2Y6R). We also collected evidence for the involvement of the P2Y6 receptor in human epithelial adenocarcinoma cell line (HeLa) cell migration induced by thymidine 5′-O-monophosphorothioate analog. The stimulatory effect of TMPS was abolished by siRNAmediated P2Y6 knockdown and diisothiocyanate derivative MRS 2578, a selective antagonist of the P2Y6R. Our results indicate for the first time that increased stability of thymidine 5′-O-monophosphorothioate as well as its affinity toward the P2Y6R may be responsible for some long-term effects mediated by this receptor.
Development of three-dimensional scaffolds mimicking in vivo cells’ environment is an ongoing challenge for tissue engineering. Bacterial nano-cellulose (BNC) is a well-known biocompatible material with enormous water-holding capacity. However, a tight spatial organization of cellulose fibers limits cell ingrowth and restricts practical use of BNC-based scaffolds. The aim of this study was to address this issue avoiding any chemical treatment of natural nanomaterial. Genetic modifications of Komagataeibacter hansenii ATCC 23769 strain along with structural and mechanical properties characterization of obtained BNC membranes were conducted. Furthermore, the membranes were evaluated as scaffolds in in vitro assays to verify cells viability and glycosaminoglycan synthesis by chondrogenic ATDC5 cells line as well as RBL-2H3 mast cells degranulation. K. hansenii mutants with increased cell lengths and motility were shown to produce BNC membranes with increased pore sizes. Novel, BNC membranes with relaxed fiber structure revealed superior properties as scaffolds when compared to membranes produced by a wild-type strain. Obtained results confirm that a genetic modification of productive bacterial strain is a plausible way of adjustment of bacterial cellulose properties for tissue engineering applications without the employment of any chemical modifications.
Diabetes leads to impairment of the normal course of wound healing. Interestingly, recent studies have implicated a critical role of P2X/P2Y nucleotide receptors in dermal tissue regeneration and maintaining vascular homeostasis. As new vessel generation and keratinization process are decreased in diabetic patients we determined whether nucleoside 5'-O-phosphorothioate analogues might accelerate vascular endothelial growth factor (VEGF) production as well as the growth and migration of human keratinocytes under hyperglycaemic conditions. We also investigated the expression pattern of P2X/P2Y receptors in human keratinocyte HaCaT cells. We show here that nucleoside 5'-Ophosphorothioate analogues are better candidates to overcome hyperglycaemia-induced impairment of angiogenesis as compared to their unmodified counterparts. The greatest potency for VEGF release and stimulation of cell migration by thiophosphate analogues of ATP and UTP correlates with the highest P2Y2 receptor expression by HaCaT cells. We also found that UTPαS significantly increased the viability and proliferation of the HaCaT cells. These findings suggest that thiophosphate analogues of nucleotides could serve as potential therapeutic agents for promoting impaired angiogenesis under diabetic conditions.
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