An attractive strategy for the regeneration of tissues has been the use of extracellular matrix analogous biomaterials. Peptide-based fibrillar hydrogels have been shown to mimic the structure of extracellular matrix offering cells a niche to undertake their physiological functions. In this study, the capability of an ionic-complementary peptide FEFEFKFK (F, E, and K are phenylalanine, glutamic acid, and lysine, respectively) hydrogel to host human mesenchymal stem cells in three dimensions and induce their osteogenic differentiation is demonstrated. Assays showed sustained cell viability and proliferation throughout the hydrogel over 12 days of culture and these human mesenchymal stem cells differentiated into osteoblasts simply upon addition of osteogenic stimulation. Differentiated osteoblasts synthesized key bone proteins, including collagen-1 (Col-1), osteocalcin, and alkaline phosphatase. Moreover, mineralization occurred within the hydrogel. The peptide hydrogel is a naturally biodegradable material as shown by oscillatory rheology and reversed-phase high-performance liquid chromatography, where both viscoelastic properties and the degradation of the hydrogel were monitored over time, respectively. These findings demonstrate that a biodegradable octapeptide hydrogel can host and induce the differentiation of stem cells and has the potential for the regeneration of hard tissues such as alveolar bone.

Bacterial nanocellulose (BNC) is a promising biomedical material. However, the haemocompatibility (haemolysis and thrombogenicity) and acute and sub-chronic immune responses to three-dimensional (3D) BNC biomaterials have not been evaluated. Accordingly, this manuscript focused on the effect of 3D microporosity on BNC haemocompatibility and a comparison with 2D BNC architecture, followed by the evaluation of the immune response to 3D BNC. Blood ex vivo studies indicated that compared with other 2D and 3D BNC architectures, never-dried 2D BNC presented antihemolytic and antithrombogenic effects. Nevertheless, in vivo studies indicated that 3D BNC did not interfere with wound haemostasis and elicited a mild acute inflammatory response, not a foreign body or chronic inflammatory response. Moreover, compared with the polyethylene controls, the implant design with micropores ca . 60 µm in diameter showed a high level of collagen, neovascularization and low fibrosis. Cell/tissue infiltration increased to 91% after 12 weeks and was characterized by fibroblastic, capillary and extracellular matrix infiltration. Accordingly, 3D BNC biomaterials can be considered a potential implantable biomaterial for soft tissue augmentation or replacement.

One of the most common mechanisms of hepatotoxicity is drug-induced cholestasis. Hence, new approaches for screening the cholestatic potential of drug candidates are desirable. In this context, we describe herein the use of synthetic 4-nitrobenzo-2-oxa-1,3-diazole (NBD) fluorescent conjugates of cholic acid (ChA) at positions 3alpha, 3beta, 7alpha, and 7beta for in vitro assessment of bile acid uptake. All the conjugates show a strong absorption band between 400 and 550 nm and have a fluorescence quantum yield of approximately 0.45, with an emission maximum centered at approximately 530 nm. After their photophysical characterization, 3alpha-, 3beta-, 7alpha-, and 7beta-NBD-ChA were used to monitor uptake in freshly isolated rat hepatocytes by means of a previously optimized flow cytometry technique. Transport of the cholic acid derivatives inside the cell was detected and quantified by measuring the increase of NBD green fluorescence within cells over time. The effect of troglitazone, a well-known inhibitor of bile acid uptake by the sodium taurocholate co-transporting polypeptide, supports the specificity of fluorescent NBD-ChA transport. According to the final intracellular fluorescence level attained and the uptake rate, 3alpha-NBD-ChA was found to be the most efficient derivative. Furthermore, sodium valproate, cyclosporin A, and chlorpromazine decreased the uptake of 3alpha-NBD-ChA, in agreement with their relative in vivo potency as cholestatic compounds; in contrast, sodium citrate (the negative control) had no effect. These results support the suitability of the in vitro flow cytometric assay with NBD-ChA to detect compounds that affect bile acid uptake.

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Self‐assembling peptide hydrogels (SAPHs) represent emerging cell cultures systems in several biomedical applications. The advantages of SAPHs are mainly ascribed to the absence of toxic chemical cross‐linkers, the presence of ECM‐like fibrillar structures and the possibility to produce hydrogels with a large range of different mechanical properties. We will present a two‐component peptide system with tuneable mechanical properties, consisting of a small pentapeptide (SFFSF‐NH 2 , SA5N) that acts as a gelator and a larger 21‐mer peptide (SFFSF‐GVPGVGVPGVG‐SFFSF, SA21) designed as a physical cross‐linker. The hydrogels formed by different mixtures of the two peptides are made up mainly of antiparallel β‐sheet nanofibers entangling in an intricate network. The effect of the addition of SA21 on the morphology of the hydrogels was investigated by atomic force microscopy and transmission electron microscopy and correlated to the mechanical properties of the hydrogel. Finally, the biocompatibility of the hydrogels using 2D cell cultures was tested. © 2018 The Authors. journal Of Biomedical Materials Research Part A Published By Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 535–544, 2019.