Background In recent decades, tooth derivatives such as dentin (D) and enamel (E) have been considered as potential graft biomaterials to treat bone defects. This study aimed to investigate the effects of demineralization on the physical-chemical and biological behavior of D and E. Methods Human D and E were minced into particles (Ø<1 mm), demineralized and sterilized. Thorough physical-chemical and biochemical characterizations of native and demineralized materials were performed by SEM and EDS analysis and ELISA kits to determine mineral, collagen type I and BMP-2 contents. In addition, MG63 and SAOS-2 cells were seeded on tooth-derived materials and Bio-Oss®, and a comparison of cell responses in terms of adhesion and proliferation was carried out. Results The sterilization process, as a combination of chemical and thermal treatments, was found to be effective for all materials. On the other hand, D demineralization allowed preserving the collagen content, while increasing BMP-2 bioavailability. D and demineralized D (dD) displayed excellent biocompatibility, even greater than Bio-Oss®. Conversely, the high mineral content displayed by E, as confirmed by EDS analysis, inhibited cell proliferation. Of note, even though the demineralization process was somehow less effective in E than in D, demineralized E (dE) displayed increased BMP-2 bioavailability and improved performance in vitro compared with native E. Conclusions Our results substantiate the idea that the demineralization process lead to an increase of BMP-2 bioavailability, thus paving the way toward development of more effective, osteoinductive tooth-derived materials for bone regeneration and replacement.

Genetic variation in α-adducin cytoskeletal protein is implicated in the polymerization and bundling of actin and alteration of the Na/K pump, resulting in abnormal renal sodium transport and hypertension in Milan hypertensive rats and humans. To investigate the molecular involvement of α-adducin in controlling Na/K pump activity, wild-type or mutated rat and human α-adducin forms were, respectively, transfected into several renal cell lines. Through multiple experimental approaches (microscopy, enzymatic assays, coimmunoprecipitation), we showed that rat and human mutated forms increased Na/K pump activity and the number of pump units; moreover, both variants coimmunoprecipitate with Na/K pump. The increased Na/K pump activity was not due to changes in its basolateral localization, but to an alteration of Na/K pump residential time on the plasma membrane. Indeed, both rat and human mutated variants reduced constitutive Na/K pump endocytosis and similarly affected transferrin receptor trafficking and fluid-phase endocytosis. In fact, α-adducin was detected in clathrin-coated vesicles and coimmunoprecipitated with clathrin. These results indicate that adducin, besides its modulatory effects on actin cytoskeleton dynamics, might play a direct role in clathrin-dependent endocytosis. The constitutive reduction of the Na/K pump endocytic rate induced by mutated adducin variants may be relevant in Na-dependent hypertension.

Despite their outstanding potential and the success that has already been achieved with three-dimensional (3D) printed hydrogel scaffolds, there has been little investigation into their application in the regeneration of damaged or missing adipose tissue (AT). Due to their macroscopic shape, microarchitecture, extracellular matrix-mimicking structure, degradability and soft tissue biomimetic mechanical properties, 3D printed hydrogel scaffolds have great potential for use in aesthetic, structural and functional restoration of AT. Here, we propose a simple and cost-effective 3D printing strategy using gelatin-based ink to fabricate scaffolds suitable for AT engineering. The ink, successfully printed here for the first time, was prepared by mixing gelatin and methylenebisacrylamide (a crosslinker) to initiate the crosslinking reaction. The solution was then loaded into the cartridge (temperature T = 35 °C) of a pneumatic extrusion-based 3D printer and printed on a cooled surface (T = 4 °C) in the appropriate time window for ink printability as verified by rheological tests. Subsequently, the printed gelatin hydrogels were crosslinked at different temperatures to optimize their stability and fix the printed structure. The gelatin scaffolds crosslinked at 20 °C remained stable for 21 days at physiological temperature, with compressive mechanical properties mimicking those of AT (i.e. elastic modulus = 20 kPa). The 3D printed scaffolds showed no indirect cytotoxic effects on a 3T3-L1 pre-adipocyte cell line. Moreover, the printed scaffolds successfully promoted adhesion and proliferation of primary human pre-adipocytes, as demonstrated by LIVE/DEAD staining and Alamar Blue assay. The differentiation of primary human pre-adipocytes isolated from three different donors according to adipogenic phenotype was demonstrated by an increase in PPARγ gene expression detected by real-time PCR and accumulated lipid droplets stained by Oil Red O, thus proving the potential of the 3D printed gelatin hydrogels as scaffolds for AT engineering.

The design of scaffolding materials that mimic the properties of the target tissue to be regenerated is a mandatory requirement to engineer a successful scaffold; however, the heterogeneous properties of adipose tissue (AT), strictly dependent on the AT depot, are often underestimated when engineering AT scaffolds. Moreover, a scaffolding material with versatile properties, suitable for the regeneration of different AT depots, is currently missing. Chemically crosslinked gelatin hydrogels are here prepared, and their properties tuned by varying gelatin concentration and reaction stoichiometry to obtain hydrogels suitable for AT regeneration. All hydrogel formulations are stable in water at 37 °C, showing swelling behavior dependent on synthesis parameters. The mechanical compressive response mimics the viscoelastic response typical of native AT, with elastic modulus values covering the range of breast and heel pad AT. The rheological properties vary among the hydrogel formulations, showing a typical shear thinning response, comparable to other AT scaffolds described in literature. In vitro cytotoxicity tests using 3T3‐L1 preadipocytes show no cytotoxic effects up to 7 days. 3T3‐L1 cells seeded on the hydrogels show good adhesion, proliferation, and adipogenic differentiation, confirmed by an increase in peroxisome proliferator‐activated receptor gamma gene expression and lipid droplets accumulation observed by Oil Red O staining. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47104.

Background: Great interest has recently been focused on tooth and tooth derivatives as suitable substrates for the treatment of alveolar bone defects. Here, we propose the use of demineralized baby teeth (BT) as potential grafting materials for bone augmentation procedures. Methods: Particles of human BT (Ø < 1 mm) were demineralized by means of a chemical/thermal treatment. Demineralized BT particles were thoroughly characterized by scanning electron microscopy/energy dispersive X-ray analyses to evaluate the effects of the demineralization on BT topography and mineral phase composition, and by enzyme-linked immunosorbent assays (ELISA) to quantify collagen and bone morphogenetic protein-2 (BMP-2) protein contents. The response of SAOS-2 cells to exogenous BMP-2 stimulation was evaluated to identify the minimum BMP-2 concentration able to induce osteodifferentiation in vitro (alkaline phosphatase (ALP) activity). Results: The demineralization treatment led to a dramatic decrease in relative Ca and P content (%) of ≈75% with respect to the native BT particles, while preserving native protein conformation and activity. Interestingly, the demineralization process led to a rise in the bioavailability of BMP-2 in BT particles, as compared to the untreated counterparts. The BMP-2 content found in demineralized BT was also proved to be very effective in enhancing ALP activity, thus in the osteodifferentiation of SAOS-2 cells in vitro, as confirmed by cell experiments performed upon exogenously added BMP-2. Conclusions: In this study we demonstrate that the BMP-2 content found in demineralized BT is very effective in inducing cell osteodifferentiation, and strengthens the idea that BTs are very attractive bioactive materials for bonegrafting procedures.