Epithelial cell adhesion efficacy of a novel peptide identified by panning on a smooth titanium surface

Programmable soft DNA hydrogels stimulate cellular endocytic pathways and proliferation

Hydrogels are pivotal in tissue engineering, regenerative medicine, and drug delivery applications. Existing hydrogel platforms are not easily customizable and often lack precise programmability, making them less suited for 3D tissue culture and programming of cells. DNA molecules stand out among other promising biomaterials due to their unparalleled precision, programmability, and customization. In this study, we introduced a palette of novel cellular scaffolding platforms made of pure DNA-based hydrogel systems while improving the shortcomings of the existing platforms. We showed a quick and easy one step synthesis of DNA hydrogels using thermal annealing based on sequence specific hybridization strategy. We also demonstrated the formation of multi-armed branched supramolecular scaffolds with custom mechanical stiffness, porosity, and network density by increasing or decreasing the number of branching arms. These mechanically tuneable DNA hydrogels proved to be a suitable suitable platform for modulating the physiological processes of retinal pigment epithelial cells (RPE1). In-vitro studies showed dynamic changes at multiple levels, ranging from a change in morphology to protein expression patterns, enhanced membrane traffic, and proliferation. The soft DNA hydrogels explored here are mechanically compliant and pliable, thus excellently suited for applications in cellular programming and reprogramming. This research lays the groundwork for developing a DNA hydrogel system with a higher dynamic range of stiffness, which will open exciting avenues for tissue engineering and beyond.

Enhancing Antibacterial Properties of Titanium Implants through Covalent Conjugation of Self-Assembling Fmoc-Phe-Phe Dipeptide on Titania Nanotubes

Bacterial infections and biofilm formation are significant challenges for medical implants. While titanium nanotube engineering improves biocompatibility, it cannot prevent bacterial adhesion and biofilm formation. Optimizing the biomaterial's surface chemistry is vital for its desired functioning in the biological environment. This study demonstrates the covalent conjugating of the self-assembling dipeptide N-fluorenylmethyloxycarbonyl-diphenylalanine (Fmoc-FF) onto titanium nanotube surfaces (TiNTs) without altering the topography. Fmoc-FF peptides, in conjugation with TiNTs, can inhibit biofilm formation, eradicate pre-existing biofilms, and kill bacteria. This functionalization imparts antibacterial properties to the surface while retaining beneficial nanotube topography, synergistically enhancing bioactivity. Surface characterization by XPS, FT-IR, EDS, and SEM confirmed the successful functionalization. Bacterial adhesion experiments showed a significantly improved antibacterial activity of the functionalized TiNT surfaces. This study opens future possibilities for associating biomedical applications such as cell-cell interactions, tissue engineering, and controlled drug delivery of multifunctional self-assembling short peptides with implant materials through surface functionalization.

Microscopic in-situ analysis of the mucosal healing around implants treated by protease activated receptor 4-agonist peptide or perpendicularly protruded type I collagen in rats

Enhanced mucosal sealing around titanium implants can reduce complications such as peri-implantitis. The present study aims to investigate the mucosal healing at the early stage around the protease activated receptor 4-agonist peptide (PAR4-AP)- or perpendicularly protruded type I collagen (pCol)-treated titanium implants. A total of 72 implants were placed in 36 rats in the study. Following extractions, two tissue-level implants among the following three different surfaces, PAR4-AP-coated (PAR4 group, n = 24), pCol-treated (pCol group, n = 24) and non-treated (control group, n = 24) ones, were placed in the maxillae of each rat based on a split-mouth design. The specimens retrieved at 8 h (n = 8 per group), 3 days (n = 8 per group), and 2 weeks (n = 8 per group), were immunostained and tissue-cleared, and the signals of laminin-5 and collagen fibers were observed under multiphoton microscopy. Statistical analyses were performed using linear mixed model with post hoc tests to compare differences between the groups. While there was no intergroup difference at 8 h, the laminin-5 at 3 days was more abundant near the PAR4-group-surface, and its area was significantly larger in the PAR4 group (0.0204 ± 0.0194 mm2 ) than the control (0.0019 ± 0.0025 mm2 , p = .001) and pCol (0.0023 ± 0.0022 mm2 , p < .001) groups. The pCol group showed a significantly larger area of collagen fibers (0.0230 ± 0.0148 mm2 ) compared to the control (0.0035 ± 0.0051 mm2 , p = .002) and PAR4 (0.0031 ± 0.0057 mm2 , p < .001) groups at 3 days. At 3 days and 2 weeks, the collagen fiber orientation of the pCol group showed a more perpendicular manner compared to the control and PAR4 groups. The signal of basal lamina and collagen fibers were stronger around the PAR4-AP- and pCol-treated titanium surfaces, respectively during the early healing stage. This could have implications for improved mucosal sealing around dental implants, potentially reducing complications such as peri-implantitis.

Nanostructured graphene oxide enriched with metallic nanoparticles as a biointerface to enhance cell adhesion through mechanosensory modifications

Nanostructuring is a process involving surface manipulation at the nanometric level, which improves the mechanical and biological properties of biomaterials. Specifically, it affects the mechanotransductive perception of the microenvironment of cells. Mechanical force conversion into an electrical or chemical signal contributes to the induction of a specific cellular response. The relationship between the cells and growth surface induces a biointerface-modifying cytophysiology and consequently a therapeutic effect. In this study, we present the fabrication of graphene oxide (GO)-based nanofilms decorated with metallic nanoparticles (NPs) as potential coatings for biomaterials. Our investigation showed the effect of decorating GO with metallic NPs for the modification of the physicochemical properties of nanostructures in the form of nanoflakes and nanofilms. A comprehensive biocompatibility screening panel revealed no disturbance in the metabolic activity of human fibroblasts (HFFF2) and bone marrow stroma cells (HS-5) cultivated on the GO nanofilms decorated with gold and copper NPs, whereas a significant cytotoxic effect of the GO nanocomplex decorated with silver NPs was demonstrated. The GO nanofilm decorated with gold NPs beneficially managed early cell adhesion as a result of the transient upregulation of α1β5 integrin expression, acceleration of cellspreading, and formation of elongated filopodia. Additionally, the cells, sensing the substrate derived from the nanocomplex enriched with gold NPs, showed reduced elasticity and altered levels of vimentin expression. In the future, GO nanocomplexes decorated with gold NPs can be incorporated in the structure of architecturally designed biomimetic biomaterials as biocompatible nanostructuring agents with proadhesive properties.

Peptides in Dentistry: A Scoping Review

Currently, it remains unclear which specific peptides could be appropriate for applications in different fields of dentistry. The aim of this scoping review was to scan the contemporary scientific papers related to the types, uses and applications of peptides in dentistry at the moment. Literature database searches were performed in the following databases: PubMed/MEDLINE, Scopus, Web of Science, Embase, and Scielo. A total of 133 articles involving the use of peptides in dentistry-related applications were included. The studies involved experimental designs in animals, microorganisms, or cells; clinical trials were also identified within this review. Most of the applications of peptides included caries management, implant osseointegration, guided tissue regeneration, vital pulp therapy, antimicrobial activity, enamel remineralization, periodontal therapy, the surface modification of tooth implants, and the modification of other restorative materials such as dental adhesives and denture base resins. The in vitro and in vivo studies included in this review suggested that peptides may have beneficial effects for treating early carious lesions, promoting cell adhesion, enhancing the adhesion strength of dental implants, and in tissue engineering as healthy promotors of the periodontium and antimicrobial agents. The lack of clinical trials should be highlighted, leaving a wide space available for the investigation of peptides in dentistry.

Integration of collagen fibers in connective tissue with dental implant in the transmucosal region

Dental implants have been widely accepted as an ideal therapy to replace the missing teeth for its good performance in aspects of mechanical properties and aesthetic outcomes. Its restorative success is contributed by not only the successful osseointegration of the implant but also the tight soft tissue integration, especially the collagen fibers, in the transmucosal region. Soft tissue attaching to the dental implant/abutment is overall similar, but in some aspects distinct with that seen around natural teeth and soft tissue integration can be enhanced via several surface modification methods. This review is going to focus on the current knowledge of the transmucosal zone around the dental implants (compared with natural teeth), and latest strategies in use to fine-tune the collagen fibers assembly in the connective tissue, in an attempt to enhance soft tissue integration.

Macrophage Heterogeneity in the Intestinal Cells of Salmon: Hints From Transcriptomic and Imaging Data

The intestine has many types of cells that are present mostly in the epithelium and lamina propria. The importance of the intestinal cells for the mammalian mucosal immune system is well-established. However, there is no in-depth information about many of the intestinal cells in teleosts. In our previous study, we reported that adherent intestinal cells (AIC) predominantly express macrophage-related genes. To gather further evidence that AIC include macrophage-like cells, we compared their phagocytic activity and morphology with those of adherent head kidney cells (AKC), previously characterized as macrophage-like cells. We also compared equally abundant as well as differentially expressed mRNAs and miRNAs between AIC and AKC. AIC had lower phagocytic activity and were larger and more circular than macrophage-like AKC. RNA-Seq data revealed that there were 18309 mRNAs, with 59 miRNAs that were equally abundant between AIC and AKC. Integrative analysis of the mRNA and miRNA transcriptomes revealed macrophage heterogeneity in both AIC and AKC. In addition, analysis of AIC and AKC transcriptomes revealed functional characteristics of mucosal and systemic macrophages. Five pairs with significant negative correlations between miRNA and mRNAs were linked to macrophages and epithelial cells and their interaction could be pointing to macrophage activation and differentiation. The potential macrophage markers suggested in this study should be investigated under different immune conditions to understand the exact macrophage phenotypes.

Nonthermal Plasma Brush Treatment on Titanium and Zirconia To Improve Periabutment Epithelium Formation

The peri-implant soft tissue with inferior adhesion takes a long healing period to form, which is undesirable for the reaction around the peri-implant soft tissues. The aim of this study is to improve the physicochemical properties of titanium (Ti) and zirconia (ZrO₂) implant abutments and shorten the formation period of periabutment epithelium tissue. A nonthermal atmospheric plasma brush (NTAPB, N) was employed for Ti and ZrO₂ activation. The surface topographies, roughness, crystallinity, wettability, and chemical elements of the abutment materials were examined. The epithelial cell behavior analysis and tissue remodeling of the periabutment epithelial tissue were performed in vitro and in vivo. N-Ti and N-ZrO₂ had a similar good surface wettability, with a 65 and 70% increase in oxygen content and a 70 and 75% decrease in carbon content, respectively. Both N-Ti and N-ZrO₂ showed excellent adhesion, spread, and proliferation of epithelial cells in vitro, with improved adhesion molecule expression levels compared to untreated samples. N-Ti and N-ZrO₂ abutments were placed in the implantation sites of rats. From week 2 to week 6 after implantation, N-Ti and N-ZrO₂ had similar periabutment epithelium tissue formation, and both had increased plectin-positive and laminin γ2-positive cell numbers compared to Ti and ZrO₂. The NTAPB shows promising abutment modification abilities. It promotes the expression levels of adhesion molecules and the epithelial cell performance, which later leads to a quicker formation and remodeling of the important periabutment epithelial tissue.

Influence of sterilization on the performance of anodized nanoporous titanium implants

Towards clinical translation of bioactive nano-engineered titanium implants, achieving appropriate sterilization and understanding its influence on the modified implant characteristics is essential. With limited studies exploring the influence of sterilization techniques on electrochemically anodized titanium with TiO₂ nanostructures, we aimed to advance this domain by performing an in-depth evaluation of the influence of common sterilization techniques (ethanol immersion, various UV irradiation times, gamma irradiation, and dry/wet autoclaving) on TiO₂ nanopores fabricated on micro-rough Ti surfaces (dual micro-nano) via single step anodization. Various sterilized surfaces were systematically compared in terms of topographical, chemical, crystalline, wettability and mechanical characteristics. Next, we investigated the protein adhesion capacity and functions of primary gingival fibroblasts (proliferation, adhesion/alignment and spreading morphology) to compare the bioactivity of the sterilized nanopores. Ethanol immersion, gamma irradiation and UV irradiation conserved the topography of the fabricated nanopores, while autoclave sterilization (both dry and wet) compromised the nanoporous structures. Various duration of UV-sterilization resulted in no significant changes in the surface topography and chemistry of the fabricated TNPs. Our findings revealed that UV irradiation is the most appropriate technique to sterilize nano-engineered titanium implants for appropriate wettability, protein adhesion capacity and enhanced metabolism and proliferation of human gingival fibroblasts (hGFs). This study systematically investigated the influence of sterilization on anodized nano-engineered titanium implants towards achieving reproducible outcomes (in terms of topography, chemistry and bioactivity), and found that UV irradiation holds great promise for application across different nano-engineered metal surfaces.

Bioscaffolds embedded with regulatory modules for cell growth and tissue formation: A review

The demand for artificial organs has greatly increased because of various aging-associated diseases and the wide need for organ transplants. A recent trend in tissue engineering is the precise reconstruction of tissues by the growth of cells adhering to bioscaffolds, which are three-dimensional (3D) structures that guide tissue and organ formation. Bioscaffolds used to fabricate bionic tissues should be able to not only guide cell growth but also regulate cell behaviors. Common regulation methods include biophysical and biochemical stimulations. Biophysical stimulation cues include matrix hardness, external stress and strain, surface topology, and electromagnetic field and concentration, whereas biochemical stimulation cues include growth factors, proteins, kinases, and magnetic nanoparticles. This review discusses bioink preparation, 3D bioprinting (including extrusion-based, inkjet, and ultraviolet-assisted 3D bioprinting), and regulation of cell behaviors. In particular, it provides an overview of state-of-the-art methods and devices for regulating cell growth and tissue formation and the effects of biophysical and biochemical stimulations on cell behaviors. In addition, the fabrication of bioscaffolds embedded with regulatory modules for biomimetic tissue preparation is explained. Finally, challenges in cell growth regulation and future research directions are presented.

Orchestrating soft tissue integration at the transmucosal region of titanium implants

Osseointegration at the bone-implant interface and soft tissue integration (STI) at the trans-mucosal region are crucial for the long-term success of dental implants, especially in compromised patient conditions. The STI quality of conventional smooth and bio-inert titanium-based implants is inferior to that of natural tissue (i.e. teeth), and hence various surface modifications have been suggested. This review article compares and contrasts the various modification strategies (physical, chemical and biological) utilized to enhance STI of Ti implants. It also details the STI challenges associated with conventional Ti-based implants, current surface modification strategies and cutting-edge nano-engineering solutions. The topographical, biological and therapeutic advances achievable via electrochemically anodized Ti implants with TiO₂ nanotubes/nanopores are highlighted. Finally, the status and future directions of such nano-engineered implants is discussed, with emphasis on bridging the gap between research and clinical translation.

Biological efficacy of perpendicular type-I collagen protruded from TiO2-nanotubes

The aim of this study was to evaluate the biological efficacy of a unique perpendicular protrusion of type-I collagen (Col-I) from TiO2 nanotubes (NT-EPF surface). We hypothesized that the NT-EPF surface would play bifunctional roles in stimulating platelet-mediated fibroblast recruitment and anchoring fibroblast-derived Col-I to form a perpendicular collagen assembly, mimicking the connective tissue attachment around natural teeth for the long-term maintenance of dental implants. Ti surface modification was accomplished in two steps. First, TiO2 nanotubes (NT) array was fabricated via anodization. Diameters and depths of NTs were controlled by applied voltage and duration. Subsequently, an electrophoretic fusion (EPF) method was applied to fuse Col-I into nanotube arrays in a perpendicular fashion. Surface wettability was assessed by contact angle measurement. The bioactivity of modified TiO2 surfaces was evaluated in terms of NIH3T3 fibroblast attachment, platelet activation, and collagen extension. Early attachment, aggregation, and activation of platelets as well as release of platelet-related growth factors were demonstrated on NT-EPF surfaces. Platelet-mediated NIH3T3 cells migration toward NT-EPF was significantly increased and the attached cells showed a typical fibrous morphology with elongated spindle shape. A direct linkage between pseudopod-like processes of fibroblasts to NT-EPF surfaces was observed. Furthermore, the engineered EPF collagen protrusion linked with cell-derived collagen in a perpendicular fashion. Within the limitation of this in vitro study, the TiO2 nanotube with perpendicular Col-I surface (NT-EPF) promoted better cell attachment, induced a strong platelet activation which suggested the ability to create a more robust soft tissue seal.

Adherent Intestinal Cells From Atlantic Salmon Show Phagocytic Ability and Express Macrophage-Specific Genes

Our knowledge of the intestinal immune system of fish is rather limited compared to mammals. Very little is known about the immune cells including the phagocytic cells in fish intestine. Hence, employing imaging flow cytometry and RNA sequencing, we studied adherent cells isolated from healthy Atlantic salmon. Phagocytic activity and selected gene expression of adherent cells from the distal intestine (adherent intestinal cells, or AIC) were compared with those from head kidney (adherent kidney cells, or AKC). Phagocytic activity of the two cell types was assessed based on the uptake of Escherichia coli BioParticles^TM. AIC showed phagocytic ability but the phagocytes were of different morphology compared to AKC. Transcriptomic analysis revealed that AIC expressed genes associated with macrophages, T cells, and endothelial cells. Heatmap analysis of selected genes indicated that the adherent cells from the two organs had apparently higher expression of macrophage-related genes. We believe that the adherent intestinal cells have phagocytic characteristics and high expression of genes commonly associated with macrophages. We envisage the possibilities for future studies on enriched populations of adherent intestinal cells.

Biophysics of Cell-Substrate Interactions Under Shear

Cells adhere to substrates through mechanosensitive focal adhesion complexes. Measurements that probe how cells detach from substrates when they experience an applied force connect molecular-scale aspects of cell adhesion with the biophysical properties of adherent cells. Such forces can be applied through shear devices that flow fluid in a controlled manner across cells. The signaling pathways associated with focal adhesions, in particular those that involve integrins and receptor tyrosine kinases, are complex, receiving mechano-chemical feedback from the sensing of substrate stiffness as well as of external forces. This article reviews the signaling processes involved in mechanosensing and mechanotransduction during cell-substrate interactions, describing the role such signaling plays in cancer metastasis. We examine some recent progress in quantifying the strength of these interactions, describing a novel fluid shear device that allows for the visualization of the cell and its sub-cellular structures under a shear flow. We also summarize related results from a biophysical model for cellular de-adhesion induced by applied forces. Quantifying cell-substrate adhesions under shear should aid in the development of mechano-diagnostic techniques for diseases in which cell-adhesion is mis-regulated, such as cancers.