Native Collagen Research Articles

Reconstructive surgical treatment of isolated deep intrabony defects with guided tissue regeneration using entire papilla preservation technique: A prospective case series.

The aim of this prospective study is to evaluate the clinical applicability of the entire papilla preservation (EPP) technique in the regenerative treatment of isolated deep intrabony defects using native collagen membrane and bone grafting materials. Fifteen healthy and non-smoker patients (nine males and six females; mean age: 47.73 ± 12.18; range 21 to 63 years) with one isolated deep intrabony defect each (baseline probing depth (PD): 9.03 ± 1.62mm; clinical attachment level (CAL): 11.16 ± 1.81mm) were treated with guided tissue regeneration. Surgical access to the defect was provided by a single buccal vertical incision with an interdental tunneling flap. Following the granulation tissue removal, intrabony defect was filled with bone substitutes. A collagen barrier was trimmed and placed under the intact defect-associated papilla with palatal positioning suture. Microsurgical sutures were used for primary closure. At 1week, healing of the 15 sites was uneventful. During the study, all sites showed 100% primary closure rate. At 1-year follow-up, an average CAL gain of 5.86 ± 1.28mm (P<0.0001), PD reduction of 6.1 ± 1.47mm (P<0.0001), and minimal increase in gingival recession of 0.23 ± 0.62mm (P=0.168) were observed. This novel surgical technique, that keeps the interdental papilla intact, seems promising to provide optimal biomaterial protection and healing conditions, even when a collagen barrier and bone substitutes are applied.

In vivo cartilage regeneration in a multi-layered articular cartilage architecture mimicking scaffold.

AimsExtracellular matrix (ECM) and its architecture have a vital role in articular cartilage (AC) structure and function. We hypothesized that a multi-layered chitosan-gelatin (CG) scaffold that resembles ECM, as well as native collagen architecture of AC, will achieve superior chondrogenesis and AC regeneration. We also compared its in vitro and in vivo outcomes with randomly aligned CG scaffold.MethodsRabbit bone marrow mesenchymal stem cells (MSCs) were differentiated into the chondrogenic lineage on scaffolds. Quality of in vitro regenerated cartilage was assessed by cell viability, growth, matrix synthesis, and differentiation. Bilateral osteochondral defects were created in 15 four-month-old male New Zealand white rabbits and segregated into three treatment groups with five in each. The groups were: 1) untreated and allogeneic chondrocytes; 2) multi-layered scaffold with and without cells; and 3) randomly aligned scaffold with and without cells. After four months of follow-up, the outcome was assessed using histology and immunostaining.ResultsIn vitro testing showed that the secreted ECM oriented itself along the fibre in multi-layered scaffolds. Both types of CG scaffolds supported cell viability, growth, and matrix synthesis. In vitro chondrogenesis on scaffold showed an around 400-fold increase in collagen type 2 (COL2A1) expression in both CG scaffolds, but the total glycosaminoglycan (GAG)/DNA deposition was 1.39-fold higher in the multi-layered scaffold than the randomly aligned scaffold. In vivo cartilage formation occurred in both multi-layered and randomly aligned scaffolds treated with and without cells, and was shown to be of hyaline phenotype on immunostaining. The defects treated with multi-layered + cells, however, showed significantly thicker cartilage formation than the randomly aligned scaffold.ConclusionWe demonstrated that MSCs loaded CG scaffold with multi-layered zonal architecture promoted superior hyaline AC regeneration.Cite this article: Bone Joint Res 2020;9(9):601–612.

Controlled Delivery of Growth Factor by Hierarchical Nanostructured Core-Shell Nanofibers for the Efficient Repair of Critical-Sized Rat Calvarial Defect.

Electrospun nanofibers have received much attention as bone tissue-engineered scaffolds for their capacity to mimic the structure of natural extracellular matrix (ECM). Most studies have reproduced nanofibers with smooth surface for tissue engineering. This is quite different from the triple-helical nanotopography of natural collagen nanofibrils. In this study, hierarchical nanostructures were coated on the surface of drug-loaded core-shell nanofibers to mimic natural collagen nanofibrils. The nanoshish-kebab (SK) structure was decorated regularly on the surface of the nanofibers, and the inner-loaded bone morphogenetic protein 2 (BMP2) exhibited a gentle release pattern, similar to a zero-order release pattern in kinetics. The in vitro study also showed that the SK structure could accelerate cell proliferation, attachment, and osteogenic differentiation. Four groups of scaffolds were implanted in vivo to repair critical-sized rat calvarial defects: (1) PCL/PVA (control); (2) SK-PCL/PVA; (3) PCL/PVA-BMP2; and (4) SK-PCL/PVA-BMP2. Much more bone was formed in the SK-PCL/PVA group (24.57 ± 3.81%) than in the control group (1.21 ± 0.23%). The BMP2-loaded core-shell nanofibers with nanopatterned structure (SK-PCL/PVA-BMP2) displayed the best repair efficacy (76.38 ± 4.13%), followed by the PCL/PVA-BMP2 group (39.86 ± 5.74%). It was believed that the hierarchical nanostructured core-shell nanofibers could promote osteogeneration and that the SK structure showed synergistic ability with nanofiber-loaded BMP2 in vivo for bone regeneration. Thus, this BMP2-loaded core-shell nanofiber scaffold with hierarchical nanostructure holds great potential for bone tissue engineering applications.

Ultrasound as an alternative method to increase the extraction yield from chicken mecanically separated meatresidue collagen.

The residue from chicken mechanically separated meat (MSM) is a potential source for the extraction of collagen. However, this process requires the removal of many covalent crosslinks, which makes it quite complex. Ultrasound has been successfully used to extract collagen; it reduces the process time and increases the yield. However, information regarding the effects of this treatment on the structural and functional properties of proteins is still very limited. Therefore, the aims of the present study were to obtain collagen from chicken MSM residue and to test the effects of pre-treatment with ultrasonic probe and enzymatic extraction with pepsin in its yield, as well as to evaluate the properties of extracted collagen using gel electrophoresis, Fourier-transform infrared spectroscopy, solubility, and differential scanning calorimetry. Both the ultrasound and the enzymatic extraction had a positive effect on the extraction yield of collagen from chicken MSM residue without affecting its integrity. Using ultrasound led to an increase of up to 40% in yield when compared to treatments without ultrasound application. Five extraction treatments were considered. The extracted collagen exhibited high thermal stability (43.9-47.0°C) and mainly type I structure. The use of ultrasound as pre-treatment, together with enzymatic extraction with pepsin, were effective in increasing the extraction yield of collagen from chicken MSM residue, as well as preserving the triple helical structure of the native collagen.

Broad range of substrate specificities in papain and fig latex enzymes preparations improve enumeration of Listeria monocytogenes

Numerous applications of proteolytic enzymes include dissociation of fermented meat products for the enumeration of `foodborne pathogenic bacteria. The use of trypsin for this cause is abandoned due to the high concentration of the enzyme affecting released bacteria. Papain, as a suggested replacement, and fig latex preparation with high extent of papain-like enzymes have the potential to be applied for bacteria enumeration. Both enzymatic preparations, originating from papaya and fig, showed a broader range of substrate specificities including gelatinolytic activity, especially prominent in the case of ficin and attributed to both, cysteine protease ficin and serine protease by the analysis of 2D zymography with specific inhibitors. The activity towards native collagen, mild in the case of papain, and extensive in the case of fig latex was proved by structural analysis of digested collagen by infrared spectroscopy. Further exploration of their potential for dissociation of fermented meat products showed that both papain and fig latex enzymes are stable in the presence of detergents Tween 20 and Triton X-100 and effective in the enumeration of Listeria monocytogenes. Gelatenolytic activity, and at least partial collagenolytic activity and stability in procedure conditions make papaya and fig latex proteases potent for this application in significantly lower concentrations than previously used enzymes. As a mixture of proteolytic enzymes with divergent characteristics, fig latex preparation shows higher efficiency in Listeria monocytogenes release than papain, conserved even in the presence of stronger non-ionic detergent Triton X-100.

Hard and soft tissue changes after guided bone regeneration using two different barrier membranes: an experimental in vivo investigation

To assess the contour and volumetric changes of hard and soft tissues after guided bone regeneration (GBR) using two types of barrier membranes together with a xenogeneic bone substitute in dehiscence-type defects around dental implants. In 8 Beagle dogs, after tooth extraction, two-wall chronified bone defects were developed. Then, implants were placed with a buccal dehiscence defect that was treated with GBR using randomly: (i) deproteinized bovine bone mineral (DBBM) covered by a synthetic polylactic membrane (test group), (ii) DBBM plus a porcine natural collagen membrane (positive control) and (iii) defect only covered by the synthetic membrane (negative control group). Outcomes were evaluated at 4 and 12weeks. Micro-CT was used to evaluate the hard tissue volumetric changes and STL files from digitized cast models were used to measure the soft tissues contour linear changes. Test and positive control groups were superior in terms of volume gain and contour changes when compared with the negative control. Soft tissue changes showed at 4weeks statistically significant superiority for test and positive control groups compared with negative control. After 12weeks, the results were superior for test and positive control groups but not statistically significant, although, with a lesser magnitude, the negative control group exhibited gains in both, soft and hard tissues. Both types of membranes (collagen and synthetic) attained similar outcomes, in terms of hard tissue volume gain and soft tissue contours when used in combination with DBBM CLINICAL RELEVANCE: Synthetic membranes were a valid alternative to the "gold standard" natural collagen membrane for treating dehiscence-type defects around dental implants when used with a xenogeneic bone substitute scaffold.

Collagen–iron oxide nanoparticle based ferrogel: large reversible magnetostrains with potential for bioactuation

Smart materials such as stimuli responsive polymeric hydrogels offer unique possibilities for tissue engineering and regenerative medicine. As, however, most synthetic polymer systems and their degradation products lack complete biocompatibility and biodegradability, this study aims to synthesize a highly magnetic responsive hydrogel, based on the abundant natural biopolymer collagen. As the main component of vertebratal extracellular matrix, it reveals excellent biocompatibility. In combination with incorporated magnetic iron oxide nanoparticles, a novel smart nano-bio-ferrogel can be designed. While retaining its basic biophysical properties and interaction with living cells, this collagen-nanoparticle hydrogel can be compressed to 38% of its original size and recovers to 95% in suitable magnetic fields. Besides the phenomenology of this scenario, the underlying physical scenarios are also discussed within the framework of network models. The observed reversible peak strains as large as 150% open up possibilities for the fields of biomedical actuation, soft robotics and beyond.

Eco-friendly collagen-based bio-organic field effect transistor with improved memory characteristics

Abstract With the miniaturization race, organic field-effect transistor (OFET) devices have gained much attention in recent years due to their advantages of flexibility, light weight, solution processability and low manufacturing cost. However, some inorganic or organic materials are eco-unfriendly. Therefore, in this study, the natural biological proteins collagen hydrolysate acts as dielectric material due to the presence of hydroxyl groups. Cationic surfactant hexadecyltrimethylammonium chloride (CTMA) is added into collagen hydrolysate to form a dielectric layer in bio thin film transistor (BioTFT) device. Experimental results highlight that the collagen-CTMA mixture at 3 wt% (Col-CTMA3) has shown an average mobility of 3.36 × 10−2 cm2V−1s−1 and an on/off ratio up to 2.7 × 106.1-aminopyrene is embedded into Col-CTMA3 mixture to form Col-CTMA3-1-aminopyrene (Col-CTMA3-AP) mixture to fabricate bio field-effect transistor (BioFET) type memory device. Furthermore, the optimized addition of 1-aminopyrene in the Col-CTMA3-AP mixture for memory device has provided enhanced performances associated to an average mobility of 1.23 × 10−2 cm2V−1s−1, an on/off ratio up to 5.22 × 105 and a memory window of 13.6 V, as the proportion of 1-aminopyrene increased, the charge-trapping ability of collagen strengthened. Environment effect studies have shown that BioFET memory devices placed under water environment highlight the role of the hydroxyl group for the improved BioFET performance.

Bottom-Up Self-assembled Hydrogel-Mineral Composites Regenerate Rabbit Ulna Defect without Added Growth Factors.

Hydrogel-based biomaterials have advanced bone tissue engineering approaches in the last decade, through their ability to serve as a carrier for potent growth factor, bone morphogenic protein-2 (BMP-2). However, biophysical properties of hydrogels such as multiscale structural hierarchy and bone extracellular matrix (ECM)-mimetic microarchitecture are underutilized while designing current bone grafts. Incorporation of these properties offers great potential to create a favorable biomimetic microenvironment to harness their regenerative potential. Here, we present our approach to fabricate collagen-inspired bioactive hydrogel scaffolds (referred to as "RegenMatrix") to guide and enhance bone regeneration in a rabbit ulna defect model through the mimicry of multiscale architecture of bone ECM, i.e., native collagen. Specifically, we employed polyelectrolyte complexation to promote bottom-up self-assembly of oppositely charged polysaccharides (chitosan and kappa-carrageenan) at multiple length scales forming fibrils, which further assemble into fibers. The self-assembly and bioinspired scaffold fabrication method resulted in robust cylindrical RegenMatrix with excellent retention of the multiscale architecture and uniform mineral deposition throughout the scaffolds. RegenMatrix, in both nonmineralized and mineralized forms, enhanced bone regeneration in the semiload-bearing ulna defect when compared to the empty defect. RegenMatrix also showed greater histocompatibility without any fibrous tissue formation. Collectively, the RegenMatrix developed in this study has a great potential as a bioactive bone graft without any added growth factors.

Probing short and long‐range interactions in native collagen inside the bone matrix by BioSolids CryoProbe

Solid-state nuclear magnetic resonance is a promising technique to probe bone mineralization and interaction of collagen protein in the native state. However, many of the developments are hampered due to the low sensitivity of the technique. In this article, we report solid-state nuclear magnetic resonance (NMR) experiments using the newly developed BioSolids CryoProbe™ to access its applicability for elucidating the atomic-level structural details of collagen protein in native state inside the bone. We report here approximately a fourfold sensitivity enhancement in the natural abundance 13 C spectrum compared with the room temperature conventional solid-state NMR probe. With the advantage of sensitivity enhancement, we have been able to perform natural abundance 15 N cross-polarization magic angle spinning (CPMAS) and two-dimensional (2D) 1 H-13 C heteronuclear correlation (HETCOR) experiments of native collagen within a reasonable timeframe. Due to high sensitivity, 2D 1 H/13 C HETCOR experiments have helped in detecting several short and long-range interactions of native collagen assembly, thus significantly expanding the scope of the method to such challenging biomaterials.

Production of Injectable Marine Collagen-Based Hydrogel for the Maintenance of Differentiated Chondrocytes in Tissue Engineering Applications.

Cartilage is an avascular tissue with limited ability of self-repair. The use of autologous chondrocyte transplants represent an effective strategy for cell regeneration; however, preserving the differentiated state, which ensures the ability to regenerate damaged cartilage, represents the main challenge during in vitro culturing. For this purpose, we produced an injectable marine collagen-based hydrogel, by mixing native collagen from the jellyfish Rhizostoma pulmo with hydroxy-phenyl-propionic acid (HPA)-functionalized marine gelatin. This biocompatible hydrogel formulation, due to the ability of enzymatically reticulate using horseradish peroxidase (HPR) and H2O2, gives the possibility of trap cells inside, in the absence of cytotoxic effects, during the cross-linking process. Moreover, it enables the modulation of the hydrogel stiffness merely varying the concentration of H2O2 without changes in the concentration of polymer precursors. The maintenance of differentiated chondrocytes in culture was then evaluated via morphological analysis of cell phenotype, GAG production and cytoskeleton organization. Additionally, gene expression profiling of differentiation/dedifferentiation markers provided evidence for the promotion of the chondrogenic gene expression program. This, combined with the biochemical properties of marine collagen, represents a promising strategy for maintaining in vitro the cellular phenotype in the aim of the use of autologous chondrocytes in regenerative medicine practices.

Fabrication and characterization of collagen-oxidized pullulan scaffold for biomedical applications

Pullulan, a naturally occurring polysaccharide was oxidized using sodium periodate and converted into its aldehyde derivative and used as a bio crosslinker for stabilizing collagen. The crosslinking mainly occurred due to Schiff's base reaction between amino group of lysine or hydroxylysine present in collagen with the aldehyde groups of oxidized pullulan. A known concentration of collagen was crosslinked with different concentrations of oxidized pullulan and scaffolds were prepared by freeze drying method. The crosslinking efficiency and biodegradation of the crosslinked scaffolds showed higher degree of crosslinking and slower degradation rate with increase in cross linker concentration. The surface morphology of scaffolds using SEM showed that the scaffolds with 3% concentration of crosslinker (Col-OxP-3) exhibited highly porous nature with interconnecting pores of 66.35 μm size compared to other groups, which was also supported by porosity and tensile strength measurement. The tensile strength was 10 times higher in Col-OxP-3 scaffold compared to native collagen. The swelling capacity of the scaffolds increased with increase in crosslinker concentration and the equilibrium was retained up to 60 min. The crosslinked scaffolds were non-toxic to 3T3 fibroblast cell line proving their biocompatible nature. Thus, this new class of bio-crosslinker can be used in replacement of synthetic crosslinkers for biomaterial synthesis.

From Food Waste to Innovative Biomaterial: Sea Urchin-Derived Collagen for Applications in Skin Regenerative Medicine.

Collagen-based skin-like scaffolds (CBSS) are promising alternatives to skin grafts to repair wounds and injuries. In this work, we propose that the common marine invertebrate sea urchin represents a promising and eco-friendly source of native collagen to develop innovative CBSS for skin injury treatment. Sea urchin food waste after gonad removal was here used to extract fibrillar glycosaminoglycan (GAG)-rich collagen to produce bilayer (2D + 3D) CBSS. Microstructure, mechanical stability, permeability to water and proteins, ability to exclude bacteria and act as scaffolding for fibroblasts were evaluated. Our data show that the thin and dense 2D collagen membrane strongly reduces water evaporation (less than 5% of water passes through the membrane after 7 days) and protein diffusion (less than 2% of BSA passes after 7 days), and acts as a barrier against bacterial infiltration (more than 99% of the different tested bacterial species is retained by the 2D collagen membrane up to 48 h), thus functionally mimicking the epidermal layer. The thick sponge-like 3D collagen scaffold, structurally and functionally resembling the dermal layer, is mechanically stable in wet conditions, biocompatible in vitro (seeded fibroblasts are viable and proliferate), and efficiently acts as a scaffold for fibroblast infiltration. Thus, thanks to their chemical and biological properties, CBSS derived from sea urchins might represent a promising, eco-friendly, and economically sustainable biomaterial for tissue regenerative medicine.

Collagen-Inspired Helical Peptide Coassembly Forms a Rigid Hydrogel with Twisted Polyproline II Architecture.

Collagen, the most abundant protein in mammals, possesses notable cohesion and elasticity properties and efficiently induces tissue regeneration. The Gly-Pro-Hyp canonical tripeptide repeating unit of the collagen superhelix has been well-characterized. However, to date, the shortest tripeptide repeat demonstrated to attain a helical conformation contained 3–10 peptide repeats. Here, taking a minimalistic approach, we studied a single repeating unit of collagen in its protected form, Fmoc-Gly-Pro-Hyp. The peptide formed single crystals displaying left-handed polyproline II superhelical packing, as in the native collagen single strand. The crystalline assemblies also display head-to-tail H-bond interactions and an “aromatic zipper” arrangement at the molecular interface. The coassembly of this tripeptide, with Fmoc-Phe-Phe, a well-studied dipeptide hydrogelator, produced twisted helical fibrils with a polyproline II conformation and improved hydrogel mechanical rigidity. The design of these peptides illustrates the possibility to assemble superhelical nanostructures from minimal collagen-inspired peptides with their potential use as functional motifs to introduce a polyproline II conformation into hybrid hydrogel assemblies.

A Molecular Cascade Underlying Articular Cartilage Degeneration.

Preserving of articular cartilage is an effective way to protect synovial joints from becoming osteoarthritic (OA) joints. Understanding of the molecular basis of articular cartilage degeneration will provide valuable information in the effort to develop cartilage preserving drugs. There are currently no disease-modifying OA drugs (DMOADs) available to prevent articular cartilage destruction during the development of OA. Current drug treatments for OA focus on the reduction of joint pain, swelling, and inflammation at advanced stages of the disease. However, based on discoveries from several independent research laboratories and our laboratory in the past 15 to 20 years, we believe that we have a functional molecular understanding of articular cartilage degeneration. In this review article, we present and discuss experimental evidence to demonstrate a sequential chain of the molecular events underlying articular cartilage degeneration, which consists of transforming growth factor beta 1, high-temperature requirement A1 (a serine protease), discoidin domain receptor 2 (a cell surface receptor tyrosine kinase for native fibrillar collagens), and matrix metalloproteinase 13 (an extracellularmatrix degrading enzyme). If, as we strongly suspect, this molecular pathway is responsible for the initiation and acceleration of articular cartilage degeneration, which eventually leads to progressive joint failure, then these molecules may be ideal therapeutic targets for the development of DMOADs.

A Green Approach towards Native Collagen Scaffolds: Environmental and Physicochemical Assessment.

Native collagen scaffolds were prepared in this work, in which both materials and environmental approaches were considered with the aim of providing a global strategy towards more sustainable biomaterials. From the environmental perspective, it is worth mentioning that acid and enzymatic treatments have been avoided to extract collagen, allowing the reduction in the use of resources, in terms of chemicals, energy, and time, and leading to a low environmental load of this step in all the impact categories under analysis. With the incorporation of chitosan into the scaffold-forming formulations, physical interactions occurred between collagen and chitosan, but the native collagen structure was preserved, as observed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The incorporation of chitosan also led to more homogenous porous microstructures, with higher elastic moduli and compression resistance for both dry and hydrated scaffolds. Furthermore, hydrated scaffolds preserved their size and shape after some compression cycles.

Insights into the effect of artificial sweeteners on the structure, stability, and fibrillation of type I collagen

Artificial sweeteners (AS) are widely used as sugar substitutes because natural sweetener (sugar) leads to a number of health issues, including diabetes, obesity, and tooth decay. Since natural sugar (sucrose), diabetes and skin are highly interlinked, and also sucrose is known to inhibit the fibrillation of collagen, the major protein of the skin, a study on the impact of AS on collagen is important and essential. Herein, we have studied the influence of commonly used AS such as Sucralose (SUC), Aspartame (APM), and Saccharin (SAC) on the structure, stability, and fibrillation of collagen using various spectroscopic methods. The circular dichroism and turbidity results suggest that the AS does not disrupt the triple helix structure and also the fibrillar property of collagen, respectively. The fibrillar morphology was sustained, although there was a trivial difference in the entanglement of fibrils in the presence of SAC, compared to native collagen fibrils. The thermal stability of collagen is maintained in the presence of AS. Fluorescence and STD-NMR results indicate that the interaction between AS and collagen was weak, which supports the intact structure, stability, and fibrillation property of collagen. The current study thus suggests that the chosen AS does not influence collagen properties.

A fundamental insight on developing biological value product from plant wastes

Collagen has significant contributions to the field of biomedical and tissue engineering applications. Native collagen biomaterials are mechanically feeble and require stabilization against enzymes for multivariate applications. In this study, phytoconstituents are extracted from Artemisia pallens and interacted with collagen for enhancing its chemical properties for biomedical use. From FTIR analysis, it is evident that Artemisia pallens influences the conformational changes, and this change does not affect the stability of collagen, which is ascertained by the electrophoretic study. In the fibrillogenesis study, there is a decrease in the T½ time, which indicates the reduction in the gelling time due to the influence of Artemisia pallens. Histology characterization also confirms the formation of fibrils under the control of Artemisia pallens at a pH < pI. Moreover, anti-glycation activity has been enhanced at a higher concentration owing to its antioxidant characteristics of the phytoconstituents. From the results, it is inferred that influence of Artemisia pallens creates a nucleation center for the monomeric collagen to aggregate in an uniform order, thus stimulating fibrillogenesis and along with its antiglycation activity, Artemisia pallens can assist in establishing a new way in collagen-based biomaterial preparation.

Hybrid Freeze-Dried Dressings Composed of Epidermal Growth Factor and Recombinant Human-Like Collagen Enhance Cutaneous Wound Healing in Rats.

Epidermal growth factor (EGF) is important for promoting skin repair and remodeling. Native collagen is also widely used as a scaffold for skin tissue engineering. The limitations of EGF include easy decomposition or inactivation, whereas native collagen is immunogenic and has poor solubility. Therefore, we constructed a freeze-dried dressing based on the recombinant human-like collagen (RHC) to act as a carrier for EGF (RHC/EGF freeze-dried dressing) and promote skin wound closure. Here, the freeze-dried dressing that combined EGF and RHC significantly enhanced the proliferation, adhesion, and spreading of NIH/3T3 fibroblasts and migration of HaCaT keratinocytes at the wound site. The physicochemical characteristics of the RHC/EGF freeze-dried dressing investigated using scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry revealed that it was a loose and porous cake that redissolved quickly. The molecular mechanisms involved in cell proliferation and angiogenesis were also assessed. The expression levels of the markers Ki-67, proliferating cell nuclear antigen, vascular endothelial growth factor, and cluster of differentiation 31 were significantly increased after treatment with the RHC/EGF freeze-dried dressing (P < 0.01, vs. RHC or EGF alone). This increase indicated that the RHC/EGF freeze-dried dressing significantly accelerated wound closure, re-epithelialization, and the orderly arrangement and deposition of collagen in the Sprague–Dawley rats with full-thickness skin defects. This work describes a significant step toward the development of wound environments conducive to healing, and the RHC/EGF freeze-dried dressing is a potential therapeutic strategy in wound management.

The influence of simultaneous lateral grafting on clinical outcomes following one-stage implant placement: a cross-sectional analysis

BackgroundTo investigate the influence of lateral bone augmentation procedures performed simultaneously with implant placement on peri-implant health or disease.Material and methodsA total of 232 patients showing the same type of a two-piece implant placed either simultaneously with lateral bone grafting using a bovine bone mineral and a native collagen membrane (n = 291 implants; test group) or at pristine bone sites without lateral bone grafting (n = 283 implants; control group) were enrolled in this cross-sectional analysis. Clinical outcomes (i.e., modified plaque index (mPI), bleeding on probing (BOP), probing depth (PD), and mucosal recession (MR)), and the frequency of peri-implant disease were evaluated after a mean follow-up period of 9.97 ± 6.55 years.ResultsNo differences were found between the patients in the test and control groups for any of the parameters investigated (i.e., mPI, BOP, PD, and MR). For the implants in both groups, PD values of 4–6 mm were more frequently noted in the upper jaw. A significant correlation between increased PD values and a larger implant diameter was noted for test implant sites. A KM of < 2 mm was associated with increased MR values in both groups. The prevalence of peri-implant mucositis and peri-implantitis was 68% and 5% for the patients in the test group and 61% and 10% in the control group, respectively.ConclusionsSimultaneous lateral grafting was associated with peri-implant tissue health and stability.