Search Results (106)

This research focuses on designing polymer membranes as biocompatible materials using home-built electrospinning equipment, offering alternative solutions for tissue regeneration applications. This technological development supports cell growth on biomaterial substrates, including hepatocellular carcinoma (Hep-G2) cells. This work researches the compatibility of polymer membranes (fiber mats) made of polyvinylidene difluoride (PVDF) for possible use in cellular engineering. A standard culture medium was employed to support the proliferation of Hep-G2 cells under controlled conditions (37 °C, 4.8% CO₂, and 100% relative humidity). Subsequently, after the incubation period, electrochemical impedance spectroscopy (EIS) assays were conducted in a physiological environment to characterize the electrical cellular response, providing insights into the biocompatibility of the material. Scanning electron microscopy (SEM) was employed to evaluate cell adhesion, morphology, and growth on the PVDF polymer membranes. The results suggest that PVDF polymer membranes can be successfully produced through electrospinning technology, resulting in the formation of a dipole structure, including the possible presence of a polar β-phase, contributing to piezoelectric activity. EIS measurements, based on R_ct and C_dl values, are indicators of ion charge transfer and strong electrical interactions at the membrane interface. These findings suggest a favorable environment for cell proliferation, thereby enhancing cellular interactions at the fiber interface within the electrolyte. SEM observations displayed a consistent distribution of fibers with a distinctive spherical agglomeration on the entire PVDF surface. Finally, integrating piezoelectric properties into cell culture systems provides new opportunities for investigating the influence of electrical interactions on cellular behavior through electrochemical techniques. Based on the experimental results, this electrospun polymer demonstrates great potential as a promising candidate for next-generation biomaterials, with a probable application in tissue regeneration. Full article

In this paper, voxel-based Asymptotic Homogenization (AH) is employed to calculate the thermal expansion and thermal conductivity characteristics of lattice materials that have a Representative Volume Element (RVE) with non-orthogonal periodic bases. The non-orthogonal RVE of the cellular lattice is discretized using voxel elements (iso-parametric hexahedral element, on a cartesian grid). A homogenization framework is developed in python that uses a fast-nearest neighbor algorithm to approximate the (non-orthogonal) periodic boundary conditions of the discretized RVE. Validation studies are performed where results of the homogenized Thermal Expansion Coefficient (TEC) and thermal conduction performed in this paper are compared with results generated by commercially available software. These included comparison with the results for (a) bi-material unidirectional composite with orthogonal RVE cell envelope; (b) bi-material hexagon lattice with orthogonal cell envelope; (c) bi-material hexagon lattice with non-orthogonal cell envelope; and (d) bi-material square lattice. A novel approach of visualizing the contribution of each voxel towards the individual terms within the homogenized thermal conductivity matrix is presented, which is necessary to mitigate any potential errors arising from the numerical model. Additionally, the effect of the thermal expansion and thermal conductivity for bi-material hexagon lattice (orthogonal and non-orthogonal RVE cell envelope) are presented for varying internal cell angles and all permutations of material assignments for a relative density of 0.3. It is found that when comparing the non-orthogonal RVE with the Orthogonal RVE as a reference model, the numerical error due to approximating the periodic boundary condition for the non-orthogonal bi-material hexagon is generally less than 2% as the numerical error is pseudo-cyclically dependent on the discretization along the cartesian axis. Full article

A challenge in orthodontic treatment is the long time taken to move teeth, which extends the long treatment period. Accordingly, various treatment protocols and orthodontic materials have been developed to shorten the orthodontic treatment period. However, controlling biological reactions is considered necessary to further shorten this treatment period. Orthodontic force results in compression of the periodontal ligament in the direction of tooth movement, resulting in various reactions in the periodontal ligament that induce osteoclast development, alveolar bone absorption, and teeth movement. The aforementioned reactions include immune reactions. Cytokines are substances responsible for intercellular communication and are involved in various physiological actions, including immune and inflammatory reactions. They cause various cellular responses, including cell proliferation, differentiation, cell death, and functional expression. Various cytokines are involved in biological reactions during orthodontic tooth movement (OTM). It is important to understand the role of cytokines during OTM in order to elucidate their biological response. This review discusses the role of cytokines during OTM. Full article

Although publications have documented the osteo-inductive effects of various bioactive materials on tissue sections, the associated morphologic patterns of tissue remodeling pathways at the cellular level have not been detailed. Therefore, we present a comparative histopathological follow-up evaluation of bone defect repair mediated by silica aerogels and methacrylate hydrogels over a 6-month period, which is the widely accepted time course for complete resolution. Time-dependent microscopic analysis was conducted using the “critical size model”. In untreated rat calvaria bone defects (control), re-ossification exclusively started at the lateral regions from the edges of the remaining bone. At the 6th month, only a few new bones were formed, which were independent of the lateral ossification. The overall ossification resulted in a 57% osseous encroachment of the defect. In contrast, aerogels (AE), hydrogels (H), and their β-tricalcium-phosphate (βTCP)-containing counterparts, which were used to fill the bone defects, characteristically induced rapid early ossification starting from the 1st month. This was accompanied by fibrous granulomatous inflammation with multinucleated giant macrophages, which persisted in decreasing intensity throughout the observational time. In addition to lateral ossification, multiple and intense intralesional osseous foci developed as early as the 1st month, and grew progressively thereafter, reflecting the osteo-inductive effects of all compounds. However, both βTCP-containing bone substituents generated larger amounts and more mature new bones inside the defects. Nevertheless, only 72.8–76.9% of the bone defects treated with AE and H and 80.5–82.9% of those treated with βTCP-containing counterparts were re-ossified by the 6th month. Remarkably, by this time, some intra-osseous hydrogels were found, and traces of silica from AE were still detectable, indicating these as the causative agents for the persistent osseous–fibrous granulomatous inflammation. When silica or methacrylate-based bone substituents are used, chronic ossifying fibrous granulomatous inflammation develops. Although 100% re-ossification takes more than 6 months, by this time, the degree of osteo-fibrous solidification provides functionally well-suited bone repair. Full article

The design of scaffolds and prostheses benefits from the opportunities provided by additive manufacturing technologies. Specifically, scaffold design using cellular structures based on lattices has become a significant focus. These lattice-based scaffolds exhibit intricate and complex shapes with controlled macro-porosity. In this study, a method is presented that enables the modeling of a graded-density lattice structure for material extrusion additive manufacturing, without relying on a geometric lattice model. The methodology utilizes computed tomography (CT) scans as inputs to obtaining a 3D scalar field and a surface model. The lattice structure is designed and generated within the computer-aided manufacturing (CAM) software, ensuring consistent machine toolpaths. The 3D scalar field, representing a relative density map derived from CT Hounsfield units, drives the variation of the extrusion parameters generated by the CAM, achieving a graded-density lattice. To demonstrate the effectiveness of the method, a section of a human femur bone with a lattice with a triply periodic minimal surface (TPMS) gyroid pattern was designed and 3D-printed, replicating the relative density of the target tissue. Full article

The aim of this study was to evaluate the effect of suture material made of polyester (PET), polypropylene (PP), and polytetrafluoroethylene (PTFE) on the calcification of a bovine pericardium (BP) consisting of collagen biopolymer preserved with an epoxy compound. Non-porous film made of the synthetic reinforced polymer REPEREN^® was chosen as a control material. Samples of the material (sutured or non-sutured with each of the three types of surgical sutures) were implanted subcutaneously in 45 young rats for 30, 60, and 90 days. The calcium content of the explants was quantified using atomic absorption spectrometry, a histological examination was performed using hematoxylin and eosin and von Kossa staining, and the structure of the calcium phosphate deposits was studied using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) with color field mapping. The results demonstrated the absence of calcification in the non-sutured BP and in all the REPEREN^® groups. In the sutured BP samples, a dynamic increase in the Ca content and the Ca/P ratio to 1.67–1.7 (crystalline hydroxyapatite) was observed by the 90th day. The minimum Ca content among the sutured BP groups was detected in samples where the PET thread was used. The cellular reaction to BP was significantly more pronounced than the reaction to REPEREN^® throughout the entire observation period; collagen homogenization was noted near the sutures. It can be concluded that all the studied suture materials provoke BP calcification. PET has the minimal negative effect. Full article

As a potential raw material with a variety of bioactive compounds, Pu-erh raw tea can produce rich flavor and health benefits through natural fermentation or microbial fermentation in traditional processing. However, the traditional fermentation process has some problems such as a long fermentation period and unstable quality. Monascus, a kind of fungus used in both medicine and food, has been proved to have many beneficial effects such as lowering cholesterol and regulating blood lipids. Therefore, in this study we investigated whether the fermentation of mixed monascus could significantly improve the flavor quality and lipid-lowering activity of Pu-erh raw tea. We added four kinds of monascus to unfermented Pu-erh raw tea (UT) to obtain a fermented Pu-erh raw tea (FT). The quality of the two tea samples was determined and an in vitro lipid-lowering experiment was conducted. The results show that the contents of water extractives, flavone, trans-catechins (GCG and CG), theabrownins, and caffeine in FT are significantly higher than those in UT, increasing by 19.41%, 14.47%, 18.76%, 29.82%, and 10.67%, respectively. In terms of aroma, linalool was the characteristic compound of UT, presenting a floral note. D-Limonene was the key characteristic substance of FT, manifested as lemon, toast, and wood. In terms of taste, FT has a high content of bitter amino acids and caffeine, a low content of catechins, and is rich in carbohydrate substances, forming a characteristic mild and mellow slightly bitter taste with reduced astringency. In addition, the relative contents of active substances with lipid-lowering effects such as quercetin, quercitrin, ascorbic acid, and sorbitol in FT were higher than those in UT, increasing by 83.09%, 81.73%, 89.86%, and 92.76%, respectively. The effect of FT on regulating cellular lipid metabolism was superior to UT based on cell experiments. The research results provide a scientific basis for the deep processing and functional development of Pu-erh raw tea. Full article

Background and Objectives: Dexamethasone has been widely researched for its ability to promote osteogenic differentiation in mesenchymal stem cells in basic research. This study focused on examining the effects of dexamethasone on both cell viability and osteogenic differentiation in three-dimensional stem cell spheroids. Materials and Methods: These spheroids were created using concave microwells and exposed to dexamethasone at concentrations ranging from 0 μM to 100 μM, including intermediate levels of 0.1 μM, 1 μM, and 10 μM. Microscopic analysis was used to qualitatively assess cellular viability, while a water-soluble tetrazolium salt-based assay provided quantitative viability data. Osteogenic differentiation was evaluated by measuring alkaline phosphatase activity and calcium deposition using Alizarin Red staining. Additionally, the expression levels of genes associated with osteogenesis were measured through quantitative polymerase chain reaction. Results: The spheroids successfully self-assembled within the first 24 h and maintained their structural integrity over a seven-day period. Analysis of cell viability showed no statistically significant differences across the various dexamethasone concentrations tested. Although there was an observed increase in alkaline phosphatase activity and calcium deposition following dexamethasone treatment, these differences were not statistically significant. RUNX2 gene expression was upregulated in the 1 μM, 10 μM, and 100 μM groups, while COL1A1 expression significantly increased at 0.1 μM and 1 μM. Conclusions: These results indicate that dexamethasone supports cell viability and enhances RUNX2 and COL1A1 expression in stem cell spheroids. Full article

At the forefront of regenerative medicine, orthobiologics represent a spectrum of biological substances that offer promising alternatives for tissue repair and regeneration. Traditional surgical treatments often involve significant risks, extended recovery periods, and may not fully restore tissue functionality, creating a strong demand for less invasive options. This paper presents a concise overview of orthobiologics, reexamining their role within the broader landscape of regenerative medicine. Beginning with a brief introduction to orthobiologics, the paper navigates through various types of biological materials and their associated mechanisms of action and clinical applications. By highlighting platelet derivatives, bone marrow-derived products, and processed adipose tissue, among others, it underscores the pivotal role of orthobiologics in prompting biological responses like cellular proliferation, differentiation, and angiogenesis, thereby fostering tissue healing. Furthermore, this paper explores the diverse applications of orthobiologics in orthopedic conditions, outlining their utility in the treatment of bone and soft-tissue injuries. Addressing clinical considerations, it discusses safety profiles, efficacy, patient selection criteria, and emerging challenges. With the limitations of traditional medicine becoming more apparent, orthobiologics offer an innovative and less invasive approach to patient care. Looking forward, this paper approaches future directions in orthobiologics research, emphasizing the need for continued innovation and exploration. Through a concise perspective, this paper aims to provide clinicians, researchers, and stakeholders with a comprehensive understanding of orthobiologics and their evolving role in regenerative medicine. Full article

This research introduced a strategy to fabricate sub-millimeter-diameter artificial liver tissue by extruding a combination of a liver decellularized extracellular matrix (dECM), alginate, endothelial cells, and hepatocytes. Vascularization remains a critical challenge in liver tissue engineering, as replicating the liver’s intricate vascular network is essential for sustaining cellular function and viability. Seven scaffold groups were evaluated, incorporating different cell compositions, scaffold materials, and structural configurations. The hepatocyte and endothelial cell scaffold treated with alginate lyase demonstrated the highest diffusion rate, along with enhanced albumin secretion (2.8 µg/mL) and urea synthesis (220 µg/mL) during the same period by day 10. A dense and interconnected endothelial cell network was observed as early as day 4 in the lyased coculture group. Furthermore, three-week implantation studies in rats showed a stable integration to the host with no adverse effects. This approach offers significant potential for advancing functional liver tissue replacements, combining accelerated diffusion, enhanced albumin secretion, improved urea synthesis, dense vascular network formation, and stable implantation outcomes. Full article

Chronic wounds present a substantial healthcare obstacle, marked by an extended healing period that can persist for weeks, months, or even years. Typically, they do not progress through the usual phases of healing, which include hemostasis, inflammation, proliferation, and remodeling, within the expected timeframe. Therefore, to address the socioeconomic burden in taking care of chronic wounds, hydrogel-based therapeutic materials have been proposed. Hydrogels are hydrophilic polymer networks with a 3D structure which allows them to become skin substitutes for chronic wounds. Knowing that peptides are abundant in the human body and possess distinct biological functionality, activity, and selectivity, their adaptability as peptide-based hydrogels to individual therapeutic requirements has made them a significant potential biomaterial for the treatment of chronic wounds. Peptide-based hydrogels possess excellent physicochemical and mechanical characteristics such as biodegradability and swelling, and suitable rheological properties as well great biocompatibility. Moreover, they interact with cells, promoting adhesion, migration, and proliferation. These characteristics and cellular interactions have driven peptide-based hydrogels to be applied in chronic wound healing. Full article

This study advances the state of the art by computing the macroscopic elastic properties of 2D periodic functionally graded microcellular materials, incorporating both isotropic and orthotropic solid phases, as seen in additively manufactured components. This is achieved through numerical homogenization and several novel MATLAB implementations (known in this study as Cellular_Solid, Homogenize_test, homogenize_ortho, and Homogenize_test_ortho_principal). The developed codes in the current work treat each cell as a material point, compute the corresponding cell elasticity tensor using numerical homogenization, and assign it to that specific point. This is conducted based on the principle of scale separation, which is a fundamental concept in homogenization theory. Then, by deriving a fit function that maps the entire material domain, the homogenized material properties are predicted at any desired point. It is shown that this method is very capable of capturing the effects of orthotropy during the solid phase of the material and that it effectively accounts for the influence of void geometry on the macroscopic anisotropies, since the obtained elasticity tensor has different $E_1$ and $E_2$ values. Also, it is revealed that the complexity of the void patterns and the intensity of the void size changes from one cell to another can significantly affect the overall error in terms of the predicted material properties. As the stochasticity in the void sizes increases, the error also tends to increase, since it becomes more challenging to interpolate the data accurately. Therefore, utilizing advanced computational techniques, such as more sophisticated fitting methods like the Fourier series, and implementing machine learning algorithms can significantly improve the overall accuracy of the results. Furthermore, the developed codes can easily be extended to accommodate the homogenization of composite materials incorporating multiple orthotropic phases. This implementation is limited to periodic void distributions and currently supports circular, rectangular, square, and hexagonal void shapes. Full article

This paper deals with the actual and challenging process of the optimal design of topologies of periodic structures taking into account the design-dependent loads. The topology formulation used in this paper minimizes the compliance value of the structure and is subject to a total volume constraint while maintaining a periodic pattern and self-weight load. This combination represents a promising and original contribution to the field of ongoing research, although it is not yet widely recognized. This paper aims to fill this gap by presenting the first results of numerical optimization tests. The redistribution of material within a design domain is governed by the rules of Cellular Automata, a locally oriented optimization tool that can be applied to all types of structural optimization, including topology optimization. The technique has been demonstrated by numerical tests on two- and three-dimensional examples. The calculations were performed for different types of periodic schemes. The optimized structures did not show the checkerboard effect or the presence of residual gray elements in the final topologies. The strategy used in this paper ensures connectivity between periodic subdomains without imposing additional conditions on the algorithm. Full article

Objective. In this study, the biological effect of MTA Repair HP (Mineral Trioxide Aggregate Repair High Plasticity) and Biodentine have been tested on a stabilized fibroblast cell line NCTC clone 929. Materials and Methods. We assessed quantitative and qualitative parameters related to cytotoxic effect of the investigated products. The experimental period was 96 hours. Statistical analysis was performed with Kruskal-Wallis and Wilcoxon tests. Results. The detached cells test showed no statistically significant difference on cell culture for Biodentine and MTA Repair HP, while for the cellular density assay we found the same biological effect on the tested fibroblasts in the first 24 and 48 h, but a significant different cellular response for the investigated pulp capping materials for the next 48 h of the experiment. Conclusions. The results demonstrated that the materials presented a very low level of cytotoxicity. Biodentine showed in all parameters better biological effects than MTA Repair HP, expressed by lower and limited cellular damage and a higher cell density. Full article

Background and Objectives: Angiomatoid fibrous histiocytoma (AFH) is a rare soft-tissue tumor with a low-grade malignancy. It typically arises in superficial soft tissues of the extremities, head, neck and trunk in children or young adults. Because of its rare entity, it tends to be confused and misdiagnosed. Materials and Methods: A 12-year-old male presented with a painless mass located on his right upper back. The CT finding showed a 7.3 × 2.8 × 5.4 cm-sized, well-defined heterogeneous soft tissue mass in the right infrascapular area. We performed a complete excision, including the surrounding capsule. Result: The final pathology revealed an AFH of intermediate malignancy. On pathologic examination, the lesion was a 5.8 × 4.5 × 2.6 cm-sized mass with a mitotic count of 12/10 HPF, tumor necrosis of 0% and marked increased cellularity and spindle cell morphology. The immunohistochemical study showed negative for S100 and positive for SMA, focal positive for Ki-67, CD68 and positive for CD99, Desmin staining. During the five years of follow-up period, he did not show any evidence of recurrence. Conclusions: The result was satisfactory. We report a case of AFH of the back initially misdiagnosed as an elastofibroma dorsi (ED) with the review of the literature for this uncommon entity. Full article