Alginate nanofibrous mats with adjustable degradation rate for regenerative medicine.

The broad utilization of electrospun scaffolds of sodium alginate in tissue engineering is strongly limited by their high solubility in aqueous environments and by the difficulty to adjust their degradation dynamics. Here, an alternative strategy to enhance the stability and to control the degradability of alginate nanofibers is described by treating them with trifluoroacetic acid for specific time intervals. It is demonstrated that, by increasing the duration of the acid treatment procedure, a lower degradation rate of the resulting fibers in buffer solutions can be achieved. Furthermore, the produced mats are free from cytotoxic compounds and are highly biocompatible. The properties conferred to the alginate nanofibrous mats by the proposed method are extremely attractive in the production of innovative biomedical devices.

Enhanced chondrogenic potential in GelMA-based 3D cartilage model via Wnt3a surface immobilization.

Cartilage tissue engineering aims to develop functional substitutes for treating cartilage defects and osteoarthritis. Traditional two-dimensional (2D) cell culture systems lack the complexity of native cartilage, leading to the development of 3D regenerative cartilage models. In this study, we developed a 3D model using Gelatin Methacryloyl (GelMA)-based hydrogels seeded with Y201 cells, a bone marrow mesenchymal stem cell line. The model investigated chondrogenic differentiation potential in response to Wnt3a stimulation within the GelMA scaffold and validated using known chondrogenic agonists. Y201 cells demonstrated suitability for the model, with increased proteoglycan content and upregulated chondrogenic marker expression under chondrogenic conditions. Wnt3a enhanced cell proliferation, indicating activation of the Wnt/ß-catenin pathway, which plays a role in cartilage development. GelMA hydrogels provided an optimal scaffold, supporting cell viability and proliferation. The 3D model exhibited consistent responses to chondrogenic agonists, with TGF-ß3 enhancing cartilage-specific extracellular matrix (ECM) production and chondrogenic differentiation. The combination of Wnt3a and TGF-ß3 showed synergistic effects, promoting chondrogenic differentiation and ECM production. This study presents a 3D regenerative cartilage model with potential for investigating cartilage biology, disease mechanisms, and drug screening. The model provides insights into complex cartilage regeneration mechanisms and offers a platform for developing therapeutic approaches for cartilage repair and osteoarthritis treatment.

Remote Activation of Mechanotransduction via Integrin Alpha-5 via Aptamer-Conjugated Magnetic Nanoparticles Promotes Osteogenesis.

Bone regeneration and repair are complex processes in the adult skeleton, and current research has focused on understanding and controlling these processes. Magnetic nanoparticle (MNP)-based platforms have shown potential in tissue engineering and regenerative medicine through the use of magnetic nanomaterials combined with remotely applied dynamic fields. Previous studies have demonstrated the ability of MNP-induced mechanoactivation to trigger downstream signaling and promote new bone formation. In this study, we aimed to compare the osteogenic induction achieved using the mechanoreceptor targets, Piezo1, Fzd1, Fzd2, and integrin alpha-5. We compared the binding efficacy of different types of agonists (antibodies vs. aptamers) to these receptors. Moreover, we optimized the aptamer concentration (2.5, 5, and 10 µg/mg) for the selected receptor to determine the optimum concentration for promoting bone formation. Our data demonstrated that the mechanoactivation of integrins (CD49e) significantly upregulated the RUNX2 and LEF1 genes compared to other selected receptors. Furthermore, comparing the mechanoactivation of cells using MNPs conjugated with CD49e antibodies and aptamers revealed that MNP-aptamers significantly enhanced the upregulation of LEF1 genes. This suggests that aptamer-mediated mechanoactivation is a promising alternative to antibody-mediated activation. Finally, our results showed that the concentration of the aptamer loaded onto the MNPs strongly influenced the mechanoactivation of the cells. These findings provide valuable insights into the use of MNP platforms for bone regeneration and highlight the potential of aptamers in promoting signaling pathways related to bone formation. The novelty of our study lies in elucidating the unique advantages of aptamers in mediating mechanoactivation, presenting a promising avenue for advancing bone regenerative strategies.

Review of emerging nanotechnology in bone regeneration: progress, challenges, and perspectives.

The application of nanotechnology to regenerative medicine has increased over recent decades. The development of materials that can influence biology at the nanoscale has gained interest as our understanding of the interactions between cells and biomaterials at the nanoscale has grown. Materials that are either nanostructured or influence the nanostructure of the cellular microenvironment have been developed and shown to have advantages over their microscale counterparts. There are several reviews which have been published that discuss how nanomaterials have been used in regenerative medicine, particularly in bone regeneration. Most of these studies have explored this concept in specific areas, such as the application of glass-based nanocomposites, nanotechnology for targeted drug delivery to stimulate bone repair, and the progress in nanotechnology for the treatment of osteoporosis. In this review paper, the impact of nanotechnology in biomaterials development for bone regeneration will be discussed highlighting specifically, nanostructured materials that influence mechanical properties, biocompatibility, and osteoinductivity.

Preparation of a novel biodegradable nanocomposite scaffold based on poly (3-hydroxybutyrate)/bioglass nanoparticles for bone tissue engineering.

One of the most important challenges in composite scaffolds is pore architecture. In this study, poly (3-hydroxybutyrate) with 10% bioglass nanoparticles was prepared by the salt leaching processing technique, as a nanocomposite scaffold. The scaffolds were characterized by SEM, FTIR and DTA. The SEM images demonstrated uniformed porosities of appropriate sizes (about 250-300 microm) which are interconnected. Furthermore, higher magnification SEM images showed that the scaffold possesses less agglomeration and has rough surfaces that may improve cell attachment. In addition, the FTIR and DTA results showed favorable interaction between polymer and bioglass nanoparticles which improved interfaces in the samples. Moreover, the porosity of the scaffold was assessed, and the results demonstrated that the scaffold has uniform and high porosity in its structure (about 84%). Finally it can be concluded that this scaffold has acceptable porosity and morphologic character paving the way for further studies to be conducted from the perspective of bone tissue engineering.

Spinal cord astrocytomas: progresses in experimental and clinical investigations for developing recovery neurobiology-based novel therapies.

Spinal cord astrocytomas (SCAs) have discernibly unique signatures in regards to epidemiology, clinical oncological features, genetic markers, pathophysiology, and research and therapeutic challenges. Overall, there are presently very limited clinical management options for high grade SCAs despite progresses made in validating key molecular markers and standardizing tumor classification. The endeavors were aimed to improve diagnosis, therapy design and prognosis assessment, as well as to define more effective oncolytic targets. Efficacious treatment for high grade SCAs still remains an unmet medical demand. This review is therefore focused on research state updates that have been made upon analyzing clinical characteristics, diagnostic classification, genetic and molecular features, tumor initiation cell biology, and current management options for SCAs. Particular emphasis was given to basic and translational research endeavors targeting SCAs, including establishment of experimental models, exploration of unique profiles of SCA stem cell-like tumor survival cells, characterization of special requirements for effective therapeutic delivery into the spinal cord, and development of donor stem cell-based gene-directed enzyme prodrug therapy. We concluded that precise understanding of molecular oncology, tumor survival mechanisms (e.g., drug resistance, metastasis, and cancer stem cells/tumor survival cells), and principles of Recovery Neurobiology can help to create clinically meaningful experimental models of SCAs. Establishment of such systems will expedite the discovery of efficacious therapies that not only kill tumor cells but simultaneously preserve and improve residual neural function.

Nanofibrous Scaffolds Support a 3D in vitro Permeability Model of the Human Intestinal Epithelium.

Advances in drug research not only depend on high throughput screening to evaluate large numbers of lead compounds but also on the development of in vitro models which can simulate human tissues in terms of drug permeability and functions. Potential failures, such as poor permeability or interaction with efflux drug transporters, can be identified in epithelial Caco-2 monolayer models and can impact a drug candidate's progression onto the next stages of the drug development process. Whilst monolayer models demonstrate reasonably good prediction of in vivo permeability for some compounds, more developed in vitro tools are needed to assess new entities that enable closer in vivo in vitro correlation. In this study, an in vitro model of the human intestinal epithelium was developed by utilizing nanofibers, fabricated using electrospinning, to mimic the structure of the basement membrane. We assessed Caco-2 cell response to these materials and investigated the physiological properties of these cells cultured on the fibrous supports, focusing on barrier integrity and drug-permeability properties. The obtained data illustrate that 2D Caco-2 Transwell® cultures exhibit artificially high trans-epithelial electrical resistance (TEER) compared to cells cultured on the 3D nanofibrous scaffolds which show TEER values similar to ex vivo porcine tissue (also measured in this study). Furthermore, our results demonstrate that the 3D nanofibrous scaffolds influence the barrier integrity of the Caco-2 monolayer to confer drug-absorption properties that more closely mimic native gut tissue particularly for studying passive epithelial transport. We propose that this 3D model is a suitable in vitro model for investigating drug absorption and intestinal metabolism.

Interconnectable Dynamic Compression Bioreactors for Combinatorial Screening of Cell Mechanobiology in Three Dimensions.

Biophysical cues can potently direct a cell's or tissue's behavior. Cells interpret their biophysical surroundings, such as matrix stiffness or dynamic mechanical stimulation, through mechanotransduction. However, our understanding of the various aspects of mechanotransduction has been limited by the lack of proper analysis platforms capable of screening three-dimensional (3D) cellular behaviors in response to biophysical cues. Here, we developed a dynamic compression bioreactor to study the combinational effects of biomaterial composition and dynamic mechanical compression on cellular behavior in 3D hydrogels. The bioreactor contained multiple actuating posts that could apply cyclic compressive strains ranging from 0 to 42% to arrays of cell-encapsulated hydrogels. The bioreactor could be interconnected with other compressive bioreactors, which enabled the combinatorial screenings of 3D cellular behaviors simultaneously. As an application of the screening platform, cell spreading, and osteogenic differentiation of human mesenchymal stem cells (hMSCs) were characterized in 3D gelatin methacryloyl (GelMA) hydrogels. Increasing hydrogel concentration from 5 to 10% restricted the cell spreading, however, dynamic compressive strain increased cell spreading. Osteogenic differentiation of hMSCs was also affected by dynamic compressive strains. hMSCs in 5% GelMA hydrogel were more sensitive to strains, and the 42% strain group showed a significant increase in osteogenic differentiation compared to other groups. The interconnectable dynamic compression bioreactor provides an efficient way to study the interactions of cells and their physical microenvironments in three dimensions.

Alginate-lavender nanofibers with antibacterial and anti-inflammatory activity to effectively promote burn healing.

One of the current challenges in wound care is the development of multifunctional dressings that can both protect the wound from external agents and promote the regeneration of the new tissue. Here, we show the combined use of two naturally derived compounds, sodium alginate and lavender essential oil, for the production of bioactive nanofibrous dressings by electrospinning, and their efficacy for the treatment of skin burns induced by midrange ultraviolet radiation (UVB). We demonstrate that the engineered dressings reduce the risk of microbial infection of the burn, since they stop the growth of Staphylococcus aureus. Furthermore, they are able to control and reduce the inflammatory response that is induced in human foreskin fibroblasts by lipopolysaccharides, and in rodents by UVB exposure. In particular, we report a remarkable reduction of pro-inflammatory cytokines when fibroblasts or animals are treated with the alginate-based nanofibers. The down-regulation of cytokines production and the absence of erythema on the skin of the treated animals confirm that the here described dressings are promising as advanced biomedical devices for burn management.

Investigation of the electro-spinnability of alginate solutions containing gold precursor HAuCl4.

Alginate nanofibers with an average diameter of 75nm have been prepared by the electrospinning process. In addition, the spinnability of the solutions in the presence of the gold precursor HAuCl4 was investigated. At low concentrations of HAuCl4 well-formed nanofibers were produced, whereas as its concentration increases the nanofibrous mats present an increased number of bead-like defects. Herein, the in situ preparation of gold nanoparticles (Au NPs) is discussed since sodium alginate (SA) acts as the reducing agent and a mechanism is proposed in order to explain the bead-effect as well as the surface morphology of the alginate fibers decorated with Au NPs.

Low-Cost and Effective Fabrication of Biocompatible Nanofibers from Silk and Cellulose-Rich Materials.

Here, we show the production of nanofibrous mats with controlled mechanical properties and excellent biocompatibility by combining fibroin with pure cellulose and cellulose-rich parsley powder agro-waste. To this end, trifluoroacetic acid was used as a common solvent for all of the involved biomaterials, achieving highly homogeneous blends that were suitable for the electrospinning technique. Morphological analysis revealed that the electrospun composite nanofibers were well-defined and defect-free, with a diameter in the range of 65-100 nm. Mechanical investigations demonstrated that the fibrous mats exhibited an increased stiffness when pure fibroin was combined with cellulose, whereas they possessed an increased flexibility when the parsley waste was added to fibroin. Lastly, the produced mats were highly biocompatible, as demonstrated by the promoted proliferation of fibroblast cells. The characteristics of the hybrid fibroin-cellulose nanofibers, in terms of nanoscale topography, mechanical properties, and biocompatibility, are attractive and potentially applicable in the biomedical sector.

The influence of bioglass nanoparticles on the biodegradation and biocompatibility of poly (3-hydroxybutyrate) scaffolds.

Nanocomposite scaffolds have been developed in order to achieve better mechanical and physiological properties in bone tissue engineering applications. In this study, reinforced poly (3-hydroxybutyrate) (PHB) composite scaffolds made with different weight ratios of nanobioglass (0, 2.5, 5, 7.5, and 10 wt%) and various porosities (70, 80 and 90 wt% of NaCl) were prepared by the salt leaching process. The scaffolds were placed in a PBS solution and their weight loss was measured. The biocompatibility of samples was examined in vitro using the MG63 cell line by indirect test, cell proliferation, and alkaline phosphatase (ALP) assays. Cell attachment on the surface of the scaffolds was observed by scanning electron microscopy (SEM). The biodegradation results showed that increasing the volume fraction of porosity and concentration of bioglass nanoparticles enhanced the weight loss of the scaffolds. The cell study demonstrated that a certain concentration of nanobioglass (7.5 wt%) in the scaffolds can significantly improve cell proliferation, inducing better osteoconductivity, compared to that of the pure PHB scaffolds and controls. In addition, the SEM results showed high cell attachment on these samples. All these factors indicate that samples with 7.5 wt% nanobioglass are a promising scaffold for bone tissue engineering.

Electrospun PGA/gelatin nanofibrous scaffolds and their potential application in vascular tissue engineering.

BACKGROUND AND METHODS: In this study, gelatin was blended with polyglycolic acid (PGA) at different ratios (0, 10, 30, and 50 wt%) and electrospun. The morphology and structure of the scaffolds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The mechanical properties were also measured by the tensile test. Furthermore, for biocompatibility assessment, human umbilical vein endothelial cells and human umbilical artery smooth muscle cells were cultured on these scaffolds, and cell attachment and viability were evaluated. RESULTS: PGA with 10 wt% gelatin enhanced the endothelial cells whilst PGA with 30 wt% gelatin increased smooth muscle cell adhesion, penetration, and viability compared with the other scaffold blends. Additionally, with the increase in gelatin content, the mechanical properties of the scaffolds were improved due to interaction between PGA and gelatin, as revealed by Fourier transform infrared spectroscopy and differential scanning calorimetry. CONCLUSION: Incorporation of gelatin improves the biological and mechanical properties of PGA, making promising scaffolds for vascular tissue engineering.