Characteristic Evaluation of Recombinant MiSp/Poly(lactic-co-glycolic) Acid (PLGA) Nanofiber Scaffolds as Potential Scaffolds for Bone Tissue Engineering.

Biomaterial-based nanofibrous scaffolds are the most effective alternative to bone transplantation therapy. Here, two recombinant minor ampullate spidroins (spider silk proteins), R1SR2 and NR1SR2C, were blended with Poly(lactic-co-glycolic) Acid (PLGA), respectively, to generate nanofiber scaffolds by electrospinning. The N-terminal (N), C-terminal (C), repeating (R1 and R2) and spacer (S) modules were all derived from the minor ampullate spidroins (MiSp). The physical properties and structures of the blended scaffolds were measured by scanning electron microscopy (SEM), water contact angle measurement, Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and Tensile mechanical testing. The results showed that blending of MiSp (R1SR2 and NR1SR2C) reduced the diameter of nanofibers, increased the porosity and glass transition temperatures of nanofibrous scaffolds, and effectively improved the hydrophilicity and ultimate strain of scaffolds. It is worth noting that the above changes were more significant in the presence of the N- and C-termini of MiSp. In cell culture assays, human bone mesenchymal stem cells (HBMSCs) grown on NR1SR2C/PLGA (20/80) scaffolds displayed markedly enhanced proliferative and adhesive abilities compared with counterparts grown on pure PLGA scaffolds. Jointly, these findings indicated recombinant MiSp/PLGA, particularly NR1SR2C/PLGA (20/80) blend nanofibrous scaffolds, is promising for bone tissue engineering.

Neural Differentiation of Human-Induced Pluripotent Stem Cells (hiPSc) on Surface-Modified Nanofibrous Scaffolds Coated with Platelet-Rich Plasma.

The field of tissue engineering exploits living cells in a variety of ways to restore, maintain, or enhance tissues and organs. Between stem cells, human induced pluripotent stem cells (hiPSCs), are very important due to their wide abilities. Growth factors can support proliferation, differentiation, and migration of hiPSCs. Platelet-rich plasma (PRP) could be used as the source of growth factors for hiPSCs. In the present study, proliferation and neural differentiation of hiPSCs on surface-modified nanofibrous Poly-L-lactic acid (PLLA) coated with platelet-rich plasma was investigated. The results of in vitro analysis showed that on the surface, which was modified nanofibrous scaffolds coated with platelet-rich plasma, significantly enhanced hiPSCs proliferation and neural differentiation were observed. Whereas the MTT ([3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide]) results showed biocompatibility of surface-modified nanofibrous scaffolds coated with platelet-rich plasma and the usage of these modified nanoscaffolds in neural tissue engineering in vivo is promising for the future.

Electrospun Biomimetic Nanofibrous Scaffolds: A Promising Prospect for Bone Tissue Engineering and Regenerative Medicine.

Skeletal-related disorders such as arthritis, bone cancer, osteosarcoma, and osteoarthritis are among the most common reasons for mortality in humans at present. Nanostructured scaffolds have been discovered to be more efficient for bone regeneration than macro/micro-sized scaffolds because they sufficiently permit cell adhesion, proliferation, and chemical transformation. Nanofibrous scaffolds mimicking artificial extracellular matrices provide a natural environment for tissue regeneration owing to their large surface area, high porosity, and appreciable drug loading capacity. Here, we review recent progress and possible future prospective electrospun nanofibrous scaffolds for bone tissue engineering. Electrospun nanofibrous scaffolds have demonstrated promising potential in bone tissue regeneration using a variety of nanomaterials. This review focused on the crucial role of electrospun nanofibrous scaffolds in biological applications, including drug/growth factor delivery to bone tissue regeneration. Natural and synthetic polymeric nanofibrous scaffolds are extensively inspected to regenerate bone tissue. We focused mainly on the significant impact of nanofibrous composite scaffolds on cell adhesion and function, and different composites of organic/inorganic nanoparticles with nanofiber scaffolds. This analysis provides an overview of nanofibrous scaffold-based bone regeneration strategies; however, the same concepts can be applied to other organ and tissue regeneration tactics.

Electrospun PEO/rGO Scaffolds: The Influence of the Concentration of rGO on Overall Properties and Cytotoxicity.

Reduced graphene oxide (rGO) is one of the graphene derivatives that can be employed to engineer bioactive and/or electroactive scaffolds. However, the influence of its low and especially high concentrations on scaffolds' overall properties and cytotoxicity has yet to be explored. In this study, polyethylene oxide (PEO)-based scaffolds containing from 0.1 to 20 wt% rGO were obtained by electrospinning. Morphological, thermal and electrical properties of the scaffolds were characterized by SEM, Raman spectroscopy, XRD, DSC and electrical measurements. The diameter of the fibers decreased from 0.52 to 0.19 µm as the concentration of rGO increased from 0.1 wt% to 20 wt%. The presence of rGO above the percolation threshold (5.7 wt%) resulted in a significantly reduced electrical resistivity of the scaffolds. XRD and Raman analysis revealed delamination of the graphene layers (interlayer spacing increased from 0.36 nm to 0.40-0.41 nm), and exfoliation of rGO was detected for the samples with an rGO concentration lower than 1 wt%. In addition, an evident trend of increasing cell viability as a function of the rGO concentration was evidenced. The obtained results can serve as further guidance for the judicious selection of the rGO content incorporated into the PEO matrix for constructing electroactive scaffolds.

A 3D, Compartmental Tumor-Stromal Microenvironment Model of Patient-Derived Bone Metastasis.

Bone is a frequent site of tumor metastasis. The bone-tumor microenvironment is heterogeneous and complex in nature. Such complexity is compounded by relations between metastatic and bone cells influencing their sensitivity/resistance to chemotherapeutics. Standard chemotherapeutics may not show efficacy for every patient, and new therapeutics are slow to emerge, owing to the limitations of existing 2D/3D models. We previously developed a 3D interface model for personalized therapeutic screening, consisting of an electrospun poly lactic acid mesh activated with plasma species and seeded with stromal cells. Tumor cells embedded in an alginate-gelatin hydrogel are overlaid to create a physiologic 3D interface. Here, we applied our 3D model as a migration assay tool to verify the migratory behavior of different patient-derived bone metastasized cells. We assessed the impact of two different chemotherapeutics, Doxorubicin and Cisplatin, on migration of patient cells and their immortalized cell line counterparts. We observed different migratory behaviors and cellular metabolic activities blocked with both Doxorubicin and Cisplatin treatment; however, higher efficiency or lower IC50 was observed with Doxorubicin. Gene expression analysis of MDA-MB231 that migrated through our 3D hybrid model verified epithelial-mesenchymal transition through increased expression of mesenchymal markers involved in the metastasis process. Our findings indicate that we can model tumor migration in vivo, in line with different cell characteristics and it may be a suitable drug screening tool for personalized medicine approaches in metastatic cancer treatment.

Dual Spinneret Electrospun Polyurethane/PVA-Gelatin Nanofibrous Scaffolds Containing Cinnamon Essential Oil and Nanoceria for Chronic Diabetic Wound Healing: Preparation, Physicochemical Characterization and In-Vitro Evaluation.

In this study, a dual spinneret electrospinning technique was applied to fabricate a series of polyurethane (PU) and polyvinyl alcohol-gelatin (PVA/Gel) nanofibrous scaffolds. The study aims to enhance the properties of PU/PVA-Gel NFs loaded with a low dose of nanoceria through the incorporation of cinnamon essential oil (CEO). The as-prepared nCeO2 were embedded into the PVA/Gel nanofibrous layer, where the cinnamon essential oil (CEO) was incorporated into the PU nanofibrous layer. The morphology, thermal stability, mechanical properties, and chemical composition of the produced NF mats were investigated by STEM, DSC, and FTIR. The obtained results showed improvement in the mechanical, and thermal stability of the dual-fiber scaffolds by adding CEO along with nanoceria. The cytotoxicity evaluation revealed that the incorporation of CEO to PU/PVA-Gel loaded with a low dose of nanoceria could enhance the cell population compared to using pure PU/PVA-Gel NFs. Moreover, the presence of CEO could inhibit the growth rate of S. aureus more than E. coli. To our knowledge, this is the first time such nanofibrous membranes composed of PU and PVA-Gel have been produced. The first time was to load the nanofibrous membranes with both CEO and nCeO2. The obtained results indicate that the proposed PU/PVA-Gel NFs represent promising platforms with CEO and nCeO2 for effectively managing diabetic wounds.

Nanocarriers, Progenitor Cells, Combinational Approaches, and New Insights on the Retinal Therapy.

Progenitor cells derived from the retinal pigment epithelium (RPECs) have shown promise as therapeutic approaches to degenerative retinal disorders including diabetic retinopathy, age-related macular degeneration and Stargardt disease. However, the degeneration of Bruch's membrane (BM), the natural substrate for the RPE, has been identified as one of the major limitations for utilizing RPECs. This degeneration leads to decreased support, survival and integration of the transplanted RPECs. It has been proposed that the generation of organized structures of nanofibers, in an attempt to mimic the natural retinal extracellular matrix (ECM) and its unique characteristics, could be utilized to overcome these limitations. Furthermore, nanoparticles could be incorporated to provide a platform for improved drug delivery and sustained release of molecules over several months to years. In addition, the incorporation of tissue-specific genes and stem cells into the nanostructures increased the stability and enhanced transfection efficiency of gene/drug to the posterior segment of the eye. This review discusses available drug delivery systems and combination therapies together with challenges associated with each approach. As the last step, we discuss the application of nanofibrous scaffolds for the implantation of RPE progenitor cells with the aim to enhance cell adhesion and support a functionally polarized RPE monolayer.

Smart, Elastic, and Nanofiber-Based 3D Scaffolds with Self-Deploying Capability for Osteoporotic Bone Regeneration.

It has been a major challenge to treat osteoporotic bone defects with irregular shapes. Although bioactive glass offers an attractive material for bone regeneration, its inherent brittleness has greatly limited its scope of application. Herein, we report the fabrication of bioactive glass (SiO2-CaO) nanofibers with excellent flexibility to even allow for 180° bending. The bioactive glass nanofibers could be further assembled into 3D fibrous scaffolds with chitosan serving as the linkers. The scaffolds constructed from an assembly of 85SiO2-15CaO nanofibers and chitosan (85SiO2-15CaO NF/CS) possessed significantly better mechanical properties when benchmarked against both 75SiO2-25CaO nanofiber- and chitosan-based scaffolds. Moreover, the 85SiO2-15CaO NF/CS scaffolds exhibited an elastic behavior, with full recovery from 80% compression and good fatigue resistance over 1000 cycles of compression under water. Upon implantation, the elastic fibrous scaffolds were able to deform and fit irregularly shaped bone defects, followed by a self-deploying behavior to achieve a perfect match with the cavities. When applied to the repair of an osteoporotic calvarial defect in a rat model, the 85SiO2-15CaO NF/CS scaffolds showed substantial promotion of bone regrowth and vascularization. This new class of 3D fibrous scaffold provides a promising advancement in engineering smart materials for complex bone repair.

Embryonic stem cells differentiated into neuron-like cells using SB431542 small molecule on nanofibrous PLA/CS/Wax scaffold.

Electrospun nanofibrous scaffolds show huge potential to improve the neurological outcome in central nervous system disorders. In this study, we cultured mouse embryonic stem cells (mESCs) on an electrospun nanofibrous polylactic acid/Chitosan/Wax (PLA/CS/Wax) scaffold and surveyed the attachment, behavior, and differentiation of mESCs into neural cells. Differentiation in neural-like cells (NLCs) was investigated with a medium containing SB431542 as a small molecule and conjugated linolenic acid after 20 days. We used Immunocytochemistry and quantitative real-time polymerase chain reaction (RT-PCR) techniques to assess neural marker expression in differentiated cells. SEM imaging demonstrated that mESCs could strongly attach, stretch, and differentiate on PLA/CS/Wax scaffolds. MESCs that were cultured on PLA/CS/Wax scaffolds showed enhanced numbers of neural structures and neural markers including Nestin, NF-H, Tuj-1, and Map2 in neural induction medium compared to the control sample. These results revealed that electrospun PLA/CS/Wax scaffolds associated with the induction medium can assemble proper conditions for stem cell differentiation into NLCs. We hope that the development of new technologies in neural tissue engineering may pave a new avenue for neural tissue regeneration.

Osteogenic Differentiation of Mesenchymal Stem Cells with Silica-Coated Gold Nanoparticles for Bone Tissue Engineering.

Multifunctional nanofibrous scaffolds for effective bone tissue engineering (BTE) application must incorporate factors to promote neovascularization and tissue regeneration. In this study, silica-coated gold nanoparticles Au(SiO2) were tested for their ability to promote differentiation of human mesenchymal stem cells (hMSCs) into osteoblasts. Biocompatible poly-ε-caprolactone (PCL), PCL/silk fibroin (SF) and PCL/SF/Au(SiO2) loaded nanofibrous scaffolds were first fabricated by an electrospinning method. Electrospun nanofibrous scaffolds were characterized for fiber architecture, porosity, pore size distribution, fiber wettability and the relevant mechanical properties using field emission scanning electron microscopy (FESEM), porosimetry, determination of water contact angle, measurements by a surface analyzer and tabletop tensile-tester measurements. FESEM images of the scaffolds revealed beadless, porous, uniform fibers with diameters in the range of 164 ± 18.65 nm to 215 ± 32.12 nm and porosity of around 88-92% and pore size distribution around 1.45-2.35 µm. Following hMSCs were cultured on the composite scaffolds. Cell-scaffold interaction, morphology and proliferation of were analyzed by FESEM analysis, MTS (3-(4,5-dimethyl thiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt) and CMFDA (5-choromethyl fluorescein acetate) dye assays. Osteogenic differentiation of MSCs into osteogenic cells were determined by alkaline phosphatase (ALP) activity, mineralization by alizarin red S (ARS) staining and osteocalcin expression by immunofluorescence staining. The results revealed that the addition of SF and Au(SiO2) to PCL scaffolds enhanced the mechanical strength, interconnecting porous structure and surface roughness of the scaffolds. This, in turn, led to successful osteogenic differentiation of hMSCs with improved cell adhesion, proliferation, differentiation, mineralization and expression of pro-osteogenic cellular proteins. This provides huge support for Au(SiO2) as a suitable material in BTE.

Exploration of physical and chemical cues on retinal cell fate.

Identification of the key components in the physical and chemical milieu directing donor cells into a desired phenotype is a requirement in the investigation of bioscaffolds for the advancement of cell-based therapies for retinal neurodegeneration. We explore the effect of electrospun poly-ε-caprolactone (PCL) fiber scaffold topography and functionalization and culture medium, on the behavior of mouse retinal cells. Dissociated mouse retinal post-natal cells were seeded on random or aligned oriented fibers, with or without laminin coating and cultured with either basic or neurotrophins enriched medium for 7days. Addition of laminin in combination with neurotrophins clearly promoted cell- morphology, fate, and neurite extension. Nanotopography per se significantly affected cell morphology, with mainly bipolar profiles on aligned fibers and more multipolar profiles on random fibers. Laminin induced a remarkable 90° switch of neurite orientation. Herewith, we demonstrate that the chemical cue is stronger than the physical cue for the orientation of retinal neurites and describe the requirement of both neurotrophins and extracellular matrix proteins for extended neurite outgrowth and formation of complex retinal neuronal networks. Therefore, tailor-made PCL fiber mats, which can be physically and chemically modified, indeed influence cell behavior and hence motivate further retinal restorative studies using this system.

Cryopreservation of hMSCs seeded silk nanofibers based tissue engineered constructs.

Long term cryopreservation of tissue engineering constructs is of paramount importance to meet off-the shelf requirements for medical applications. In the present study, the effect of cryopreservation using natural osmolytes such as trehalose and ectoin with and without conventional Me2SO on the cryopreservation of tissue engineered constructs (TECs) was evaluated. MSCs derived from umbilical cord were seeded on electrospun nanofibrous silk fibroin scaffolds and cultured to develop TECs. TECs were subjected to controlled rate freezing using nine different freezing solutions. Among these, freezing medium consisting of natural osmolytes like trehalose (40mM), ectoin (40mM), catalase (100µg) as antioxidant and Me2SO (2.5%) was found to be the most effective. Optimality of the chosen cryoprotectants was confirmed by cell viability (PI live/dead staining), cell proliferation (MTT assay), microstructure analysis (SEM), membrane integrity (confocal microscopy) and in vitro osteogenic differentiation (ALP assay, RT-PCR and histology) study carried out with post-thaw cryopreserved TECs. The mechanical integrity of the cryopreserved scaffold was found to be unaltered. The performance of the freezing medium towards cryopreservation of TEC was superior than the performance achieved using conventional Me2SO and similar to the non cryopreserved TEC. Overall we have formulated an efficient freezing medium that may pave the way of long term preservation of TECs with maintaining its integrity, MSCs viability and differentiation potentiality. It was observed that the performance of freezing medium for cryopreservation of TECs was better than the Me2SO.

Development of Poly(methyl methacrylate)/nano-hydroxyapatite (PMMA/nHA) Nanofibers for Tissue Engineering Regeneration Using an Electrospinning Technique.

The study explores the in vitro biocompatibility and osteoconductivity of poly(methyl methacrylate)/nano-hydroxyapatite (PMMA/nHA) composite nanofibrous scaffolds for bone tissue engineering (BTE). Electrospun scaffolds, exhibiting both low and high fiber orientation, were investigated. The inclusion of hydroxyapatite nanoparticles enhances the osteoconductivity of the scaffolds while maintaining the ease of fabrication through electrospinning. SEM analysis confirms the high-quality morphology of the scaffolds, with successful incorporation of nHA evidenced by SEM-EDS and FTIR methods. DSC analysis indicates that nHA addition increases the PMMA glass transition temperature (Tg) and reduces stress relaxation during electrospinning. Furthermore, higher fiber orientation affects PMMA Tg and stress relaxation differently. Biological studies demonstrate the composite material's non-toxicity, excellent osteoblast viability, attachment, spreading, and proliferation. Overall, PMMA/nHA composite scaffolds show promise for BTE applications.

Engineering biomimetic scaffolds by combining silk protein nanofibrils and hyaluronic acid.

Nanofibrous scaffolds mimicking important features of the native extracellular matrix (ECM) provide a promising strategy for tissue regeneration. However, 3D scaffolds mimicking natural protein nanofibers and bioactive glycosaminoglycans remain poorly developed. In this study, a biomimetic nanofibrous scaffold composed of natural silk protein nanofibers and glycosaminoglycan hyaluronic acid (HA) was developed. HA functionalization significantly improved the hydrophilicity and bioactivity of silk nanofibers (SNFs). SNFs can be assembled into nanofibrous aerogel scaffolds with low density and desirable shapes on a large scale. More importantly, with the assistance of HA, the silk nanofibrous aerogel scaffolds with ultra-high porosity, natural bioactivity, and structural stability in aqueous environment can be fabricated. In the protease/hyaluronidase solution, the SNF scaffolds with 10.0 % HA can maintain their monolithic shape for >3 weeks. The silk nanofibrous scaffolds not only imitate the composition of ECM but also mimic the hierarchical structure of ECM, providing a favorable microenvironment for cell adhesion and proliferation. These results indicate that this structurally and functionally biomimetic system is a promising tissue engineering scaffold.

Biopolymeric nanofibrous scaffolds of poly(3-hydroxybuthyrate)/chitosan loaded with biogenic silver nanoparticle synthesized using curcumin and their antibacterial activities.

The increasing prevalence of multi-drug resistant bacteria poses a significant threat to public health, especially in wound infections. Developing new bactericidal agents and treatment strategies is crucial to address this issue. In this study, biopolymeric nanofibrous scaffolds containing green-synthesized silver nanoparticles (AgNPs) with curcumin (CUR) were evaluated as antimicrobial materials for wound healing therapy. Firstly, CUR was utilized to synthesize AgNPs, which were then analyzed using various analytical methods. The microstructural analysis revealed that the biogenic AgNPs, which had a spherical shape and an average size of 19.83 nm, were uniformly anchored on PHB/CTS nanofibers. Then, the AgNPs with various content (0.25-1%wt) were incorporated into PHB/CTS matrix to enhance its wettability, thermal and bactericidal behaviors. The nanofibrous scaffolds were characterized by FT-IR, FE-SEM, TGA analysis and water contact angle measurement. Overall, the addition of CUR-AgNPs to the PHB/CTS matrix led to a reduction in fiber diameter, enhanced hydrophilicity and improved thermal properties. Additionally, antibacterial activity against Staphylococcus aureus and Escherichia coli was performed on samples of AgNPS and PHB/CTS/CUR-Ag. The synthesized AgNPs showed antibacterial activity against both microorganisms, especially against S. aureus. Higher concentrations of AgNPs in nanofibers led to a significant reduction in bacterial colony formation. The results displayed that PHB/CTS/CUR-AgNPs nanofibrous scaffolds could be a promising material for the biomedical applications such as wound healing.

Evaluation of MDR-specific phage Pɸ-Mi-Pa loaded mucoadhesive electrospun nanofibrous scaffolds against drug-resistant Pseudomonas aeruginosa- induced wound infections in an animal model.

Given the escalating prevalence of drug-resistant wounds, there is a justified imperative to explore innovative and more efficacious therapies that diverge from conventional, ineffective wound healing approaches. This research has introduced a strategy to address multi-drug resistant (MDR) Pseudomonas aeruginosa infections in a chronic wound model, employing MDR-specific phage Pɸ-Mi-Pa loaded onto mucoadhesive electrospun scaffolds. A cocktail of three isolates of P. aeruginosa-specific lytic phages, Pɸ-Mi-Pa 51, Pɸ-Mi-Pa 120, and Pɸ-Mi-Pa 133 were incorporated into varying ratios of fabricated PCL-PVP polymer. These formulations were assessed for their therapeutic efficacy in achieving bacterial clearance in P. aeruginosa-induced wound infections. The study encompassed biological characterization through in vivo wound healing assessments, histology, and histomorphometry. Additionally, morphological, mechanical, and chemical analyses were conducted on the fabricated PCL-PVP electrospun nanofibrous scaffolds. Three clonal differences of the MDR P. aeruginosa-specific phages (Pɸ-Mi-Pa 51, Pɸ-Mi-Pa 120, and Pɸ-Mi-Pa 133) produced lytic activity and were seen to produce distinct and clear zones of inhibition against MDR P. aeruginosa strains Pa 051, Pa 120 and Pa 133 respectively. The average porosity of the nanofibrous scaffolds PB 1, PB 2, PB 3, and PB 4 were 12.2 ± 0.3 %, 22.1 ± 0.7 %, 31.1 ± 2.4 %, 28.0 ± 0.8 % respectively. In vitro cumulative release of MDR-specific phage Pɸ-Mi-Pa from the mucoadhesive electrospun nanofibrous scaffolds was found to be 70.91 % ± 1.02 % after 12 h of incubation after an initial release of 42.8 % ± 3.01 % after 1 h. Results from the in vivo wound healing study revealed a substantial reduction in wound size, with formulations PB 2 and PB 3 exhibiting the most significant reduction in wound size, demonstrating statistically significant results on day 5 (100 % ± 31.4 %). These findings underscore the potential of bacteriophage-loaded electrospun PCL-PVP nanofibrous scaffolds for treating drug-resistant wounds, generating tissue substitutes, and overcoming certain limitations associated with conventional wound care matrices.

Biodegradable Honeycomb-Mimic Scaffolds Consisting of Nanofibrous Walls.

The scaffold is a porous three-dimensional (3D) material that supports cell growth and tissue regeneration. Such 3D structures should be generated with simple techniques and nontoxic ingredients to mimic bio-environment and facilitate tissue regeneration. In this work, simple but powerful techniques are demonstrated for the fabrication of lamellar and honeycomb-mimic scaffolds with poly(L-lactic acid). The honeycomb-mimic scaffolds with tunable pore size ranging from 70 to 160 µm are fabricated by crystal needle-guided thermally induced phase separation in a directional freezing apparatus. The compressive modulus of the honeycomb-mimic scaffold is ≈4 times higher than that of scaffold with randomly oriented pore structure. The fabricated honeycomb-mimic scaffold exhibits a hierarchical structure from nanofibers to micro-/macro-tubular structures. Pre-osteoblast MC3T3-E1 cells cultured on the honeycomb-mimic nanofibrous scaffolds exhibit an enhanced osteoblastic phenotype, with elevated expression levels of osteogenic marker genes, than those on either porous lamellar scaffolds or porous scaffolds with randomly oriented pores. The advanced techniques for the fabrication of the honeycomb-mimic structure may potentially be used for a wide variety of advanced functional materials.

Hypoxia and re-oxygenation effects on human cardiomyocytes cultured on polycaprolactone and polyurethane nanofibrous mats.

Heart diseases are caused mainly by chronic oxygen insufficiency (hypoxia), leading to damage and apoptosis of cardiomyocytes. Research into the regeneration of a damaged human heart is limited due to the lack of cellular models that mimic damaged cardiac tissue. Based on the literature, nanofibrous mats affect the cardiomyocyte morphology and stimulate the growth and differentiation of cells cultured on them; therefore, nanofibrous materials can support the production of in vitro models that faithfully mimic the 3D structure of human cardiac tissue. Nanofibrous mats were used as scaffolds for adult primary human cardiomyocytes (HCM) and immature human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). This work focuses on understanding the effects of hypoxia and re-oxygenation on human cardiac cells cultured on polymer nanofibrous mats made of poly(ε-caprolactone) (PCL) and polyurethane (PU). The expression of selected genes and proteins in cardiomyocytes during hypoxia and re-oxygenation were evaluated. In addition, the type of cell death was analyzed. To the best of our knowledge, there are no studies on the effects of hypoxia on cardiomyocyte cells cultured on nanofibrous mats. The present study aimed to use nanofiber mats as scaffolds that structurally could mimic cardiac extracellular matrix. Understanding the impact of 3D structural properties in vitro cardiac models on different human cardiomyocytes is crucial for advancing cardiac tissue engineering and regenerative medicine. Observing how 3D scaffolds affect cardiomyocyte function under hypoxic conditions is necessary to understand the functioning of the entire human heart.

Improving rodents and humans cardiac cell maturityin vitrothrough polycaprolactone and polyurethane nanofibers.

Currently, numerous studies are conducted using nanofibers as a scaffold for culture cardiac cells; however, there still needs to be more research evaluating the impact of the physicochemical properties of polymer nanofibers on the structure and function of cardiac cells. We have studied how poly(ϵ-caprolactone) and polyurethane nanofibrous mats with different physicochemical properties influence the viability, morphology, orientation, and maturation of cardiac cells. For this purpose, the cells taken from different species were used. They were rat ventricular cardiomyoblasts (H9c2), mouse atrial cardiomyocytes (CMs) (HL-1), and human ventricular CMs. Based on the results, it can be concluded that cardiac cells cultured on nanofibers exhibit greater maturity in terms of orientation, morphology, and gene expression levels compared to cells cultured on polystyrene plates. Additionally, the physicochemical properties of nanofibers affecting the functionality of cardiac cells from different species and different parts of the heart were evaluated. These studies can support research on understanding and explaining mechanisms leading to cellular maturity present in the heart and the selection of nanofibers that will effectively help the maturation of CMs.

Poly(N-isopropylacrylamide) based smart nanofibrous scaffolds for use as on-demand delivery systems for oral and dental tissue regeneration.

Stimuli-responsive domains capable of releasing loaded molecules, "on-demand," have garnered increasing attention due to their enhanced delivery, precision targeting, and decreased adverse effects. The development of an on-demand delivery system that can be easily triggered by dental clinicians might have major roles in dental and oral tissue engineering. A series of random graft poly(NIPAm-co-HEMA-Lactate) copolymers were synthesized using 95:5, 85:5, 60:40, and 40:60 ratios of thermosensitive NIPAm and HEMA-poly lactate respectively then electrospun to produce nanofibrous scaffolds loaded with bovine serum albumin (BSA). Cumulative BSA release was assessed at 25C and 37°C. To appraise the use of scaffolds as on-demand delivery systems, they were subjected to thermal changes in the form cooling and warming cycles during which BSA release was monitored. To confirm the triggered releasing ability of the synthesized scaffolds, the copolymer made with 60% NIPAm was selected, based on the results of the release tests, and loaded with bone morphogenetic protein-2 (BMP-2). The loaded scaffolds were placed with mesenchymal-like stem cells (iMSCs) derived from induced pluripotent stem cells (iPSCs), and subjected to temperature alterations. Then, the osteogenic differentiation of iMSCs, which might have resulted from the released protein, was evaluated after 10 days by analyzing runt-related transcription factor 2 (RUNX-2) osteogenic gene expression by the cells using real-time quantitative polymerase chain reaction (qRT-PCR). BSA release profiles showed a burst release at the beginning followed by a more linear pattern at 25°C, and a much slower release at 37°C. The release also decreased when the PNIPAm content decreased in the scaffolds. Thermal triggering led to a step-like release pattern in which the highest release was reported 30 min through the warming cycles. The iMSCs cultivated with scaffolds loaded with BMP-2 and exposed to temperature alteration showed significantly higher RUNX-2 gene expression than cells in the other experimental groups. The synthesized scaffolds are thermo-responsive and could be triggered to deliver biological biomolecules to be used in oral and dental tissue engineering. Thermal stimuli could be simulated by dental clinicians using simple means of cold therapy, for example, cold packs in intraoral accessible sites for specified times.