Preparation of xyloglucan-grafted poly(N-hydroxyethyl acrylamide) copolymer by free-radical polymerization for in vitro evaluation of human dermal fibroblasts

Xyloglucan is a rigid polysaccharide that belongs to the carbohydrate family. This hemicellulose compound has been widely used in biomedical research because of its pseudoplastic, mucoadhesive, mucomimetic, and biocompatibility properties. Xyloglucan is a polyose with no amino groups in its structure, which also limits its range of applications. It is still unknown whether grafting hydrophilic monomers onto xyloglucan can produce derivatives that overcome these shortcomings. This work aimed to prepare the first copolymers in which N-hydroxyethyl acrylamide is grafted onto tamarind xyloglucan by free-radical polymerization. The biocompatibility of these structures in vitro was evaluated using human dermal fibroblasts. Gamma radiation-induced graft polymerization was employed as an initiator by varying the radiation dose from 5-25 kGy. The structure of the graft copolymer, Xy-g-poly(N-hydroxyethyl acrylamide), was verified by thermal analysis, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The findings indicate that the degree of grafting and the cytotoxicity/viability of the xyloglucan-based copolymer were independent of dose. Notably, the grafted galactoxyloglucan exhibited efficient support for human dermal fibroblasts, showing heightened proliferative capacity and superior migration capabilities compared to the unmodified polymer. This copolymer might have the potential to be used in skin tissue engineering.

In Vitro Modulation of Spontaneous Activity in Embryonic Cardiomyocytes Cultured on Poly(vinyl alcohol)/Bioglass Type 58S Electrospun Scaffolds

Because of the physiological and cardiac changes associated with cardiovascular disease, tissue engineering can potentially restore the biological functions of cardiac tissue through the fabrication of scaffolds. In the present study, hybrid nanofiber scaffolds of poly (vinyl alcohol) (PVA) and bioglass type 58S (58SiO2-33CaO-9P2O5, Bg) were fabricated, and their effect on the spontaneous activity of chick embryonic cardiomyocytes in vitro was determined. PVA/Bg nanofibers were produced by electrospinning and stabilized by chemical crosslinking with glutaraldehyde. The electrospun scaffolds were analyzed to determine their chemical structure, morphology, and thermal transitions. The crosslinked scaffolds were more stable to degradation in water. A Bg concentration of 25% in the hybrid scaffolds improved thermal stability and decreased degradation in water after PVA crosslinking. Cardiomyocytes showed increased adhesion and contractility in cells seeded on hybrid scaffolds with higher Bg concentrations. In addition, the effect of Ca2+ ions released from the bioglass on the contraction patterns of cultured cardiomyocytes was investigated. The results suggest that the scaffolds with 25% Bg led to a uniform beating frequency that resulted in synchronous contraction patterns.

Bovine dentin collagen/poly(lactic acid) scaffolds for teeth tissue regeneration

Electrospun scaffolds with diameter fibers compared to those in the extracellular matrix were produced with poly(lactic acid) (PLA) and non-denatured collagen from bovine dentin (DCol). DCol was obtained through an improved version of the Longin method by acid erosion of the hydroxyapatite of the roots of teeth from a 2-year-old cattle. The dentin collagen was characterized by energy dispersive X-ray spectroscopy (EDS), and carbon, nitrogen, and oxygen were found to be the main elements of the protein. Infrared analysis revealed the typical bands of collagen at about 3300, 1631, 1539, and 1234 cm−1 for amides A, I, II, and III, respectively. Calorimetric and infrared analyses also demonstrated that the collagen was non-denatured. With scanning electron microscopy, it was found that the thinnest fibers with a diameter comparable to that of fibers in the extracellular matrix were obtained when dentin collagen and acetic acid (AAc) were added to the solution of PLA in trifluoroethanol (TFE). The scaffolds with the thinnest diameter had also the highest porosity, and we considered that they could be beneficial in the growth of dentin cell. Human placenta-derived mesenchymal stem cells were seeded onto electrospun scaffolds. After 24, 48 and 96 h of culture, cell proliferation was evaluated by two independent strategies. In both assays, it was found that the pl-MSCs were capable of adhering and proliferating in different scaffolds. It was also observed that cell adhesion and proliferation increased significantly in scaffolds containing collagen, although the addition of AAc slightly decreased this effect on all scaffolds.

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Influence of the PLGA/gelatin ratio on the physical, chemical and biological properties of electrospun scaffolds for wound dressings

Chronic wounds are a global health problem, and their treatments are difficult and long lasting. The development of medical devices through tissue engineering has been conducted to heal this type of wound. In this study, it was demonstrated that the combination of natural and synthetic polymers, such as poly (D-L lactide-co-glycolide) (PLGA) and gelatin (Ge), were useful for constructing scaffolds for wound healing. The aim of this study was to evaluate the influence of different PLGA/gelatin ratios (9:1, 7:3 and 5:5 (v/v)) on the physical, chemical and biological properties of electrospun scaffolds for wound dressings. These PLGA/Ge scaffolds had randomly oriented fibers with smooth surfaces and exhibited distances between fibers of less than 10 μm. The 7:3 and 5:5 PLGA/Ge scaffolds showed higher swelling, hydrophilicity and degradation rates than pure PLGA and 9:1 (v/v) PLGA/Ge scaffolds. Young's moduli of the scaffolds were 72 ± 10, 48 ± 6, 58 ± 6 and 6 ± 1 MPa for the pure PLGA scaffold and the 9:1, 7:3 and 5:5 (v/v) PLGA/Ge scaffolds, respectively. Mesenchymal stem cells (MSCs) seeded on all the PLGA/Ge scaffolds were viable, and the cells were attached to the fibers at the different analyzed timepoints. The most significant proliferation rate was observed for cells on the 7:3 PLGA/Ge scaffolds. Biocompatibility analysis showed that all the scaffolds produced inflammation at the first week postimplantation; however, the 7:3 and 5:5 (v/v) PLGA/Ge scaffolds were degraded completely, and there was no inflammatory reaction observed at the fourth week after implantation. In contrast, the 9:1 PLGA/Ge scaffolds persisted in the tissue for more than four weeks; however, at the eighth week, no traces of the scaffolds were found. In conclusion, the scaffolds with the 7:3 PLGA/Ge ratio showed suitable physical, chemical and biological properties for applications in chronic wound treatments.

Tubular electrospun scaffolds tested in vivo for tissue engineering

Tissue engineering has been widely used for its great variety of functions. It has been seen as a solution to satisfy the need for vascular substitutes like small diameter vessels, veins, and nerves. One of the most used methods is electrospinning, due to the fact that it allows the use of various polymers, sizes, mandrels and it can adjust the conditions to create personalized scaffolds. For the creation of scaffolds is fundamental to understand the advantages and disadvantages of each polymer, of this, will depend the biodegradability, biocompatibility, porosity, cellular adhesion, and cell proliferation as it is essential to mimic the extracellular matrix and provide structural support for the cells. The aim of this review was to investigate which materials are being used for the creation of tubular scaffolds by electrospinning. Here we selected only in vivo evaluation to demonstrate remodeling of the grafts into native-like tissues, in vitro evaluations had been excluded from this review. We analyze the conditions like speed, distance and voltage and the modifications like growth factors and combinations of natural and synthetic polymers that allow the authors to have a functional scaffold that will suit its purpose.

Morphological Study of Chitosan/Poly (Vinyl Alcohol) Nanofibers Prepared by Electrospinning, Collected on Reticulated Vitreous Carbon

In this work, chitosan (CS)/poly (vinyl alcohol) (PVA) nanofibers were prepared by using the electrospinning method. Different CS concentrations (0.5, 1, 2, and 3 wt %), maintaining the PVA concentration at 8 wt %, were tested. Likewise, the studied electrospinning experimental parameters were: syringe/collector distance, solution flow and voltage. Subsequently, the electrospun fibers were collected on a reticulated vitreous carbon (RVC) support for 0.25, 0.5, 1, 1.5, and 2 h. The morphology and diameter of the CS/PVA nanofibers were characterized by scanning electron microscopy (SEM), finding diameters in the order of 132 and 212 nm; the best results (uniform fibers) were obtained from the solution with 2 wt % of chitosan and a voltage, distance, and flow rate of 16 kV, 20 cm, and 0.13 mL/h, respectively. Afterwards, a treatment with an ethanolic NaOH solution was performed, observing a change in the fiber morphology and a diameter decrease (117 ± 9 nm).