Wet-electrospun PCL/PLLA Blend Scaffolds: Effects of Versatile Coagulation Baths on Physicochemical and Biological Properties of the Scaffolds

Introduction: High surface/volume ratio and 3-dimensionality of nanofibers increases cell-scaffold interactions and promote migration and proliferation of cells. Wet electrospinning is a variant of electrospinning technology that is utilized to produce nanofibrous scaffolds. Altering the parameters governing the wet electrospinning process such as applied voltage, polymer concentration, composition and depth of the coagulation bath, and tip to bath distance can affect the morphology of the produced scaffolds. In this study, the influence of various coagulation baths on the physicochemical properties of the wet-electrospun nanofibers was investigated. Materials and Methods: Poly (ε-caprolactone)/Poly (L-lactic) acid 15% (w/v) blends under an applied voltage of 15 kV, and a tip-to-bath distance of 10 cm. were used to prepare fibrous scaffolds via wet-electrospinning technique into aqueous solution of sodium hydroxide (NaOH) (pH~13), distilled water, ethanol, water/ethanol (3:7) (v/v) and water/ethanol/methanol (6:2:2) (v/v). The final products were characterized by scanning electron microscopy (SEM), liquid displacement technique, contact angle measurement, compressive and tensile tests. As well as, cell adhesion and cell viability through human adipose-derived stem cells (hADSCs) cell culture. Results: Wet-electrospun fibers, except in the almost fully beaded structure of water/ethanol (3:7) (v/v) specimen exhibited random, dispersive and non-woven morphology under SEM observation. The coagulation bath composition significantly influenced on porosity, wettability, mechanical properties and biocompatibility of the scaffolds. The porosity measurement via liquid displacement method showed that except for the specimen in which the blend was spun into NaOH, other scaffolds could not meet the accepted ideal porosity percentage of above 80%. According to the contact angle measurement data, it was expected that all scaffolds experience low cellular attachment and proliferation. Conversely, in vitro hADSCs culture demonstrated that the scaffolds presented a non-toxic environment and enhanced cell proliferation and attachment. Conclusion: The data indicated that the scaffold spun into NaOH was the best candidate among other specimens to culture hADSCs

The Role of Aryl Hydrocarbon Receptor Signaling in Human Cytomegalovirus Infection

Human Cytomegalovirus (HCMV) is a ubiquitous beta-herpesvirus, which causes life-threatening disease in immunocompromised patients and severe birth defects in newborn infants. It is not, however, definitively associated with significant pathology in immunocompetent adults. The virus extensively reprograms host cell metabolism and gene expression upon infection. To efficiently complete an infectious cycle, HCMV must both block the replication of host cell DNA and counteract the cellular innate immune responses. The latter involves the production of interferons and subsequent induction of interferon-stimulated genes (ISGs). Indoleamine 2,3-dioxygenase (IDO1), specifically, is recognized as an important effector ISG in the antiviral innate immune response. It catalyzes the first reaction in Tryptophan (TRP) catabolism, i.e., the conversion of tryptophan to kynurenine (KYN). Activation of IDO1 is believed to restrict HCMV replication by depriving the infected cells of TRP, an essential amino acid. Consequently, the regulation of IDO1 expression and activity by HCMV infection has been the subject of several studies. Notably, KYN and its biological effect on HCMV replication, on the other hand, have received less attention. KYN is an endogenous ligand for the Aryl hydrocarbon Receptor (AhR), a ligand-activated transcription factor. Our group has shown that intracellular KYN levels are elevated during HCMV replication. Moreover, high plasma KYN levels have been correlated with HCMV reactivation in renal transplant recipients, and the exogenous activation of AhR has been shown to enhance viral replication. Therefore, I aimed my graduate studies at determining the molecular mechanisms by which endogenous AhR signaling modulates HCMV infection. Herein, I will discuss how I discovered: (i) HCMV infection of primary human fibroblasts triggers the persistent induction of AhR transcriptional activity; (ii) sustained AhR activity is associated with tightly balanced IDO1 activity; (iii) AhR signaling is required for the efficient replication of virus; (iv) HCMV{induced G1/S cell cycle arrest depends on AhR activity; and (v) the virus exploits AhR signaling to counteract the innate antiviral immune response, in a negative feedback loop containing IDO1-KYN-AhR

The Role of Aryl Hydrocarbon Receptor Signaling in Human Cytomegalovirus Infection

Human Cytomegalovirus (HCMV) is a ubiquitous beta-herpesvirus, which causes life-threatening disease in immunocompromised patients and severe birth defects in newborn infants. It is not, however, definitively associated with significant pathology in immunocompetent adults. The virus extensively reprograms host cell metabolism and gene expression upon infection. To efficiently complete an infectious cycle, HCMV must both block the replication of host cell DNA and counteract the cellular innate immune responses. The latter involves the production of interferons and subsequent induction of interferon-stimulated genes (ISGs). Indoleamine 2,3-dioxygenase (IDO1), specifically, is recognized as an important effector ISG in the antiviral innate immune response. It catalyzes the first reaction in Tryptophan (TRP) catabolism, i.e., the conversion of tryptophan to kynurenine (KYN). Activation of IDO1 is believed to restrict HCMV replication by depriving the infected cells of TRP, an essential amino acid. Consequently, the regulation of IDO1 expression and activity by HCMV infection has been the subject of several studies. Notably, KYN and its biological effect on HCMV replication, on the other hand, have received less attention. KYN is an endogenous ligand for the Aryl hydrocarbon Receptor (AhR), a ligand-activated transcription factor. Our group has shown that intracellular KYN levels are elevated during HCMV replication. Moreover, high plasma KYN levels have been correlated with HCMV reactivation in renal transplant recipients, and the exogenous activation of AhR has been shown to enhance viral replication. Therefore, I aimed my graduate studies at determining the molecular mechanisms by which endogenous AhR signaling modulates HCMV infection. Herein, I will discuss how I discovered: (i) HCMV infection of primary human fibroblasts triggers the persistent induction of AhR transcriptional activity; (ii) sustained AhR activity is associated with tightly balanced IDO1 activity; (iii) AhR signaling is required for the efficient replication of virus; (iv) HCMV{induced G1/S cell cycle arrest depends on AhR activity; and (v) the virus exploits AhR signaling to counteract the innate antiviral immune response, in a negative feedback loop containing IDO1-KYN-AhR

Wound dressings from naturally-occurring polymers: A review on homopolysaccharide-based composites

Wound dressings are designed to support the wound bed and protect it from the factors that may delay or impede its healing such as contaminations and moisture-loss, thereby facilitating and accelerating the healing process. The materials used to prepare wound dressings include natural and synthetic polymers, as well as their combinations, in the forms of films, sponges and hydrogels. Polysaccharides are naturally-occurring polymers that have been extensively used as wound dressing materials. Homopolysaccharides are a class of polysaccharides consist of only one type of monosaccharide. The current review intends to overview the studies in which wound dressings from naturally-occurring polymers, based on homopolysaccharides, were prepared and evaluated. Homopolysaccharides such as cellulose, chitosan, chitin, pullulan, starch and β-glucan were considered

Polyurethane/Gelatin Nanofibrils Neural Guidance Conduit Containing Platelet-Rich Plasma and Melatonin for Transplantation of Schwann Cells

The current study aimed to enhance the efficacy of peripheral nerve regeneration using a biodegradable porous neural guidance conduit as a carrier to transplant allogeneic Schwann cells (SCs). The conduit was prepared from polyurethane (PU) and gelatin nanofibrils (GNFs) using thermally induced phase separation technique and filled with melatonin (MLT) and platelet-rich plasma (PRP). The prepared conduit had the porosity of 87.17 ± 1.89, the contact angle of 78.17 ± 5.30° and the ultimate tensile strength and Young�s modulus of 5.40 ± 0.98 MPa and 3.13 ± 0.65 GPa, respectively. The conduit lost about 14 of its weight after 60 days in distilled water. The produced conduit enhanced the proliferation of SCs demonstrated by a tetrazolium salt-based assay. For functional analysis, the conduit was seeded with 1.50 � 104 SCs (PU/GNFs/PRP/MLT/SCs) and implanted into a 10-mm sciatic nerve defect of Wistar rat. Three control groups were used: (1) PU/GNFs/SCs, (2) PU/GNFs/PRP/SCs, and (3) Autograft. The results of sciatic functional index, hot plate latency, compound muscle action potential amplitude and latency, weight-loss percentage of wet gastrocnemius muscle and histopathological examination using hematoxylin�eosin and Luxol fast blue staining, demonstrated that using the PU/GNFs/PRP/MLT conduit to transplant SCs to the sciatic nerve defect resulted in a higher regenerative outcome than the PU/GNFs and PU/GNFs/PRP conduits. © 2017, Springer Science+Business Media, LLC

Polyurethane/Gelatin Nanofibrils Neural Guidance Conduit Containing Platelet-Rich Plasma and Melatonin for Transplantation of Schwann Cells

The current study aimed to enhance the efficacy of peripheral nerve regeneration using a biodegradable porous neural guidance conduit as a carrier to transplant allogeneic Schwann cells (SCs). The conduit was prepared from polyurethane (PU) and gelatin nanofibrils (GNFs) using thermally induced phase separation technique and filled with melatonin (MLT) and platelet-rich plasma (PRP). The prepared conduit had the porosity of 87.17 ± 1.89, the contact angle of 78.17 ± 5.30° and the ultimate tensile strength and Young�s modulus of 5.40 ± 0.98 MPa and 3.13 ± 0.65 GPa, respectively. The conduit lost about 14 of its weight after 60 days in distilled water. The produced conduit enhanced the proliferation of SCs demonstrated by a tetrazolium salt-based assay. For functional analysis, the conduit was seeded with 1.50 � 104 SCs (PU/GNFs/PRP/MLT/SCs) and implanted into a 10-mm sciatic nerve defect of Wistar rat. Three control groups were used: (1) PU/GNFs/SCs, (2) PU/GNFs/PRP/SCs, and (3) Autograft. The results of sciatic functional index, hot plate latency, compound muscle action potential amplitude and latency, weight-loss percentage of wet gastrocnemius muscle and histopathological examination using hematoxylin�eosin and Luxol fast blue staining, demonstrated that using the PU/GNFs/PRP/MLT conduit to transplant SCs to the sciatic nerve defect resulted in a higher regenerative outcome than the PU/GNFs and PU/GNFs/PRP conduits. © 2017, Springer Science+Business Media, LLC

Naringin-loaded Poly(ε-caprolactone)/Gelatin Electrospun Mat as a Potential Wound Dressing: In vitro and In vivo Evaluation

In the present study, naringin, a flavonoid isolated from the grape and citrus fruit species, was incorporated with poly(ε-caprolactone)/gelatin composite mats in order to develop a potential wound dressing. The composite mats were prepared by electrospinning of poly(ε-caprolactone)/gelatin (1:1 (w/w)) solution incorporated with 1.50 , 3 and 6 (w/w) of naringin. The electrospun mats were evaluated regarding their morphology, contact angle, water-uptake capacity, water vapor transmission rate, tensile properties, drug release, cellular response and in vivo wound healing activity. The study showed that after 2 weeks, the full-thickness excisional wounds of Wistar rats treated with the naringin-loaded dressings achieved a wound closure of higher than 94 and the dressing containing 6 (w/w) naringin had almost 100 wound closure. The sterile gauze, as the control group, showed nearly 86 of wound closure after this period of time. Our results provided evidence that supports the possible applicability of naringin-loaded wound dressing for successful wound treatment. © 2018, The Korean Fiber Society and Springer Science+Business Media B.V., part of Springer Nature

Naringin-loaded Poly(ε-caprolactone)/Gelatin Electrospun Mat as a Potential Wound Dressing: In vitro and In vivo Evaluation

In the present study, naringin, a flavonoid isolated from the grape and citrus fruit species, was incorporated with poly(ε-caprolactone)/gelatin composite mats in order to develop a potential wound dressing. The composite mats were prepared by electrospinning of poly(ε-caprolactone)/gelatin (1:1 (w/w)) solution incorporated with 1.50 , 3 and 6 (w/w) of naringin. The electrospun mats were evaluated regarding their morphology, contact angle, water-uptake capacity, water vapor transmission rate, tensile properties, drug release, cellular response and in vivo wound healing activity. The study showed that after 2 weeks, the full-thickness excisional wounds of Wistar rats treated with the naringin-loaded dressings achieved a wound closure of higher than 94 and the dressing containing 6 (w/w) naringin had almost 100 wound closure. The sterile gauze, as the control group, showed nearly 86 of wound closure after this period of time. Our results provided evidence that supports the possible applicability of naringin-loaded wound dressing for successful wound treatment. © 2018, The Korean Fiber Society and Springer Science+Business Media B.V., part of Springer Nature