Gun-Woo Oh

Fish collagen/alginate/chitooligosaccharides integrated scaffold for skin tissue regeneration application.

An emerging paradigm in wound healing techniques is that a tissue-engineered skin substitute offers an alternative approach to create functional skin tissue. Here we developed a fish collagen/alginate (FCA) sponge scaffold that was functionalized by different molecular weights of chitooligosaccharides (COSs) with the use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as a cross-linking agent. The effects of cross-linking were analyzed by Fourier transform infrared spectroscopy. The results indicate that the homogeneous materials blending and cross-linking intensity were dependent on the molecular weights of COSs. The highly interconnected porous architecture with 160-260μm pore size and over 90% porosity and COSs MW driven swelling and retention capacity, tensile property and in vitro biodegradation behavior guaranteed the FCA/COS scaffolds for skin tissue engineering application. Further improvement of these properties enhanced the cytocompatibility of all the scaffolds, especially the scaffolds containing COSs with MW in the range of 1-3kDa (FCA/COS1) showed the best cytocompatibility. These physicochemical, mechanical, and biological properties suggest that the FCA/COS1 scaffold is a superior candidate that can be used for skin tissue regeneration.

Fabrication, characterization and determination of biological activities of poly(ε-caprolactone)/chitosan-caffeic acid composite fibrous mat for wound dressing application

In the present study, we designed and fabricated composite fibrous mats consisting of poly(ε-caprolactone) (PCL), chitosan (CH), or chitosan-caffeic acid conjugate (CCA) by an electrospinning technique for wound dressing application. The average fiber diameters of PCL, PCL/CH, and PCL/CCA composite fibrous mats were 1.30±1.07, 1.20±1.22, and 0.94±0.68μm, respectively. Based on universal tensile machine (UTM) analysis, the PCL/CCA fibrous mat significantly increased tensile properties compared with the PCL and PCL/CH fibrous mat. Additionally, initial cell attachment and cell proliferation of the composites using normal human dermal fibrolast-neonatal (NHDF-neo) cells, as well as the antimicrobial effect against Staphylococcus aureus, was investigated. The PCL/CCA fibrous mat show significantly higher initial cell attachment and cell proliferation than the PCL and PCL/CH fibrous mat, and a high antimicrobial effect was observed compared to the PCL and PCL/CH fibrous mat. Based on these results, the PCL/CCA fibrous mat can be used as candidate biomaterial for wound dressing applications and skin tissue engineering.

Anti-inflammatory effects of sodium alginate/gelatine porous scaffolds merged with fucoidan in murine microglial BV2 cells.

Microglia are the immune cells of the central nervous system (CNS). Overexpression of inflammatory mediators by microglia can induce several neurological diseases. Thus, the underlying basic requirement for neural tissue engineering is to develop materials that exhibit little or no neuro-inflammatory effects. In this study, we have developed a method to create porous scaffolds by adding fucoidan (Fu) into porous sodium alginate (Sa)/gelatine (G) (SaGFu). For mechanical characterization, in vitro degradation, stress/strain, swelling, and pore size were measured. Furthermore, the biocompatibility was evaluated by assessing the adhesion and proliferation of BV2 microglial cells on the SaGFu porous scaffolds using scanning electron microscopy (SEM) and lactate dehydrogenase (LDH) assay, respectively. Moreover, we studied the neuro-inflammatory effects of SaGFu on BV2 microglial cells. The effect of gelatine and fucoidan content on the various properties of the scaffold was investigated and the results showed that mechanical properties increased porosity and swelling ratio with an increase in the gelatine and fucoidan, while the in vitro biodegradability decreased. The average SaGFu diameter attained by fabrication of SaGFu ranged from 60 to 120μm with high porosity (74.44%-88.30%). Cell culture using gelatine 2.0% (SaG2Fu) and 4.0% (SaG4Fu), showed good cell proliferation; more than 60-80% that with Sa alone. Following stimulation with 0.5μg/mL LPS, microglia cultured in porous SaGFu decreased their expression of nitric oxide (NO), prostaglandin E2 (PGE2), and reactive oxygen species (ROS). SaG2Fu and SaG4Fu also inhibited the activation and translocation of p65 NF-κB protein levels, resulting in reduction of NO, ROS, and PGE2 production. These results provide insights into the diverse biological effects and opens new avenues for the applications of SaGFu in neuroscience.

Biomedical Materials for Regenerating Bone Tissue Utilizing Marine Invertebrate

Tissue engineering is an emerging, innovative technology to improve or replace the biological functions of damaged tissues and organs. Scaffolds are important materials for tissue engineering as they support cell attachment, migration, and differentiation. Marine sponges naturally contain scaffolds ...

A heptameric peptide purified from Spirulina sp. gastrointestinal hydrolysate inhibits angiotensin I-converting enzyme- and angiotensin II-induced vascular dysfunction in human endothelial cells

In this study, a marine microalga Spirulina sp.-derived protein was hydrolyzed using gastrointestinal enzymes to produce an angiotensin I (Ang I)-converting enzyme (ACE) inhibitory peptide. Following consecutive purification, the potent ACE inhibitory peptide was composed of 7 amino acids, Thr-Met-Glu-Pro-Gly-Lys-Pro (molecular weight, 759 Da). Analysis using the Lineweaver-Burk plot and molecular modeling suggested that the purified peptide acted as a mixed non-competitive inhibitor of ACE. The inhibitory effects of the peptide against the cellular production of vascular dysfunction-related factors induced by Ang II were also investigated. In human endothelial cells, the Ang II-induced production of nitric oxide and reactive oxygen species was inhibited, and the expression of inducible nitric oxide synthase (iNOS) and endothelin-1 (ET-1) was downregulated when the cells were cultured with the purified peptide. Moreover, the peptide blocked the activation of p38 mitogen-activated protein kinase. These results indicated that this Spirulina sp.-derived peptide warrants further investigation as a potential pharmacological inhibitor of ACE and vascular dysfunction.

Fabrication and characterization of phlorotannins/poly (vinyl alcohol) hydrogel for wound healing application

Abstract Phlorotannins (PH) derived from brown algae have been shown to have biological effects. However, the application of PH in biomedical materials has not been investigated. Here, we investigated the effects of PH on normal human dermal fibroblast (NHDF) proliferation and fabricated a composite hydrogel consisting PH and poly (vinyl alcohol) (PVA) (PVA/PH) by a freezing-thawing method for wound healing applications. Cell proliferation was significantly higher in the PH-treated (0.01 and 0.02%) cells than in non-treated cells. Based on the mechanical properties, the PVA/PH hydrogel had a significantly increased swelling ratio and ultimate strain compared to the PVA hydrogel, but the ultimate tensile strength and tensile modulus were decreased. Additionally, cell attachment and proliferation on the composites were evaluated using NHDFs. The results showed that after 1 and 5 days, cell attachment and proliferation were significantly increased on the PVA/PH hydrogel compared with that on the PVA hydrogel. The findings from this study suggest that the PVA/PH hydrogel may be a candidate biomedical material for wound healing applications.

Antioxidant and Angiotensin I Converting Enzyme Inhibition Effects and Antihypertensive Effect in Spontaneously Hyertensive Rats of Peptide Isolated from Boiled Abalone By-Products, Hallotis discus hannai

ABSTRACT Abalone is a marine gastropod that is an important fishery and food industrial resource, massively maricultured in Asia, Africa, Australia, and America. Marine by-products from boiled abalone, normally discarded as industrial waste in manufacturing plants, were fractionated and concentrated using an ultrafiltration membrane system (˂ 1 kDa). In this study, the antioxidant and angiotensin I converting enzyme (ACE) inhibition effects of the boiled abalone by-products (BABs) were investigated. BABs have high antioxidant activities against free radicals (1,1-diphenyl-2-pycryl-hydrazyl (DPPH), hydroxyl, peroxyl, and superoxide radicals), reactive oxygen species (ROS) stress, and DNA damage in H2O2-treated RAW 264.7 macrophages. The structure of the purified peptide was identified to be ATPGDEG (MW 752 Da), and the ACE inhibition pattern of the peptide was found to be noncompetitive. In addition, the peptide exhibited an antihypertensive effect according to time-course measurement after oral administration to spontaneously hypertensive rats (SHR). BABs from this genus may be potential candidates for the development of unique natural substances for further industrial applications as functional foods and pharmaceuticals.

Characterization and biological activity of PVA hydrogel containing chitooligosaccharides conjugated with gallic acid

Propionibacterium acnes plays a key role in the onset of inflammation leading to acne and in downregulation of the defense system against oxidative stress. Therefore, antibiotics such as macrolides, tetracyclines, azelaic acid, and erythromycin are used to reduce microbial proliferation and resulting inflammation. Nonetheless, antibiotic treatment has side effects including cytotoxicity, allergy, and diarrhea. Therefore, recent studies were focused on the development of alternative antimicrobial materials. We conjugated chitooligosaccharide (COS) with gallic acid (GA) by the hydrogen peroxide-mediated method and evaluated antioxidant and antimicrobial activities. Then, we fabricated a polyvinyl alcohol (PVA) hydrogel containing COS conjugated with GA (GA-COS) for acne treatment. GA-COS at 5-10 kDa showed an excellent antioxidant activity and a better antimicrobial activity against P. acnes as compared with COS. In addition, the PVA hydrogel with GA-COS inhibited intracellular formation of reactive oxygen species and exerted antimicrobial action better than controls did.