• Macromolecular Research
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• 제16권6호
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• pp.517-523
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• 2008

A RGD (Arg-Gly-Asp) conjugated chitosan hydrogel was used as a cell-supporting scaffold for articular cartilage regeneration. Thermosensitive chitosan-Pluronic (CP) has potential biomedical applications on account of its biocompatibility and injectability. A RGD-conjugated CP (RGD-CP) copolymer was prepared by coupling the carboxyl group in the peptide with the residual amine group in the CP copolymer. The chemical structure of RGD-CP was characterized by $^1H$ NMR and FT IR. The concentration of conjugated RGD was quantified by amino acid analysis (AAA) and rheology of the RGD-CP hydrogel was investigated. The amount of bound RGD was $0.135{\mu}g$ per 1 mg of CP copolymer. The viscoelastic parameters of RGD-CP hydrogel showed thermo-sensitivity and suitable mechanical strength at body temperature for cell scaffolds (a> 100 kPa storage modulus). The viability of the bovine chondrocyte and the amount of synthesized glycosaminoglycans (GAGs) on the RGD-CP hydrogels were evaluated together with the alginate hydrogels as a control over a 14 day period. Both results showed that the RGD-CP hydrogel was superior to the alginate hydrogel. These results show that conjugating RGD to CP hydro gels improves cell viability and proliferation, including extra cellular matrix (ECM) expression. Therefore, RGD conjugated CP hydrogels are quite suitable for a chondrocyte culture and have potential applications to the tissue engineering of articular cartilage tissue.

• 폴리머
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• 제26권3호
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• pp.300-306
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• 2002

본 연구에서는 세포접착성에 관한 영향을 검토하기 위하여 L-malic acid (L-MA)와 glycolic acid (GA)의 복합단위로 된 3-(S)-[(dodecyloxycarbonyl)methyl] -1,4-dioxane-2,5-dione (DMD)의 합성 및 DMD와 L-lactide의 공중합을 촉매로서 tin (II) octanoate를 사용하여 행하였다. 얻어진 공중합체를 필름으로 제작하여 RGD고정화를 실시한 결과, 필름표면에 세포접착성 펩티드를 고정화할 수 있었고, MA단위의 도입량의 증가에 따라 RGD의 고정화량이 증가하는 것을 확인하였으며, glycolic acid-$\beta$-dodecylmalate-lactic acid (D-PGML)는 서서히 분해되어 장기간에 있어 잔류 및 축적이 발생하지 않아 생체재료로서 크게 기대된다.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.193-196
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• 2004

The peptide Arg-Gly-Asp (RGD) was immobilized through their amino terminus to ends of a sugar bearing copolymer, producing a functional hybrid copolymer. Poly(N-p-vinylbenzyl-D-maltonamide-co-6-(p-vinylbenzamido)-hexanoic acid-g-GRGDS) [p(VMA-co-VBGRGDS)] promoted the attachment and growth of NIH fibroblast cells. The interaction between fibroblast cells and p(VMA-co- VBGRGDS) copolymer resulted in effective cell attachment, proliferation, and morphological changes by introduction of a GRGDS sequence. Moreover, when pretreated with soluble RGD monomer, attachment of fibroblast cells was suppressed approximately 50% from that of the p(VMA-co-VBGRGDS) surface.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.268-268
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• 2006

Due to their multipotency, stem cells can differentiate into a variety of specialized cell types, such as chondrocytes, osteoblasts, myoblasts, and nerve cells. As an alternative to mature tissue cells, stem cells are of importance in tissue engineering and regenerative medicine. Since interactions between scaffold and cells play an important role in the tissue development in vitro, synthetic oligopeptides have been immobilized onto polymeric scaffolds to improve specific cell attachment and even to stimulate cell differentiation. In this study, chondrogenic differentiation of stem cells was evaluated using surface-modified PLLA scaffolds, i.e., either hydrophilic acrylic acid (AA)-grafted PLLA or RGD-immobilized one. Porous PLLA scaffolds were prepared using a gas foaming method, followed by plasma treatment and subsequent grafting of AA to introduce a hydrophilicity (PLLA-PAA). This was further processed to fix RGD peptide to make an RGD-immobilized scaffold (PLLA-PAA-RGD). Stem cells were seeded at $1{\times}10^{6}$ cells per scaffold and the cell-PLLA constructs were cultured for up to 4 weeks in the chondrogenic medium. Using these surface-modified scaffolds, adhesion, proliferation, and chondrogenic differentiation of stem cells were evaluated. The surface of PLLA scaffolds turned hydrophilic (water contact angle, 45 degrees) with both plasma treatment and AA grafting. The hydrophilicity of RGD-immobilized surface was not significantly altered. Cell proliferation rate on the either PLLA-PAA or PLLA-PAA-RGD surface was obviously improved, especially with the RGD-immobilized one as compared to the control PLLA one. Chondrogenic differentiation was clearly identified with Safranin O staining of GAG in the AA- or RGD-grafted PLLA substrates. This study demonstrated that modified polymer surfaces may provide better environment for chondrogenesis of stem cells.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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• pp.1817-1820
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• 2009

Controlling cell-matrix interactions is critical in regulating cell phenotypes for tissue engineering applications. Cellular adhesion to synthetic extracellular matrices (ECMs) can be enhanced by introduction of adhesion ligands to the matrices. We tested the hypothesis that biophysical cues such as ligand organization in synthetic ECMs play an important role in modulating cell responses to the microenvironment. To investigate and monitor cell-matrix interactions, we used a fluorescence resonance energy transfer (FRET) technique with cell-interactive polymers generated by conjugating a peptide with the sequence of arginine-glycine-aspartic acid (RGD) to alginate hydrogels.

• BMB Reports
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• 제31권5호
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• pp.515-518
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• 1998

Adhesive interaction of the platelet glycoprotien IIb-IIIa (GP IIb-IIIa) with a plasma protein, such as fibrinogen, plays an important role in thrombosis and hemostasis. The specific sequence Arg-Gly-Asp (RGD) is critical for the binding of fibrinogen to platelet. To examine and characterize the GP IIb-IIIa antagonist from natural sources, we have developed a simple enzyme-linked immunosorbant assay (ELISA) system. The GP IIb-IIIa complex was purified to homogeneity from platelet Iysates by the combination of two affinity chromatographic methods using the synthetic RGD peptide (GRGDSPK)-immobilized Sepharose and wheat germ lectin-Sepharose. The synthetic peptide GRGDSP inhibits GP IIb-IIIa binding to immobilized fibrinogen with an $IC_{50}$ of $1.5\;{\mu}M$. Venoms of three different snake species and a Korean scolopendra extract have strong antagonistic activities for the binding of human fibrinogen to the platelet GP IIb-IIIa complex. The $IC_{50}$ values of the snake venom s and scolopendra were in the range of $5.5\;{\mu}g$ to $60\;{\mu}g$. These results provide meaningful information for developing antiplatelet agents.

• 대한방사성의약품학회지
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• 제1권1호
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• pp.46-52
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• 2015

Herein we present the synthesis of $^{68}Ga$-labeled gold nanoparticles for in vivo PET imaging. A novel chelator DTPA-Cys was easily prepared from diethylenetriaminepentaacetic dianhydride in high yield. The ${\alpha}_v{\beta}_3$ integrin receptor targeted gold nanoparticle probe was synthesized by using DTPA-Cys, polyethylene glycol and cRGD peptide. $^{68}Ga$ labeling of cRGD conjugated gold nanoparticle was carried out at $40^{\circ}C$ for 30 min. Observed radiochemical yield was more than 75% as determined by radio-TLC and the probe was purified by centrifugation. In vitro stability test showed that 90% of $^{68}Ga$-labeled gold nanoparticle probe was stable in FBS for 1 h. Those results demonstrated that $^{68}Ga$-labeled gold nanoparticle could be used as a potentially useful probe for specific tumor imaging.

• Macromolecular Research
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• 제13권5호
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• pp.446-452
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• 2005

The interactions between the surface of scaffolds and specific cells play an important role in tissue engineering applications. Some cell adhesive ligand peptides including Arg-Gly-Asp (RGD) have been grafted into polymeric scaffolds to improve specific cell attachment. In order to make cell adhesive scaffolds for tissue regeneration, biodegradable nonporous poly(L-lactic acid) (PLLA) films were prepared by using a solvent casting technique with chloroform. The hydrophobic PLLA films were surface-modified by Argon plasma treatment and in situ direct acrylic acid (AA) grafting to get hydrophilic PLLA-g-PAA. The obtained carboxylic groups of PLLA-g-PAA were coupled with the amine groups of Gly-Arg-Asp-Gly (GRDG, control) and GRGD as a ligand peptide to get PLLA-g-GRDG and PLLA-g-GRGD, respectively. The surface properties of the modified PLLA films were examined by various surface analyses. The surface structures of the PLLA films were confirmed by ATR-FTIR and ESCA, whereas the immobilized amounts of the ligand peptides were 138-145 pmol/$cm^2$. The PLLA surfaces were more hydrophilic after AA and/or RGD grafting but their surface morphologies showed still relatively smoothness. Fibroblast adhesion to the PLLA surfaces was improved in the order of PLLA control

• 대한방사성의약품학회지
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• 제2권2호
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• pp.118-122
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• 2016

Integrin ${\alpha}_v{\beta}_3$ plays an important role in the tumor metastases and angiogenesis. Arginine-glycine-aspartate (RGD) peptide motif binds to the integrin ${\alpha}_v{\beta}_3$. General $^{68}Ga$-labeled cyclic RGD peptides was rapidly eliminated from the circulatory system by renal excretion because of its hydrophilic property. The purpose of this study was to develop a novel $^{68}Ga$-labeled cyclic RGD peptides, which could acquire enhanced PET tumor images with improved pharmacokinetics by adopting biphenyl group between chelator and RGD peptides. $^{68}Ga$-DOTA-2P-c(RGDyK) was demonstrated a 12% higher lipophilicity level than $^{68}Ga$-DOTA-c(RGDyK) as a reference compound. In the animal PET, $^{68}Ga$-DOTA-2P-c(RGDyK) represented relatively lower blood-clearance, and an increased signal to noise ratio compared to $^{68}Ga$-DOTA-c(RGDyK). From these perspective, $^{68}Ga$-DOTA-2P-c(RGDyK) could be a good candidate for in integrin ${\alpha}_v{\beta}_3$-expressed tumor imaging.

• Animal cells and systems
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• 제8권1호
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• pp.27-32
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• 2004

Endothellial cells are subjected to hemodynamic shear stress, the dragging force generated by blood flow. Shear stress regulates endothelial cell shape, structure, and function, including gene expression. Since endothelial cells must be anchored to their extracellular matrices(ECM) for their survival and growth, we hypothesized that ECMs are crucial for shear-dependent activation of extracellular signalactivated regulated kinase(ERK) that is important for cell proliferation. Shear stress-dependent activation of ERK was observed in cells plated on two different matrices, fibronectin and vitronectin(the two most physiologically relevant ECM in endothelial cells). We then treated bovine aortic endothelial cells(BAECs) with Arg-Gly-Asp(RGD) peptides that block the functional activation of integrin binding to fibronectin and vitronectin, and a nonfunctional peptide as a control. Treatment of cells with the RGD peptides, but not the control peptide, significantly inhibited ERK activity in a concentration-dependent manner. This supports the idea that integrin adhesion to the ligands, fibronectin and vitronectin, mediates shear stress-dependent activation of ERK. Subsequently, whereas antagonists of vitronectin(LM 609, an antibody for integrin ${\alpha}_{\gamma}$/${\beta}_3$ and XT 199, an antagonist specific for integrin ${\alpha}_{\gamma}$/${\beta}_3$) did not have any effect on shear-dependent activation of ERK, antagonists of fibronectin(a neutralizing antibody for integrin ${\alpha}_5$/${\beta}_1$or ${\alpha}_4$${\beta}_1$ and SM256) had an inhibitory effect. These results clearly demonstrate that mechanoactivation of ERK requires anchoring of endothelial cells to fibronectin through integrins.