RGD Peptide Modification Research Articles

Supercharged nanoadhesive through co-assembly of recombinant protein and tetrahedral DNA for corneal transplantation

Abstract Atraumatic tissue adhesive technology is highly desired for ophthalmic surgery, while numerous polymeric adhesives still face significant limitations in clinical ophthalmology, especially corneal transplantation. The biggest challenge is achieving rapid adhesion without creating polymer barrier or chemical toxicity from cross-linking. To develop a cornea-specific adhesive, we introduced a novel nanoadhesive constructed through protein-DNA co-assembly and applied it in corneal transplantation. Within this system, a rigid tetrahedral DNA framework was used to guide the spatial distribution of the polycationic recombinant proteins (K72) and act as the core of nanoadhesive for energy conversion during connecting tissues. The adhesive strength of this nanoadhesive achieved 2.3 kPa between corneal lenticules. After RGD peptide modification, this adhesive system significantly improved corneal epithelialization, reduced inflammation and neovascularization, and finally facilitated corneal repairing. This work is the first attempt of nanoadhesive in ophthalmic surgery, and provides a solution to develop novel ophthalmic-specific adhesives for clinical application.

Integrated organosilica nanomedicine enables sonoimaging, sonochemistry and antitumor sonodynamic therapy.

Sonography with its non-invasive and deep tissue-penetrating characteristics, not only contributes to promising developments in clinical disease diagnosis but also obtains acknowledgments as a prospective therapeutic approach in the field of tumor treatment. However, it remains a challenge for sonography simultaneously to achieve efficient imaging and therapeutic functionality. Here, we present an innovative integrated diagnosis and treatment paradigm by developing the nanomedicine of percarbamide-bromide-mesoporous organosilica spheres (MOS) with RGD peptide modification (PBMR) by loading percarbamide and bromide in MOS which were prepared by a one-step O/W microemulsion method. The PBMR nanomedicine effectively modifies the tumor acoustic environment to improve sonoimaging efficacy and induces sonochemical reactions to enhance the production of reactive oxygen species (ROS) for tumor treatment efficiency under sonography. The combination of PBMR nanomedicine and SDT achieved multiple ROS generation through the controlled sonochemical reactions and significantly boosted the potency of sonodynamic therapy and induced significant tumor regression with non-invasive tissue penetrability and minimizing damage to healthy tissues. Simultaneously, the generation of oxygen gas in the sonochemical process augments ultrasound reflection, resulting in a 4.9-fold increase in imaging grayscale. Our research establishes an effective platform for the synergistic integration of sonoimaging and sonodynamic antitumor therapy, offering a novel approach for precise antitumor treatment in the potential clinical applications.

BIODEGRADABLE VASCULAR GRAFT MODIFIED BY RGD-PEPTIDES: EXPERIMENTAL RESEARCH

Research goals. To study the effectiveness of RGD-peptide modification of the small-diameter biodegradable vascular grafts depending on the type of a linker and RGD configuration.Material and Methods. Tubular scaffolds with a diameter of 1.5 and 4.0 mm were produced by electrospinning from polyhydroxybutyrate/valerate (PHBV) and polycaprolactone (PCL). The PHBV/PCL grafts were modified with RGD peptides. In vitro experiments showed the degree of erythrocyte hemolysis and adhesion of the platelets and endothelial cells when in contact with a modified surface. The physico-mechanical properties and the structure of graft surface were studied before and after modification. The PHBV/PCL and PHBV/PCL/RGD vascular grafts were implanted into the abdominal aorta of rats for the periods of 1 and 3 months. Explant samples were studied using confocal microscopy and histological methods.Results. The results of physical and mechanical tests showed a significant decrease in the strength properties of the PHBV/PCL/RGD grafts relative to the unmodified analogs. A significant increase in platelet aggregation was found in the modified grafts. The level of adhesion of the endothelial cells on the modified surfaces was higher than that on the unmodified surfaces. Shortterm implantation of the grafts for 1 and 3 months showed that the modified grafts had higher patency and a less tendency to calcification compared with the unmodified grafts. Immunofluorescence study demonstrated the significant superiority of the modified vascular grafts in terms of stimulating the formation of a mature endothelial monolayer. A longer linker of 4,7,10-trioxa-1,13-tridecane diamine was found to increase the bioavailability of RGD peptides; the use of RGDK and c[RGDFK] for surface modification of the grafts stimulated early endothelialization of the internal surface of the implants and reduced the prosthetic wall calcification tendency, which together increased the patency of the implanted grafts.Conclusion. In short-term implantation of biodegradable vascular grafts modified with RGD peptides, the grafts with RGDK and c[RGDFK], attached to the surface of the prostheses through the 4,7,10-triox-1,13-tridecane diamine linker, showed the best results in terms of endothelial adhesion and maintenance of the viability of the endothelial cells in vitro and endothelialization in vivo; these grafts had high patency after implantation into the bloodstream of small laboratory animals and a less tendency to calcification.

RGD-modified PEGylated paclitaxel nanocrystals with enhanced stability and tumor-targeting capability

Nanocrystals has been constructed for insoluble drugs as a novel type of nanoscale drug delivery systems with high drug loading. How to prepare nanocrystals with good stability and tumor targeting capability is still challenging. This study was to modify paclitaxel nanocrystals with polyethylene glycol (PEG) for stabilization and RGD peptide for tumor targeting. Inspired by the structure of mussel's foot protein, polydopamine (PDA) was introduced to the drug delivery system for the modification of nanocrystals. Briefly, PDA was coated on the surface of nanocrystals to form a reaction platform for further PEGylation and RGD peptide conjugation. PEGylated nanocrystals with RGD peptide modification (NC@PDA-PEG-RGD) were prepared with near-spheroid shape, drug loading 45.12 ± 1.81% and a hydrodynamic diameter 419.9 ± 80.9 nm. The size of NC@PDA-PEG-RGD remained basically unchanged for at least 72 h in the presence of plasma while the size of unmodified nanocrystals (NC) increased and exceeded 1000 nm in 12 h. Cellular uptake and cellular growth inhibition experiments using the lung cancer cell line A549 demonstrated the superiority of NC@PDA-PEG-RGD over NC or PEGylated nanocrystals without RGD modification (NC@PDA-PEG). In A549 model tumor bearing-mice, NC@PDA-PEG-RGD showed significantly higher intratumor accumulation and slower tumor growth than NC@PDA-PEG or free paclitaxel. In summary, our study suggested the superiority of RGDmodified PEGylated paclitaxel nanocrystals as a lung cancer-targeted delivery system and the potential of PDA coating technique for targeting functionalization of nanocrystals.

Enhancing the apoptotic effect of IL-24/mda-7 on the human hepatic stellate cell through RGD peptide modification

ABSTRACTInduction of apoptosis or quiescent hepatic stellate cells (HSCs) can be an attractive molecular strategy due to the importance of activation of HSCs during hepatic fibrogenesis. Interleukin-24/melanoma differentiation-associated gene-7 (IL-24/mda-7) is a cytokine that has attracted a great deal of attention in the tumor killing as well as pathophysiology of the diseases. In this study, the Pro-apoptotic and senescence inductive properties of IL-24/mda-7 were assessed in human-derived HSCs. Three plasmids expressing natural mda-7, peptide modified version, mda-7-RGD genes beside a recombinant IL-24 protein, were added or transfected into activated LX-2 cells. Cell viability and the amount of apoptosis were analyzed using MTT and Annexin V staining method, respectively. Hence, the expression levels of apoptotic genes and PPARγ in different groups were also compared by real-time PCR analysis. Furthermore, the senescence effect of IL-24/mda-7 by a β-galactosidase (SA-β-gal) senescence assay, was evaluated. The viability assessment showed that pmda-7-RGD had the most significant growth inhibitory effect when compared to the control group, pcDNA3.1 (P = 0.0002). The apoptosis analysis also revealed a significant impact of different mda-7 forms in apoptosis induction. The measuring of cell senescence also indicated that IL-24/mda-7 in plasmid and protein forms exhibited a senescence inductive activity as determined by an increase in PPARγ gene expression and beta-galctosidase activity. In conclusion, our findings demonstrated that both endogenous and soluble forms of IL-24/mda-7 induced apoptosis and senescence in activated LX-2 cells and more importantly, fusion of RGD peptide to this cytokine enhanced these activities. So, RGD-modified IL-24/mda-7 could be a suitable candidate for further molecular therapy of fibrosis.

Easy Manipulation of Architectures in Protein-based Hydrogels for Cell Culture Applications.

Hydrogels are recognized as promising materials for cell culture applications due to their ability to provide highly hydrated cell environments. The field of 3D templates is rising due to the potential resemblance of those materials to the natural extracellular matrix. Protein-based hydrogels are particularly promising because they can easily be functionalized and can achieve defined structures with adjustable physicochemical properties. However, the production of macroporous 3D templates for cell culture applications using natural materials is often limited by their weaker mechanical properties compared to those of synthetic materials. Here, different methods were evaluated to produce macroporous bovine serum albumin (BSA)-based hydrogel systems, with adjustable pore sizes in the range of 10 to 70 µm in radius. Furthermore, a method to generate channels in this protein-based material that are several hundred microns long was established. The different methods to produce pores, as well as the influence of pore size on material properties such as swelling ratio, pH, temperature stability, and enzymatic degradation behavior, were analyzed. Pore sizes were investigated in the native, swollen state of the hydrogels using confocal laser scanning microscopy. The feasibility for cell culture applications was evaluated using a cell-adhesive RGD peptide modification of the protein system and two model cell lines: human breast cancer cells (A549) and adenocarcinomic human alveolar basal epithelial cells (MCF7).

Roughened titanium surfaces with silane and further RGD peptide modification in vitro

The strategy to achieve osteoregeneration of dental implants during early-stage regeneration is strongly related to surface conditions for achieving highly successful effects after implantation. Surface modifications, namely, mechanical ground, silanization, bonded and sandblasted with pentasequence Gly-Arg-Gly-Asp-Ser (GRGDS) peptide, and acid-etched with Arg-Gly-Asp (RGD) peptide, were compared for their ability to support cell attachment, proliferation, and differentiation on titanium surfaces. The characteristics and comparative in vitro bio-interactions toward osteoprogenitor cells were tested in the four groups with various surface modifications. Compared with the other groups, the sandblasted and acid-etched, and silane with subsequent RGD peptide modified surfaces had the smallest wetting angle, absence of a significant cell viability difference, and largest quantity of alkaline phosphatase production during the expressions of early-stage cell differentiation. The method of synthesizing GRGDS peptides on roughened titanium surfaces has the potential to provide a combination of early bone regeneration and implant of long-term anchored capabilities.

In vivo biodegradation and biocompatibility of PEG/sebacic acid‐based hydrogels using a cage implant system

Comprehensive in vivo biodegradability and biocompatibility of unmodified and Arg-Gly-Asp (RGD) peptide-modified PEG/sebacic acid-based hydrogels were evaluated and compared to the control material poly(lactide-co-glycolide) (PLGA) using a cage implantation system, as well as direct subcutaneous implantation for up to 12 weeks. The total weight loss after 12 weeks of implantation for unmodified PEGSDA and RGD-modified PEGSDA in the cage was approximately 42% and 52%, respectively, with no statistical difference (p > 0.05). The exudate analysis showed that PEGSDA hydrogels induced minimal inflammatory response up to 21 days following implantation, similar to the controls (empty cage and the cage containing PLGA discs). Histology analysis from direct subcutaneous implantation of the hydrogels and PLGA scaffold showed statistically similar resolution of the acute and chronic inflammatory responses with development of the fibrous capsule between the PEGSDA hydrogels and the control (PLGA). The cage system, as well as the histology analysis, demonstrated that the degradation products of both hydrogels, with or without RGD peptide modification, are biocompatible without statistically significant differences in the inflammatory responses, as compared to PLGA.

Evaluation of PRGD/FK506/NGF conduits for peripheral nerve regeneration in rats

Both tacrolimus (FK506) and nerve growth factor (NGF) enhance peripheral nerve regeneration, and in vitro experimental results demonstrate that the combination of FK506 and NGF increased neurite outgrowth compared with either treatment alone. To determine if the combination of FK506 and NGF benefits peripheral nerve regeneration compared with either treatment alone in vivo. Rat sciatic nerves were cut off to form a 10 mm defect and repaired with the nerve conduits. All of the 32 Wistar rats were randomly divided into 4 groups: Group A: RGD peptide modification of poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (PRGD)/FK506/NGF; Group B: PRGD/FK506; Group C: PRGD/NGF; and Group D: autologous nerves. At 3 months after surgery, the regenerated rat sciatic nerve was evaluated by electrophysiology, calf triceps wet weight recovery rate, and histologic assessment. The SPSS 10.0 software (Bizinsight, Beijing China) was used for statistical analysis. The compound muscle action potentials (CMAPs) of groups A and D were significantly stronger than those of groups B and C. The calf triceps wet weight recovery rate of groups A and D were higher than those of groups B and C. The regenerated nerves of groups A and D were more mature than those of groups B and C. There was no significant difference between groups A and D. PRGD/FK506/NGF sustained-release nerve conduits are more effective in regenerating nerves than both PRGD/FK506 sustained-release nerve conduits and PRGD/NGF sustained-release nerve conduits. The effect is as good as that of an autograft.

Potential of Hydrogels Based on Poly(Ethylene Glycol) and Sebacic Acid as Orthopedic Tissue Engineering Scaffolds

In this study, the bioactive effects of poly(ethylene glycol) (PEG) sebacic acid diacrylate (PEGSDA) hydrogels with or without RGD peptide modification on osteogenic differentiation and mineralization of marrow stromal cells (MSCs) were examined. In a separate experiment, the ability of PEGSDA hydrogel to serve as a delivery vehicle for bone morphogenetic protein 2 (BMP-2) was also investigated. As a scaffold, the attachment and proliferation of MSCs on PEGSDA hydrogel scaffolds with and without RGD peptide modification was similar to the control, tissue culture polystyrene. In contrast, cells were barely seen on unmodified PEG diacrylate (PEGDA) hydrogel throughout the culture period for up to 21 days. Osteogenic phenotypic expression such as alkaline phosphatase (ALP) of MSCs as well as mineralized calcium content were significantly higher on PEGSDA-based hydrogels than those on the control or PEGDA hydrogels. Potential use of PEGSDA scaffold as a delivery vehicle of osteogenic molecules such as BMP-2 was also evaluated. Initial burst release of BMP-2 from PEGSDA hydrogel scaffold (14.7%) was significantly reduced compared to PEGDA hydrogel scaffold (84.2%) during the first 3 days of a 21-day release period. ALP activity of an osteoblast was significantly higher in the presence of BMP-2 released from PEGSDA hydrogel scaffolds compared to that in the presence of BMP-2 released from PEGDA scaffolds, especially after 6 days of release. Overall, PEGSDA hydrogel scaffolds without further modification may be useful as orthopedic tissue engineering scaffolds as well as local drug carriers for prolonged sustained release of osteoinductive molecules.

Synthesis and RGD peptide modification of poly{(lactic acid)-co-[(glycolic acid )-alt-(L-lysine)

AbstractA new polymer poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (poly[LA-co-(Glc-alt-Lys)]) was synthesized and modified with a cell adhesion peptide, Gly-Arg-Gly-Asp-Tyr (GRGDY, abbreviated as RGD). The process for preparing poly[LA-co-(Glc-alt-Lys)]/RGD involved four steps: Firstly, (3S)-3-[4- (benzyloxycarbonylamino)butyl]morpholine-2,5-dione (BMD) was synthesized by bromoacetyl bromide and Nε-(benzyloxycarbonyl)-L-lysine [L-Lys(Z)]. Secondly, poly{(lactic acid)-co-[(glycolic acid)-alt-(Nεn-benzyloxycarbonyl-L-lysine)]} (poly{LAco-[ Glc-alt-Lys(z)]}) was obtained by copolymerization of D,L-lactide and BMD. Then, poly[LA-co-(Glc-alt-Lys)] was synthesized by catalytic hydrogenation of poly{LA-co-[Glc-alt-Lys(z)]}. Finally, poly[LA-co-(Glc-alt-Lys)] was modified with RGD peptide in the presence of 1,1́-carbonyldiimidazole (CDI). The structures of poly[LA-co-(Glc-alt-Lys)]/RGD and its precursors were characterized by FT-IR, 1H NMR, 13C NMR, MS, gel permeation chromatography (GPC), amino acid analysis(AAA). RSC96 cells were used to evaluate the cell affinity of the poly[LAco-( Glc-alt-Lys)]/RGD films and poly(D,L-lactide) (PDLLA ) films. The results of cell culture showed that poly[LA-co-(Glc-alt-Lys)]/RGD was more beneficial to cell adherence and growth than PDLLA.

Synthesis and Evaluation of Novel Biodegradable Hydrogels Based on Poly(ethylene glycol) and Sebacic Acid as Tissue Engineering Scaffolds

Novel biodegradable poly(ethylene glycol) (PEG) based hydrogels, namely, PEG sebacate diacrylate (PEGSDA) were synthesized, and their properties were evaluated. Chemical structures of these polymers were confirmed by Fourier transform infrared and proton nuclear magnetic resonance (1H NMR) spectroscopy. After photopolymerization, the dynamic shear modulus of the hydrogels was up to 0.2 MPa for 50% PEGSDA hydrogel, significantly higher than conventional hydrogels such as PEG diacrylate (PEGDA). The swelling ratios of these macromers were significantly lower than PEGDA. The in vitro degradation study demonstrated that these hydrogels were biodegradable with weight losses about 66% and 32% for 25% and 50% PEGSDA after 8 weeks of incubation in phosphate-buffered saline at 37 degrees C. In vitro biocompatibility was assessed using cultured rat bone marrow stromal cells (MSCs) in the presence of unreacted monomers or degradation products. Unlike conventional PEGDA hydrogels, PEGSDA hydrogel without RGD peptide modification induced MSC cell adhesion similar to tissue culture polystyrene. Finally, complex three-dimensional structures of PEGSDA hydrogels using solid free form technique were fabricated and their structure integrity was better maintained than PEGDA hydrogels. These hydrogels may find use as scaffolds for tissue engineering applications.

Comparison between RGD-peptide-modified titanium and borosilicate surfaces

The use of synthetic peptides containing adhesive sequences, such as the Arg-Gly-Asp (RGD) motif, represents a promising strategy to control biological interactions at the cell-material interface. These peptides are known to improve the tissue-material contact owing to highly specific binding to cellular membrane receptors known as integrins, thereby promoting the adhesion, migration and proliferation of cells. The peptides were coupled to borosilicate glass and titanium surfaces using silanisation chemistry. A tryptophan residue was incorporated into the amino acid sequences of selected peptides to facilitate the detection of the covalently bound peptides. Successful peptide immobilisation was proven by fluorimetric measurements. The confocal imaging analysis suggests a homogeneous distribution of the immobilised peptide across the biomaterial surface. In vitro cell proliferation assays were employed to compare the adhesion potentials of the well-known RGD-containing peptides GRGDSP, GRADSP and RGDS to the three peptides designed by our group. The results demonstrate that the RGD sequence is not necessarily required to enhance the adhesion of cells to non-biological surfaces. Moreover, it is shown that the number of adhering cells can be increased by changes in the peptide hydrophobicity. Changes in the cytoskeleton are observed depending on the type of RGD-peptide modification.

Tissue engineering: the design and fabrication of living replacement devices for surgical reconstruction and transplantation

All procedures that restore missing tissue in patients require some type of replacement structure for the area of defect or injury. This form of therapy accounts for a large part of health-care resources (table). These devices have traditionally been totally artificial substitutes (joints), non-living processed tissue (heart valves), or tissue taken from another site from the patients themselves or from other patients (transplantation).1 Now a new alternative, tissue engineering, is becoming available to clinicians: the replacement of living tissue with living tissue that is designed and constructed to meet the needs of each individual patient. Tissue engineering is an interdisciplinary field which applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function, z Examples of tissue engineering can be found as early as 1933 when Bisceglie 3 encased mouse tumour cells in a polymer membrane and inserted them into the abdominal cavity of a pig. 3 The cells lived long enough to show that they were not killed by the immune system. In 1975, Chick and colleagues 4 reported their results of encapsulating pancreatic-islet cells in semipermeable membranes to aid glucose control in patients with diabetes mellitus. Replacement of the skin with cells in collagen gels, or collagen-glycosaminoglycan composites to guide regeneration, was attempted by the early 1980s and these techniques are now in clinical use. 5'6 The next major advance came with the recognition that thicker three-dimensional systems could organise implanted cells to form vascularised tissue in vivo. Synthetic degradable polymers were used as templates for cells to form permanent new tissues. 7 Systems were designed with highly porous structures to meet the needs for the mass transfer of large numbers of cells. Angiogenesis after implantation produced permanent vascularised new tissue. With the demonstration of experimental success in many different tissues, and the engineering flexibility that synthetic materials provided, tissue engineering has now gained wide attention. 2'8 A recent survey of tissue engineering as an emerging industry found that the total capital value of companies in the industry exceeded US$3.5 billion, that the industry growth rate was 22.5% per year, and that it employed over 2500 scientists with an annual expenditure of $450 million3 It has been estimated that the total market potential of tissue-engineered products in the USA alone is $80 billion annually (Business Week, July 27, 1998, p 61).

Synthesis and RGD peptide modification of a new biodegradable copolymer: poly(lactic acid-co-lysine)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and RGD peptide modification of a new biodegradable copolymer: poly(lactic acid-co-lysine)Denise A. Barrera, Eric Zylstra, Peter T. Lansbury Jr., and Robert LangerCite this: J. Am. Chem. Soc. 1993, 115, 23, 11010–11011Publication Date (Print):November 1, 1993Publication History Published online1 May 2002Published inissue 1 November 1993https://doi.org/10.1021/ja00076a077RIGHTS & PERMISSIONSArticle Views3320Altmetric-Citations396LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (257 KB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts