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Purpose: Macrophage immune cells play crucial roles in the inflammatory (M1) and regenerative (M2) processes. The extracellular matrix (ECM) composition, including presentation of embedded ligands, governs macrophage function. Laminin concentration is abundant in the basement membrane and is dependent on pathological state: reduced in inflammation and increased during regeneration. Distinct laminin ligands, such as IKVAV and YIGSR, have disparate roles in dictating cell function. For example, IKVAV, derived from the alpha chain of laminin, promotes angiogenesis and metastasis of cancer cells whereas YIGSR, beta chain derived, impedes angiogenesis and tumor progression. Previous work has demonstrated IKVAV's inflammation inhibiting properties in macrophages. Given the divergent role of IKVAV and YIGSR in interacting with cells through varied integrin receptors, we ask: what role does laminin derived peptide YIGSR play in governing macrophage function? Methods: We quantified the influence of YIGSR on macrophage phenotype in 2D and 3D via immunostaining assessments for M1 marker inducible nitric oxide synthase (iNOS) and M2 marker Arginase−1 (Arg-1). We also analysed the secretome of human and murine macrophage response to YIGSR via a Luminex bead assay. Results: YIGSR impact on macrophage phenotype occurs in a concentration-dependent manner. At lower concentrations of YIGSR, macrophage inflammation was increased whereas, at higher concentrations of YIGSR the opposite effect was seen within the same time frame. Secretomic assessments also demonstrate that pro-inflammatory chemokines and cytokines were increased at low YIGSR concentrations in M0, M1, M2 macrophages while pro-inflammatory secretion was reduced at higher concentrations. Conclusions: YIGSR can be used as a tool to modulate macrophage inflammatory state within M1 and M2 phenotypes depending on the concentration of peptide. YIGSR's impact on macrophage function can be leveraged for the development of immunoengineering strategies in regenerative medicine and cancer therapy. [ABSTRACT FROM AUTHOR]

Background: Neural cell-electrode coupling is crucial for effective neural and retinal prostheses. Enhancing this coupling can be achieved through surface modification and geometrical design to increase neuron-electrode proximity. In the current research, we focused on designing and studying various biomolecules as a method to elicit neural cell-electrode adhesion via cellspecific integrin mechanisms. Methods: We designed extracellular matrix biomimetic molecules with different head sequences (RGD or YIGSR), structures (linear or cyclic), and spacer lengths (short or long). These molecules, anchored by a thiol (SH) group, were deposited onto gold surfaces at various concentrations. We assessed the modifications using contact angle measurements, fluorescence imaging, and X-ray Photoelectron Spectroscopy (XPS). We then analyzed the adhesion of retinal cells and HEK293 cells to the modified surfaces by measuring cell density, surface area, and focal adhesion spots, and examined changes in adhesion-related gene and integrin expression. Results: Results showed that YIGSR biomolecules significantly enhanced retinal cell adhesion, regardless of spacer length. For HEK293 cells, RGD biomolecules were more effective, especially with cyclic RGD and long spacers. Both cell types showed increased expression of specific adhesion integrins and proteins like vinculin and PTK2; these results were in agreement with the adhesion studies, confirming the cell-specific interactions with modified surfaces. Conclusion: This study highlights the importance of tailored biomolecules for improving neural cell adhesion to electrodes. By customizing biomolecules to foster specific and effective interactions with adhesion integrins, our study provides valuable insights for enhancing the integration and functionality of retinal prostheses and other neural implants. [ABSTRACT FROM AUTHOR]

BackgroundNeural cell-electrode coupling is crucial for effective neural and retinal prostheses. Enhancing this coupling can be achieved through surface modification and geometrical design to increase neuron-electrode proximity. In the current research, we focused on designing and studying various biomolecules as a method to elicit neural cell-electrode adhesion via cell-specific integrin mechanisms.MethodsWe designed extracellular matrix biomimetic molecules with different head sequences (RGD or YIGSR), structures (linear or cyclic), and spacer lengths (short or long). These molecules, anchored by a thiol (SH) group, were deposited onto gold surfaces at various concentrations. We assessed the modifications using contact angle measurements, fluorescence imaging, and X-ray Photoelectron Spectroscopy (XPS). We then analyzed the adhesion of retinal cells and HEK293 cells to the modified surfaces by measuring cell density, surface area, and focal adhesion spots, and examined changes in adhesion-related gene and integrin expression.ResultsResults showed that YIGSR biomolecules significantly enhanced retinal cell adhesion, regardless of spacer length. For HEK293 cells, RGD biomolecules were more effective, especially with cyclic RGD and long spacers. Both cell types showed increased expression of specific adhesion integrins and proteins like vinculin and PTK2; these results were in agreement with the adhesion studies, confirming the cell-specific interactions with modified surfaces.ConclusionThis study highlights the importance of tailored biomolecules for improving neural cell adhesion to electrodes. By customizing biomolecules to foster specific and effective interactions with adhesion integrins, our study provides valuable insights for enhancing the integration and functionality of retinal prostheses and other neural implants.

Silk fibroin (SF) is a suitable material for vascular prostheses for small arteries. SF is useful not only as a base material for artificial vascular grafts but also as a coating material. This study prepared three types of transgenic SF (vascular endothelial growth factor (VEGF), Arg-Glu-Asp-Val (REDV), and Tyr-Ile-Gly-Ser-Arg (YIGSR)) incorporating expression factors that are thought to be effective for endothelialization as coating materials. We compared the contribution of these materials to early endothelialization in vivo when using them as a porous transgenic SF coating. A porous coating of transgenic SF containing VEGF, REDV, and YIGSR was applied to a silk small-diameter artificial vascular graft base with a diameter of 1.5 mm and a length of 3 cm. Two and four weeks after implantation of these artificial grafts into the abdominal aorta of rats, they were removed and evaluated by histologic examination. Transgenic SF coating incorporating VEGF and REDV demonstrated higher tissue infiltration and continuous endothelialization in the center of the graft compared to YIGSR at 4 weeks after implantation. VEGF and REDV are capable of endothelialization as early as 4 weeks after implantation, confirming the usefulness of transgenic SF when used as a porous coating.

Silk fibroin (SF) is a suitable material for vascular prostheses for small arteries. SF is useful not only as a base material for artificial vascular grafts but also as a coating material. This study prepared three types of transgenic SF (vascular endothelial growth factor (VEGF), Arg-Glu-Asp-Val (REDV), and Tyr-Ile-Gly-Ser-Arg (YIGSR)) incorporating expression factors that are thought to be effective for endothelialization as coating materials. We compared the contribution of these materials to early endothelialization in vivo when using them as a porous transgenic SF coating. A porous coating of transgenic SF containing VEGF, REDV, and YIGSR was applied to a silk small-diameter artificial vascular graft base with a diameter of 1.5 mm and a length of 3 cm. Two and four weeks after implantation of these artificial grafts into the abdominal aorta of rats, they were removed and evaluated by histologic examination. Transgenic SF coating incorporating VEGF and REDV demonstrated higher tissue infiltration and continuous endothelialization in the center of the graft compared to YIGSR at 4 weeks after implantation. VEGF and REDV are capable of endothelialization as early as 4 weeks after implantation, confirming the usefulness of transgenic SF when used as a porous coating. [ABSTRACT FROM AUTHOR]

This article presents data related to the research article "Systematic optimization of an engineered hydrogel allows for selective control of human neural stem cell survival and differentiation after transplantation in the stroke brain" (P. Moshayedi, L.R. Nih, I.L. Llorente, A.R. Berg, J. Cinkornpumin, W.E. Lowry et al., 2016) [1] and focuses on the biocompatibility aspects of the hydrogel, including its stiffness and the inflammatory response of the transplanted organ. We have developed an injectable hyaluronic acid (HA)-based hydrogel for stem cell culture and transplantation, to promote brain tissue repair after stroke. This 3D biomaterial was engineered to bind bioactive signals such as adhesive motifs, as well as releasing growth factors while supporting cell growth and tissue infiltration. We used a Design of Experiment approach to create a complex matrix environment in vitro by keeping the hydrogel platform and cell type constant across conditions while systematically varying peptide motifs and growth factors. The optimized HA hydrogel promoted survival of encapsulated human induced pluripotent stem cell derived-neural progenitor cells (iPS-NPCs) after transplantation into the stroke cavity and differentially tuned transplanted cell fate through the promotion of glial, neuronal or immature/progenitor states. The highlights of this article include: (1) Data of cell and bioactive signals addition on the hydrogel mechanical properties and growth factor diffusion, (2) the use of a design of Experiment (DOE) approach (M.W. 2 Weible and T. Chan-Ling, 2007) [2] to select multi-factorial experimental conditions, and (3) Inflammatory response and cell survival after transplantation.

This article presents data related to the research article “Systematic optimization of an engineered hydrogel allows for selective control of human neural stem cell survival and differentiation after transplantation in the stroke brain” (P. Moshayedi, L.R. Nih, I.L. Llorente, A.R. Berg, J. Cinkornpumin, W.E. Lowry et al., 2016) [1] and focuses on the biocompatibility aspects of the hydrogel, including its stiffness and the inflammatory response of the transplanted organ. We have developed an injectable hyaluronic acid (HA)-based hydrogel for stem cell culture and transplantation, to promote brain tissue repair after stroke. This 3D biomaterial was engineered to bind bioactive signals such as adhesive motifs, as well as releasing growth factors while supporting cell growth and tissue infiltration. We used a Design of Experiment approach to create a complex matrix environment in vitro by keeping the hydrogel platform and cell type constant across conditions while systematically varying peptide motifs and growth factors. The optimized HA hydrogel promoted survival of encapsulated human induced pluripotent stem cell derived-neural progenitor cells (iPS-NPCs) after transplantation into the stroke cavity and differentially tuned transplanted cell fate through the promotion of glial, neuronal or immature/progenitor states. The highlights of this article include: (1) Data of cell and bioactive signals addition on the hydrogel mechanical properties and growth factor diffusion, (2) the use of a design of Experiment (DOE) approach (M.W. 2 Weible and T. Chan-Ling, 2007) [2] to select multi-factorial experimental conditions, and (3) Inflammatory response and cell survival after transplantation.

Abstract The basement membrane is a specialized extracellular matrix substrate responsible for support and maintenance of epithelial and endothelial structures. Engineered basement membrane-like hydrogel systems have the potential to advance understanding of cell-cell and cell-matrix interactions by allowing precise tuning of the substrate or matrix biochemical and biophysical properties. In this investigation, we developed tunable hydrogel substrates with conjugated bioactive peptides to modulate cell binding and growth factor signaling by endothelial cells. Hydrogels were formed by employing a poly(ethylene glycol) crosslinker to covalently crosslink gelatin polymers and simultaneously conjugate laminin-derived YIGSR peptides or vascular endothelial growth factor (VEGF)-mimetic QK peptides to the gelatin. Rheological characterization revealed rapid formation of hydrogels with similar stiffnesses across tested formulations, and swelling analysis demonstrated dependency on peptide and crosslinker concentrations in hydrogels. Levels of phosphorylated VEGF Receptor 2 in cells cultured on hydrogel substrates revealed that while human umbilical vein endothelial cells (HUVECs) responded to both soluble and conjugated forms of the QK peptide, conditionally-immortalized human glomerular endothelial cells (GEnCs) only responded to the conjugated presentation of the peptide. Furthermore, whereas HUVECs exhibited greatest upregulation in gene expression when cultured on YIGSR- and QK-conjugated hydrogel substrates after 5 days, GEnCs exhibited greatest upregulation when cultured on Matrigel control substrates at the same time point. These results indicate that conjugation of bioactive peptides to these hydrogel substrates significantly influenced endothelial cell behavior in cultures but with differential responses between HUVECs and GEnCs. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

In recent years, there has been an increasing interest toward the covalent binding of bioactive peptides from extracellular matrix proteins on scaffolds as a promising functionalization strategy in the development of biomimetic matrices for tissue engineering. A totally new approach for scaffold functionalization with peptides is based on Molecular Imprinting technology. In this work, imprinted particles with recognition properties toward laminin and fibronectin bioactive moieties were synthetized and used for the functionalization of biomimetic sponges, which were based on a blend of alginate, gelatin, and elastin. Functionalized sponges underwent a complete morphological, physicochemical, mechanical, functional, and biological characterization. Micrographs of functionalized sponges showed a highly porous structure and a quite homogeneous distribution of imprinted particles on their surface. Infrared and thermal analyses pointed out the presence of interactions between blend components. Biodegradation and mechanical properties appeared adequate for the aimed application. The results of recognition tests showed that the deposition on sponges did not alter the specific recognition and binding behavior of imprinted particles. In vitro biological characterization with cardiac progenitor cells showed that early cell adherence was promoted. In vivo analysis showed that developed scaffolds improved cardiac progenitor cell adhesion and differentiation toward myocardial phenotypes.

Substrates for embryonic stem cell culture are typified by poorly defined xenogenic, whole proteins or cellular components that are difficult and expensive to generate, characterize, and recapitulate. Herein, the generation of well-defined scaffolds of Gly-Tyr-Ile-Gly-Ser-Arg (GYIGSR) peptide-functionalized poly( ε -caprolactone) (PCL) aligned nanofibers are used to accelerate the neural lineage commitment and differentiation of D3 mouse embryonic stem cells (mESCs). Gene expression trends and immunocytochemistry analysis were similar to laminin-coated glass, and indicated an earlier differentiation progression than D3 mESCs on laminin. Further, GYIGSR-functionalized nanofiber substrates yielded an increased gene expression of Sox1 , a neural progenitor cell marker, and Tubb3 , Cdh2 , Syp , neuronal cell markers, at early time points. In addition, guidance of neurites was found to parallel the fiber direction. We demonstrate the fabrication of a well-defined, xeno-free functional nanofiber scaffold and demonstrates its use as a surrogate for xenogenic and complex matrixes currently used for the neural differentiation of stem cells ex vivo . Statement of Significance In this paper, we report the use of GYIGSR-functionalized poly( ε -caprolactone) aligned nanofibers as a tool to accelerate the neural lineage commitment and differentiation of D3 mouse embryonic stem cells. The results indicate that functional nanofiber substrates promote faster differentiation than laminin coated substrates. The data suggest that aligned nanofibers and post-electrospinning surface modification with bioactive species can be combined to produce translationally relevant xeno-free substrates for stem cell therapy. Future development efforts are focused on additional bioactive species that are able to function as surrogates for other xenogenic factors found in differentiation media. [ABSTRACT FROM AUTHOR]

Controlling the cell-matrix interaction is a critical factor in the design and fabrication of tissue engineering scaffolds. A particular peptide sequence, Arg-Gly-Asp (RGD peptide), is often used as an adhesion ligand in the engineering of different types of tissues. While in some cases this has been adequate, the use of multiple ligands may be required for the successful engineering of some tissue types. We hypothesized that hydrogels presenting both the RGD peptide and the YIGSR peptide (Tyr-Ile-Gly-Ser-Arg) could successfully regulate the phenotype of PC12 cells, thereby providing a new platform for effective tissue engineering applications. We prepared alginate hydrogels modified with both RGD and YIGSR peptides at several different bulk ligand densities and determined the ways in which PC12 cells can respond to them in vitro . We demonstrate that alginate hydrogels presenting both RGD and YIGSR peptides successfully regulate the proliferation, morphological change, and neuronal differentiation of PC12 cells in vitro . Successful adhesion and proliferation of PC12 cells were dependent on the bulk density of RGD peptides, while neuronal differentiation was significantly enhanced by increasing the YIGSR density. These results suggest that hydrogels presenting multiple adhesion ligands offer many useful applications in tissue engineering approaches. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual-modal MRI/FI gents were made by incorporation of Gd-DTPA and RhB to Laminin/Fibronectin receptor-targeting sequences. • Dual-modal MRI/FI gents possessed low cell cytotoxicity, high relativity, good tumor-targeting and good fluorescent property. • Dual-modal MRI/FI gents showed good performance of combined MRI with FI and improve the accuracy of tumor detection. Dual-modal magnetic resonance/fluorescent imaging (MRI/FI) attracts more and more attentions in diagnosis of tumors. A corresponding dual-modal imaging agent with sufficient tumor sensitivity and specificity should be matched to improve imaging quality. Tripeptide (RGD) and pentapeptide (YIGSR) were selected as the tumor-targeting groups and attached to gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) and rhodamine B (RhB), and then make two novel polypeptide-based derivatives (RGD-Gd-DTPA-RhB and YIGSR-Gd-DTPA-RhB), respectively. These derivatives were further characterized and their properties, such as cell uptake, cell cytotoxicity, MRI and FI assay, were measured. YIGSR-Gd-DTPA-RhB and RGD-Gd-DTPA-RhB had high relaxivity, good tumor-targeting property, low cell cytotoxicity and good red FI in B16F10 melanoma cells. Moreover, YIGSR-Gd-DTPA-RhB and RGD-Gd-DTPA-RhB possessed high uptake to B16F10 melanoma, and then achieve highly enhanced FI and MRI of tumors in mice for a prolonged time. Therefore, YIGSR-Gd-DTPA-RhB and RGD-Gd-DTPA-RhB can be applied as the potential agents for tumor targeted MRI/FI in vivo. [ABSTRACT FROM AUTHOR]

ABSTRACT The 37/67- kDa laminin receptor ( LAMR/ RPSA) was originally identified as a 67- kDa binding protein for laminin, an extracellular matrix glycoprotein that provides cellular adhesion to the basement membrane. LAMR has evolutionary origins, however, as a 37- kDa RPS2 family ribosomal component. Expressed in all domains of life, RPS2 proteins have been shown to have remarkably diverse physiological roles that vary across species. Contributing to laminin binding, ribosome biogenesis, cytoskeletal organization, and nuclear functions, this protein governs critical cellular processes including growth, survival, migration, protein synthesis, development, and differentiation. Unsurprisingly given its purview, LAMR has been associated with metastatic cancer, neurodegenerative disease and developmental abnormalities. Functioning in a receptor capacity, this protein also confers susceptibility to bacterial and viral infection. LAMR is clearly a molecule of consequence in human disease, directly mediating pathological events that make it a prime target for therapeutic interventions. Despite decades of research, there are still a large number of open questions regarding the cellular biology of LAMR, the nature of its ability to bind laminin, the function of its intrinsically disordered C-terminal region and its conversion from 37 to 67 kDa. This review attempts to convey an in-depth description of the complexity surrounding this multifaceted protein across functional, structural and pathological aspects. [ABSTRACT FROM AUTHOR]

The ability to supply suitable blood vessel system is a major challenge for artificial thick tissue engineering. Angiogenesis is a key point during the process of microvascular formation. Many bioactive molecules such as extra cellular matrix (ECM) proteins and adhesion peptides derived from the ECM are applied to promote angiogenesis. In this work, two adhesion peptides, YIGSR and REDV, were selected to modify sodium alginate (ALG) to obtain YIGSR- and REDV-alginate conjugates (ALG-YIGSR, and ALG-REDV, respectively). We mixed the two peptide-conjugates together in a series of concentration ratios to prepare bioactive surfaces for in vitro studies and hydrogel scaffolds for in vivo studies. In vitro studies showed that surfaces modified with 1.09 pmol/mm peptide had the best affinity to human umbilical vein endothelial cells (HUVECs) than that with high or low concentrations of peptides. In addition, surfaces modified with dual peptides could significantly promote HUVECs proliferation, where ALG-YIGSR:ALG-REDV at a mole ratio of 5:1 exhibited the best enhancement ability. Furthermore, the in vivo angiogenesis results demonstrated that hydrogel scaffolds composed of mixed ALG-YIGSR and ALG-REDV at the 5:1 ratio had angiogenic induction potential by stimulating new blood vessel formation, and showed higher blood vessel density than scaffolds composed of a single peptide. These results demonstrated that a mixed combination of peptide alginate conjugates could be a potential scaffold to stimulate and induce angiogenesis in tissue engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: Defects in the corneal stroma caused by trauma or diseases such as macular corneal dystrophy and keratoconus can be detrimental for vision. Development of therapeutic methods to enhance corneal regeneration is essential for treatment of these defects. This paper describes a bioactive peptide nanofiber scaffold system for corneal tissue regeneration. These nanofibers are formed by self-assembling peptide amphiphile molecules containing laminin and fibronectin inspired sequences. Human corneal keratocyte cells cultured on laminin-mimetic peptide nanofibers retained their characteristic morphology, and their proliferation was enhanced compared with cells cultured on fibronectin-mimetic nanofibers. When these nanofibers were used for damaged rabbit corneas, laminin-mimetic peptide nanofibers increased keratocyte migration and supported stroma regeneration. These results suggest that laminin-mimetic peptide nanofibers provide a promising injectable, synthetic scaffold system for cornea stroma regeneration. [Copyright &y& Elsevier]

Abstract: End-functional PLLA nanofibers were fabricated into mats of random or aligned fibers and functionalized post-spinning using metal-free “click chemistry” with the peptide Tyr-Ile-Gly-Ser-Arg (YIGSR). Fibers that were both aligned and functionalized with YIGSR were found to significantly increase the fraction of mouse embryonic stem cells (mESC) expressing neuron-specific class III beta-tubulin (TUJ1), the level of neurite extension and gene expression for neural markers compared to mESC cultured on random fiber mats and unfunctionalized matrices. Precise functionalization of degradable polymers with bioactive peptides created translationally-relevant materials that capitalize on the advantages of both synthetic and natural systems, while mitigating the classic limitations of each. [Copyright &y& Elsevier]

Highlights: [•] Grooved PLGA films incorporated with RGD/YIGSR peptides were fabricated. [•] Cell adhesion of C2C12 myoblasts was increased by surface presenting peptide, while cell morphology was modulated by surface topography. [•] Myotube formation was eventually enhanced by the combination of surface peptide and topography. [Copyright &y& Elsevier]

Abstract: Biocompatible and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] substrates were modified to improve the attachment of porcine urothelial cell culture. The pristine copolymer exhibits excellent mechanical properties to replace the bladder tissue, but its surface lacks chemical functionalities to interact with cells. Thus, wet chemical treatments based on NaOH and ethylenediamine in aqueous [ED(aq)] and isopropanol [ED(isoOH)] media to functionalize the P(HB-co-HHx) films surfaces were compared. Among these treatments, short ED(aq) treatment was able to decrease the hydrophobicity, rendering a surface with amino groups and without a significant alteration of the mechanical properties. Furthermore, to enhance the interaction with urothelial cells, laminin derived YIGSR sequence was covalently bound to these amino functionalized substrates. The focal attachment was clearly improved with this last treatment, comparing with those results found with the unmodified and first-step functionalized P(HB-co-HHx). [Copyright &y& Elsevier]

Abstract: The dermal ECM is synthesized from fibroblasts and is primarily compromised of fibrillar collagen and elastic fibers, which support the mechanical strength and resiliency of skin, respectively. Laminin, a major glycoprotein located in the basement membrane, promotes cell adhesion, cell growth, differentiation, and migration. The laminin tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptide, corresponding to the 929–933 sequence of the β1 chain, is known to be a functional motif with effects on the inhibition of tumor metastasis, the regulation of sensory axonal response and the inhibition of angiogenesis through high affinity to the 67kDa laminin receptor. In this study, we identified a novel function of the YIGSR peptide to enhance collagen synthesis in human dermal fibroblasts. To elucidate this novel function regarding collagen synthesis, we treated human dermal fibroblasts with YIGSR peptide in both a time- and dose-dependent manner. According to subsequent experiments, we found that the YIGSR peptide strongly enhanced collagen type 1 synthesis without changing cell proliferation or cellular MMP-1 level. This YIGSR peptide-mediated collagen type 1 synthesis was modulated by FAK inhibitor and MEK inhibitor. This study clearly reveals that YIGSR peptide plays a novel function on the collagen type 1 synthesis of dermal fibroblasts and also suggests that YIGSR is a strong candidate peptide for the treatment of skin aging and wrinkles. [Copyright &y& Elsevier]

Background: Tumor-targeted delivery is a desirable approach to improve therapeutic outcome of anticancer drug due to enhanced efficacy and reduced toxicity. Purpose: The present study was aimed to target laminin receptor over-expressed tumor cells using YIGSR (Tyr-Ile-Gly-Ser-Arg) conjugated etoposide loaded micelles in the treatment of metastasis. Methods: YIGSR conjugated micelles prepared using synthesized carboxyl and methoxy terminated poly(ethylene glycol)-b-poly(εϵ-caprolactone) block copolymers were evaluated for it efficacy against highly metastatic B16F10 cell lines conducting cytotoxicity, colony formation, cell migration, cellular uptake and flow cytometry studies. The in-vivo antimetastatic effect of micelles was evaluated using experimental metastatic model on C57BL/6 mice. Results: YIGSR conjugated micelles of particle size 45.2 ± 3.77 nm and zeta potential of−5.7 ± 1.3 mV demonstrated enhanced cytotoxicity and cellular uptake with significant reduction in colony formation and cell migration activities compared to non-conjugated micelles. Furthermore, a markedly inhibition in lung colony formation was observed with these micelles. Discussion: An enhanced cellular internalization of YIGSR conjugated micelles due to laminin receptor based endocytosis resulted in to higher cytotoxicity as well as antimetastatic effect against highly metastatic B16F10 cells. Conclusion: These studies indicate that YIGSR conjugated nanocarrier can be a promising approach in the treatment of tumor metastasis. [ABSTRACT FROM AUTHOR]

Abstract: The laminin tyrosine–isoleucine–glycine–serine–arginine (YIGSR) peptide, corresponding to the 929-933 sequence of β1 chain, is known to inhibit tumor growth and metastasis. In the present study, we observed that YIGSR not only inhibited the growth and migration of prostate cancer cells in a dose-dependent manner but also decreased mitochondrial membrane potential, inhibited ATP synthesis and increased caspase-9 activity. Investigation into the interaction of YIGSR with 67LR, the receptor for laminin and polyphenol (­) epigallocatechin-3-gallate (EGCG) employing MVD (Molegro Virtual Docker, an integrated platform for predicting protein ligand interactions), revealed that the binding site of YIGSR was the same as that of EGCG that explains as to why YIGSR is able to inhibit the cytotoxicity of EGCG against PC-3 cells. [Copyright &y& Elsevier]

Polyurethane (PU) is widely used as a cardiovascular biomaterial due to its good mechanical properties and hemocompatibility, but it is not adhesive to endothelial cells (ECs). Cell adhesive peptides, GRGDS and YIGSR, were found to promote adhesion and spreading of ECs and showed a synergistic effect when both of them were used. In this study, a surface modification was designed to fabricate an EC-active PU surface capable of promoting endothelialization using the peptides and poly(ethylene glycol) (PEG) spacer, The modified PU surfaces were characterized in vitro. The density of the grafted PEG on the PU surface was measured by acid-base back titration to the terminal-free isocyanate groups. The successful immobilization of peptides was confirmed by amino acid analysis, following hydrolysis, and contact angle measurement. The uniform distribution of peptides on the surface was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). To evaluate the EC adhesive property, cell viability test using human umbilical vein EC (HUVEC) was investigated in vitro and enhanced endothelialization was characterized by the introduction of cell adhesive peptides, GRGDS and YIGSR, and PEG spacer. Therefore, GRGDS and YIGSR co-immobilized PU surfaces can be applied to an EC-specific vascular graft with long-term patency by endothelialization. [ABSTRACT FROM AUTHOR]

Thrombosis and intimal hyperplasia are the principal causes of small‐diameter vascular graft failure. To improve the long‐term patency of polyurethane vascular grafts, we have incorporated both poly(ethylene glycol) and a diazeniumdiolate nitric oxide (NO) donor into the backbone of polyurethane to improve thromboresistance. Additionally, we have incorporated the laminin‐derived cell adhesive peptide sequence YIGSR to encourage endothelial cell adhesion and migration, while NO release encourages endothelial cell proliferation. NO production by polyurethane films under physiological conditions demonstrated biphasic release, in which an initial burst of 70% of the incorporated NO was released within 2 days, followed by sustained release over 2 months. Endothelial cell proliferation in the presence of the NO‐releasing material was increased as compared to control polyurethane, and platelet adhesion to polyethylene glycol‐containing polyurethane was decreased significantly with the addition of the NO donor. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008 [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the effects of cell-adhesion peptides incorporated into collagen scaffolds on corneal epithelial cell stratification. Peptides (YIGSR, YIGSRIKVAV, IKVAVYIGSR and negative control YISGR) were first chemically attached to dendrimers. The peptide-modified dendrimers were then used as collagen cross-linkers. This permitted the incorporation of the peptides into the bulk structure of the collagen gels. The amount of peptide incorporated into the collagen gels was determined by 125I radiolabelling to be between 0.064 and 6.4 μg/mg collagen for YIGSR, and between 0.1187 to 11.87 μg/mg collagen for YIGSRIKVAV and IKVAVYIGSR. Corneal epithelial cell monolayers were grown on the surface of the collagen scaffolds and then exposed to conditions that promoted stratification as a stratified epithelial layer is desired in a tissue-engineered cornea. It was found that all of the incorporated peptides promoted stratification of the cells with the exception of the negative control YISGR. A synergistic effect of the combined sequences from laminin was observed, with the orientation of the peptide sequences having a great impact on the ability of the materials to promote cell stratification. [ABSTRACT FROM AUTHOR]

Abstract: Residual dendrimer amine groups were modified with incorporate COOH group containing biomolecules such as cell adhesion peptides into collagen scaffolds. YIGSR, as a model cell adhesion peptide, was incorporated into both the bulk structure of the gels and onto the gel surface. The effects of the peptide modified collagen gels on corneal epithelial cell behavior were examined with an aim of improving the potential of these materials as tissue-engineering scaffolds. YIGSR was first chemically attached to dendrimers and the YIGSR attached dendrimers were then used as collagen crosslinkers, incorporating the peptide into the bulk structure of the collagen gels. YIGSR was also attached to the surface of dendrimer crosslinked collagen gels through reaction with excess amine groups. The YIGSR modified dendrimers were characterized by H-NMR and MALDI mass spectra. The amount of YIGSR incorporated into collagen gels was determined by 125I radiolabelling at maximum to be 3.1–3.4×10−2 mg/mg collagen when reacted with the bulk and 88.9–95.6μg/cm2 when attached to the surface. The amount of YIGSR could be tuned by varying the amount of peptide reacted with the dendrimer or the amount of modified dendrimer used in the crosslinking reaction. It was found that YIGSR incorporation into the bulk and YIGSR modification of surface promoted the adhesion and proliferation of human corneal epithelial cells as well as neurite extension from dorsal root ganglia. [Copyright &y& Elsevier]

Abstract: We developed a new biomaterial effective for nerve regeneration consisting of molecularly aligned chitosan with laminin peptides bonded covalently. Molecularly aligned chitosan was prepared from crab (Macrocheira kaempferi) tendons by ethanol treatment and 4wt%-NaOH aqueous solutions to remove proteins and calcium phosphate, followed by deacetyl treatment using a 50wt%-NaOH aqueous solution at 100°C. Molecularly aligned tendon chitosan was chemically thiolated by reacting 4-thiobutyrolactone with the chitosan amino group. The introduction of thiol groups and their distribution to tendon chitosan and chitosan cast film were confirmed using ATR FT-IR, 1H-NMR, and EDS. The 1.24μmol/g of thiol groups introduced on the surface of tendon chitosan and the chitosan cast film was confirmed using ultraviolet (UV) spectra. Thiol groups of cysteine located at the end of synthetic laminin peptides were then reacted chemically with thiolated chitosan to form chitosan-S-S-laminin peptide. YIGSR estimated at 0.92μmol/g and IKVAV estimated at 0.28μmol/g on thiolated tendon chitosan were confirmed using UV spectra. YIGSR was estimated at 0.85μmol/g and IKVAV was estimated at 0.34μmol/g on the thiolated chitosan cast film. [Copyright &y& Elsevier]

Polyurethanes have been investigated for use as vascular grafts due to their excellent mechanical properties and relatively good biocompatibility. However, poor retention of endothelial cells and thrombogenicity in vivo remain problematic for vascular graft applications. The peptide YIGSR has been shown to increase endothelial cell adhesion but not attachment of platelets, suggesting its possible utility for vascular graft applications. In this study, a bioactive polyurethaneurea has been synthesized by incorporating GGGYIGSRGGGK peptide sequences into the polymer backbone. Successful incorporation of the peptides was confirmed by NMR, contact angle measurement and ESCA. Uniform distribution of peptides on the surface was observed using a fluorescent probe capable of reacting with tyrosine residues on the peptides. Hard segment domains were visualized using tapping mode AFM. Endothelial cell adhesion, spreading, proliferation, migration and extra-cellular matrix production were improved on bioactive polyurethaneurea compared to control polyurethaneurea. Competitive inhibition of endothelial cell attachment and spreading by soluble YIGSR peptides indicated that cell adhesion and spreading were specifically mediated by YIGSR-sensitive cell adhesion receptor, not just by changed surface properties. There was no significant difference in the number of adherent platelets. Therefore, this bioactive polyurethanurea may improve vascular graft endothelialization without increasing thrombogenicity. [ABSTRACT FROM AUTHOR]

In order to facilitate the adhesion of corneal epithelial cells to a poly dimethyl siloxane (PDMS) substrate ultimately for the development of a synthetic keratoprosthesis, PDMS surfaces were modified by covalent attachment of combinations of cell adhesion and synergistic peptides derived from laminin and fibronectin. Peptides studied included YIGSR and its synergistic peptide PDSGR from laminin and the fibronectin derived RGDS and PHSRN. Surfaces were modified with combinations of peptides determined by an experimental design. Peptide surface densities, measured using 125-I labeled tyrosine containing analogs, were on the order of pmol/cm[sup 2]. Surface density varied as a linear function of peptide concentration in the reaction solution, and was different for the different peptides examined. The lowest surface density at all solution fractions was obtained with GYRGDS, while the highest density was consistently obtained with GYPDSGR. These results provide evidence that the surfaces were modified with multiple peptides. Water contact angles and XPS results provided additional evidence for differences in the chemical composition of the various surfaces. Significant differences in the adhesion of human corneal epithelial cells to the modified surfaces were noted. Statistical analysis of the experimental adhesion results suggested that solution concentration YIGSR, RGDS, and PHSRN as well as the interaction effect of YIGSR and PDSGR had a significant effect on cell interactions. Modification with multiple peptides resulted in greater adhesion than modification with single peptides only. Surface modification with a control peptide PPSRN in place of PHSRN resulted in a decrease in cell adhesion in virtually all cases. These results suggest that surface modification with appropriate combinations of cell adhesion peptides and synergistic peptides may result in improved cell surface interactions. [ABSTRACT FROM AUTHOR]

Epithelialization of a corneal implant is a desirable property. In this study we compared surface modification of poly (2-hydroxyethyl methacrylate) (pHEMA) with the cell adhesion peptides RGDS and YIGSR. Various parameters in the tresyl chloride activation and modification reactions were considered in order to maximize surface coverage with the peptide including tresyl chloride reaction solvent, tresyl chloride reaction time, tresyl chloride concentration, peptide concentration, and peptide reaction pH. Surface chemistry and corneal epithelial cell adhesion to the modified surfaces were examined. X-ray photoelectron spectroscopy data suggested that while peptide modification had occurred, surface coverage with the peptide was incomplete. Acetone was found to result in a higher fraction of nitrogen and surface bound carboxyl groups compared to dioxane and ether. Furthermore, corneal epithelial cell adhesion to the surfaces for which acetone was used for the activation reaction was significantly greater. Statistical analysis of the various samples suggests that lower peptide concentrations and higher tresyl chloride reaction times result in better cell adhesion. Furthermore, modification with YIGSR resulted in higher surface concentrations and better cell adhesion than modification with RGDS. Little or no cell adhesion was noted on the unmodified pHEMA controls. Protein adsorption results suggest that the differences in cell adhesion cannot be attributed to differences in serum protein adsorption from the culture medium. We conclude that YIGSR modified surfaces have significant potential for further development in corneal applications. [ABSTRACT FROM AUTHOR]

This study describes a method for the modification of polyurethane small-diameter (5 mm) vascular prostheses obtained with the phase inversion method. The modification process involves two steps: the introduction of a linker (acrylic acid) and a peptide (REDV and YIGSR). FTIR and XPS analysis confirmed the process of chemical modification. The obtained prostheses had a porosity of approx. 60%, Young's Modulus in the range of 9–11 MPa, and a water contact angle around 40°. Endothelial (EC) and smooth muscle (SMC) cell co-culture showed that the surfaces modified with peptides increase the adhesion of ECs. At the same time, SMCs adhesion was low both on unmodified and peptide-modified surfaces. Analysis of blood-materials interaction showed high hemocompatibility of obtained materials. The whole blood clotting time assay showed differences in the amount of free hemoglobin present in blood contacted with different materials. It can be concluded that the peptide coating increased the hemocompatibility of the surface by increasing ECs adhesion and, at the same time, decreasing platelet adhesion. When comparing both types of peptide coatings, more promising results were obtained for the surfaces coated with the YISGR than REDV-coated prostheses. [ABSTRACT FROM AUTHOR]

In recent years, there has been an increasing interest toward the covalent binding of bioactive peptides from extracellular matrix proteins on scaffolds as a promising functionalization strategy in the development of biomimetic matrices for tissue engineering. A totally new approach for scaffold functionalization with peptides is based on Molecular Imprinting technology. In this work, imprinted particles with recognition properties toward laminin and fibronectin bioactive moieties were synthetized and used for the functionalization of biomimetic sponges, which were based on a blend of alginate, gelatin, and elastin. Functionalized sponges underwent a complete morphological, physicochemical, mechanical, functional, and biological characterization. Micrographs of functionalized sponges showed a highly porous structure and a quite homogeneous distribution of imprinted particles on their surface. Infrared and thermal analyses pointed out the presence of interactions between blend components. Biodegradation and mechanical properties appeared adequate for the aimed application. The results of recognition tests showed that the deposition on sponges did not alter the specific recognition and binding behavior of imprinted particles. In vitro biological characterization with cardiac progenitor cells showed that early cell adherence was promoted. In vivo analysis showed that developed scaffolds improved cardiac progenitor cell adhesion and differentiation toward myocardial phenotypes.

Abnormal migration and proliferation of endothelial cells (EC) drive neovascular retinopathies. While anti-VEGF treatment slows progression, pathology is often supported by decrease in intraocular pigment epithelium-derived factor (PEDF), an endogenous inhibitor of angiogenesis. A surface helical 34-mer peptide of PEDF, comprising this activity, is efficacious in animal models of neovascular retina disease but remains impractically large for therapeutic use. We sought smaller fragments within this sequence that mitigate choroidal neovascularization (CNV). Expecting rapid intravitreal (IVT) clearance, we also developed a method to reversibly attach peptides to nano-carriers for extended delivery. Synthetic fragments of 34-mer yielded smaller anti-angiogenic peptides, and N-terminal capping with dicarboxylic acids did not diminish activity. Charge restoration via substitution of an internal aspartate by asparagine improved potency, achieving low nM apoptotic response in VEGF-activated EC. Two optimized peptides (PEDF 335, 8-mer and PEDF 336, 9-mer) were tested in a mouse model of laser-induced CNV. IVT injection of either peptide, 2–5 days before laser treatment, gave significant CNV decrease at day +14 post laser treatment. The 8-mer also decreased CNV, when administered as eye drops. Also examined was a nanoparticle-conjugate (NPC) prodrug of the 9-mer, having positive zeta potential, expected to display longer intraocular residence. This NPC showed extended efficacy, even when injected 14 days before laser treatment. Neither inflammatory cells nor other histopathologic abnormalities were seen in rabbit eyes harvested 14 days following IVT injection of PEDF 336 (>200 μg). No rabbit or mouse eye irritation was observed over 12–17 days of PEDF 335 eye drops (10 mM). Viability was unaffected in 3 retinal and 2 choroidal cell types by PEDF 335 up to 100 μM, PEDF 336 (100 μM) gave slight growth inhibition only in choroidal EC. A small anti-angiogenic PEDF epitope (G- Y - D - L-Y-R-V) was identified, variants (adipic-Sar- Y - N - L-Y-R-V) mitigate CNV, with clinical potential in treating neovascular retinopathy. Their shared active motif, Y - - - R, is found in laminin (Ln) peptide YIGSR, which binds Ln receptor 67LR, a known high-affinity ligand of PEDF 34-mer. • 18 to 34-mer peptides from PEDF are potently anti-angiogenic but impractically large for therapeutic use. • Modified 8 to 9-mer subfragments were discovered to induce EC apoptosis and inhibit CNV via intravitreal injection. • Anti-VEGF combination is not beneficial, 8-mer eye drops inhibited CNV, implies use in corneal neovascularization. • Poly-cationic nanoparticle conjugate of 9-mer shows extended CNV protection. [ABSTRACT FROM AUTHOR]

This article presents data related to the research article "Systematic optimization of an engineered hydrogel allows for selective control of human neural stem cell survival and differentiation after transplantation in the stroke brain" (P. Moshayedi, L.R. Nih, I.L. Llorente, A.R. Berg, J. Cinkornpumin, W.E. Lowry et al., 2016) [1] and focuses on the biocompatibility aspects of the hydrogel, including its stiffness and the inflammatory response of the transplanted organ. We have developed an injectable hyaluronic acid (HA)-based hydrogel for stem cell culture and transplantation, to promote brain tissue repair after stroke. This 3D biomaterial was engineered to bind bioactive signals such as adhesive motifs, as well as releasing growth factors while supporting cell growth and tissue infiltration. We used a Design of Experiment approach to create a complex matrix environment in vitro by keeping the hydrogel platform and cell type constant across conditions while systematically varying peptide motifs and growth factors. The optimized HA hydrogel promoted survival of encapsulated human induced pluripotent stem cell derived-neural progenitor cells (iPS-NPCs) after transplantation into the stroke cavity and differentially tuned transplanted cell fate through the promotion of glial, neuronal or immature/progenitor states. The highlights of this article include: (1) Data of cell and bioactive signals addition on the hydrogel mechanical properties and growth factor diffusion, (2) the use of a design of Experiment (DOE) approach (M.W. 2 Weible and T. Chan-Ling, 2007) [2] to select multi-factorial experimental conditions, and (3) Inflammatory response and cell survival after transplantation.

Understanding β cell-extracellular matrix (ECM) interactions can advance our knowledge of the mechanisms that control glucose homeostasis and improve culture methods used in islet transplantation for the treatment of diabetes. Laminin is the main constituent of the basement membrane and is involved in pancreatic β cell survival and function, even enhancing glucose-stimulated insulin secretion. Most of the studies on cell responses towards laminin have focused on integrin-mediated interactions, while much less attention has been paid on non-integrin receptors, such as the 67 kDa laminin receptor (67LR). The specificity of the receptor-ligand interaction through the adhesion of INS-1 cells (a rat insulinoma cell line) to CDPGYIGSR-, GRGDSPC- or CDPGYIGSR + GRGDSPC-covered surfaces was evaluated. Also, the effects of the 67LR knocking down over glucose-stimulated insulin secretion were investigated. Culture of the INS-1 cells on the bioactive surfaces was improved compared to the low-fouling carboxymethyl dextran (CMD) surfaces, while downregulation of the 67LR resulted in reduced cell adhesion to surfaces bearing the CDPGYIGSR peptide. Glucose-stimulated insulin secretion was hindered by downregulation of the 67LR, regardless of the biological motif available on the biomimetic surfaces on which the cells were cultured. This finding illustrates the importance of the 67LR in glucose-stimulated insulin secretion and points to a possible role of the 67LR in the mechanisms of insulin secretion., (Copyright © 2013 John Wiley & Sons, Ltd.)

End-functional PLLA nanofibers were fabricated into mats of random or aligned fibers and functionalized post-spinning using metal-free "click chemistry" with the peptide Tyr-Ile-Gly-Ser-Arg (YIGSR). Fibers that were both aligned and functionalized with YIGSR were found to significantly increase the fraction of mouse embryonic stem cells (mESC) expressing neuron-specific class III beta-tubulin (TUJ1), the level of neurite extension and gene expression for neural markers compared to mESC cultured on random fiber mats and unfunctionalized matrices. Precise functionalization of degradable polymers with bioactive peptides created translationally-relevant materials that capitalize on the advantages of both synthetic and natural systems, while mitigating the classic limitations of each., (Copyright © 2013 Elsevier Ltd. All rights reserved.)