Peptide Interfacial Biomaterials Improve Endothelial Cell Adhesion and Spreading on Synthetic Polyglycolic Acid Materials

Integrins in Cardiovascular Health and Disease: Molecular Mechanisms and Therapeutic Opportunities

Cardiovascular diseases, including atherosclerosis, hypertension, and heart failure, remain the leading cause of global mortality, with endothelial dysfunction and vascular remodeling as critical contributors. Integrins, as transmembrane adhesion proteins, are central regulators of cell adhesion, migration, and signaling, playing a pivotal role in maintaining vascular homeostasis and mediating pathological processes such as inflammation, angiogenesis, and extracellular matrix remodeling. This article comprehensively examines the role of integrins in the pathogenesis of cardiovascular diseases, focusing on their dysfunction in endothelial cells and interactions with inflammatory mediators, such as TNF-α. Molecular mechanisms of integrin action are discussed, including their involvement in mechanotransduction, leukocyte adhesion, and signaling pathways that regulate vascular integrity. The review also highlights experimental findings, such as the use of specific integrin-targeting plasmids and immunofluorescence to elucidate integrin functions under inflammatory conditions. Additionally, potential therapeutic strategies are explored, including the development of integrin inhibitors, monoclonal antibodies, and their application in regenerative medicine. These approaches aim not only to mitigate pathological vascular remodeling but also to promote tissue repair and angiogenesis. By bridging insights from molecular studies with their translational potential, this work underscores the promise of integrin-based therapies in advancing the management and treatment of cardiovascular diseases.

Transcriptome Analysis of Human Vascular Smooth Muscle Cells Cultured on a Polyglycolic Acid Mesh Scaffold

To construct tissue-engineered blood vessels (TEBVs) in vitro, it is necessary to transfer seed cells to three-dimensional (3D) scaffolds for culture. However, what happens to the behavior of the cells after they are transferred to the scaffold is unclear. Therefore, in this study, a transcriptome analysis was used to characterize the differentially expressed genes (DEGs) of vascular smooth muscle cells (VSMCs) before and after transfer to 3D polyglycolic acid (PGA) scaffolds and to understand the changes in functional gene expression in the early stage of 3D culture. Transcriptome sequencing results showed that DEGs in the seed cells were mainly enriched in cell proliferation and cell-cell adhesion. The DEGs of cells grown in a 3D PGA scaffold (PGA-VSMCs) were mainly enriched in signal transduction. Furthermore, we found that ERK1/2 was significantly activated in PGA-VSMCs and inhibiting the phosphorylation level of ERK 1/2 in PGA-VSMCs significantly increased the expression of elastin. In conclusion, the PGA scaffold material altered gene expression in VSMCs and affected the elastin production. This study advances our understanding of biomaterial-cell interactions and provides valuable insights for improving the cultivation of TEBVs.

3D-bioprinted cardiac tissues and their potential for disease modeling

Heart diseases cause over 17.9 million total deaths globally, making them the leading source of mortality. The aim of this review is to describe the characteristic mechanical, chemical and cellular properties of human cardiac tissue and how these properties can be mimicked in 3D bioprinted tissues. Furthermore, the authors review how current healthy cardiac models are being 3D bioprinted using extrusion-, laser- and inkjet-based printers. The review then discusses the pathologies of cardiac diseases and how bioprinting could be used to fabricate models to study these diseases and potentially find new drug targets for such diseases. Finally, the challenges and future directions of cardiac disease modeling using 3D bioprinting techniques are explored.

Nanoparticle and Bioparticle Deposition Kinetics: Quartz Microbalance Measurements

Controlled deposition of nanoparticles and bioparticles is necessary for their separation and purification by chromatography, filtration, food emulsion and foam stabilization, etc. Compared to numerous experimental techniques used to quantify bioparticle deposition kinetics, the quartz crystal microbalance (QCM) method is advantageous because it enables real time measurements under different transport conditions with high precision. Because of its versatility and the deceptive simplicity of measurements, this technique is used in a plethora of investigations involving nanoparticles, macroions, proteins, viruses, bacteria and cells. However, in contrast to the robustness of the measurements, theoretical interpretations of QCM measurements for a particle-like load is complicated because the primary signals (the oscillation frequency and the band width shifts) depend on the force exerted on the sensor rather than on the particle mass. Therefore, it is postulated that a proper interpretation of the QCM data requires a reliable theoretical framework furnishing reference results for well-defined systems. Providing such results is a primary motivation of this work where the kinetics of particle deposition under diffusion and flow conditions is discussed. Expressions for calculating the deposition rates and the maximum coverage are presented. Theoretical results describing the QCM response to a heterogeneous load are discussed, which enables a quantitative interpretation of experimental data obtained for nanoparticles and bioparticles comprising viruses and protein molecules.

Phage Display to Augment Biomaterial Function

Biomaterial design relies on controlling interactions between materials and their biological environments to modulate the functions of proteins, cells, and tissues. Phage display is a powerful tool that can be used to discover peptide sequences with high affinity for a desired target. When incorporated into biomaterial design, peptides identified via phage display can functionalize material surfaces to control the interaction between a biomaterial and its local microenvironment. A targeting peptide has high specificity for a given target, allowing for homing a specific protein, cell, tissue, or other material to a biomaterial. A functional peptide has an affinity for a given protein, cell, or tissue, but also modulates its target's activity upon binding. Biomaterials can be further enhanced using a combination of targeting and/or functional peptides to create dual-functional peptides for bridging two targets or modulating the behavior of a specific protein or cell. This review will examine current and future applications of phage display for the augmentation of biomaterials.

Biodegradable Nanopolymers in Cardiac Tissue Engineering: From Concept Towards Nanomedicine

Cardiovascular diseases are the number one cause of heart failure and death in the world, and the transplantation of the heart is an effective and viable choice for treatment despite presenting many disadvantages (most notably, transplant heart availability). To overcome this problem, cardiac tissue engineering is considered a promising approach by using implantable artificial blood vessels, injectable gels, and cardiac patches (to name a few) made from biodegradable polymers. Biodegradable polymers are classified into two main categories: natural and synthetic polymers. Natural biodegradable polymers have some distinct advantages such as biodegradability, abundant availability, and renewability but have some significant drawbacks such as rapid degradation, insufficient electrical conductivity, immunological reaction, and poor mechanical properties for cardiac tissue engineering. Synthetic biodegradable polymers have some advantages such as strong mechanical properties, controlled structure, great processing flexibility, and usually no immunological concerns; however, they have some drawbacks such as a lack of cell attachment and possible low biocompatibility. Some applications have combined the best of both and exciting new natural/synthetic composites have been utilized. Recently, the use of nanostructured polymers and polymer nanocomposites has revolutionized the field of cardiac tissue engineering due to their enhanced mechanical, electrical, and surface properties promoting tissue growth. In this review, recent research on the use of biodegradable natural/synthetic nanocomposite polymers in cardiac tissue engineering is presented with forward looking thoughts provided for what is needed for the field to mature.

Aptamer supported in vitro endothelialization of poly(ether imide) films

Implantation of synthetic small-diameter vascular bypass grafts is often associated with an increased risk of failure, due to thrombotic events or late intimal hyperplasia. As one of the causes an insufficient hemocompatibility of the artificial surface is discussed. Endothelialization of synthetic grafts is reported to be a promising strategy for creating a self-renewing and regulative anti-thrombotic graft surface. However, the establishment of a shear resistant cell monolayer is still challenging. In our study, cyto- and immuno-compatible poly(ether imide) (PEI) films were explored as potential biomaterial for cardiovascular applications. Recently, we reported that the initial adherence of primary human umbilical vein endothelial cells (HUVEC) was delayed on PEI-films and about 9 days were needed to establish a confluent and almost shear resistant HUVEC monolayer. To accelerate the initial adherence of HUVEC, the PEI-film surface was functionalized with an aptamer-cRGD peptide based endothelialization supporting system. With this functionalization the initial adherence as well as the shear resistance of HUVEC on PEI-films was considerable improved compared to the unmodified polymer surface. The in vitro results confirm the general applicability of aptamers for an efficient functionalization of substrate surfaces.

Dual-Peptide-Functionalized Nanofibrous Scaffolds Recruit Host Endothelial Progenitor Cells for Vasculogenesis to Repair Calvarial Defects

Vasculogenesis (de novo formation of vessels) induced by endothelial progenitor cells (EPCs) is requisite for vascularized bone regeneration. However, there exist few available options for promoting vasculogenesis within artificial bone grafts except for exogenous EPC transplantation, which suffers from the source of EPC, safety, cost, and time concerns in clinical applications. This study aimed at endogenous EPC recruitment for vascularized bone regeneration by using a bioinspired EPC-induced graft. The EPC-induced graft was created by immobilizing two bioactive peptides, WKYMVm and YIGSR, on the surface of poly(ε-caprolactone) (PCL)/poliglecaprone (PGC) nanofibrous scaffolds via a polyglycolic acid (PGA)-binding peptide sequence. Remarkable immobilization efficacy of WKYMVm and YIGSR peptides and their sustained release (over 14 days) from scaffolds were observed. In vivo and in vitro studies showed robust recruitment of EPCs, which subsequently contributed to early vasculogenesis and ultimate bone regeneration. The dual-peptide-functionalized nanofibrous scaffolds proposed in this study provide a promising therapeutic strategy for vasculogenesis in bone defect repair.

Endothelialization and characterization of titanium dioxide-coated gas-exchange membranes for application in the bioartificial lung

Fouling on the gas-exchange hollow-fiber membrane (HFM) of extracorporeal membrane oxygenation (ECMO) devices by blood components and pathogens represents the major hurdle to their long-term application in patients with lung deficiency or unstable hemodynamics. Although patients are treated with anticoagulants, deposition of blood proteins onto the membrane surface may still occur after few days, leading to insufficient gas transfer and, consequently, to device failure. The aim of this study was to establish an endothelial cell (EC) monolayer onto the gas-exchange membrane of an ECMO device with a view to developing a hemocompatible bioartificial lung. Poly(4-methyl-1-pentene) (PMP) gas-exchange membranes were coated with titanium dioxide (TiO₂), using the pulsed vacuum cathodic arc plasma deposition (PVCAPD) technique, in order to generate a stable interlayer, enabling cell adhesion onto the strongly hydrophobic PMP membrane. The TiO₂ coating reduced the oxygen transfer rate (OTR) of the membrane by 22%, and it successfully mediated EC attachment. The adhered ECs formed a confluent monolayer, which retained a non-thrombogenic state and showed cell-to-cell, as well as cell-to-substrate contacts. The established monolayer was able to withstand physiological shear stress and possessed a "self-healing" capacity at areas of induced monolayer disruption. The study demonstrated that the TiO₂ coating mediated EC attachment and the establishment of a functional EC monolayer.

STATEMENT OF SIGNIFICANCE

Surface endothelialization is considered an effective approach to achieve complete hamocompatibility of blood-contacting devices. Several strategies to enable endothelial cell adhesion onto stents and vascular prostheses have already been described in the literature. However, only few studies investigated the feasibility of establishing an endothelial monolayer onto the gas exchange membrane of ECMO devices, using peptides or proteins that were weakly adsorbed via dip coating techniques. This study demonstrated the effectiveness of an alternative and stable titanium dioxide coating for gas-exchange membranes, which enabled the establishment of a confluent, functional and non-activated endothelial monolayer, while maintaining oxygen permeability.

Surface functionalization of polymer substrates with hydroxyapatite using polymer-binding peptides

Material-binding peptides are used as non-covalent bond linkers for surface functionalization because they bind to materials under mild conditions without affecting the properties of the materials and are functionalized by conjugating with other molecules. In the present study, the surface functionalization of polyetherimide (PEI) with hydroxyapatite (HAp) was examined using two types of PEI-binding peptides conjugated with other sequences. One peptide consisted of PEI-binding peptide p1 (TGADLNT) and a triasparate sequence for the biomimetic mineralization of HAp in simulated body fluids (SBFs), while the other consisted of p1 and HAp-binding peptide (HABP, CMLPHHGAC) for the immobilization of HAp and amorphous calcium phosphate (ACP) nanoparticles. The results obtained revealed deposits of HAp on PEI films treated with the peptide consisting of p1 and triasparate. HAp and ACP nanoparticles were immobilized on PEI films treated with peptides consisting of p1 and HABP, and immersion of the resultant substrates in SBFs completely covered the surfaces of PEI films with HAp.

An In Vitro Comparison of the Incorporation, Growth, and Chondrogenic Potential of Human Bone Marrow versus Adipose Tissue Mesenchymal Stem Cells in Clinically Relevant Cell Scaffolds Used for Cartilage Repair

AIM

To compare the incorporation, growth, and chondrogenic potential of bone marrow (BM) and adipose tissue (AT) mesenchymal stem cells (MSCs) in scaffolds used for cartilage repair.

METHODS

Human BM and AT MSCs were isolated, culture expanded, and characterised using standard protocols, then seeded into 2 different scaffolds, Chondro-Gide or Alpha Chondro Shield. Cell adhesion, incorporation, and viable cell growth were assessed microscopically and following calcein AM/ethidium homodimer (Live/Dead) staining. Cell-seeded scaffolds were treated with chondrogenic inducers for 28 days. Extracellular matrix deposition and soluble glycosaminoglycan (GAG) release into the culture medium was measured at day 28 by histology/immunohistochemistry and dimethylmethylene blue assay, respectively.

RESULTS

A greater number of viable MSCs from either source adhered and incorporated into Chondro-Gide than into Alpha Chondro Shield. In both cell scaffolds, this incorporation represented less than 2% of the cells that were seeded. There was a marked proliferation of BM MSCs, but not AT MSCs, in Chondro-Gide. MSCs from both sources underwent chondrogenic differentiation following induction. However, cartilaginous extracellular matrix deposition was most marked in Chondro-Gide seeded with BM MSCs. Soluble GAG secretion increased in chondrogenic versus control conditions. There was no marked difference in GAG secretion by MSCs from either cell source.

CONCLUSION

Chondro-Gide and Alpha Chondro Shield were permissive to the incorporation and chondrogenic differentiation of human BM and AT MSCs. Chondro-Gide seeded with BM MSCs demonstrated the greatest increase in MSC number and deposition of a cartilaginous tissue.

Acceleration of vascular sprouting from fabricated perfusable vascular-like structures

Fabrication of vascular networks is essential for engineering three-dimensional thick tissues and organs in the emerging fields of tissue engineering and regenerative medicine. In this study, we describe the fabrication of perfusable vascular-like structures by transferring endothelial cells using an electrochemical reaction as well as acceleration of subsequent endothelial sprouting by two stimuli: phorbol 12-myristate 13-acetate (PMA) and fluidic shear stress. The electrochemical transfer of cells was achieved using an oligopeptide that formed a dense molecular layer on a gold surface and was then electrochemically desorbed from the surface. Human umbilical vein endothelial cells (HUVECs), adhered to gold-coated needles (ϕ600 μm) via the oligopeptide, were transferred to collagen gel along with electrochemical desorption of the molecular layer, resulting in the formation of endothelial cell-lined vascular-like structures. In the following culture, the endothelial cells migrated into the collagen gel and formed branched luminal structures. However, this branching process was strikingly slow (>14 d) and the cell layers on the internal surfaces became disrupted in some regions. To address these issues, we examined the effects of the protein kinase C (PKC) activator, PMA, and shear stress generated by medium flow. Addition of PMA at an optimum concentration significantly accelerated migration, vascular network formation, and its stabilization. Exposure to shear stress reoriented the cells in the direction of the medium flow and further accelerated vascular network formation. Because of the synergistic effects, HUVECs began to sprout as early as 3 d of perfusion culture and neighboring vascular-like structures were bridged within 5 d. Although further investigations of vascular functions need to be performed, this approach may be an effective strategy for rapid fabrication of perfusable microvascular networks when engineering three-dimensional fully vascularized tissues and organs.

Peptide-based biomaterials. Linking l-tyrosine and poly l-tyrosine to graphene oxide nanoribbons

GONRs grafted to tyrosine and poly-tyrosine can be used as biophysical tools for studying the oxidability of proteins or as fluorescent probes for detecting molecular or physical events.

Learning from nature - novel synthetic biology approaches for biomaterial design

Many biomaterials constructed today are complex chemical structures that incorporate biologically active components derived from nature, but the field can still be said to be in its infancy. The need for materials that bring sophisticated properties of structure, dynamics and function to medical and non-medical applications will only grow. Increasing appreciation of the functionality of biological systems has caused biomaterials researchers to consider nature for design inspiration, and many examples exist of the use of biomolecular motifs. Yet evolution, nature's only engine for the creation of new designs, has been largely ignored by the biomaterials community. Molecular evolution is an emerging tool that enables one to apply nature's engineering principles to non-natural situations using variation and selection. The purpose of this review is to highlight the most recent advances in the use of molecular evolution in synthetic biology applications for biomaterial engineering, and to discuss some of the areas in which this approach may be successfully applied in the future.

Lysine-appended polydiacetylene scaffolds for human mesenchymal stem cells

We report on the self-assembly based fabrication of fibrous polymers for tissue engineering applications. Directed self-assembly followed by polymerization of lysine-appended diacetylenes generated a variety of polymers (P1-P5) with distinct chemical properties. The self-assembly along with the conjugated double and triple bonds and rigid geometry of diacetylene backbone imposed a nanofibrous morphology on the resulting polymers. Chemical properties including wettability of the polymers were tuned by using lysine (Lys) with orthogonal protecting groups (Boc and Fmoc). These Lys-appended polydiacetylene scaffolds were compared in terms of their efficiency toward human mesenchymal stem cells adhesion and spreading. Interestingly, polymer P4 containing Lys N(α)-NH2 and Lys N(ε)-Boc with balanced wettability supported cell adhesion better than the more hydrophobic polymer P2 with N(ε)-Boc and N(α)-Fmoc or more hydrophilic polymer P5 containing free N(ε) and N(α) amino groups. The molecular level control in the fabrication of nanofibrous polymers compared with other existing methods for the generation of fibrous polymers is the hallmark of this work.

Reinforcement of a new calcium phosphate cement with RGD-chitosan-fiber

Calcium phosphate cement (CPC) has been widely used in orthopedic and dental applications. A critical limitation of CPC is low strength and high susceptibility to severe fracture. Surgeons can use it only to reconstruct non-stress bearing bone, raising the need for a tougher new generation of CPC. Fibers have been used as a reinforcement of CPC to improve the strength of a pure CPC scaffold. The RGD peptides (Arg-Gly-Asp) have been used to improve the biocompatibility of the scaffold, via physical adsorption. The purpose of this study was to develop a novel CPC scaffold reinforced by RGD peptide-bearing chitosan fibers (RGD-fiber-CPC). Our data showed that the RGD-fiber-CPC scaffold had an increased flexural strength, and stimulated new bone formation in an animal model. The RGD-fiber-CPC is a novel bone graft substitute in orthopedic surgery.

Biomimetic approaches to modulate cellular adhesion in biomaterials: A review

Natural extracellular matrix (ECM) proteins possess critical biological characteristics that provide a platform for cellular adhesion and activation of highly regulated signaling pathways. However, ECM-based biomaterials can have several limitations, including poor mechanical properties and risk of immunogenicity. Synthetic biomaterials alleviate the risks associated with natural biomaterials but often lack the robust biological activity necessary to direct cell function beyond initial adhesion. A thorough understanding of receptor-mediated cellular adhesion to the ECM and subsequent signaling activation has facilitated development of techniques that functionalize inert biomaterials to provide a biologically active surface. Here we review a range of approaches used to modify biomaterial surfaces for optimal receptor-mediated cell interactions, as well as provide insights into specific mechanisms of downstream signaling activation. In addition to a brief overview of integrin receptor-mediated cell function, so-called "biomimetic" techniques reviewed here include (i) surface modification of biomaterials with bioadhesive ECM macromolecules or specific binding motifs, (ii) nanoscale patterning of the materials and (iii) the use of "natural-like" biomaterials.

Surface characteristics of acrylic modified polysulfone membranes improves renal proximal tubule cell adhesion and spreading

Current polyvinylpyrrolidone-modified polysulfone (PVP-PSU) membranes in haemodialysers do not facilitate the attachment and proliferation of renal proximal tubule cells (RPTCs). For bioartificial kidney (BAK) development expensive extracellular matrices are employed to ensure the PVP-PSU membranes can serve as a substrate for RPTCs. In this study we modified PSU using an acrylic monomer (am-PSU) and polymerization using ultraviolet irradiation. We demonstrated that on adjusting the PSU or acrylic content of the membranes the wettability and surface chemistry were altered, and this affected the amount of fibronectin (Fn) that was adsorbed onto the membranes. Using an integrin blocking assay we ascertained that Fn is an important extracellular matrix component that mediates RPTC attachment. The amount of Fn adsorbed also led to different bioresponses of RPTCs, which were evaluated using attachment and proliferation assays and qualitative quantification of vinculin, focal adhesion kinase, zonula occludens and Na(+)/K(+) ATPase. Our optimized membrane, am-PSU1 (21.4% C-O groups, 19.1% PVP-PSU; contact angle 71.5-80.80, PVP-PSU: 52.4-67.50), supports a confluent monolayer of RPTCs and prevents creatinine and inulin diffusion from the apical to the basal side, meeting the requirements for application in BAKs. However, further in vivo evaluation to assess the full functionality of RPTCs on am-PSU1 is required.

Bioactive stent surface coating that promotes endothelialization while preventing platelet adhesion

A bifunctional peptide coating was designed, synthesized, and evaluated as a potential pro-healing stent coating. The bifunctional peptide consisted of a short 28-mer sequence that on the N-terminus has a motif with affinity for polystyrene binding and at the C-terminus has a motif that was shown to bind selectively human endothelial cells but not platelets. Results showed that the selective coating, a polystyrene-binding peptide terminated in RRETAWA (FFSFFFPASAWGSSGSSGK(biotin)CRRETAWAC), bound endothelial cells quantitatively as well as the common RGD motif, but unlike RGD, it did not show any preference for platelet adherence. Follow-up work examining the difference in cell line selectivity between endothelial cells, whose binding should be encouraged, and smooth muscle cells, whose binding should be deprecated in a stenting application, did identify a temporal preference of the RRETAWA-terminated peptide coating for endothelial cells. However, the in vivo implications of this apparent selectivity need to be examined in more detail before definitive conclusions can be drawn. The positive in vitro results encourage the continued development of other novel coatings that mimic biological structures, signaling capabilities, or both to direct cellular processes on the surface of synthetic materials.

Staphylococcus aureus resistance on titanium coated with multivalent PEGylated-peptides

Bacterial infections can have adverse effects on the efficacy, lifetime and safety of an implanted device and are the second most commonly attributed cause of orthopedic implant failure. We have previously shown the assembly of PEGylated titanium-binding peptides (TBPs) on Ti to obtain a bacteriophobic surface coating that can effectively resist protein adsorption and Staphylococcus aureus (S. aureus) adhesion. In the present study, we examine the effect of multiple TBP repeats on coating performance in vitro. Mono, di, and tetravalent peptides were synthesized and assessed for binding affinity and serum stability. PEGylated analogs were prepared and evaluated for their effect on S. aureus attachment and biofilm formation. Coating performance improved with the number of TBP repeats, with the tetravalent coating, TBP(4)-PEG, showing the best performance in all assays. In particular, TBP(4)-PEG forms a serum-resistant surface coating capable of preventing S. aureus colonization and subsequent biofilm formation. These results further support the role that multivalency can play in the development of improved surface coatings with enhanced stabilities and efficacy for in vivo clinical use.

The development of peptide-based interfacial biomaterials for generating biological functionality on the surface of bioinert materials

Biomaterials used in implants have traditionally been selected based on their mechanical properties, chemical stability, and biocompatibility. However, the durability and clinical efficacy of implantable biomedical devices remain limited in part due to the absence of appropriate biological interactions at the implant interface and the lack of integration into adjacent tissues. Herein, we describe a robust peptide-based coating technology capable of modifying the surface of existing biomaterials and medical devices through the non-covalent binding of modular biofunctional peptides. These peptides contain at least one material binding sequence and at least one biologically active sequence and thus are termed, "Interfacial Biomaterials" (IFBMs). IFBMs can simultaneously bind the biomaterial surface while endowing it with desired biological functionalities at the interface between the material and biological realms. We demonstrate the capabilities of model IFBMs to convert native polystyrene, a bioinert surface, into a bioactive surface that can support a range of cell activities. We further distinguish between simple cell attachment with insufficient integrin interactions, which in some cases can adversely impact downstream biology, versus biologically appropriate adhesion, cell spreading, and cell survival mediated by IFBMs. Moreover, we show that we can use the coating technology to create spatially resolved patterns of fluorophores and cells on substrates and that these patterns retain their borders in culture.