The functions and applications of RGD in tumor therapy and tissue engineering

The role of peptide-based therapeutics in oncotherapy

Cancer is the second leading cause of death worldwide, and the search for specialised therapy options has been a challenge for decades. The emergence of active targeted therapies provides the opportunity to treat cancerous tissues without harming healthy ones due to peculiar physiological changes. Herein, peptides and peptide analogs have been gaining a lot of attention over the last decade, especially for the on-site delivery of therapeutics to target tissues in order to achieve efficient and reliable cancer treatment. Combining peptides with highly efficient drug delivery platforms could potentially eliminate off-target adverse effects encountered during active targeting of conventional chemotherapeutics. Small size, ease of production and characterisation, low immunogenicity and satisfactory binding affinity of peptides offer some advantages over other complex targeting moiety, no wonder the market of peptide-based drugs continues to expand expeditiously. It is estimated that the global peptide drug market will be worth around USD 48.04 billion by 2025, with a compound annual growth rate of 9.4%. In this review, the current state of art of peptide-based therapeutics with special interest on tumour targeting peptides has been discussed. Moreover, various active targeting strategies such as the use functionalised peptides or peptide analogs are also elaborated.

Engineering oxygen-deficient ZrO2-x nanoplatform as therapy-activated "immunogenic cell death (ICD)" inducer to synergize photothermal-augmented sonodynamic tumor elimination in NIR-II biological window

Nano-zirconia, as an amphoteric semiconductor, has been industrially exploited in photocatalytic reactions and as piezoelectric sensors. However, its biomedical applications, especially in antitumor therapeutics, have been seldom investigated to date. Here, oxygen-deficient zirconia (ZrO_2-x)-based nanoplatform with surface PEGylation and cyclic-Arg-Gly-Asp (cRGD) peptide functionalization (ZrO_2-x@PEG/cRGD, abbreviated as ZPR) was rationally designed and established for the first time, which was utilized as therapy-activated "immunogenic cell death (ICD)" inducer to boost photothermal-augmented sonodynamic tumor elimination in NIR-II biological window. As-synthesized ZPR nanoparticles (NPs) exhibited intense optical absorbance in the wavelength range of 900-1100 nm, which endowed ZPR NPs with a photothermal conversion efficiency as high as 45.8% for photothermal therapy (PTT). Moreover, owing to the abundant surface oxygen defects, ZPR NPs can serve as a category of high-performance nano-sonosensitizer based on the strengthened separation of electron (e^-)/hole (h⁺) pairs from the energy band under external ultrasound (US) activation. More importantly, cytotoxic reactive oxygen species (ROS) generated from sonodynamic therapy (SDT) can effectively induce immunogenic cell death (ICD), which is regarded to be significant to boost systemic anti-tumor immunity for rendering a complete tumor eradication post-treatment. In vivo experiments on tumor xenografts demonstrated the high therapeutic efficacy upon photothermal-augmented sonodynamic therapy, with the aid of photoacoustic (PA) imaging navigation. Remarkably, the level of inflammatory cytokines, including type I interferon (IFN), tumor necrosis factor α (TNF-α) as well as interleukin (IL-6) were systemically upgraded after NIR-II/US irradiation, verifying the promotion of immunogenicity. Taken together, this study delivers useful insights for extending the applications of zirconia as promising translational medicine for tumor theranostics in the near future.

The biomedical significance of multifunctional nanobiomaterials: The key components for site-specific delivery of therapeutics

The emergence of nanotechnology has provided the possibilities to overcome the potential problems associated with the development of pharmaceuticals including the low solubility, non-specific cellular uptake or action, and rapid clearance. Regarding the biomaterials (BMs), huge efforts have been made for improving their multi-functionalities via incorporation of various nanomaterials (NMs). Nanocomposite hydrogels with suitable properties could exhibit a variety of beneficial effects in biomedicine particularly in the delivery of therapeutics or tissue engineering. NMs including the silica- or carbon-based ones are capable of integration into various BMs that might be due to their special compositions or properties such as the hydrophilicity, hydrophobicity, magnetic or electrical characteristics, and responsiveness to various stimuli. This might provide multi-functional nanobiomaterials against a wide variety of disorders. Meanwhile, inappropriate distribution or penetration into the cells or tissues, bio-nano interface complexity, targeting ability loss, or any other unpredicted phenomena are the serious challenging issues. Computational simulations and models enable development of NMs with optimal characteristics and provide a deeper knowledge of NM interaction with biosystems. This review highlights the biomedical significance of the multifunctional NMs particularly those applied for the development of 2-D or 3-D BMs for a variety of applications including the site-specific delivery of therapeutics. The powerful impacts of the computational techniques on the design process of NMs, quantitation and prediction of protein corona formation, risk assessment, and individualized therapy for improved therapeutic outcomes have also been discussed.

Assessment of Naturally Sourced Mineral Clays for the 3D Printing of Biopolymer-Based Nanocomposite Inks

The present study investigated the possibility of obtaining 3D printed composite constructs using biomaterial-based nanocomposite inks. The biopolymeric matrix consisted of methacrylated gelatin (GelMA). Several types of nanoclay were added as the inorganic component. Our aim was to investigate the influence of clay type on the rheological behavior of ink formulations and to determine the morphological and structural properties of the resulting crosslinked hydrogel-based nanomaterials. Moreover, through the inclusion of nanoclays, our goal was to improve the printability and shape fidelity of nanocomposite scaffolds. The viscosity of all ink formulations was greater in the presence of inorganic nanoparticles as shear thinning occurred with increased shear rate. Hydrogel nanocomposites presented predominantly elastic rather than viscous behavior as the materials were crosslinked which led to improved mechanical properties. The inclusion of nanoclays in the biopolymeric matrix limited hydrogel swelling due the physical barrier effect but also because of the supplementary crosslinks induced by the clay layers. The distribution of inorganic filler within the GelMA-based hydrogels led to higher porosities as a consequence of their interaction with the biopolymeric ink. The present study could be useful for the development of soft nanomaterials foreseen for the additive manufacturing of customized implants for tissue engineering.

A review on liposome-based therapeutic approaches against malignant melanoma

Melanoma is a highly aggressive form of skin cancer with a very poor prognosis and excessive resistance to current conventional treatments. Recently, the application of the liposomal delivery system in the management of skin melanoma has been widely investigated. Liposomal nanocarriers are biocompatible and less toxic to host cells, enabling the efficient and safe delivery of different therapeutic agents into the tumor site and further promoting their antitumor activities. Therefore, the liposomal delivery system effectively increases the success of current melanoma therapies and overcomes resistance. In this review, we present an overview of liposome-based targeted drug delivery methods and highlight recent advances towards the development of liposome-based carriers for therapeutic genes. We also discuss the new insights regarding the efficacy and clinical significance of combinatorial treatment of liposomal formulations with immunotherapy and conventional therapies in melanoma patients for a better understanding and successfully managing cancer.

3D-Printed Gelatin Methacryloyl-Based Scaffolds with Potential Application in Tissue Engineering

The development of materials for 3D printing adapted for tissue engineering represents one of the main concerns nowadays. Our aim was to obtain suitable 3D-printed scaffolds based on methacrylated gelatin (GelMA). In this respect, three degrees of GelMA methacrylation, three different concentrations of GelMA (10%, 20%, and 30%), and also two concentrations of photoinitiator (I-2959) (0.5% and 1%) were explored to develop proper GelMA hydrogel ink formulations to be used in the 3D printing process. Afterward, all these GelMA hydrogel-based inks/3D-printed scaffolds were characterized structurally, mechanically, and morphologically. The presence of methacryloyl groups bounded to the surface of GelMA was confirmed by FTIR and ¹H-NMR analyses. The methacrylation degree influenced the value of the isoelectric point that decreased with the GelMA methacrylation degree. A greater concentration of photoinitiator influenced the hydrophilicity of the polymer as proved using contact angle and swelling studies because of the new bonds resulting after the photocrosslinking stage. According to the mechanical tests, better mechanical properties were obtained in the presence of the 1% initiator. Circular dichroism analyses demonstrated that the secondary structure of gelatin remained unaffected during the methacrylation process, thus being suitable for biological applications.

Facile Synthesis of Cyclic Peptide-Phthalocyanine Conjugates for Epidermal Growth Factor Receptor-Targeted Photodynamic Therapy

A facile procedure for in situ peptide cyclization and phthalocyanine conjugation was developed by utilizing a bifunctional linker incorporated with a bis(bromomethyl)benzene unit and a cyclopentadiene moiety. These functional groups facilitated the nucleophilic substitution with the two cysteine residues of the linear peptides followed by the Diels-Alder reaction with the maleimide moiety attached to a zinc(II) phthalocyanine. With this approach, three cyclic peptide-phthalocyanine conjugates were prepared in 20-26% isolated yield via a one-pot procedure. One of the conjugates containing a cyclic form of the epidermal growth factor receptor (EGFR)-binding peptide sequence CMYIEALDKYAC displayed superior features as an advanced photosensitizer. It showed preferential uptake by two EGFR-positive cancer cell lines (HT29 and HCT116) compared with two EGFR-negative counterparts (HeLa and HEK293), resulting in significantly higher photocytotoxicity. Intravenous administration of this conjugate into HT29 tumor-bearing nude mice resulted in selective localization in tumor and effective inhibition of tumor growth upon photodynamic treatment.

Overcoming the barriers to optimization of adenovirus delivery using biomaterials: Current status and future perspective

Adenovirus (Ad) is emerging as a promising modality for cancer gene therapy due to its ability to induce high level of therapeutic transgene expression with no risk of insertional mutagenesis, ability to be facilely produced at a high titer, and capacity to induce robust antitumor immune response. Despite these excellent attributes of human serotype 5 Ad, poor systemic administration capability, coxsackie and adenovirus receptor (CAR)-dependent endocytic mechanism limiting potentially targetable cell types, nonspecific shedding to normal organs, and poor viral persistence in tumor tissues are major hindrances toward maximizing the therapeutic benefit of Ad in clinical setting. To address the abovementioned shortcomings, various non-immunogenic nanomaterials have been explored to modify Ad surface via physical or chemical interactions. In this review, we summarize the recent developments of different types of nanomaterials that had been utilized for modification of Ad and how tumor-targeted local and system delivery can be achieved with these nanocomplexes. Finally, we conclude by highlighting the key features of various nanomaterials-coated Ads and their prospects to optimize the delivery of virus.

Peptidomimetics - An infinite reservoir of metal binding motifs in metabolically stable and biologically active molecules

The involvement of metal ions in interactions with therapeutic peptides is inevitable. They are one of the factors able to fine-tune the biological properties of antimicrobial peptides, a promising group of drugs with one large drawback - a problematic metabolic stability. Appropriately chosen, proteolytically stable peptidomimetics seem to be a reasonable solution of the problem, and the use of D-, β-, γ-amino acids, unnatural amino acids, azapeptides, peptoids, cyclopeptides and dehydropeptides is an infinite reservoir of metal binding motifs in metabolically stable, well-designed, biologically active molecules. Below, their specific structural features, metal-chelating abilities and antimicrobial potential are discussed.

Catecholamine-Copper Redox as a Basis for Site-Specific Single-Step Functionalization of Material Surfaces

Realization of robust and facile surface functionalization processes is critical to biomaterials and biotechnology yet remains a challenge. Here, we report a new chemical approach that enables operationally simple and site-specific surface functionalization. The mechanism involves a catechol-copper redox chemistry, where the oxidative polymerization of an alkynyl catecholamine reduces Cu(II) to Cu(I), which in situ catalyzes a click reaction with azide-containing molecules of interest (MOIs). This process enables drop-coating and grafting of two- and three-dimensional solid surfaces in a single operation using as small as sub-microliter volumes. Generalizability of the method is shown for immobilizing MOIs of diverse structure and chemical or biological activity. Biological applications in anti-biofouling, cellular adhesion, scaffold seeding, and tissue regeneration are demonstrated, in which the activities or fates of cells are site-specifically manipulated. This work advances surface chemistry by integrating simplicity and precision with multipurpose surface functionalization.

Molybdenum-based hetero-nanocomposites for cancer therapy, diagnosis and biosensing application: Current advancement and future breakthroughs

In recent years, there have been significant advancements in the nanotechnology for cancer therapy. Even though molybdenum disulphide (MoS2)-based nanocomposites demonstrated extensive applications in biosensing, bioimaging, phototherapy, the review article focusing on MoS2 nanocomposite platform has not been accounted for yet. The review summarizes recent strategies on design and fabrication of MoS2-based nanocomposites and their modulated properties in cancer treatment. The review also discussed several therapeutic strategies (photothermal, photodynamic, immunotherapy, gene therapy and chemotherapy) and their combinations for efficient cancer therapy along with certain case studies. The review also inculcates various diagnostic techniques viz. magnetic resonance imaging, computed tomography, photoacoustic imaging and fluorescence imaging for diagnosis of cancer.

A new perspective in sepsis treatment: could RGD-dependent integrins be novel targets?

Sepsis is a life-threatening condition caused by the response of the body to an infection, and has recently been regarded as a global health priority because of the lack of effective treatments available. Vascular endothelial cells have a crucial role in sepsis and are believed to be a major target of pathogens during the early stages of infection. Accumulating evidence suggests that common sepsis pathogens, including bacteria, fungi, and viruses, all contain a critical integrin recognition motif, Arg-Gly-Asp (RGD), in their major cell wall-exposed proteins that might act as ligands to crosslink to vascular endothelial cells, triggering systemic dysregulation resulting in sepsis. In this review, we discuss the potential of anti-integrin therapy in the treatment of sepsis and septic shock.

Pluronic-based nanovehicles: Recent advances in anticancer therapeutic applications

Pluronics are a class of amphiphilic tri-block copolymers with wide pharmaceutical applicability. In the past decades, the ability to form biocompatible nanosized micelles was exploited to formulate stable drug nanovehicles with potential use in antitumor therapy. Due to the great potential for tuning physical and structural properties of Pluronic unimers, a panoply of drug or polynucleotide-loaded micelles was prepared and tested for their antitumoral activity. The attractive inherent antitumor properties of Pluronic polymers in combination with cell targeting and stimuli-responsive ligands greatly improved antitumoral therapeutic effects of tested drugs. In spite of that, the extraordinary complexity of biological challenges in the delivery of micellar drug payload makes their therapeutic potential still not exploited to the fullest. In this review paper we attempt to present the latest developments in the field of Pluronic based nanovehicles and their application in anticancer therapy with an overview of the chemistry involved in the preparation of these nanovehicles.

Biomedical Applications of Multifunctional Polymeric Nanocarriers: A Review of Current Literature

Polymeric nanomaterials have become a prominent area of research in the field of drug delivery. Their application in nanomedicine can improve bioavailability, pharmacokinetics, and, therefore, the effectiveness of various therapeutics or contrast agents. There are many studies for developing new polymeric nanocarriers; however, their clinical application is somewhat limited. In this review, we present new complex and multifunctional polymeric nanocarriers as promising and innovative diagnostic or therapeutic systems. Their multifunctionality, resulting from the unique chemical and biological properties of the polymers used, ensures better delivery, and a controlled, sequential release of many different therapeutics to the diseased tissue. We present a brief introduction of the classical formulation techniques and describe examples of multifunctional nanocarriers, whose biological assessment has been carried out at least in vitro. Most of them, however, also underwent evaluation in vivo on animal models. Selected polymeric nanocarriers were grouped depending on their medical application: anti-cancer drug nanocarriers, nanomaterials delivering compounds for cancer immunotherapy or regenerative medicine, components of vaccines nanomaterials used for topical application, and lifestyle diseases, ie, diabetes.

Elucidating the Surface Functionality of Biomimetic RGD Peptides Immobilized on Nano-P(3HB-co-4HB) for H9c2 Myoblast Cell Proliferation

Biomaterial scaffolds play crucial role to promote cell proliferation and foster the regeneration of new tissues. The progress in material science has paved the way for the generation of ingenious biomaterials. However, these biomaterials require further optimization to be effectively used in existing clinical treatments. It is crucial to develop biomaterials which mimics structure that can be actively involved in delivering signals to cells for the formation of the regenerated tissue. In this research we nanoengineered a functional scaffold to support the proliferation of myoblast cells. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer is chosen as scaffold material owing to its desirable mechanical and physical properties combined with good biocompatibility, thus eliciting appropriate host tissue responses. In this study P(3HB-co-4HB) copolymer was biosynthesized using Cupriavidus malaysiensis USMAA1020 transformant harboring additional PHA synthase gene, and the viability of a novel P(3HB-co-4HB) electrospun nanofiber scaffold, surface functionalized with RGD peptides, was explored. In order to immobilize RGD peptides molecules onto the P(3HB-co-4HB) nanofibers surface, an aminolysis reaction was performed. The nanoengineered scaffolds were characterized using SEM, organic elemental analysis (CHN analysis), FTIR, surface wettability and their in vitro degradation behavior was evaluated. The cell culture study using H9c2 myoblast cells was conducted to assess the in vitro cellular response of the engineered scaffold. Our results demonstrated that nano-P(3HB-co-4HB)-RGD scaffold possessed an average fiber diameter distribution between 200 and 300 nm, closely biomimicking, from a morphological point of view, the structural ECM components, thus acting as potential ECM analogs. This study indicates that the surface conjugation of biomimetic RGD peptide to the nano-P(3HB-co-4HB) fibers increased the surface wettability (15 ± 2°) and enhanced H9c2 myoblast cells attachment and proliferation. In summary, the study reveals that nano-P(3HB-co-4HB)-RGD scaffold can be considered a promising candidate to be further explored as cardiac construct for building cardiac construct.

Microfluidic-assisted preparation of RGD-decorated nanoparticles: exploring integrin-facilitated uptake in cancer cell lines

This study is about fine tuning the targeting capacity of peptide-decorated nanoparticles to discriminate between cells that express different integrin make-ups. Using microfluidic-assisted nanoprecipitation, we have prepared poly(lactic acid-co-glycolic acid) (PLGA) nanoparticles with a PEGylated surface decorated with two different arginine-glycine-aspartic acid (RGD) peptides: one is cyclic (RGDFC) and has specific affinity towards αvβ3 integrin heterodimers; the other is linear (RGDSP) and is reported to bind equally αvβ3 and α5β1. We have then evaluated the nanoparticle internalization in two cell lines with a markedly different integrin fingerprint: ovarian carcinoma A2780 (almost no αvβ3, moderate in α5β1) and glioma U87MG (very high in αvβ3, moderate/high in α5β1). As expected, particles with cyclic RGD were heavily internalized by U87MG (proportional to the peptide content and abrogated by anti-αvβ3) but not by A2780 (same as PEGylated particles). The linear peptide, on the other hand, did not differentiate between the cell lines, and the uptake increase vs. control particles was never higher than 50%, indicating a possible low and unselective affinity for various integrins. The strong preference of U87MG for cyclic (vs. linear) peptide-decorated nanoparticles was shown in 2D culture and further demonstrated in spheroids. Our results demonstrate that targeting specific integrin make-ups is possible and may open the way to more precise treatment, but more efforts need to be devoted to a better understanding of the relation between RGD structure and their integrin-binding capacity.

Biodegradable Patches for Arterial Reconstruction Modified with RGD Peptides: Results of an Experimental Study

Modification by Arg-Gly-Asp (RGD) peptides is a promising approach to improve the biocompatibility of biodegradable vascular patches for arteriotomy. In this study, we evaluated the performance of vascular patches electrospun using a blend of polycaprolactone (PCL) and polyhydroxybutyrate/valerate (PHBV) and additionally modified with RGDK, AhRGD, and c[RGDFK] peptides using 1,6-hexamethylenediamine or 4,7,10-trioxa-1,13-tridecanediamine (TTDDA) linkers. We examined mechanical properties and hemocompatibility of resulting patches before implanting them in rat abdominal aortas to assess their performance in vivo. Patches were explanted 1, 3, 6, and 12 months postoperation followed by histological and immunofluorescence analyses. Patches manufactured from the human internal mammary artery or commercially available KemPeriplas-Neo xenopericardial patches were used as a control. The tensile strength and F _max of KemPeriplas-Neo patches were 4- and 16.7-times higher than those made of human internal mammary artery, respectively. Both RGD-modified and unmodified PHBV/PCL patches demonstrated properties similar to a human internal mammary artery patch. Regardless of RGD modification, experimental PHBV/PCL patches displayed fewer lysed red blood cells and resulted in milder platelet aggregation than KemPeriplas-Neo patches. Xenopericardial patches failed to form an endothelial layer in vivo and were prone to calcification. By contrast, TTDDA/RGDK-modified biodegradable patches demonstrated a resistance to calcification. Modification by TTDDA/RGDK and TTDDA/c[RGDFK] facilitated the formation of neovasculature upon the implantation in vivo.

Poly-Epsilon-Lysine Hydrogels with Dynamic Crosslinking Facilitates Cell Proliferation

The extracellular matrix (ECM) is a three-dimensional network within which fundamental cell processes such as cell attachment, proliferation, and differentiation occur driven by its inherent biological and structural cues. Hydrogels have been used as biomaterials as they possess many of the ECM characteristics that control cellular processes. However, the permanent crosslinking often found in hydrogels fails to recapitulate the dynamic nature of the natural ECM. This not only hinders natural cellular migration but must also limit cellular expansion and growth. Moreover, there is an increased interest in the use of new biopolymers to create biomimetic materials that can be used for biomedical applications. Here we report on the natural polymer poly-ε-lysine in forming dynamic hydrogels via reversible imine bond formation, with cell attachment promoted by arginine-glycine-aspartic acid (RGD) incorporation. Together, the mechanical properties and cell behavior of the dynamic hydrogels with low poly-ε-lysine quantities indicated good cell viability and high metabolic activity.

Molecular mechanisms of bufadienolides and their novel strategies for cancer treatment

Bufadienolides are cardioactive C24 steroids with an α-pyrone ring at position C17. In the last ten years, accumulating studies have revealed the anticancer activities of bufadienolides and their underlying mechanisms, such as induction of autophagy and apoptosis, cell cycle disruption, inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and stemness, and multidrug resistance reversal. As Na⁺/K⁺-ATPase inhibitors, bufadienolides have inevitable cardiotoxicity. Short half-lives, poor stability, low plasma concentration and oral bioavailability in vivo are obstacles for their applications as drugs. To improve the drug potency of bufadienolides and reduce their side effects, prodrug strategies and drug delivery systems such as liposomes and nanoparticles have been applied. Therefore, systematic and recapitulated information about the antitumor activity of bufadienolides, with special emphasis on the molecular or cellular mechanisms, prodrug strategies and drug delivery systems, is of high interest. Here, we systematically review the anticancer effects of bufadienolides and the molecular or cellular mechanisms of action. Research advancements regarding bufadienolide prodrugs and their tumor-targeting delivery strategies are critically summarized. This work highlights recent scientific advances regarding bufadienolides as effective anticancer agents from 2011 to 2019, which will help researchers to understand the molecular pathways involving bufadienolides, resulting in a selective and safe new lead compound or therapeutic strategy with improved therapeutic applications of bufadienolides for cancer therapy.

Molecularly Imprinted Polymers: Antibody Mimics for Bioimaging and Therapy

Molecularly imprinted polymers (MIPs) are tailor-made chemical receptors that recognize and bind target molecules with a high affinity and selectivity. MIPs came into the spotlight in 1993 when they were dubbed "antibody mimics," and ever since, they have been widely studied for the extraction or trapping of chemical pollutants, in immunoassays, and for the design of sensors. Owing to novel synthesis strategies resulting in more biocompatible MIPs in the form of soluble nanogels, these synthetic antibodies have found favor in the biomedical domain since 2010, when for the first time, they were shown to capture and eliminate a toxin in live mice. This review, covering the years 2015-2020, will first describe the rationale behind these antibody mimics, and the different synthesis methods that have been employed for the preparation of MIPs destined for in vitro and in vivo targeting and bioimaging of cancer biomarkers, an emerging and fast-growing area of MIP applications. MIPs have been synthesized for targeting and visualizing glycans and protein-based cell receptors overexpressed in certain diseases, which are well-known biomarkers for example for tumors. When loaded with drugs, the MIPs could locally kill the tumor cells, making them efficient therapeutic agents. We will end the review by reporting how MIPs themselves can act as therapeutics by inhibiting cancer growth. These works mark a new opening in the use of MIPs for antibody therapy and even immunotherapy, as materials of the future in nanomedicine.

Atherosclerotic Pre-Conditioning Affects the Paracrine Role of Circulating Angiogenic Cells Ex-Vivo

In atherosclerosis, circulating angiogenic cells (CAC), also known as early endothelial progenitor cells (eEPC), are thought to participate mainly in a paracrine fashion by promoting the recruitment of other cell populations such as late EPC, or endothelial colony-forming cells (ECFC), to the injured areas. There, ECFC replace the damaged endothelium, promoting neovascularization. However, despite their regenerative role, the number and function of EPC are severely affected under pathological conditions, being essential to further understand how these cells react to such environments in order to implement their use in regenerative cell therapies. Herein, we evaluated the effect of direct incubation ex vivo of healthy CAC with the secretome of atherosclerotic arteries. By using a quantitative proteomics approach, 194 altered proteins were identified in the secretome of pre-conditioned CAC, many of them related to inhibition of angiogenesis (e.g., endostatin, thrombospondin-1, fibulins) and cell migration. Functional assays corroborated that healthy CAC released factors enhanced ECFC angiogenesis, but, after atherosclerotic pre-conditioning, the secretome of pre-stimulated CAC negatively affected ECFC migration, as well as their ability to form tubules on a basement membrane matrix assay. Overall, we have shown here, for the first time, the effect of atherosclerotic factors over the paracrine role of CAC ex vivo. The increased release of angiogenic inhibitors by CAC in response to atherosclerotic factors induced an angiogenic switch, by blocking ECFC ability to form tubules in response to pre-conditioned CAC. Thus, we confirmed here that the angiogenic role of CAC is highly affected by the atherosclerotic environment.

Preparation and characterization of a pterostilbene-peptide prodrug nanomedicine for the management of dry eye

In the present study, a pterostilbene-peptide amphiphile (PS-GA-RGD) that can spontaneously self-assemble into prodrug nanomedicine, was rationally designed and developed as a novel ophthalmic formulation for the potential management of dry eye. The formed PS-GA-RGD nanomedicine was characterized by dynamic latter scattering (DLS) and transmission electron microscopy (TEM). After esterase treatment, active pterostilbene (PS) sustainably released from the PS-GA-RGD nanomedicine within 48 h, as indicated by an in vitro release study. In comparison with native PS, the formed PS-GA-RGD nanomedicine caused minimal cytotoxicity towards RAW 264.7 and HCEC cells in the 0-20 μM range and did not delay wound healing of HCEC monolayer within 6 h. Furthermore, PS-GA-RGD nanomedicine effectively reduced the intracellular reactive oxygen species (ROS) level in H₂O₂ challenged RAW264.7 macrophages and remarkably suppressed the secretion of inflammatory cytokines (e.g., NO, TNF-α, and IL-6) in lipopolysaccharide (LPS) activated RAW264.7 macrophages. Ocular tolerance to the proposed PS-GA-RGD nanomedicine was good after a single instillation in in vivo ocular irritation tests. Overall, the proposed PS-GA-RGD nanomedicine had potent anti-oxidant capacity and anti-inflammatory efficacy, which may be a promising ophthalmic formulation for the management of dry eye.

Endothelial Cell Targeting by cRGD-Functionalized Polymeric Nanoparticles under Static and Flow Conditions

Since α_vβ₃ integrin is a key component of angiogenesis in health and disease, Arg-Gly-Asp (RGD) peptide-functionalized nanocarriers have been investigated as vehicles for targeted delivery of drugs to the α_vβ₃ integrin-overexpressing neovasculature of tumors. In this work, PEGylated nanoparticles (NPs) based on poly(lactic-co-glycolic acid) (PLGA) functionalized with cyclic-RGD (cRGD), were evaluated as nanocarriers for the targeting of angiogenic endothelium. For this purpose, NPs (~300 nm) functionalized with cRGD with different surface densities were prepared by maleimide-thiol chemistry and their interactions with human umbilical vein endothelial cells (HUVECs) were evaluated under different conditions using flow cytometry and microscopy. The cell association of cRGD-NPs under static conditions was time-, concentration- and cRGD density-dependent. The interactions between HUVECs and cRGD-NPs dispersed in cell culture medium under flow conditions were also time- and cRGD density-dependent. When washed red blood cells (RBCs) were added to the medium, a 3 to 8-fold increase in NPs association to HUVECs was observed. Moreover, experiments conducted under flow in the presence of RBC at physiologic hematocrit and shear rate, are a step forward in the prediction of in vivo cell–particle association. This approach has the potential to assist development and high-throughput screening of new endothelium-targeted nanocarriers.

RGD-decorated solid lipid nanoparticles enhance tumor targeting, penetration and anticancer effect of asiatic acid

Aim: Asiatic acid (AA) is a promising anticancer agent, however, its delivery to glioblastoma is a major challenge. This work investigates the beneficial therapeutic efficacy of RGD-conjugated solid lipid nanoparticles (RGD-SLNs) for the selective targeting of AA to gliblastoma. Materials & methods: AA-containing RGD-SLNs were prepared using two different PEG-linker size. Targetability and efficacy were tested using monolayer cells and spheroid tumor models. Results: RGD-SLNs significantly improved cytotoxicity of AA against U87-MG monolayer cells and enhanced cellular uptake compared with non-RGD-containing SLNs. In spheroid models, AA-containing RGD-SLNs showed superior control in tumor growth, improved cytotoxicity and enhanced spheroid penetration when compared with AA alone or non-RGD-containing SLNs. Conclusion: This study illustrates the potential of AA-loaded RGD-SLNs as efficacious target-specific treatment for glioblastoma.

c(RGDfK)- and ZnTriMPyP-Bound Polymeric Nanocarriers for Tumor-Targeted Photodynamic Therapy

Active targeting strategies are currently being extensively investigated in order to enhance the selectivity of photodynamic therapy. The aim of the present research was to evaluate whether the external decoration of nanopolymeric carriers with targeting peptides could add more value to a photosensitizer formulation and increase antitumor therapeutic efficacy and selectivity. To this end, we assessed PLGA-PLA-PEG nanoparticles (NPs) covalently attached to a hydrophilic photosensitizer 5-[4-azidophenyl]-10,15,20-tri-(N-methyl-4-pyridinium)porphyrinato zinc (II) trichloride (ZnTriMPyP) and also to c(RGDfK) peptides, in order to target α_v β₃ integrin-expressing cells. In vitro phototoxicity investigations showed that the ZnTriMPyP-PLGA-PLA-PEG-c(RGDfK) nanosystem is effective at submicromolar concentrations, is devoid of dark toxicity, successfully targets α_v β₃ integrin-expressing cells and is 10-fold more potent than related nanosystems where the PS is occluded instead of covalently bound.

Problem of Diminished cRGD Surface Activity and What Can Be Done about It

RGD peptides play a pivotal role in growing and diverse areas of biological research, ranging from in vitro experiments probing fundamental molecular mechanisms of cell adhesion to more applied in vivo strategies in medical imaging and cancer therapeutics. To better understand the outcomes of RGD-based approaches, we quantified the degree to which cyclic RGD (cRGD) activity is blocked by nonspecific binding of commonly used medium constituents. First, we show that recombinant α_Vβ₃ integrins can be used as a highly sensitive cell-free sensor to quantitatively and reliably characterize the activity of cRGD-functionalized surfaces via surface plasmon resonance (SPR). Next, SPR experiments were utilized to measure the extent of blocking of cRGD-functionalized surfaces by the commonly used agents BSA, PLL-g-PEG, and fetal calf serum (FCS)-supplemented media, using recombinant α_Vβ₃ integrin as a probe for cRGD binding activity in the presence of blocking agents. All three additives were highly efficient blockers of cRGD activity, as exemplified by cell culture media containing 1% FCS which reduced the cRGD activity by 33-fold. We then developed a strategy to combat these deleterious effects by employing the recombinant integrins as a protective cap. We show that the unblocked cRGD activity can be preserved in the presence of PLL-g-PEG by employing the α_Vβ₃ integrin as a removable protective cap, both in cell-free and in vitro experiments. In vitro studies with MDA-MB-231 cells cultured atop cRGD-functionalized surfaces found that cell adhesion and migration prevented by PLL-g-PEG were restored when this protective cap approach was used.

Bacterial outer membrane vesicles as a platform for biomedical applications: An update

Outer membrane vesicles (OMVs) are produced by Gram-negative bacteria both in vitro and in vivo. OMVs are nano-sized spherical vehicles formed by lipid bilayer membranes and contain multiple parent bacteria-derived components. Based on the presence of bacterial antigens, pathogen-associated molecular patterns (PAMPs), adhesins, various proteins and the vesicle structure, OMVs have been developed for biomedical applications as bacterial vaccines, adjuvants, cancer immunotherapy agents, drug delivery vehicles, and anti-bacteria adhesion agents. In this review, we analyze the contributions of the structure and composition of OMVs to their applications, summarize the methods used to isolate and characterize OMVs, and highlight recent progress and future perspectives of OMVs in biomedical applications.

Pre-culture of mesenchymal stem cells within RGD-modified hyaluronic acid hydrogel improves their resilience to ischaemic conditions

The incorporation of the RGD peptide (arginine-glycine-aspartate) into biomaterials has been proposed to promote cell adhesion to the matrix, which can influence and control cell behaviour and function. While many studies have utilised RGD modified biomaterials for cell delivery, few have examined its effect under the condition of reduced oxygen and nutrients, as found at ischaemic injury sites. Here, we systematically examine the effect of RGD on hMSCs in hyaluronic acid (HA) hydrogel under standard and ischaemic culture conditions, to elucidate under what conditions RGD has beneficial effects over unmodified HA and its effectiveness in improving cell viability. Results demonstrate that under standard culture conditions, RGD significantly increased hMSC spreading and the release of vascular endothelial factor-1 (VEGF) and monocyte chemoattractant factor-1 (MCP-1), compared to unmodified HA hydrogel. As adhesion is known to influence cell survival, we hypothesised that cells in RGD hydrogels would exhibit increased cell viability under ischaemic culture conditions. However, results demonstrate that cell viability and protein release was comparable in both RGD modified and unmodified HA hydrogels. Confocal imaging revealed cellular morphology indicative of weak cell adhesion. Subsequent investigations found that RGD was could exert positive effects on encapsulated cells under ischaemic conditions but only if hMSCs were pre-cultured under standard conditions to allow strong adhesion to RGD before exposure. Together, these results provide novel insight into the value of RGD introduction and suggest that the adhesion of hMSCs to RGD prior to delivery could improve survival and function at ischaemic injury sites. STATEMENT OF SIGNIFICANCE: The development of a biomaterial scaffold capable of maintaining cell viability while promoting cell function is a major research goal in the field of cardiac tissue engineering. This study confirms the suitability of a modified HA hydrogel whereby stem cells in the modified hydrogel showed significantly greater cell spreading and protein secretion compared to cells in the unmodified HA hydrogel. A pre-culture period allowing strong adhesion of the cells to the modified hydrogel was shown to improve cell survival under conditions that mimic the myocardium post-MI. This finding may have a significant impact on the use and timelines of modifications to improve stem cell survival in harsh environments like the injured heart.

3D Extracellular Matrix Mimics: Fundamental Concepts and Role of Materials Chemistry to Influence Stem Cell Fate

Synthetic 3D extracellular matrices (ECMs) find application in cell studies, regenerative medicine, and drug discovery. While cells cultured in a monolayer may exhibit unnatural behavior and develop very different phenotypes and genotypes than in vivo, great efforts in materials chemistry have been devoted to reproducing in vitro behavior in in vivo cell microenvironments. This requires fine-tuning the biochemical and structural actors in synthetic ECMs. This review will present the fundamentals of the ECM, cover the chemical and structural features of the scaffolds used to generate ECM mimics, discuss the nature of the signaling biomolecules required and exploited to generate bioresponsive cell microenvironments able to induce a specific cell fate, and highlight the synthetic strategies involved in creating functional 3D ECM mimics.

Enzyme assisted peptide self-assemblies trigger cell adhesion in high density oxime based host gels

Peptide supramolecular self-assemblies are recognized as important components in responsive hydrogel based materials with applications in tissue engineering and regenerative medicine. Studying the influence of hydrogel matrices on the self-assembly behavior of peptides and interaction with cells is essential to guide the future development of engineered biomaterials. In this contribution, we present a PEG based host hydrogel material generated by oxime click chemistry that shows cellular adhesion behavior in response to enzyme assisted peptide self-assembly (EASA) within the host gel. This hydrogel prepared from poly(dimethylacrylamide-co-diacetoneacrylamide), poly(DMA-DAAM) with high molar fractions (49%) of DAAM and dialkoxyamine PEG cross-linker, was studied in the presence of embedded enzyme alkaline phosphatase (AP) and a non-adhesive cell behavior towards NIH 3T3 fibroblasts was observed. When brought into contact with a Fmoc-FFpY peptide solution (pY: phosphorylated tyrosine), the gel forms intercalated Fmoc-FFY peptide self-assemblies upon diffusion of Fmoc-FFpY into the cross-linked hydrogel network as was confirmed by circular dichroism, fluorescence emission spectroscopy and confocal microscopy. Nevertheless, the mechanical properties do not change significantly after the peptide self-assembly in the host gel. This enzyme assisted peptide self-assembly promotes fibroblast cell adhesion that can be enhanced if Fmoc-F-RGD peptides are added to the pre-gelator Fmoc-FFpY peptide solution. Cell adhesion results mainly from interactions of cells with the non-covalent peptide self-assemblies present in the gel despite the fact that the mechanical properties are very close to those of the native host gel. This result is in contrast to numerous studies which showed that the mechanical properties of a substrate are key parameters of cell adhesion. It opens up the possibility to develop a diverse set of hybrid materials to control cell fate in culture due to tailored self-assemblies of peptides responding to the environment provided by the host guest gel.

Nose-to-Brain Delivery of Cancer-Targeting Paclitaxel-Loaded Nanoparticles Potentiates Antitumor Effects in Malignant Glioblastoma

Glioblastoma multiforme (GBM) is an aggressive tumor with no curative treatment. The tumor recurrence after resection often requires chemotherapy or radiation to delay the infiltration of tumor remnants. Intracerebral chemotherapies are preferentially being used to prevent tumor regrowth, but treatments remain unsuccessful because of the poor drug distribution in the brain. In this study, we investigated the therapeutic efficacy of cancer-targeting arginyl-glycyl-aspartic tripeptide (RGD) conjugated paclitaxel (PTX)-loaded nanoparticles (NPs) against GBM by nose-to-brain delivery. Our results demonstrated that RGD-modified PTX-loaded NPs showed cancer-specific delivery and enhanced anticancer effects in vivo. The intranasal (IN) inoculation of RGD-PTX-loaded NPs effectively controls the tumor burden (75 ± 12% reduction) by inducing apoptosis and/or inhibiting cancer cell proliferation without affecting the G₀ stage of normal brain cells. Our data provide therapeutic evidence supporting the use of intranasally delivered cancer-targeted PTX-loaded NPs for GBM therapy.

Photodynamic Therapy and the Biophysics of the Tumor Microenvironment

Targeting the tumor microenvironment (TME) provides opportunities to modulate tumor physiology, enhance the delivery of therapeutic agents, impact immune response and overcome resistance. Photodynamic therapy (PDT) is a photochemistry-based, nonthermal modality that produces reactive molecular species at the site of light activation and is in the clinic for nononcologic and oncologic applications. The unique mechanisms and exquisite spatiotemporal control inherent to PDT enable selective modulation or destruction of the TME and cancer cells. Mechanical stress plays an important role in tumor growth and survival, with increasing implications for therapy design and drug delivery, but remains understudied in the context of PDT and PDT-based combinations. This review describes pharmacoengineering and bioengineering approaches in PDT to target cellular and noncellular components of the TME, as well as molecular targets on tumor and tumor-associated cells. Particular emphasis is placed on the role of mechanical stress in the context of targeted PDT regimens, and combinations, for primary and metastatic tumors.

3D cultures for modeling nanomaterial-based photothermal therapy

Photothermal therapy (PTT) is one of the most promising techniques for cancer tumor ablation. Nanoparticles are increasingly being investigated for use with PTT and can serve as theranostic agents. Based on the ability of near-infrared nano-photo-absorbers to generate heat under laser irradiation, PTT could prove advantageous in certain situations over more classical cancer therapies. To analyze the efficacy of nanoparticle-based PTT, preclinical in vitro studies typically use 2D cultures, but this method cannot completely mimic the complex tumor organization, bioactivity, and physiology that all control the complex penetration depth, biodistribution, and tissue diffusion parameters of nanomaterials in vivo. To fill this knowledge gap, 3D culture systems have been explored for PTT analysis. These models provide more realistic microenvironments that allow spatiotemporal oxygen gradients and cancer cell adaptations to be considered. This review highlights the work that has been done to advance 3D models for cancer microenvironment modeling, specifically in the context of advanced, functionalized nanoparticle-directed PTT.

Anti-Adhesive, Platelet Gathering Effects of c-RGD Modified Poly(p-dioxanone-co-l-Phe) Electrospun Membrane and Its Comprehensive Application in Intestinal Anastomosis

Intestinal resection and anastomosis are performed in over a million people with various bowel diseases annually. Excessive fibrosis and anastomotic site leakage are the main complications of anastomosis surgery, despite great improvements in operative technique and equipment in recent years. In this study, cRGD modified poly(p-dioxanone-co-l-Phe) (PDPA) membranes are designed and applied in intestinal anastomosis to simultaneously solve the two aforementioned complications. cRGD is modified onto PDPA membranes through both physical absorption and π-π accumulation between d-Phe of cRGD and l-Phe of PDPA. Although cRGD modification enhanced the biocompatibility of PDPA membranes, cRGD modified PDPA membrane suppresses fibroblast proliferation both in vitro and in vivo as a result of degradation and subsequent release of fibroblast suppressive l-Phe from PDPA. Meanwhile, platelets are entrapped by cRGD modified PDPA membranes through the specific binding of cRGD and platelet GP_IIbIIIa . cRGD modified PDPA membranes are applied in rat intestinal anastomosis, and both adhesion and stenosis are successfully prevented at anastomotic sites. At the same time, bursting pressure, which represents healing intensity at anastomotic sites, is promoted. The gathering and activation of platelets on PDPA membranes induce secretion of autologous PDGF and VEGF to facilitate angiogenesis and subsequent healing of anastomotic sites.

Inflammatory Cytokines and Biodegradable Scaffolds in Dental Mesenchymal Stem Cells Priming

Mesenchymal stem cells (MSCs) are multipotent stem cells with wide-ranging clinical applications due to their ability to regenerate tissue from mesenchymal origin and their capability of suppressing immune responses, thus reducing the likelihood of graft versus host disease after transplantation. MSCs can be isolated from a variety of sources including bone marrow, adipose tissue, umbilical cord blood, and immature teeth. Dental stem cells (DSCs) possess progenitor and immunomodulatory abilities as the other MSC types and because they can be easily isolated, are considered as attractive therapeutic agents in regenerative dentistry. Recently, it has been shown that DSCs seeded onto newly developed synthetic biomaterial scaffolds have retained their potential for proliferation and at the same time have enhanced capabilities for differentiation and immunosuppression. The scaffolds are becoming more efficient at MSC priming as researchers learn how short peptide sequences alter the adhesive and proliferative capabilities of the scaffolds by stimulating or inhibiting classical osteogenic pathways. New findings on how to modulate the inflammatory microenvironment, which can prime DSCs for differentiation, combined with the use of next generation scaffolds may significantly improve their therapeutic potential. In this review, we summarize current findings regarding DSCs as a potential regenerative therapy, including stem cell priming with inflammatory cytokines, types of scaffolds currently being explored and the modulation of scaffolds to regulate immune response and promote growth.

Peptide-Conjugated Nanoparticles as Targeted Anti-angiogenesis Therapeutic and Diagnostic in Cancer

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Targeting angiogenesis in the microenvironment of a tumor can enable suppression of tumor angiogenesis and delivery of anticancer drugs into the tumor. Anti-angiogenesis targeted delivery systems utilizing passive targeting such as Enhanced Permeability and Retention (EPR) and specific receptor-mediated targeting (active targeting) should result in tumor-specific targeting. One targeted anti-angiogenesis approach uses peptides conjugated to nanoparticles, which can be loaded with anticancer agents. Anti-angiogenesis agents can suppress tumor angiogenesis and thereby affect tumor growth progression (tumor growth arrest), which may be further reduced with the targetdelivered anticancer agent. This review provides an update of tumor vascular targeting for therapeutic and diagnostic applications, with conventional or long-circulating nanoparticles decorated with peptides that target neovascularization (anti-angiogenesis) in the tumor microenvironment.

Poly-ε-lysine based hydrogels as synthetic substrates for the expansion of corneal endothelial cells for transplantation

Dysfunction of the corneal endothelium (CE) resulting from progressive cell loss leads to corneal oedema and significant visual impairment. Current treatments rely upon donor allogeneic tissue to replace the damaged CE. A donor cornea shortage necessitates the development of biomaterials, enabling in vitro expansion of corneal endothelial cells (CECs). This study investigated the use of a synthetic peptide hydrogel using poly-ε-lysine (pεK), cross-linked with octanedioic-acid as a potential substrate for CECs expansion and CE grafts. PεK hydrogel properties were optimised to produce a substrate which was thin, transparent, porous and robust. A human corneal endothelial cell line (HCEC-12) attached and grew on pεK hydrogels as confluent monolayers after 7 days, whereas primary porcine CECs (pCECs) detached from the pεK hydrogel. Pre-adsorption of collagen I, collagen IV and fibronectin to the pεK hydrogel increased pCEC adhesion at 24 h and confluent monolayers formed at 7 days. Minimal cell adhesion was observed with pre-adsorbed laminin, chondroitin sulphate or commercial FNC coating mix (fibronectin, collagen and albumin). Functionalisation of the pεK hydrogel with synthetic cell binding peptide H-Gly-Gly-Arg-Gly-Asp-Gly-Gly-OH (RGD) or α2β1 integrin recognition sequence H-Asp-Gly-Glu-Ala-OH (DGEA) resulted in enhanced pCEC adhesion with the RGD peptide only. pCECs grown in culture at 5 weeks on RGD pεK hydrogels showed zonula occludins 1 staining for tight junctions and expression of sodium-potassium adenosine triphosphase, suggesting a functional CE. These results demonstrate the pεK hydrogel can be tailored through covalent binding of RGD to provide a surface for CEC attachment and growth. Thus, providing a synthetic substrate with a therapeutic application for the expansion of allogenic CECs and replacement of damaged CE.

Supramolecular trap for catching polyamines in cells as an anti-tumor strategy

Polyamines are essential for the growth of eukaryotic cells and can be dysregulated in tumors. Here we describe a strategy to deplete polyamines through host-guest encapsulation using a peptide-pillar[5]arene conjugate (P1P5A, P1 = RGDSK(N₃)EEEE) as a supramolecular trap. The RGD in the peptide sequence allows the molecule to bind to integrin α_vβ₃-overexpressing tumor cells. The negative charged glutamic acid residues enhance the inclusion affinities between the pillar[5]arene and cationic polyamines via electrostatic interactions and facilitate the solubility of the conjugate in aqueous media. The trap P1P5A efficiently encapsulates polyamines with association constants of 10⁵-10⁶ M^-1. We show that P1P5A has a wide spectrum of antitumor activities, and induces apoptosis via affecting the polyamine biosynthetic pathway. Experiments in vivo show that P1P5A effectively inhibits the growth of breast adenocarcinoma xenografts in female nude mice. This work reveals an approach for suppressing tumor growth by using supramolecular macrocycles to trap polyamines in tumor cells.

Promotion of angiogenesis by M13 phage and RGD peptide in vitro and in vivo

One of the most important goals of regenerative medicines is to generate alternative tissues with a developed vascular network. Endothelial cells are the most important cell type required in angiogenesis process, contributing to the blood vessels formation. The stimulation of endothelial cells to initiate angiogenesis requires appropriate extrinsic signals. The aim of this study was to evaluate the effects of M13 phage along with RGD peptide motif on in vitro and in vivo vascularization. The obtained results demonstrated the increased cellular proliferation, HUVECs migration, cells altered morphology, and cells attachment to M13 phage-RGD coated surface. In addition, the expression of Vascular Endothelial Growth Factor A (VEGF-A), VEGF Receptors 2 and 3, Matrix Metalloproteinase 9 (MMP9), and epithelial nitric oxide synthase (eNOS) transcripts were significantly upregulated due to the HUVECs culturing on M13 phage-RGD coated surface. Furthermore, VEGF protein secretion, nitric oxide, and reactive oxygen species (ROS) production were significantly increased in cells cultured on M13 phage-RGD coated surface.

Laminin-derived peptides: Applications in drug delivery systems for targeting

Recently, the development of drug delivery systems (DDSs) for clinical application of anticancer drugs and gene therapy has rapidly progressed. In particular, DDS carriers used for chemotherapy and gene therapy are required to selectively deliver drugs and genes to cancer cells. Both the carrier and the molecule must in combination be highly selective in most cases. Possible candidate targeting molecules are the laminins, major basement membrane proteins that interact with various cells through their multiple constituent active peptide sequences. Laminin-derived peptides bind to various cellular receptors and have been used for DDSs as a targeting moiety. Here, we review the progress in laminin-derived peptide-conjugated DDSs. Drug and gene carriers as well as ultrasound diagnostic contrast agents utilizing laminin-derived peptides for selective targeting are useful components of DDSs and play important roles in cancer and in the neovasculature.