A bio-instructive parylene-based conformal coating suppresses thrombosis and intimal hyperplasia of implantable vascular devices

Implantable vascular devices are widely used in clinical treatments for various vascular diseases. However, current approved clinical implantable vascular devices generally have high failure rates primarily due to their surface lacking inherent functional endothelium. Here, inspired by the pathological mechanisms of vascular device failure and physiological functions of native endothelium, we developed a new generation of bioactive parylene (poly(p-xylylene))-based conformal coating to address these challenges of the vascular devices. This coating used a polyethylene glycol (PEG) linker to introduce an endothelial progenitor cell (EPC) specific binding ligand LXW7 (cGRGDdvc) onto the vascular devices for preventing platelet adhesion and selectively capturing endogenous EPCs. Also, we confirmed the long-term stability and function of this coating in human serum. Using two vascular disease-related large animal models, a porcine carotid artery interposition model and a porcine carotid artery-jugular vein arteriovenous graft model, we demonstrated that this coating enabled rapid generation of self-renewable "living" endothelium on the blood contacting surface of the expanded polytetrafluoroethylene (ePTFE) grafts after implantation. We expect this easy-to-apply conformal coating will present a promising avenue to engineer surface properties of "off-the-shelf" implantable vascular devices for long-lasting performance in the clinical settings.

Discovery of Peptidic Ligands against the SARS-CoV-2 Spike Protein and Their Use in the Development of a Highly Sensitive Personal Use Colorimetric COVID-19 Biosensor

In addition to efficacious vaccines and antiviral therapeutics, reliable and flexible in-home personal use diagnostics for the detection of viral antigens are needed for effective control of the COVID-19 pandemic. Despite the approval of several PCR-based and affinity-based in-home COVID-19 testing kits, many of them suffer from problems such as a high false-negative rate, long waiting time, and short storage period. Using the enabling one-bead-one-compound (OBOC) combinatorial technology, several peptidic ligands with a nanomolar binding affinity toward the SARS-CoV-2 spike protein (S-protein) were successfully discovered. Taking advantage of the high surface area of porous nanofibers, immobilization of these ligands on nanofibrous membranes allows the development of personal use sensors that can achieve low nanomolar sensitivity in the detection of the S-protein in saliva. This simple biosensor employing naked-eye reading exhibits detection sensitivity comparable to some of the current FDA-approved home detection kits. Furthermore, the ligand used in the biosensor was found to detect the S-protein derived from both the original strain and the Delta variant. The workflow reported here may enable us to rapidly respond to the development of home-based biosensors against future viral outbreaks.

Structure-Activity Relationship Study Identifies A Novel Lipophilic Amiloride Derivative That Induces Lysosome-Dependent Cell Death in Therapy-Resistant Breast Cancer Cells

Amiloride and its derivatives have long attracted attention as potential anticancer therapeutic agents. Several early studies characterized amilorides as inhibitors of sodium-proton antiporter-dependent tumor growth and urokinase plasminogen activator-mediated metastasis. However, more recent observations indicate that amiloride derivatives are specifically cytotoxic toward tumor cells relative to normal cells and have the capacity to target tumor cell populations resistant to currently-employed therapies. A major barrier to clinical translation of the amilorides is their modest cytotoxic potency, with EC 50 values in the high micromolar to low millimolar range. Here we report structure-activity relationship observations that underscore the importance of the guanidinium group and the presence of lipophilic substituents at the C(5) position of the amiloride pharmacophore in promoting cytotoxicity. Moreover, we demonstrate that our most potent derivative called LLC1 is specifically cytotoxic toward mouse mammary tumor organoids and drug-resistant populations of various breast cancer cell lines, and induces lysosomal membrane permeabilization as a prelude to lysosome-dependent cell death. Our observations offer a roadmap for the future development of amiloride-based cationic amphiphilic drugs that engage the lysosome to specifically kill breast tumor cells.

Protocol for vision transformer-based evaluation of drug potency using images processed by an optimized Sobel operator

Conventional approaches for screening anticancer drugs rely on chemical reactions, which are time consuming, labor intensive, and costly. Here, we present a protocol for label-free and high-throughput assessment of drug efficacy using a vision transformer and a Conv2D. We describe the steps for cell culture, drug treatment, data collection, and preprocessing. We then detail the building of deep learning models and their use to predict drug potency. This protocol can be adapted for screening chemicals that affect the density or morphological features of cells. For complete details on the use and execution of this protocol, please refer to Wang et al.1.

Engineered multi-functional, pro-angiogenic collagen-based scaffolds loaded with endothelial cells promote large deep burn wound healing

The lack of vascularization associated with deep burns delays the construction of wound beds, increases the risks of infection, and leads to the formation of hypertrophic scars or disfigurement. To address this challenge, we have fabricated a multi-functional pro-angiogenic molecule by grafting integrin αvβ3 ligand LXW7 and collagen-binding peptide (SILY) to a dermatan sulfate (DS) glycosaminoglycan backbone, named LXW7-DS-SILY (LDS), and further employed this to functionalize collagen-based Integra scaffolds. Using a large deep burn wound model in C57/BLK6 mice (8-10 weeks old, 26-32g, n = 39), we demonstrated that LDS-modified collagen-based Integra scaffolds loaded with endothelial cells (ECs) accelerate wound healing rate, re-epithelialization, vascularization, and collagen deposition. Specifically, a 2 cm × 3 cm full-thickness skin burn wound was created 48 h after the burn, and then wounds were treated with four groups of different dressing scaffolds, including Integra + ECs, Integra + LDS, and Integra + LDS + ECs with Integra-only as the control. Digital photos were taken for wound healing measurement on post-treatment days 1, 7, 14, 21, 28, and 35. Post-treatment photos revealed that treatment with the Intgera + LDS + ECs scaffold exhibited a higher wound healing rate in the proliferation phase. Histology results showed significantly increased re-epithelialization, increased collagen deposition, increased thin and mixed collagen fiber content, increased angiogenesis, and shorter wound length within the Integra + LDS + ECs group at Day 35. On Day 14, the Integra + LDS + ECs group showed the same trend. The relative proportions of collagen changed from Day 14 to Day 35 in the Integra + LDS + ECs and Integra + ECs groups demonstrated decreased thick collagen fiber deposition and greater thin and mixed collagen fiber deposition. LDS-modified Integra scaffolds represent a promising novel treatment to accelerate deep burn wound healing, thereby potentially reducing the morbidity associated with open burn wounds. These scaffolds can also potentially reduce the need for autografting and morbidity in patients with already limited areas of harvestable skin.

SIC50: Determining drug inhibitory concentrations using a vision transformer and an optimized Sobel operator

As a measure of cytotoxic potency, half-maximal inhibitory concentration (IC50) is the concentration at which a drug exerts half of its maximal inhibitory effect against target cells. It can be determined by various methods that require applying additional reagents or lysing the cells. Here, we describe a label-free Sobel-edge-based method, which we name SIC50, for the evaluation of IC50. SIC50 classifies preprocessed phase-contrast images with a state-of-the-art vision transformer and allows for the continuous assessment of IC50 in a faster and more cost-efficient manner. We have validated this method using four drugs and 1,536-well plates and also built a web application. We anticipate that this method will assist in the high-throughput screening of chemical libraries (e.g., small-molecule drugs, small interfering RNA [siRNA], and microRNA and drug discovery).

A bioactive material with dual integrin-targeting ligands regulates specific endogenous cell adhesion and promotes vascularized bone regeneration in adult and fetal bone defects

Significant progress has been made in designing bone materials capable of directing endogenous cells to promote vascularized bone regeneration. However, current strategies lack regulation of the specific endogenous cell populations for vascularized bone regeneration, thus leading to adverse tissue formation and decreased regenerative efficiency. Here, we engineered a biomaterial to regulate endogenous cell adhesion and promote vascularized bone regeneration. The biomaterial works by presenting two synthetic ligands, LLP2A and LXW7, explicitly targeting integrins α4β1 and αvβ3, respectively, expressed on the surfaces of the cells related to bone formation and vascularization, such as mesenchymal stem cells (MSCs), osteoblasts, endothelial progenitor cells (EPCs), and endothelial cells (ECs). In vitro, the LLP2A/LXW7 modified biomaterial improved the adhesion of MSCs, osteoblasts, EPCs, and ECs via integrin α4β1 and αvβ3, respectively. In an adult rat calvarial bone defect model, the LLP2A/LXW7 modified biomaterial enhanced bone formation and vascularization by synergistically regulating endogenous cells with osteogenic and angiogenic potentials, such as DLX5⁺ cells, osteocalcin⁺ cells, CD34⁺/CD45^- cells and CD31⁺ cells. In a fetal sheep spinal bone defect model, the LLP2A/LXW7 modified biomaterial augmented bone formation and vascularization without any adverse effects. This innovative biomaterial offers an off-the-shelf, easy-to-use, and biologically safe product suitable for vascularized bone regeneration in both fetal and adult disease environments.

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Two integrin-binding ligands for constructing vascularized bone biomaterial.

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Extracellular matrix (ECM)-mimicking collagen-based biomaterial with specific integrin binding sites for cell adhesion.

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Biomaterial regulates adhesion of endogenous stem cells with osteogenic and angiogenic potentials.

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Biomaterial promotes vascularized bone formation in adult and fetal bone defects without safety issues.

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An easy-to-make and off-the-shelf biomaterial for treatment of clinical bone diseases.

Determining structure and action mechanism of LBF14 by molecular simulation

The recently discovered, membrane-active peptide LBF14 contains several non-proteinogenic amino acids and is able to transform vesicles into tubule networks. The exact membrane interaction mechanism and detailed secondary structure are yet to be determined. We performed molecular dynamics simulations of LBF14 and let it fold de novo into its ensemble of native secondary structures. Histidine protonation state effects on secondary structure were investigated. An MD simulation of the peptide with a lipid bilayer was performed. Simulation results were compared to circular dichroism and electron paramagnetic resonance data of previous studies. LBF14 contains a conserved helical section in an otherwise random structure. Helical stability is influenced by histidine protonation. The peptide localized to the polar layer of the membrane, consistent with experimental results. While the overall secondary structure is unaffected by membrane interaction, Ramachandran plot analysis yielded two distinct peptide conformations during membrane interaction. This conformational change was accompanied by residue repositioning within the membrane. LBF14 only affected the local order in the membrane, and had no measurable effect on pressure. The simulation results are consistent with the previously proposed membrane interaction mechanism of LBF14 and can additionally explain the local interaction mechanism. Communicated by Ramaswamy H. Sarma.

Site-Specific Albumin-Selective Ligation to Human Serum Albumin under Physiological Conditions

Human serum albumin (HSA) is the most abundant protein in human blood plasma. It plays a critical role in the native transportation of numerous drugs, metabolites, nutrients, and small molecules. HSA has been successfully used clinically as a noncovalent carrier for insulin (e.g., Levemir), GLP-1 (e.g., Liraglutide), and paclitaxel (e.g., Abraxane). Site-specific bioconjugation strategies for HSA only would greatly expand its role as the biocompatible, non-toxic platform for theranostics purposes. Using the enabling one-bead one-compound (OBOC) technology, we generated combinatorial peptide libraries containing myristic acid, a well-known binder to HSA at Sudlow I and II binding pockets, and an acrylamide. We then used HSA as a probe to screen the OBOC myristylated peptide libraries for reactive affinity elements (RAEs) that can specifically and covalently ligate to the lysine residue at the proximity of these pockets. Several RAEs have been identified and confirmed to be able to conjugate to HSA covalently. The conjugation can occur at physiological pH and proceed with a high yield within 1 h at room temperature. Tryptic peptide profiling of derivatized HSA has revealed two lysine residues (K225 and K414) as the conjugation sites, which is much more specific than the conventional lysine labeling strategy with N-hydroxysuccinimide ester. The RAE-driven site-specific ligation to HSA was found to occur even in the presence of other prevalent blood proteins such as immunoglobulin or whole serum. Furthermore, these RAEs are orthogonal to the maleimide-based conjugation strategy for Cys34 of HSA. Together, these attributes make the RAEs the promising leads to further develop in vitro and in vivo HSA bioconjugation strategies for numerous biomedical applications.

Phototherapy with Cancer-Specific Nanoporphyrin Potentiates Immunotherapy in Bladder Cancer

PURPOSE

Immune checkpoint inhibitors (ICI) in general have shown poor efficacy in bladder cancer. The purpose of this project was to determine whether photodynamic therapy (PDT) with bladder cancer-specific porphyrin-based PLZ4-nanoparticles (PNP) potentiated ICI.

EXPERIMENTAL DESIGN

SV40 T/Ras double-transgenic mice bearing spontaneous bladder cancer and C57BL/6 mice carrying syngeneic bladder cancer models were used to determine the efficacy and conduct molecular correlative studies.

RESULTS

PDT with PNP generated reactive oxygen species, and induced protein carbonylation and dendritic cell maturation. In SV40 T/Ras double-transgenic mice carrying spontaneous bladder cancer, the median survival was 33.7 days in the control, compared with 44.8 (P = 0.0123), 52.6 (P = 0.0054), and over 75 (P = 0.0001) days in the anti-programmed cell death-1 antibody (anti-PD-1), PNP PDT, and combination groups, respectively. At Day 75 when all mice in other groups died, only 1 in 7 mice in the combination group died. For the direct anti-tumor activity, compared with the control, the anti-PD-1, PNP PDT, and combination groups induced a 40.25% (P = 0.0003), 80.72% (P < 0.0001), and 93.03% (P < 0.0001) tumor reduction, respectively. For the abscopal anticancer immunity, the anti-PD-1, PNP PDT, and combination groups induced tumor reduction of 45.73% (P = 0.0001), 54.92% (P < 0.0001), and 75.96% (P < 0.0001), respectively. The combination treatment also diminished spontaneous and induced lung metastasis. Potential of immunotherapy by PNP PDT is multifactorial.

CONCLUSIONS

In addition to its potential for photodynamic diagnosis and therapy, PNP PDT can synergize immunotherapy in treating locally advanced and metastatic bladder cancer. Clinical trials are warranted to determine the efficacy and toxicity of this combination.

Bioinspired Screening of Anti-Adhesion Peptides against Blood Proteins for Intravenous Delivery of Nanomaterials

Nanomaterials (NMs) inevitably adsorb proteins in blood and form "protein corona" upon intravenous administration as drug carriers, potentially changing the biological properties and intended functions. Inspired by anti-adhesion properties of natural proteins, herein, we employed the one-bead one-compound (OBOC) combinatorial peptide library method to screen anti-adhesion peptides (AAPs) against proteins. The library beads displaying random peptides were screened with three fluorescent-labeled plasma proteins. The nonfluorescence beads, presumed to have anti-adhesion property against the proteins, were isolated for sequence determination. These identified AAPs were coated on gold nanorods (GNRs), enabling significant extension of the blood circulating half-life of these GNRs in mice to 37.8 h, much longer than that (26.6 h) of PEG-coated GNRs. In addition, such AAP coating was found to alter the biodistribution profile of GNRs in mice. The bioinspired screening strategy and resulting peptides show great potential for enhancing the delivery efficiency and targeting ability of NMs.

Nanoradiosensitizer with good tissue penetration and enhances oral cancer radiotherapeutic effect

Low dose non-toxic disulfide cross-linked micelle (DCM) encapsulated paclitaxel (PTX) was found to be highly efficacious as a radiosensitizer against oral cancer preclinical model. Intensity-modulated radiation therapy was locally administered for three consecutive days 24 h after intravascular injection of DCM-[PTX] at 5 mg/kg PTX. DCM-[PTX] NPs combined with conventional radiotherapy (2 Gy) resulted in a 1.7-fold improvement in therapeutic efficacy compared to conventional PTX plus radiotherapy. Interestingly, we found that radiotherapy can decrease tight junctions and increase the accumulation of DCM-[PTX] in tumor sites. Stereotactic body radiotherapy (SBRT) given at 6 Gy was used to further investigate the synergistic anti-tumor effect. Tumor tissues were collected to analyze the relationship between the time interval after SBRT and the biodistribution of the nanomaterials. Compared to combination DCM-[PTX] with conventional radiation dose, combination DCM-PTX with SBRT was found to be more efficacious in inhibiting tumor growth.

Programmable Bispecific Nano-immunoengager That Captures T Cells and Reprograms Tumor Microenvironment

Immune checkpoint blockade (ICB) therapy has revolutionized clinical oncology. However, the efficacy of ICB therapy is limited by the ineffective infiltration of T effector (T_eff) cells to tumors and the immunosuppressive tumor microenvironment (TME). Here, we report a programmable tumor cells/T_eff cells bispecific nano-immunoengager (NIE) that can circumvent these limitations to improve ICB therapy. The peptidic nanoparticles (NIE-NPs) bind tumor cell surface α₃β₁ integrin and undergo in situ transformation into nanofibrillar network nanofibers (NIE-NFs). The prolonged retained nanofibrillar network at the TME captures T_eff cells via the activatable α₄β₁ integrin ligand and allows sustained release of resiquimod for immunomodulation. This bispecific NIE eliminates syngeneic 4T1 breast cancer and Lewis lung cancer models in mice, when given together with anti-PD-1 antibody. The in vivo structural transformation-based supramolecular bispecific NIE represents an innovative class of programmable receptor-mediated targeted immunotherapeutics to greatly enhance ICB therapy against cancers.

MAIA, Fc receptor-like 3, supersedes JUNO as IZUMO1 receptor during human fertilization

Gamete fusion is a critical event of mammalian fertilization. A random one-bead one-compound combinatorial peptide library represented synthetic human egg mimics and identified a previously unidentified ligand as Fc receptor-like 3, named MAIA after the mythological goddess intertwined with JUNO. This immunoglobulin super family receptor was expressed on human oolemma and played a major role during sperm-egg adhesion and fusion. MAIA forms a highly stable interaction with the known IZUMO1/JUNO sperm-egg complex, permitting specific gamete fusion. The complexity of the MAIA isotype may offer a cryptic sexual selection mechanism to avoid genetic incompatibility and achieve favorable fitness outcomes.

Engineered extracellular vesicles with high collagen-binding affinity present superior in situ retention and therapeutic efficacy in tissue repair

Although stem cell-derived extracellular vesicles (EVs) have remarkable therapeutic potential for various diseases, the therapeutic efficacy of EVs is limited due to their degradation and rapid diffusion after administration, hindering their translational applications. Here, we developed a new generation of collagen-binding EVs, by chemically conjugating a collagen-binding peptide SILY to EVs (SILY-EVs), which were designed to bind to collagen in the extracellular matrix (ECM) and form an EV-ECM complex to improve EVs' in situ retention and therapeutic efficacy after transplantation. Methods: SILY was conjugated to the surface of mesenchymal stem/stromal cell (MSC)-derived EVs by using click chemistry to construct SILY-EVs. Nanoparticle tracking analysis (NTA), ExoView analysis, cryogenic electron microscopy (cryo-EM) and western-blot analysis were used to characterize the SILY-EVs. Fluorescence imaging (FLI), MTS assay, ELISA and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to evaluate the collagen binding and biological functions of SILY-EVs in vitro. In a mouse hind limb ischemia model, the in vivo imaging system (IVIS), laser doppler perfusion imaging (LDPI), micro-CT, FLI and RT-qPCR were used to determine the SILY-EV retention, inflammatory response, blood perfusion, gene expression, and tissue regeneration. Results:In vitro, the SILY conjugation significantly enhanced EV adhesion to the collagen surface and did not alter the EVs' biological functions. In the mouse hind limb ischemia model, SILY-EVs presented longer in situ retention, suppressed inflammatory responses, and significantly augmented muscle regeneration and vascularization, compared to the unmodified EVs. Conclusion: With the broad distribution of collagen in various tissues and organs, SILY-EVs hold promise to improve the therapeutic efficacy of EV-mediated treatment in a wide range of diseases and disorders. Moreover, SILY-EVs possess the potential to functionalize collagen-based biomaterials and deliver therapeutic agents for regenerative medicine applications.

Discovery and Characterization of a Potent Antifungal Peptide through One-Bead, One-Compound Combinatorial Library Screening

This work describes the discovery of a bead-bound membrane-active peptide (MAP), LBF127, that selectively binds fungal giant unilamellar vesicles (GUVs) over mammalian GUVs. LBF127 was re-synthesized in solution form and demonstrated to have antifungal activity with limited hemolytic activity and cytotoxicity against mammalian cells. Through systematic structure-activity relationship studies, including N- and C-terminal truncation, alanine-walk, and d-amino acid substitution, an optimized peptide, K-oLBF127, with higher potency, less hemolytic activity, and cytotoxicity emerged. Compared to the parent peptide, K-oLBF127 is shorter by three amino acids and has a lysine at the N-terminus to confer an additional positive charge. K-oLBF127 was found to have improved selectivity toward the fungal membrane over mammalian membranes by 2-fold compared to LBF127. Further characterizations revealed that, while K-oLBF127 exhibits a spectrum of antifungal activity similar to that of the original peptide, it has lower hemolytic activity and cytotoxicity against mammalian cells. Mice infected with Cryptococcus neoformans and treated with K-oLBF127 (16 mg/kg) for 48 h had significantly lower lung fungal burden compared to untreated animals, consistent with K-oLBF127 being active in vivo. Our study demonstrates the success of the one-bead, one-compound high-throughput strategy and sequential screening at identifying MAPs with strong antifungal activities.

Abstract 818: New targets in prostate cancer: Nuclear localization of galectin-1 in androgen receptor indifferent prostate cancer

Currently, no morphological characteristics have been described in clinical specimens to delineate an androgen receptor (AR)-active from an AR-inactive phenotype in AR-expressing aggressive variant prostate cancer (AVPC). 36 localized and 51 metastatic prostate cancer (CaP) samples were analyzed - 19 (37.3%) of the metastases were in the bone, 20 (39.2%) were in the lung, while the rest were in other areas such as brain, lymph node, bladder, etc). Expression level of Gal-1 was graded individually in the nucleus and the cytoplasm of both primary and metastatic tissues. Very low Gal-1 expression was observed in epithelial cells of benign prostate, while stromal staining was strong. Localized prostate tumors obtained from prostatectomy samples showed strong gal-1 expression in the epithelial cells, but remarkably the Gal-1 staining was confined to the cytoplasm. In contrast, in metastatic tumors many nuclei stained for Gal-1. Among localized tumors, Kaplan-Meier curves showed a significant increase in metastasis formation (p=0.022) and decreased overall survival (p=0.015) among those expressing nuclear Gal-1 (n=16) compared to those with no nuclear Gal-1 (n=20). Whereas cytoplasmic Gal-1 negatively correlated with patient age (R=-0.51, p=0.008) and PSA (R=-0.41, p=0.006), and positively correlated with Ki67 (R=0.35, p=0.014), the expression of nuclear Gal-1 correlated strongly with the expression of NE markers including chromogranin A (R=0.32, p=0.031). Significantly, nuclear Gal-1 was expressed in AVPC models but not in those derived from localized tissues. Significantly, androgen deprivation, including treatment with AR antagonists, resulted in nuclear localization of Gal-1. We adapted the powerful one-bead-two-compound (OB2C) combinatorial library method for the discovery of synthetic small molecule death ligands against cancer cells in an ultra-high throughput fashion. One of these benzimidazole-based ligands, LLS80, was active against tumor cells at low micromolar IC50. Pull-down assay followed by LC MS/MS indicated that galectin-1 is the target protein of LLS80, which induced apoptosis preferentially in AVPC cells expressing high level of Gal-1. LLS80 has all the indicators of being a good therapeutic agent: (i) LLS80 has a low in vitro IC50 in AVPC cells, (ii) it shows significant in vivo anti-tumor efficacy using xenograft models, (iii) it is a novel small molecule that can penetrate AVPC cells, (iv) it can synergize with enzalutamide in vivo and in vitro, (v) it inhibits a known therapeutic target, Gal-1, and (vi) low toxicity. Treatment with LLS80 (2 µM) prevented AR antagonist-induced Gal-1 nuclear localization, and also downregulated NE markers in AVPC models of CaP progression. We conclude that nuclear Gal-1 is a novel marker of AVPC.

Citation Format: Maria Malvina Tsamouri, Salma Siddiqui, Blythe P. Durbin-Johnson, Kit S. Lam, Ruiwu Liu, Paramita M. Ghosh. New targets in prostate cancer: Nuclear localization of galectin-1 in androgen receptor indifferent prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 818.

Targeting Epigenetic Modifiers of Tumor Plasticity and Cancer Stem Cell Behavior

Tumor heterogeneity poses one of the greatest challenges to a successful treatment of cancer. Tumor cell populations consist of different subpopulations that have distinct phenotypic and genotypic profiles. Such variability poses a challenge in successfully targeting all tumor subpopulations at the same time. Relapse after treatment has been previously explained using the cancer stem cell model and the clonal evolution model. Cancer stem cells are an important subpopulation of tumor cells that regulate tumor plasticity and determine therapeutic resistance. Tumor plasticity is controlled by genetic and epigenetic changes of crucial genes involved in cancer cell survival, growth and metastasis. Targeting epigenetic modulators associated with cancer stem cell survival can unlock a promising therapeutic approach in completely eradicating cancer. Here, we review various factors governing epigenetic dysregulation of cancer stem cells ranging from the role of epigenetic mediators such as histone and DNA methyltransferases, histone deacetylases, histone methyltransferases to various signaling pathways associated with cancer stem cell regulation. We also discuss current treatment regimens targeting these factors and other promising inhibitors in clinical trials.

Bioactive extracellular matrix scaffolds engineered with proangiogenic proteoglycan mimetics and loaded with endothelial progenitor cells promote neovascularization and diabetic wound healing

Diabetic ischemic wound treatment remains a critical clinical challenge. Neovascularization plays a significant role in wound healing during all stages of the tissue repair process. Strategies that enhance angiogenesis and neovascularization and improve ischemic pathology may promote the healing of poor wounds, particularly diabetic wounds in highly ischemic conditions. We previously identified a cyclic peptide LXW7 that specifically binds to integrin αvβ3 on endothelial progenitor cells (EPCs) and endothelial cells (ECs), activates vascular endothelial growth factor (VEGF) receptors, and promotes EC growth and maturation. In this study, we designed and synthesized a multi-functional pro-angiogenic molecule by grafting LXW7 and collagen-binding peptides (SILY) to a dermatan sulfate (DS) glycosaminoglycan backbone, named LXW7-DS-SILY, and further employed this multi-functional molecule to functionalize collagen-based extracellular matrix (ECM) scaffolds. We confirmed that LXW7-DS-SILY modification significantly promoted EPC attachment and growth on the ECM scaffolds in vitro and supported EPC survival in vivo in the ischemic environment. When applied in an established Zucker Diabetic Fatty (ZDF) rat ischemic skin flap model, LXW7-DS-SILY-functionalized ECM scaffolds loaded with EPCs significantly improved wound healing, enhanced neovascularization and modulated collagen fibrillogenesis in the ischemic environment. Altogether, this study provides a promising novel treatment to accelerate diabetic ischemic wound healing, thereby reducing limb amputation and mortality of diabetic patients.

Fatty acid oxidation fuels glioblastoma radioresistance with CD47-mediated immune evasion

Glioblastoma multiforme (GBM) remains the top challenge to radiotherapy with only 25% one-year survival after diagnosis. Here, we reveal that co-enhancement of mitochondrial fatty acid oxidation (FAO) enzymes (CPT1A, CPT2 and ACAD9) and immune checkpoint CD47 is dominant in recurrent GBM patients with poor prognosis. A glycolysis-to-FAO metabolic rewiring is associated with CD47 anti-phagocytosis in radioresistant GBM cells and regrown GBM after radiation in syngeneic mice. Inhibition of FAO by CPT1 inhibitor etomoxir or CRISPR-generated CPT1A^-/-, CPT2^-/-, ACAD9^-/- cells demonstrate that FAO-derived acetyl-CoA upregulates CD47 transcription via NF-κB/RelA acetylation. Blocking FAO impairs tumor growth and reduces CD47 anti-phagocytosis. Etomoxir combined with anti-CD47 antibody synergizes radiation control of regrown tumors with boosted macrophage phagocytosis. These results demonstrate that enhanced fat acid metabolism promotes aggressive growth of GBM with CD47-mediated immune evasion. The FAO-CD47 axis may be targeted to improve GBM control by eliminating the radioresistant phagocytosis-proofing tumor cells in GBM radioimmunotherapy.

Magnetic resonance imaging of tumor-associated-macrophages (TAMs) with a nanoparticle contrast agent

In the tumor micro-environment, tumor associated macrophages (TAMs) represent a predominant component of the total tumor mass, and TAMs play a complex and diverse role in cancer pathogenesis with potential for either tumor suppressive, or tumor promoting biology. Thus, understanding macrophage localization and function are essential for cancer diagnosis and treatment. Typically, tissue biopsy is used to evaluate the density and polarization of TAMs, but provides a limited "snapshot" in time of a dynamic and potentially heterogeneous tumor immune microenvironment. Imaging has the potential for three-dimensional mapping; however, there is a paucity of macrophage-targeted contrast agents to specifically detect TAM subtypes. We have previously found that sulfated-dextran coated iron oxide nanoparticles (SDIO) can target macrophage scavenger receptor A (SR-A, also known as CD204). Since CD204 (SR-A) is considered a biomarker for the M2 macrophage polarization, these SDIO might provide M2-specific imaging probes for MRI. In this work, we investigate whether SDIO can label M2-polarized cells in vitro. We evaluate the effect of degree of sulfation on uptake by primary cultured bone marrow derived macrophages (BMDM) and found that a higher degree of sulfation led to higher uptake, but there were no differences across the subtypes. Further analysis of the BMDM showed similar SR-A expression across stimulation conditions, suggesting that this classic model for macrophage subtypes may not be ideal for definitive M2 subtype marker expression, especially SR-A. We further examine the localization of SDIO in TAMs in vivo, in the mammary fat pad mouse model of breast cancer. We demonstrate that uptake by TAMs expressing SR-A scales with degree of sulfation, consistent with the in vitro studies. The TAMs demonstrate M2-like function and secrete Arg-1 but not iNOS. Uptake by these M2-like TAMs is validated by immunohistochemistry. SDIO show promise as a valuable addition to the toolkit of imaging probes targeted to different biomarkers for TAMs.

Selectin-targeting glycosaminoglycan-peptide conjugate limits neutrophil-mediated cardiac reperfusion injury

AIMS

One of the hallmarks of myocardial infarction (MI) is excessive inflammation. During an inflammatory insult, damaged endothelial cells shed their glycocalyx, a carbohydrate-rich layer on the cell surface which provides a regulatory interface to immune cell adhesion. Selectin-mediated neutrophilia occurs as a result of endothelial injury and inflammation. We recently designed a novel selectin-targeting glycocalyx mimetic (termed DS-IkL) capable of binding inflamed endothelial cells. This study examines the capacity of DS-IkL to limit neutrophil binding and platelet activation on inflamed endothelial cells, as well as the cardioprotective effects of DS-IkL after acute myocardial infarction.

METHODS AND RESULTS

In vitro, DS-IkL diminished neutrophil interactions with both recombinant selectin and inflamed endothelial cells, and limited platelet activation on inflamed endothelial cells. Our data demonstrated that DS-IkL localized to regions of vascular inflammation in vivo after 45 min of left anterior descending coronary artery ligation-induced MI. Further, findings from this study show DS-IkL treatment had short- and long-term cardioprotective effects after ischaemia/reperfusion of the left anterior descending coronary artery. Mice treated with DS-IkL immediately after ischaemia/reperfusion and 24 h later exhibited reduced neutrophil extravasation, macrophage accumulation, fibroblast and endothelial cell proliferation, and fibrosis compared to saline controls.

CONCLUSIONS

Our findings suggest that DS-IkL has great therapeutic potential after MI by limiting reperfusion injury induced by the immune response.

Rapid discovery of self-assembling peptides with one-bead one-compound peptide library

Self-assembling peptides have shown tremendous potential in the fields of material sciences, nanoscience, and medicine. Because of the vast combinatorial space of even short peptides, identification of self-assembling sequences remains a challenge. Herein, we develop an experimental method to rapidly screen a huge array of peptide sequences for self-assembling property, using the one-bead one-compound (OBOC) combinatorial library method. In this approach, peptides on beads are N-terminally capped with nitro-1,2,3-benzoxadiazole, a hydrophobicity-sensitive fluorescence molecule. Beads displaying self-assembling peptides would fluoresce under aqueous environment. Using this approach, we identify eight pentapeptides, all of which are able to self-assemble into nanoparticles or nanofibers. Some of them are able to interact with and are taken up efficiently by HeLa cells. Intracellular distribution varied among these non-toxic peptidic nanoparticles. This simple screening strategy has enabled rapid identification of self-assembling peptides suitable for the development of nanostructures for various biomedical and material applications.

Self-assembling peptides have a range of potential applications but developing self-assembling sequences can be challenging. Here, the authors report on a one-bead one-compound combinatorial library where fluorescence is used to detect the potential for self-assembly and identified candidates are evaluated.

LHRH-Targeted Redox-Responsive Crosslinked Micelles Impart Selective Drug Delivery and Effective Chemotherapy in Triple-Negative Breast Cancer

Systemic chemotherapy is efficacious against triple-negative breast cancer (TNBC), but it is often associated with serious side effects. Here, a luteinizing hormone-releasing hormone (LHRH) receptor-targeted and tumor microenvironment-responsive nanoparticle system to selectively deliver chemotherapeutic drugs to TNBC cells, is reported. This delivery system (termed "LHRH-DCMs") contains poly(ethylene glycol) and dendritic cholic acid as a micellar carrier, reversible intra-micellar disulfide bond as a redox-responsive crosslink, and synthetic high-affinity (D-Lys)-LHRH peptide as a targeting moiety. LHRH-DCMs exhibit high drug loading efficiency, optimal particle size, good colloidal stability, and glutathione-responsive drug release. As expected, LHRH-DCMs are more efficiently internalized into human TNBC cells through receptor-mediated endocytosis, resulting in stronger cytotoxicity against these cancer cells than the non-targeted counterpart when encapsulated with paclitaxel (PTX). Furthermore, near-infrared fluorescence and magnetic resonance imaging demonstrate that LHRH-DCMs facilitate the tumor distribution and penetration of payloads in three different animal models of breast cancer, including cell line-derived xenograft (CDX), patient-derived xenograft (PDX), and transgenic mammary carcinoma. Finally, in vivo therapeutic studies show that PTX-LHRH-DCMs outperform both the corresponding nontargeted PTX-DCMs and the current clinical formulation (Taxol) in an orthotopic TNBC model. These results provide new insights into approaches for precise drug delivery of TNBC.

Tumor Receptor-Mediated In Vivo Modulation of the Morphology, Phototherapeutic Properties, and Pharmacokinetics of Smart Nanomaterials

To be clinically efficacious, nanotherapeutic drugs need to reach disease tissues reliably and cause limited side effects to normal organs and tissues. Here, we report a proof-of-concept study on the development of a smart peptidic nanophototherapeutic agent in line with clinical requirements, which can transform its morphology from nanoparticles to nanofibrils at the tumor sites. This in vivo receptor-mediated transformation process resulted in the formation and prolonged tumor-retention of highly ordered (J-aggregate type of photosensitizer) photosensitive peptide nanofibrillar network with greatly enhanced photothermal and photodynamic properties. This strategy of "multiple daily low-intensity laser radiation after each intravenous injection of significantly low-dose of nanomaterials" demonstrated effective elimination of 4T1 orthotopic syngeneic breast cancer in mice. The technology for nanomaterial modulation based on living cell surface receptors, in this case tumor-associated α₃β₁ integrin, has great potential for clinical translation and is expected to improve the therapeutic efficacy against many cancers.

A new anabolic compound, LLP2A-Ale, reserves periodontal bone loss in mice through augmentation of bone formation

BACKGROUND

Currently, there are no effective medications to reverse periodontal disease (PD)-induced bone loss. The objective of this study was to test a new anabolic compound, LLP2A-Ale, or with the combination treatment of mesenchymal stromal cell (MSC), in the treatment of bone loss secondary to PD.

METHODS

PD was induced in mice by placing a ligature around the second right molar. At one week after disease induction, the mice were treated with placebo, LLP2A-Ale, MSCs, or combination of LLP2A-Ale + MSCs, and euthanized at week 4.

RESULTS

We found that PD induced alveolar bone loss that was associated with reduced bone formation. LLP2A-Ale alone or in combination with MSCs sustained alveolar bone formation and reversed alveolar bone loss. Additionally, PD alone caused systemic inflammation and increased the circulating levels of G-CSF, IP-10, MIP-1a, and MIP2, which were suppressed by LLP2A-Ale +/- MSCs. LLP2A-Ale +/- MSCs increased bone formation at the peripheral skeletal site (distal femur), which was otherwise suppressed by PD.

CONCLUSION

Our findings indicated that LLP2A-Ale treatment rescued alveolar bone loss caused by PD, primarily by increasing bone formation. LLP2A-Ale also attenuated the circulating levels of a series of inflammatory cytokines and reversed the PD-induced suppression of systemic bone formation.

Discovery and mechanistic characterization of a structurally-unique membrane active peptide

Membrane active peptides (MAPs) have gained wide interest due to their far reaching applications in drug discovery and drug delivery. The search for new MAPs, however, has been largely skewed with bias selecting for physicochemical parameters believed to be important for membrane activity, such as alpha helicity, cationicity and hydrophobicity. Here we carry out a search-and-find strategy to screen a 100,000-membered one-bead-one-compound (OBOC) combinatorial peptide library for lead compounds, agnostic of those physicochemical constraints. Such a synthetic strategy also permits expansion of our peptide repertoire to include unnatural amino acids. Using this approach, we discovered a structurally unique lead peptide LBF14, a linear 14-mer peptide, that induces gross morphological disruption of membranes, irrespective of membrane composition. Further, we demonstrate that the unique insertion mechanism of the peptide, visualized by spinning disc confocal microscopy and further analyzed by electron paramagnetic resonance measurements, may be the cause of this large scale membrane deformation. We also demonstrate the robustness, reproducibility, and potential application of this technique to discover and characterize new membrane active peptides that display activity by local insertion and subsequent allosteric effects leading to global membrane disruption.

Dual blockade of CD47 and HER2 eliminates radioresistant breast cancer cells

Although the efficacy of cancer radiotherapy (RT) can be enhanced by targeted immunotherapy, the immunosuppressive factors induced by radiation on tumor cells remain to be identified. Here, we report that CD47-mediated anti-phagocytosis is concurrently upregulated with HER2 in radioresistant breast cancer (BC) cells and RT-treated mouse syngeneic BC. Co-expression of both receptors is more frequently detected in recurrent BC patients with poor prognosis. CD47 is upregulated preferentially in HER2-expressing cells, and blocking CD47 or HER2 reduces both receptors with diminished clonogenicity and augmented phagocytosis. CRISPR-mediated CD47 and HER2 dual knockouts not only inhibit clonogenicity but also enhance macrophage-mediated attack. Dual antibody of both receptors synergizes with RT in control of syngeneic mouse breast tumor. These results provide the evidence that aggressive behavior of radioresistant BC is caused by CD47-mediated anti-phagocytosis conjugated with HER2-prompted proliferation. Dual blockade of CD47 and HER2 is suggested to eliminate resistant cancer cells in BC radiotherapy.

Identification of osteogenic progenitor cell-targeted peptides that augment bone formation

Activation and migration of endogenous mesenchymal stromal cells (MSCs) are critical for bone regeneration. Here, we report a combinational peptide screening strategy for rapid discovery of ligands that not only bind strongly to osteogenic progenitor cells (OPCs) but also stimulate osteogenic cell Akt signaling in those OPCs. Two lead compounds are discovered, YLL3 and YLL8, both of which increase osteoprogenitor osteogenic differentiation in vitro. When given to normal or osteopenic mice, the compounds increase mineral apposition rate, bone formation, bone mass, and bone strength, as well as expedite fracture repair through stimulated endogenous osteogenesis. When covalently conjugated to alendronate, YLLs acquire an additional function resulting in a “tri-functional” compound that: (i) binds to OPCs, (ii) targets bone, and (iii) induces “pro-survival” signal. These bone-targeted, osteogenic peptides are well suited for current tissue-specific therapeutic paradigms to augment the endogenous osteogenic cells for bone regeneration and the treatment of bone loss.

Activation of osteogenic cells is essential for bone regeneration. Here, the authors screen a peptide library and identify 2 compounds that promote osteogenic progenitor cell differentiation in vitro, and show that they increase bone formation and fracture repair in mice.

Developing an Injectable Nanofibrous Extracellular Matrix Hydrogel With an Integrin αvβ3 Ligand to Improve Endothelial Cell Survival, Engraftment and Vascularization

Endothelial cell (EC) transplantation via injectable collagen hydrogel has received much attention as a potential treatment for various vascular diseases. However, the therapeutic effect of transplanted ECs is limited by their poor viability, which partially occurs as a result of cellular apoptosis triggered by the insufficient cell-extracellular matrix (ECM) engagement. Integrin binding to the ECM is crucial for cell anchorage to the surrounding matrix, cell spreading and migration, and further activation of intracellular signaling pathways. Although collagen contains several different types of integrin binding sites, it still lacks sufficient specific binding sites for ECs. Previously, using one-bead one-compound (OBOC) combinatorial technology, we identified LXW7, an integrin αvβ3 ligand, which possessed a strong binding affinity to and enhanced functionality of ECs. In this study, to improve the EC-matrix interaction, we developed an approach to molecularly conjugate LXW7 to the collagen backbone, via a collagen binding peptide SILY, in order to increase EC specific integrin binding sites on the collagen hydrogel. Results showed that in the in vitro 2-dimensional (2D) culture model, the LXW7-treated collagen surface significantly improved EC attachment and survival and decreased caspase 3 activity in an ischemic-mimicking environment. In the in vitro 3-dimensional (3D) culture model, LXW7-modified collagen hydrogel significantly improved EC spreading, proliferation, and survival. In a mouse subcutaneous implantation model, LXW7-modified collagen hydrogel improved the engraftment of transplanted ECs and supported ECs to form vascular network structures. Therefore, LXW7-functionalized collagen hydrogel has shown promising potential to improve vascularization in tissue regeneration and may be used as a novel tool for EC delivery and the treatment of vascular diseases.

Galectin-1 inhibition induces cell apoptosis through dual suppression of CXCR4 and Ras pathways in human malignant peripheral nerve sheath tumors

BACKGROUND

The Ras signaling pathway is commonly dysregulated in human malignant peripheral nerve sheath tumors (MPNSTs). It is well known that galectin-1 (Gal-1) is essential to stabilize membrane Ras and thereby induce the activation of Ras. However, the role of Gal-1 in MPNST progression remains unknown. The aim of this study was to examine whether Gal-1 knockdown could have an effect on the Ras signaling pathway.

METHODS

Cell viability, apoptosis assay, and colony formation were performed to examine the effects of inhibition of Gal-1 in MPNST cells. We used a human MPNST xenograft model to assess growth and metastasis inhibitory effects of Gal-1 inhibitor LLS2.

RESULTS

Gal-1 was upregulated in MPNST patients and was highly expressed in MPNST cells. Knockdown of Gal-1 by small interfering (si)RNA in Gal-1 expressing MPNST cells significantly reduces cell proliferation through the suppression of C-X-C chemokine receptor type 4 (CXCR4) and the rat sarcoma viral oncogene homolog (RAS)/extracellular signal-regulated kinase (ERK) pathway, which are important oncogenic signaling in MPNST development. Moreover, Gal-1 knockdown induces apoptosis and inhibits colony formation. LLS2, a novel Gal-1 allosteric small molecule inhibitor, is cytotoxic against MPNST cells and was able to induce apoptosis and suppress colony formation in MPNST cells. LLS2 treatment and Gal-1 knockdown exhibited similar effects on the suppression of CXCR4 and RAS/ERK pathways. More importantly, inhibition of Gal-1 expression or function by treatment with either siRNA or LLS2 resulted in significant tumor responses in an MPNST xenograft model.

CONCLUSION

Our results identified an oncogenic role of Gal-1 in MPNST and that its inhibitor, LLS2, is a potential therapeutic agent, applied topically or systemically, against MPNST.

Extracellular Matrix Mimicking Nanofibrous Scaffolds Modified With Mesenchymal Stem Cell-Derived Extracellular Vesicles for Improved Vascularization

The network structure and biological components of natural extracellular matrix (ECM) are indispensable for promoting tissue regeneration. Electrospun nanofibrous scaffolds have been widely used in regenerative medicine to provide structural support for cell growth and tissue regeneration due to their natural ECM mimicking architecture, however, they lack biological functions. Extracellular vesicles (EVs) are potent vehicles of intercellular communication due to their ability to transfer RNAs, proteins, and lipids, thereby mediating significant biological functions in different biological systems. Matrix-bound nanovesicles (MBVs) are identified as an integral and functional component of ECM bioscaffolds mediating significant regenerative functions. Therefore, to engineer EVs modified electrospun scaffolds, mimicking the structure of the natural EV-ECM complex and the physiological interactions between the ECM and EVs, will be attractive and promising in tissue regeneration. Previously, using one-bead one-compound (OBOC) combinatorial technology, we identified LLP2A, an integrin α4β1 ligand, which had a strong binding to human placenta-derived mesenchymal stem cells (PMSCs). In this study, we isolated PMSCs derived EVs (PMSC-EVs) and demonstrated they expressed integrin α4β1 and could improve endothelial cell (EC) migration and vascular sprouting in an ex vivo rat aortic ring assay. LLP2A treated culture surface significantly improved PMSC-EV attachment, and the PMSC-EV treated culture surface significantly enhanced the expression of angiogenic genes and suppressed apoptotic activity. We then developed an approach to enable "Click chemistry" to immobilize LLP2A onto the surface of electrospun scaffolds as a linker to immobilize PMSC-EVs onto the scaffold. The PMSC-EV modified electrospun scaffolds significantly promoted EC survival and angiogenic gene expression, such as KDR and TIE2, and suppressed the expression of apoptotic markers, such as caspase 9 and caspase 3. Thus, PMSC-EVs hold promising potential to functionalize biomaterial constructs and improve the vascularization and regenerative potential. The EVs modified biomaterial scaffolds can be widely used for different tissue engineering applications.

Two-way magnetic resonance tuning and enhanced subtraction imaging for non-invasive and quantitative biological imaging

Distance-dependent magnetic resonance tuning (MRET) technology enables the sensing and quantitative imaging of biological targets in vivo, with the advantage of deep tissue penetration and fewer interactions with the surroundings as compared with those of fluorescence-based Förster resonance energy transfer. However, applications of MRET technology in vivo are currently limited by the moderate contrast enhancement and stability of T₁-based MRET probes. Here we report a new two-way magnetic resonance tuning (TMRET) nanoprobe with dually activatable T₁ and T₂ magnetic resonance signals that is coupled with dual-contrast enhanced subtraction imaging. This integrated platform achieves a substantially improved contrast enhancement with minimal background signal and can be used to quantitatively image molecular targets in tumours and to sensitively detect very small intracranial brain tumours in patient-derived xenograft models. The high tumour-to-normal tissue ratio offered by TMRET in combination with dual-contrast enhanced subtraction imaging provides new opportunities for molecular diagnostics and image-guided biomedical applications.

Rapid endothelialization of small diameter vascular grafts by a bioactive integrin-binding ligand specifically targeting endothelial progenitor cells and endothelial cells

Establishing and maintaining a healthy endothelium on vascular and intravascular devices is crucial for the prevention of thrombosis and stenosis. Generating a biofunctional surface on vascular devices to recruit endothelial progenitor cells (EPCs) and endothelial cells (ECs) has proven efficient in promoting in situ endothelialization. However, molecules conventionally used for EPC/EC capturing generally lack structural stability, capturing specificity, and biological functionalities, which have limited their applications. Discovery of effective, specific, and structurally stable EPC/EC capturing ligands is desperately needed. Using the high-throughput One-Bead One-Compound combinatorial library screening technology, we recently identified a disulfide cyclic octa-peptide LXW7 (cGRGDdvc), which possesses strong binding affinity and functionality to EPCs/ECs, weak binding to platelets, and no binding to inflammatory cells. Because LXW7 is cyclic and 4 out of the 8 amino acids are unnatural D-amino acids, LXW7 is highly proteolytically stable. In this study, we applied LXW7 to modify small diameter vascular grafts using a Click chemistry approach. In vitro studies demonstrated that LXW7-modified grafts significantly improved EPC attachment, proliferation and endothelial differentiation and suppressed platelet attachment. In a rat carotid artery bypass model, LXW7 modification of the small diameter vascular grafts significantly promoted EPC/EC recruitment and rapidly achieved endothelialization. At 6 weeks after implantation, LXW7-modified grafts retained a high patency of 83%, while the untreated grafts had a low patency of 17%. Our results demonstrate that LXW7 is a potent EPC/EC capturing and platelet suppressing ligand and LXW7-modified vascular grafts rapidly generate a healthy and stable endothelial interface between the graft surface and the circulation to reduce thrombosis and improve patency. STATEMENT OF SIGNIFICANCE: In this study, One-Bead One-Compound (OBOC) technology has been applied for the first time in discovering bioactive ligands for tissue regeneration applications. Current molecules used to modify artificial vascular grafts generally lack EPC/EC capturing specificity, biological functionalities and structural stability. Using OBOC technology, we identified LXW7, a constitutionally stable disulfide cyclic octa-peptide with strong binding affinity and biological functionality to EPCs/ECs, very weak binding to platelets and no binding to inflammatory cells. These characteristics are crucial for promoting rapid endothelialization to prevent thrombosis and improve patency of vascular grafts. LXW7 coating technology could be applied to a wide range of vascular and intravascular devices, including grafts, stents, cardiac valves, and catheters, where a "living" endothelium and healthy blood interface are needed.

Sequential Targeting in Crosslinking Nanotheranostics for Tackling the Multibarriers of Brain Tumors

The efficacy of therapeutics for brain tumors is seriously hampered by multiple barriers to drug delivery, including severe destabilizing effects in the blood circulation, the blood-brain barrier/blood-brain tumor barrier (BBB/BBTB), and limited tumor uptake. Here, a sequential targeting in crosslinking (STICK) nanodelivery strategy is presented to circumvent these important physiological barriers to improve drug delivery to brain tumors. STICK nanoparticles (STICK-NPs) can sequentially target BBB/BBTB and brain tumor cells with surface maltobionic acid (MA) and 4-carboxyphenylboronic acid (CBA), respectively, and simultaneously enhance nanoparticle stability with pH-responsive crosslinkages formed by MA and CBA in situ. STICK-NPs exhibit prolonged circulation time (17-fold higher area under curve) than the free agent, allowing increased opportunities to transpass the BBB/BBTB via glucose-transporter-mediated transcytosis by MA. The tumor acidic environment then triggers the transformation of the STICK-NPs into smaller nanoparticles and reveals a secondary CBA targeting moiety for deep tumor penetration and enhanced uptake in tumor cells. STICK-NPs significantly inhibit tumor growth and prolong the survival time with limited toxicity in mice with aggressive and chemoresistant diffuse intrinsic pontine glioma. This formulation tackles multiple physiological barriers on-demand with a simple and smart STICK design. Therefore, these features allow STICK-NPs to unleash the potential of brain tumor therapeutics to improve their treatment efficacy.

Surface modification of polymeric electrospun scaffolds via a potent and high-affinity integrin α4β1 ligand improved the adhesion, spreading and survival of human chorionic villus-derived mesenchymal stem cells: a new insight for fetal tissue engineering

Cell-biomaterial interactions are primarily governed by cell adhesion, which arises from the binding of cellular integrins to the extracellular matrix (ECM). Integrins drive the assembly of focal contacts that serve as mechanotransducers and signaling nexuses for stem cells, for example integrin α4β1 plays pivotal roles in regulating mesenchymal stem cell (MSC) homing, adhesion, migration and differentiation. The strategy to control the integrin-mediated cell adhesion to bioinspired, ECM-mimicking materials is essential to regulate cell functions and tissue regeneration. Previously, using one-bead one-compound (OBOC) combinatorial technology, we discovered that LLP2A was a high-affinity peptidomimetic ligand (IC50 = 2 pM) against integrin α4β1. In this study, we identified that LLP2A had a strong binding to human early gestation chorionic villi-derived MSCs (CV-MSCs) via integrin α4β1. To improve CV-MSC seeding, expansion and delivery for regenerative applications, we constructed artificial scaffolds simulating the structure of the native ECM by immobilizing LLP2A onto the scaffold surface as cell adhesion sites. LLP2A modification significantly enhanced CV-MSC adhesion, spreading and viability on the polymeric scaffolds via regulating signaling pathways including phosphorylation of focal adhesion kinase (FAK), and AKT, NF-kB and Caspase 9. In addition, we also demonstrated that LLP2A had strong binding to MSCs of other sources, such as bone marrow-derived mesenchymal stem cells (BM-MSCs) and adipose tissue-derived mesenchymal stem cells (AT-MSCs). Therefore, LLP2A and its derivatives not only hold great promise for improving CV-MSC-mediated treatment of fetal diseases, but they can also be widely applied to functionalize various biological and medical materials, which are in need of MSC recruitment, enrichment and survival, for regenerative medicine applications.

Size-Transformable Hyaluronan Stacked Self-Assembling Peptide Nanoparticles for Improved Transcellular Tumor Penetration and Photo-Chemo Combination Therapy

Size-transformable nanomedicine has the potential to overcome systemic and local barriers, leading to efficient accumulation and penetration throughout the tumor tissue. However, the design of this type of nanomedicine was seldom based on active targeting and intracellular size transformation. Here, we report an intracellular size-transformable nanosystem, in which small and positively charged nanoparticles (<30 nm) prepared from the self-assembly of an amphiphilic hexadecapeptide derivative was coated by folic acid- and dopamine-decorated hyaluronan (HA) to form large and negatively charged nanoparticles (∼130 nm). This nanosystem has been proven to improve the blood circulation half-life of the drug and prevent premature intravascular drug leakage from the nanocarrier. Once accumulated in the tumor, the nanoparticles were prone to HA- and folic acid-mediated cellular uptake, followed by intracellular size transformation and discharge of transformed small nanoparticles. The size-transformable nanosystem facilitated the transcytosis-mediated tumor penetration and improved the internalization of nanoparticles by cells and the intracellular release of 7-ethyl-10 hydroxycamptothecin. With an indocyanine green derivative as the intrinsic component of the amphiphilic polymer, the nanosystem has exhibited additional theranostic functions: photoacoustic imaging, NIR-laser-induced drug release, and synergistic chemotherapy and phototherapy, leading to a 50% complete cure rate in a subcutaneous B16 melanoma model. This nanosystem with multimodalities and efficient tumor penetration has shown potentials in improving anticancer efficacy.

Transformable peptide nanoparticles arrest HER2 signalling and cause cancer cell death in vivo

Human epidermal growth factor receptor 2 (HER2) is overexpressed in >20% of breast cancers. Dimerization of HER2 receptors leads to the activation of downstream signals enabling the proliferation and survival of malignant phenotypes. Owing to the high expression levels of HER2, combination therapies are currently required for the treatment of HER2⁺ breast cancer. Here, we designed non-toxic transformable peptides that self-assemble into micelles under aqueous conditions but, on binding to HER2 on cancer cells, transform into nanofibrils that disrupt HER2 dimerization and subsequent downstream signalling events leading to apoptosis of cancer cells. The phase transformation of peptides enables specific HER2 targeting, and inhibition of HER2 dimerization blocks the expression of proliferation and survival genes in the nucleus. We demonstrate, in mouse xenofraft models, that these transformable peptides can be used as a monotherapy in the treatment of HER2⁺ breast cancer.

Tunable hydrogels for mesenchymal stem cell delivery: Integrin-induced transcriptome alterations and hydrogel optimization for human wound healing

Therapeutic applications for mesenchymal stem/stromal cells (MSCs) are growing; however, the successful implementation of these therapies requires the development of appropriate MSC delivery systems. Hydrogels are ideally suited to cultivate MSCs but tuning hydrogel properties to match their specific in vivo applications remains a challenge. Thus, further characterization of how hydrogel-based delivery vehicles broadly influence MSC function and fate will help lead to the next generation of more intelligently designed delivery vehicles. To date, few attempts have been made to comprehensively characterize hydrogel impact on the MSC transcriptome. Herein, we have synthesized cell-degradable hydrogels based on bio-inert poly(ethylene glycol) tethered with specific integrin-binding small molecules and have characterized their resulting effect on the MSC transcriptome when compared with 2D cultured and untethered 3D hydrogel cultured MSCs. The 3D culture systems resulted in alterations in the MSC transcriptome, as is evident by the differential expression of genes related to extracellular matrix production, glycosylation, metabolism, signal transduction, gene epigenetic regulation, and development. For example, genes important for osteogenic differentiation were upregulated in 3D hydrogel cultures, and the expression of these genes could be partially suppressed by tethering an integrin-binding RGD peptide within the hydrogel. Highlighting the utility of tunable hydrogels, when applied to ex vivo human wounds the RGD-tethered hydrogel was able to support wound re-epithelialization, possibly due to its ability to increase PDGF expression and decrease IL-6 expression. These results will aid in future hydrogel design for a broad range of applications.

Peptide-based materials for cancer immunotherapy

Peptide-based materials hold great promise as immunotherapeutic agents for the treatment of many malignant cancers. Extensive studies have focused on the development of peptide-based cancer vaccines and delivery systems by mimicking the functional domains of proteins with highly specific immuno-regulatory functions or tumor cells fate controls. However, a systemic understanding of the interactions between the different peptides and immune systems remains unknown. This review describes the role of peptides in regulating the functions of the innate and adaptive immune systems and provides a comprehensive focus on the design, categories, and applications of peptide-based cancer vaccines. By elucidating the impacts of peptide length and formulations on their immunogenicity, peptide-based immunomodulating agents can be better utilized and dramatic breakthroughs may also be realized. Moreover, some critical challenges for translating peptides into large-scale synthesis, safe delivery, and efficient cancer immunotherapy are posed to improve the next-generation peptide-based immunotherapy.

RORγ is a targetable master regulator of cholesterol biosynthesis in a cancer subtype

Tumor subtype-specific metabolic reprogrammers could serve as targets of therapeutic intervention. Here we show that triple-negative breast cancer (TNBC) exhibits a hyper-activated cholesterol-biosynthesis program that is strongly linked to nuclear receptor RORγ, compared to estrogen receptor-positive breast cancer. Genetic and pharmacological inhibition of RORγ reduces tumor cholesterol content and synthesis rate while preserving host cholesterol homeostasis. We demonstrate that RORγ functions as an essential activator of the entire cholesterol-biosynthesis program, dominating SREBP2 via its binding to cholesterol-biosynthesis genes and its facilitation of the recruitment of SREBP2. RORγ inhibition disrupts its association with SREBP2 and reduces chromatin acetylation at cholesterol-biosynthesis gene loci. RORγ antagonists cause tumor regression in patient-derived xenografts and immune-intact models. Their combination with cholesterol-lowering statins elicits superior anti-tumor synergy selectively in TNBC. Together, our study uncovers a master regulator of the cholesterol-biosynthesis program and an attractive target for TNBC.

One-bead one-compound combinatorial library derived targeting ligands for detection and treatment of oral squamous cancer

Oral squamous cancers (OSC) are hallmarked by poor prognosis, delayed clinical detection, and a lack of defined, characteristic biomarkers. By screening combinatorial one-bead one-compound (OBOC) peptide libraries against oral squamous cancer cell lines, two cyclic peptide ligands, LLY12 and LLY13 were previously identified. These ligands are capable of specific binding to the oral cancer cell lines (MOK-101, HSC-3, SCC-4 and SCC-10a) but not non-cancerous keratinocytes, leukocytes, fibroblast, and endothelial cells. These two peptides were synthesized and evaluated for their binding property, cytotoxicity and cell permeability. In vitro studies indicate that both LLY12 and LLY13 were able to bind to oral cancer cells with high specificity but did not show any cytotoxicity against human keratinocytes. Biotinylated LLY13, in complex with streptavidin-alexa488 was taken up by live oral cancer cells, thus rendering it as an excellent candidate vehicle for efficient delivery of drug loaded-nanoparticles. In vivo and ex vivo near infra-red fluorescence imaging studies confirmed the in vivo targeting efficiency and specificity of LLY13 in oral cancer orthotopic murine xenograft model. In vivo studies also showed that LLY13 was able to accumulate in the OSC tumors and demarcate the tumor margins in orthotopic xenograft model. Together, our data supports LLY13 as a promising theranostic agent against OSC.

High-affinity peptide ligand LXY30 for targeting α3β1 integrin in non-small cell lung cancer

Background

α3β1 integrin is a promising cancer biomarker and drug target. We previously identified a 9-amino-acid cyclic peptide LXY30 for detecting α3β1 integrin on the surface of live tumor cells. This study was undertaken to characterize LXY30 in the detection, cellular function, imaging, and targeted delivery of in vitro and in vivo non-small cell lung cancer (NSCLC) models.

Methods

The whole-cell binding assay was performed by incubating NSCLC cells, extracellular vesicles (EVs), and peripheral blood mononuclear cells (PBMCs) with TentaGel resin beads coated with LXY30. In this study, we defined the nanosize EVs as exosomes, which were characterized by flow cytometry, transmission electron microscopy, dynamic light scattering, and Western blots. The function of LXY30 was determined by modulating the epidermal growth factor receptor (EGFR) signaling pathway by growth inhibition and Western blots. For in vivo biodistribution, mice bearing subcutaneous and intracranial NSCLC xenograft tumors were administrated intraveneously with LXY30-biotin/streptavidin-Cy5.5 complex and then analyzed for in vivo and ex vivo optical imaging and histopathology.

Results

We showed that LXY30 specifically and sensitively detected α3β1 integrin-expressing NSCLC cells and tumor-derived exosomes. Tumor DNA isolated from LXY30-enriched plasma exosomes might be used to detect driver oncogenic mutations in patients with metastatic NSCLC. LXY30 only enriches tumor cells but not neutrophils, macrophages, or monocytes in the malignant pleural effusion of NSCLC patients for detecting genomic alterations by next-generation sequencing. LXY30 detected increased α3β1 integrin expression on the EGFR-mutant NSCLC cells with acquired resistance to erlotinib compared to parental erlotinib-sensitive EGFR-mutant NSCLC cells. We further showed that LXY30 modulated the EGFR signaling pathway independently from another peptide ligand LXW64 targeting αvβ3 integrin in erlotinib-resistant, EGFR-mutant H1975 cells. Analysis of The Cancer Genome Atlas (TCGA) revealed high α3 integrin expression was associated with poor prognosis in lung squamous cell carcinoma. LXY30-biotin/streptavidin-Cy5.5 complex had higher uptakes in the subcutaneous and intracranial xenografts of various α3β1 integrin-expressing lung adenocarcinoma and patient-derived lung squamous cell carcinoma xenografts while sparing the surrounding normal tissues.

Conclusion

LXY30 is a promising peptide for the cancer diagnosis and in vivo targeted delivery of imaging agents and cancer drugs in NSCLC, independent of histology and tumor genotype.

Electronic supplementary material

The online version of this article (10.1186/s13045-019-0740-7) contains supplementary material, which is available to authorized users.

Daunorubicin-containing CLL1-targeting nanomicelles have anti-leukemia stem cell activity in acute myeloid leukemia

Patients with acute myeloid leukemia have a very poor prognosis related to a high rate of relapse and drug-related toxicity. The ability of leukemia stem cells (LSCs) to survive chemotherapy is primarily responsible for relapse, and eliminating LSCs is ultimately essential for cure. We developed novel disulfide-crosslinked CLL1-targeting micelles (DC-CTM), which can deliver high concentrations of daunorubicin (DNR) into both bulk leukemia cells and LSCs. Compared to free DNR, DC-CTM-DNR had a longer half-life, increased DNR area under the curve concentration by 11-fold, and exhibited a superior toxicity profile. In patient-derived AML xenograft models, DC-CTM-DNR treatment led to significant decreases in AML engraftment and impairment of secondary transplantation compared to control groups. Collectively, we demonstrate superior anti-LSC/AML efficacy, and preferable pharmacokinetic and toxicity profiles of DC-CTM-DNR compared to free DNR. DC-CTM-DNR has the potential to significantly improve treatment outcomes and reduce therapy-related morbidity and mortality for patients with AML.

Alternative Splicing of MXD3 and Its Regulation of MXD3 Levels in Glioblastoma

The transcription factor MXD3 is an atypical member of the MYC/MAX/MXD transcriptional network and has been previously shown to be an important regulator of cell proliferation. MXD3 has been shown to be overexpressed and to be required for medulloblastoma and acute lymphoblastic leukemia cell proliferation. In this study we leveraged datasets from The Cancer Genome Atlas to examine MXD3 across several cancers. We find that MXD3 transcripts are significantly overexpressed in ~72% of the available datasets. The gene itself is not frequently altered, while the promoter appears to be hypomethylated. We examine the possibility that aberrant regulation of the MXD3 message is the cause of abnormal MXD3 expression across cancers. Specifically, we looked at MXD3 alternative splicing in glioblastoma multiforme (GBM) and find notable functional differences between the splice variants. The 3′UTR confers differential message stability. Furthermore, the different coding sequences lead to different protein stabilities and localizations. Altogether, these data extend our knowledge of MXD3 in the context of human cancers while characterizing a previously unstudied splice variant of MXD3.