Mesenchymal Stem Cell-Mediated Deep Tumor Delivery of Gold Nanorod for Photothermal Therapy.

Gold nanoparticles (AuNPs) with various sizes and morphologies have been extensively investigated for effective photothermal therapy (PTT) against multiple cancer types. However, a highly dynamic and complex tumor microenvironment (TME) considerably reduces the efficacy of PTT by limiting deep tumor penetration of AuNPs. Herein, we propose a mesenchymal stem cell (MSC)-mediated deep tumor delivery of gold nanorod (AuNR) for a potent PTT. First, MSCs are treated with tetraacylated N-azidomannosamine (Ac4ManNAz) to introduce modifiable azide (N3) groups on the cell surface via metabolic glycoengineering. Then, AuNRs modified with bio-orthogonal click molecules of bicyclo[6.1.0]nonyne (AuNR@BCN) are chemically conjugated to the N3 groups on the MSC surface by copper-free click chemistry reaction, resulting in AuNR@MSCs. In cultured MSCs, the appropriate condition to incorporate the AuNR into the MSCs is optimized; in addition, the photothermal efficiency of AuNR-MSCs under light irradiation are assessed, showing efficient heat generation in vitro. In colon tumor-bearing mice, intravenously injected AuNR@MSCs efficiently accumulate within the tumor tissues by allowing deep tissue penetration owing to the tumor homing effect by natural tumor tropism of AuNR@MSCs. Upon localized light irradiation, the AuNR@MSCs significantly inhibit colon tumor growth by the enhanced photothermal effect compared to conventional AuNRs. Collectively, this study shows a promising approach of MSCs-mediated deep tumor delivery of AuNR for effective PTT.

A Multivalent Vaccine Based on Ferritin Nanocage Elicits Potent Protective Immune Responses against SARS-CoV-2 Mutations.

The SARS-CoV-2 pandemic has created a global public crisis and heavily affected personal lives, healthcare systems, and global economies. Virus variants are continuously emerging, and, thus, the pandemic has been ongoing for over two years. Vaccines were rapidly developed based on the original SARS-CoV-2 (Wuhan-Hu-1) to build immunity against the coronavirus disease. However, they had a very low effect on the virus' variants due to their low cross-reactivity. In this study, a multivalent SARS-CoV-2 vaccine was developed using ferritin nanocages, which display the spike protein from the Wuhan-Hu-1, B.1.351, or B.1.429 SARS-CoV-2 on their surfaces. We show that the mixture of three SARS-CoV-2 spike-protein-displaying nanocages elicits CD4+ and CD8+ T cells and B-cell immunity successfully in vivo. Furthermore, they generate a more consistent antibody response against the B.1.351 and B.1.429 variants than a monovalent vaccine. This leads us to believe that the proposed ferritin-nanocage-based multivalent vaccine platform will provide strong protection against emerging SARS-CoV-2 variants of concern (VOCs).

FLEX-IoT: Secure and Resource-Efficient Network Boot System for Flexible-IoT Platform.

In an internet of things (IoT) platform with a copious number of IoT devices and active variation of operational purpose, IoT devices should be able to dynamically change their system images to play various roles. However, the employment of such features in an IoT platform is hindered by several factors. Firstly, the trivial file transfer protocol (TFTP), which is generally used for network boot, has major security vulnerabilities. Secondly, there is an excessive demand for the server during the network boot, since there are numerous IoT devices requesting system images according to the variation of their roles, which exerts a heavy network overhead on the server. To tackle these challenges, we propose a system termed FLEX-IoT. The proposed system maintains a FLEX-IoT orchestrater which uses an IoT platform operation schedule to flexibly operate the IoT devices in the platform. The IoT platform operation schedule contains the schedules of all the IoT devices on the platform, and the FLEX-IoT orchestrater employs this schedule to flexibly change the mode of system image transfer at each moment. FLEX-IoT consists of a secure TFTP service, which is fully compatible with the conventional TFTP, and a resource-efficient file transfer method (adaptive transfer) to streamline the system performance of the server. The proposed secure TFTP service comprises of a file access control and attacker deception technique. The file access control verifies the identity of the legitimate IoT devices based on the hash chain shared between the IoT device and the server. FLEX-IoT provides security to the TFTP for a flexible IoT platform and minimizes the response time for network boot requests based on adaptive transfer. The proposed system was found to significantly increase the attack-resistance of TFTP with little additional overhead. In addition, the simulation results show that the volume of transferred system images on the server decreased by 27% on average, when using the proposed system.

Bioorthogonally surface-edited extracellular vesicles based on metabolic glycoengineering for CD44-mediated targeting of inflammatory diseases.

Extracellular vesicles (EVs) are essential mediators in intercellular communication that have emerged as natural therapeutic nanomedicines for the treatment of intractable diseases. Their therapeutic applications, however, have been limited by unpredictable in vivo biodistribution after systemic administration. To control the in vivo fate of EVs, their surfaces should be properly edited, depending on the target site of action. Herein, based on bioorthogonal copper-free click chemistry (BCC), surface-edited EVs were prepared by using metabolically glycoengineered cells. First, the exogenous azide group was generated on the cellular surface through metabolic glycoengineering (MGE) using the precursor. Next, PEGylated hyaluronic acid, capable of binding specifically to the CD44-expressing cells, was labelled as the representative targeting moiety onto the cell surface by BCC. The surface-edited EVs effectively accumulated into the target tissues of the animal models with rheumatoid arthritis and tumour, primarily owing to prolonged circulation in the bloodstream and the active targeting mechanism. Overall, these results suggest that BCC combined with MGE is highly useful as a simple and safe approach for the surface modification of EVs to modulate their in vivo fate.

Intracellular Uptake Mechanism of Bioorthogonally Conjugated Nanoparticles on Metabolically Engineered Mesenchymal Stem Cells.

Nanoparticles have been used for effectively delivering imaging agents and therapeutic drugs into stem cells. However, nanoparticles are not sufficiently internalized into stem cells; thus, new delivery method of nanoparticles into stem cells is urgently needed. Herein, we develop bicyclo[6.1.0]nonyne (BCN)-conjugated gold nanoparticles (BCN-AuNPs), which can be bioorthogonally conjugated to azide (-N3) groups on the surface of metabolically engineered stem cells via bioorthogonal click chemistry. For incorporating azide groups on the cell surface, first, human adipose-derived mesenchymal stem cells (hMSCs) were metabolically engineered with N-azidoacetylmannosamine-tetraacylated (Ac4ManNAz). Second, clickable BCN-AuNPs were bioorthogonally conjugated to azide groups on Ac4ManNAz-treated hMSCs. Importantly, a large amount of BCN-AuNPs was specifically conjugated to metabolically engineered hMSCs and then internalized rapidly into stem cells through membrane turnover mechanism, compared to the conventional nanoparticle-derived endocytosis mechanism. Furthermore, BCN-AuNPs entrapped in endosomal/lysosomal compartment could escape efficiently to the cytoplasm of metabolically engineered stem cells. Finally, BCN-AuNPs in stem cells were very safe, and they did not affect stem cell functions, such as self-renewal and differentiation capacity. These bioorthogonally conjugated nanoparticles on metabolically engineered stem cells can enhance the cellular uptake of nanoparticles via bioorthogonal conjugation mechanism.

In vivo tracking of bioorthogonally labeled T-cells for predicting therapeutic efficacy of adoptive T-cell therapy.

Non-invasive tracking of T-cells may help to predict the patient responsiveness and therapeutic outcome. Herein, we developed bioorthogonal T-cell labeling and tracking strategy using bioorthogonal click chemistry. First, ovalbumin (OVA) antigen-specific cytotoxic T-cells (CTLs) were incubated with N-azidoacetyl-D-mannosamine-tetraacylated (Ac4ManNAz) for incorporating azide (N3) groups on the surface of CTLs via metabolic glycoengineering. Subsequently, azide groups on the CTLs were chemically labeled with near infrared fluorescence (NIRF) dye, Cy5.5, conjugated dibenzylcyclooctyne (DBCO-Cy5.5) via bioorthogonal click chemistry, resulting in Cy5.5-labeled CTLs (Cy5.5-CTLs). The labeling efficiency of Cy5.5-CTLs could be readily controlled by changing concentrations of Ac4ManNAz and DBCO-Cy5.5 in cultured cells. Importantly, Cy5.5-CTLs presented the strong NIRF signals in vitro and they showed no significant changes in the functional properties, such as cell viability, proliferation, and antigen-specific cytolytic activity. In ovalbumin (OVA)-expressing E.G-7 tumor-bearing immune-deficient mice, intravenously injected Cy5.5-CTLs were clearly observed at targeted solid tumors via non-invasive NIRF imaging. Moreover, tumor growth inhibition of E.G-7 tumors was closely correlated with the intensity of NIRF signals from Cy5.5-CTLs at tumors after 2-3 days post-injection. The Cy5.5-CTLs showed different therapeutic responses in E.G-7 tumor-bearing immune-competent mice, in which they were divided by their tumor growth efficacy as 'high therapeutic response (TR (+))' and 'low therapeutic response (TR (-))'. These different therapeutic responses of Cy5.5-CTLs were highly correlated with the NIRF signals of Cy5.5-CTLs at targeted tumor tissues in the early stage. Therefore, non-invasive tracking of T-cells can be able to predict and elicit therapeutic responses in the adoptive T-cell therapy.

Predicting in vivo therapeutic efficacy of bioorthogonally labeled endothelial progenitor cells in hind limb ischemia models via non-invasive fluorescence molecular tomography.

Human embryonic stem cells-derived endothelial progenitor cells (hEPCs) were utilized as cell therapeutics for the treatment of ischemic diseases. However, in vivo tracking of hEPCs for predicting their therapeutic efficacy is very difficult. Herein, we developed bioorthogonal labeling strategy of hEPCs that could non-invasively track them after transplantation in hind limb ischemia models. First, hEPCs were treated with tetraacylated N-azidomannosamine (Ac4ManNAz) for generating unnatural azide groups on the hEPCs surface. Second, near-infrared fluorescence (NIRF) dye, Cy5, conjugated dibenzocylooctyne (DBCO-Cy5) was chemically conjugated to the azide groups on the hEPC surface via copper-free click chemistry, resulting Cy5-hEPCs. The bioorthogonally labeled Cy5-hEPCs showed strong NIRF signal without cytotoxicity and functional perturbation in tubular formation, oxygen consumption and paracrine effect of hEPCs in vitro. In hind limb ischemia models, the distribution and migration of transplanted Cy5-hEPCs were successfully monitored via fluorescence molecular tomography (FMT) for 28 days. Notably, blood reperfusion and therapeutic neovascularization effects were significantly correlated with the initial transplantation forms of Cy5-hEPCs such as 'condensed round shape' and 'spread shape' in the ischemic lesion. The condensed transplanted Cy5-hEPCs substantially increased the therapeutic efficacy of hind limb ischemia, compared to that of spread Cy5-hEPCs. Therefore, our new stem cell labeling strategy can be used to predict therapeutic efficacy in hind limb ischemia and it can be applied a potential application in developing cell therapeutics for regenerative medicine.

Doxorubicin-Loaded PLGA Nanoparticles for Cancer Therapy: Molecular Weight Effect of PLGA in Doxorubicin Release for Controlling Immunogenic Cell Death.

Direct local delivery of immunogenic cell death (ICD) inducers to a tumor site is an attractive approach for leading ICD effectively, due to enabling the concentrated delivery of ICD inducers to the tumor site. Herein, we prepared doxorubicin (DOX)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) using different molecular weight PLGA (7000 g/mol and 12,000 g/mol), showing different drug release kinetics. The different release kinetics of DOX might differently stimulate a tumor cell-specific immune response by releasing damage-associated molecular patterns (DAMPs), resulting in showing a different antitumor response in the living body. DOX-PLGA7K NPs showed faster DOX release kinetics than DOX-PLGA12K NPs in the physiological condition. DOX-PLGA7K NPs and DOX-PLGA12K NPs were successfully taken up by the CT-26 tumor cells, subsequently showing different DOX localization times at the nucleus. Released DOX successfully lead to cytotoxicity and HMGB1 release in vitro. Although the DOX-PLGA7K NPs and DOX-PLGA12K NPs showed different sustained DOX release kinetics in vitro, tumor growth of the CT-26 tumor was similarly inhibited for 28 days post-direct tumor injection. Furthermore, the immunological memory effect was successfully established by the ICD-based tumor-specific immune responses, including DC maturation and tumor infiltration of cytotoxic T lymphocytes (CTLs). We expect that the controlled release of ICD-inducible chemotherapeutic agents, using different types of nanomedicines, can provide potential in precision cancer immunotherapy by controlling the tumor-specific immune responses, thus improving the therapeutic efficacy.

Cancer-specific drug-drug nanoparticles of pro-apoptotic and cathepsin B-cleavable peptide-conjugated doxorubicin for drug-resistant cancer therapy.

Chemotherapy has shown remarkable therapeutic efficacy for various types of cancer. However, drug resistance reduces the effectiveness and sensitivity of chemotherapy, leading treatment failure and cancer relapse in many clinical indications. Herein, we propose cancer-specific drug-drug nanoparticles (DD-NPs) that improve the therapeutic efficacy of chemotherapy against drug-resistant cancer. Cancer-specific and pro-apoptotic drug-drug conjugate was prepared by conjugating the pro-apoptotic peptide drug (SMAC; Ala-Val-Pro-Ile-Ala-Gln, AVPIAQ) and cathepsin B-cleavable peptide (Phe-Arg-Arg-Gly, FRRG) to a doxorubicin (DOX), resulting in SMAC-FRRG-DOX that allows self-assembled into nanoparticles. The resulting DD-NPs were specifically cleaved to pro-apoptotic SMAC and cytotoxic DOX only in cathepsin B-overexpressing cancer cells, inducing a synergy of the pro-apoptotic activity with the chemotherapy. In MCF-7 breast tumor-bearing mice, intravenously injected DD-NPs highly accumulated at targeted tumor tissues via enhanced permeability and retention (EPR) effect, releasing SMAC and DOX, which showed a synergetic pro-apoptotic/chemotherapy. Furthermore, DD-NPs greatly suppressed tumor growth and improved overall survival in a metastatic lung cancer model. Collectively, these cancer-specific drug-drug nanoparticles may be a promising strategy to treat drug-resistant cancers with high cancer cell-specificity.

Heat-Generating Iron Oxide Multigranule Nanoclusters for Enhancing Hyperthermic Efficacy in Tumor Treatment.

The development of heat-generating magnetic nanostructures is critical for the effective management of tumors using magnetic hyperthermia. Herein, we demonstrate that polyethylene glycol (PEG)-coated iron oxide (magnetite, Fe3O4) multigranule nanoclusters (PEG-MGNCs) can enhance the efficiency of hyperthermia-based tumor suppression in vitro and in vivo. MGNCs consisting of granules (crystallites) measuring 22.9 nm in diameter were prepared via the hydrothermal polyol method, followed by the surface modification of MGNCs with PEG-dopamine. The freshly prepared PEG-MGNCs exhibit 145.9 ± 10.2 nm diameter on average under aqueous conditions. The three-dimensional structures of PEG-MGNCs enhance the hyperthermic efficacy compared with PEGylated single iron-oxide nanoparticles (NPs), resulting in severe heat damage to tumor cells in vitro. In the SCC7 tumor-bearing mice, near-infrared fluorescence dye (Cy5.5)-labeled PEG-MGNCs are successfully accumulated in the tumor tissues because of NP-derived enhanced permeation and retention effect. Finally, the tumor growth is significantly suppressed in PEG-MGNC-treated mice after two-times heat generation by using a longitudinal solenoid, which can generate an alternating magnetic field under high-frequency (19.5 kA/m, 389 kHz) induction. This study shows for the first time that the PEG-MGNCs greatly enhance the hyperthermic efficacy of tumor treatment both in vitro and in vivo.

In Situ One-Step Fluorescence Labeling Strategy of Exosomes via Bioorthogonal Click Chemistry for Real-Time Exosome Tracking In Vitro and In Vivo.

Exosomes are cellular components with promising uses in cancer diagnostics and therapeutics, and their imaging and tracking are essential to study their biological properties. Herein, we report on an in situ one-step fluorescence labeling strategy for exosomes via bioorthogonal click chemistry. First, exosome donor cancer cells were treated with tetraacetylated N-azidoacetyl-d-mannosamine (Ac4ManNAz) to generate unnatural azide groups (-N3) on their surface via metabolic glycoengineering. Then, the azide groups were labeled with near-infrared fluorescent dye-conjugated dibenzylcyclooctyne (DBCO-Cy5) via bioorthogonal click chemistry. After 2 days of incubation, the DBCO-Cy5-labeled exosomes (Cy5-Exo) were successfully secreted from the donor cancer cells and were isolated via classical ultracentrifugation, providing a high-yield of fluorescent dye-labeled exosomes. This in situ one-step bioorthogonal click chemistry offers improved labeling efficiency, biocompatibility, and imaging sensitivy compared to standard exosomes (ST-Exo), purified with classical ultracentrifugation or carbocyanine lipophilic dye (DiD)-labeled exosomes (DiD-Exo) in vitro. In particular, the Cy5-Exo were successfully taken up by A549 cells in a time-dependent manner, and they could escape from lysosome confinement, showing their possible use as a delivery carrier of therapeutic drugs or imaging agents. Finally, intraveneously injected Cy5-Exo were noninvasively tracked and imaged via near-infrared fluorescence (NIRF) imaging in tumor-bearing mice. This new fluorescence labeling strategy for natural exosomes may be useful to provide better understanding of their theranostic effects in many biomedical applications.

Compression-Assisted Adaptive ECC and RAID Scattering for NAND Flash Storage Devices.

NAND flash memory-based storage devices are vulnerable to errors induced by NAND flash memory cells. Error-correction codes (ECCs) are integrated into the flash memory controller to correct errors in flash memory. However, since ECCs show inherent limits in checking the excessive increase in errors, a complementary method should be considered for the reliability of flash storage devices. In this paper, we propose a scheme based on lossless data compression that enhances the error recovery ability of flash storage devices, which applies to improve recovery capability both of inside and outside the page. Within a page, ECC encoding is realized on compressed data by the adaptive ECC module, which results in a reduced code rate. From the perspective of outside the page, the compressed data are not placed at the beginning of the page, but rather is placed at a specific location within the page, which makes it possible to skip certain pages during the recovery phase. As a result, the proposed scheme improves the uncorrectable bit error rate (UBER) of the legacy system.

Necroptosis-Inducible Polymeric Nanobubbles for Enhanced Cancer Sonoimmunotherapy.

Necroptosis, caspase-independent programmed necrosis, has emerged as a therapeutic target to make dying cancer cells stimulants for antitumor immune responses. The clinical translations exploiting necroptosis, however, have been limited since most cancer cells downregulate receptor-interacting protein kinase 3 (RIPK3) as a key enzyme for necroptosis. Herein, nanobubbles (NBs) that can trigger RIPK3-independent necroptosis, facilitating cell-membrane rupture via the acoustic cavitation effect are reported. The NBs, imbibing perfluoropentane as the gas precursor, are prepared using an amphiphilic polymer conjugate, composed of PEGylated carboxymethyl dextran as the hydrophilic backbone and chlorin e6 as the hydrophobic sonosensitizer. When exposed to ultrasound, the NBs efficiently promote the release of biologically active damage-associated molecular patterns by inducing burst-mediated cell-membrane disintegration. Consequently, the necroptosis-inducible NBs significantly improve antitumor immunity by maturation of dendritic cells and activation of CD8+ cytotoxic T cells both in vitro and in vivo. In addition, the combination of NBs and immune checkpoint blockade leads to complete regression of the primary tumor and beneficial therapeutic activity against metastatic tumors in an RIPK3-deficient CT26 tumor-bearing mouse model. Overall, the innovative NB that causes immunogenic cell death of cancer via RIPK3-independent necroptosis is a promising enhancer for cancer immunotherapy.

A Comparative Study on Albumin-Binding Molecules for Targeted Tumor Delivery through Covalent and Noncovalent Approach.

Various types of albumin-binding molecules have been conjugated to anticancer drugs, and these modified prodrugs could be effective in cancer treatments compared to free anticancer drugs. However, the tumor targeting of albumin-binding prodrugs has not been clearly investigated. Herein, we examined the in vitro and in vivo tumor-targeting efficiency of three different albumin-binding molecules including albumin-binding peptide (DICLPRWGCLW: PEP), fatty acid (palmitic acid: PA), and maleimide (MI), respectively. In order to characterize the different targeting efficiency of albumin-binding molecules, PEP, PA, or MI was chemically labeled with near-infrared fluorescence (NIRF) dye, Cy5.5, in resulting PEP-Cy5.5, PA-Cy5.5, and MI-Cy5.5. These NIRF dye-labeled albumin-binding molecules were physically or chemically bound to albumin via gentle incubation in aqueous conditions in vitro. Notably, PA-Cy5.5 with reversible and multivalent binding affinities formed stable albumin complexes, compared to PEP-Cy5.5 and MI-Cy5.5, confirmed via surface plasmon resonance measurement, gel electrophoresis assay, and albumin-bound column-binding test. In tumor-bearing mice model, the different albumin-binding affinities of PA-Cy5.5, PEP-Cy5.5, and MI-Cy5.5 greatly contributed to their tumor-targeting ability. Even though the binding affinity of PEP-Cy5.5 and MI-Cy5.5 to albumin is higher than that of PA-Cy5.5 in vitro, intravenous PA-Cy5.5 showed a higher tumor-targeting efficiency in tumor-bearing mice compared to that of PEP-Cy5.5 and MI-Cy5.5. The reversible and multivalent affinities of albumin-binding molecules to native serum albumin greatly increased the pharmacokinetics and tumor-targeting efficiency in vivo.

Recent advances and challenges of repurposing nanoparticle-based drug delivery systems to enhance cancer immunotherapy.

Cancer immunotherapy is an attractive treatment option under clinical settings. However, the major challenges of immunotherapy include limited patient response, limited tumor specificity, immune-related adverse events, and immunosuppressive tumor microenvironment. Therefore, nanoparticle (NP)-based drug delivery has been used to not only increase the efficacy of immunotherapeutic agents, but it also significantly reduces the toxicity. In particular, NP-based drug delivery systems alter the pharmacokinetic (PK) profile of encapsulated or conjugated immunotherapeutic agents to targeted cancer cells or immune cells and facilitate the delivery of multiple therapeutic combinations to targeted cells using single NPs. Recently, advanced NP-based drug delivery systems were effectively utilized in cancer immunotherapy to reduce the toxic side effects and immune-related adverse events. Repurposing these NPs as delivery systems of immunotherapeutic agents may overcome the limitations of current cancer immunotherapy. In this review, we focus on recent advances in NP-based immunotherapeutic delivery systems, such as immunogenic cell death (ICD)-inducing drugs, cytokines and adjuvants for promising cancer immunotherapy. Finally, we discuss the challenges facing current NP-based drug delivery systems that need to be addressed for successful clinical application.

Dual-Modal Imaging-Guided Precise Tracking of Bioorthogonally Labeled Mesenchymal Stem Cells in Mouse Brain Stroke.

Noninvasive and precise stem cell tracking after transplantation in living subject is very important to monitor both stem cell destinations and their in vivo fate, which is closely related to their therapeutic efficacy. Herein, we developed bicyclo[6.1.0]nonyne (BCN)-conjugated glycol chitosan nanoparticles (BCN-NPs) as a delivery system of dual-modal stem cell imaging probes. Near-infrared fluorescent (NIRF) dye Cy5.5 was chemically conjugated to the BCN-NPs, and then oleic acid-coated superparamagnetic iron oxide nanoparticles (OA-Fe3O4 NPs) were encapsulated into BCN-NPs, resulting in Cy5.5-labeled and OA-Fe3O4 NP-encapsulated BCN-NPs (BCN-dual-NPs). For bioorthogonal labeling of human adipose-derived mesenchymal stem cells (hMSCs), first, hMSCs were treated with tetra-acetylated N-azidoacetyl-d-mannosamine (Ac4ManNAz) for generating azide (-N3) groups onto their surface via metabolic glycoengineering. Second, azide groups on the cell surface were successfully chemically labeled with BCN-dual-NPs via bioorthogonal click chemistry in vitro. This bioorthogonal labeling of hMSCs could greatly increase the cell labeling efficiency, safety, and imaging sensitivity, compared to only nanoparticle-derived labeling technology. The dual-modal imaging-guided precise tracking of bioorthogonally labeled hMSCs was tested in the photothrombotic stroke mouse model via intraparenchymal injection. Finally, BCN-dual-NPs-labeled hMSCs could be effectively tracked by their migration from the implanted site to the brain stroke lesion using NIRF/T2-weighted magnetic resonance (MR) dual-modal imaging for 14 days. Our observation would provide a potential application of bioorthogonally labeled stem cell imaging in regenerative medicine by providing safety and high labeling efficiency in vitro and in vivo.

Visible light-induced apoptosis activatable nanoparticles of photosensitizer-DEVD-anticancer drug conjugate for targeted cancer therapy.

The therapeutic efficacy of photodynamic therapy (PDT) in cancer treatment is attributed to the conversion of tumor oxygen into reactive singlet oxygen (1O2) using photosensitizers. However, poor tissue penetration and rapid oxygen depletion have limited the effectiveness of PDT. Therefore, we have developed visible light-induced apoptosis activatable nanoparticles of the photosensitizer (Ce6)-caspase 3 cleavable peptide (Asp-Glu-Val-Asp, DEVD)-anticancer drug monomethyl auristatin E (MMAE) conjugate, resulting in Ce6-DEVD-MMAE nanoparticles. The average size of self-assembled Ce6-DEVD-MMAE nanoparticles was 90.8 ±â€¯18.9 nm. Compared with conventional PDT based on high-energy irradiation, the new therapy uses lower-energy irradiation to induce apoptosis of cancer cells, and activation of caspase 3 to successfully cleave the anticancer drug MMAE from the Ce6-DEVD-MMAE nanoparticles, resulting in strong cytotoxic effects in cancer cells. Notably, the one-time activation of MMAE in the Ce6-DEVD-MMAE nanoparticles further amplified the cytotoxic effect resulting in additional cell death in the absence of visible light irradiation. Furthermore, Ce6-DEVD-MMAE nanoparticles passively accumulated in the targeted tumor tissues via enhanced permeation and retention (EPR) effect in mice with squamous cell carcinoma (SCC7). The high levels of toxicity were retained after exposure to lower-energy irradiation. However, Ce6-DEVD-MMAE nanoparticles did not show any toxicity in the absence of exposure to visible light irradiation, in contrast to the toxicity of free MMAE (1-10 nM). Thus, the light-induced therapeutic strategy based on apoptotic activation of Ce6-DEVD-MMAE nanoparticles can be used to treat solid tumors inaccessible to conventional PDT.

Tumor-targeting glycol chitosan nanocarriers: overcoming the challenges posed by chemotherapeutics.

Introduction: In the past decade, the glycol chitosan nanocarriers (GCNCs) have been widely used for tumor-targeted delivery of anticancer agents such as chemo drugs, peptides, and genes due to their biocompatibility, biodegradability, and easy fabrication. In particular, GCNCs can effectively solubilize water-insoluble chemo drugs as well as improve the delivery efficiency of chemo drugs to the tumor, resulting in maximizing therapeutic efficacy and minimizing side effect. In this review, we introduce the various applications of GCNCs for cancer treatment and these GCNCs demonstrate the great potential in overcoming challenges of chemotherapeutics. Areas covered: Various designs of GC nanocarriers have been reviewed. The current state of GC nanocarriers for delivering chemotherapeutics with a focus on their physicochemical properties including solubilization of anti-cancer drugs, sustained release, and tumor-selectivity. Furthermore, state of the art in delivery and therapeutic strategy using GC nanocarriers also introduced for overcoming challenges of chemotherapeutics. Expert opinion: Based on the reviewed literature, physicochemical properties of GC nanocarriers will have a great potential to overcome challenges posed by chemotherapeutics.

In vivo stem cell tracking with imageable nanoparticles that bind bioorthogonal chemical receptors on the stem cell surface.

It is urgently necessary to develop reliable non-invasive stem cell imaging technology for tracking the in vivo fate of transplanted stem cells in living subjects. Herein, we developed a simple and well controlled stem cell imaging method through a combination of metabolic glycoengineering and bioorthogonal copper-free click chemistry. Firstly, the exogenous chemical receptors containing azide (-N3) groups were generated on the surfaces of stem cells through metabolic glycoengineering using metabolic precursor, tetra-acetylated N-azidoacetyl-d-mannosamine(Ac4ManNAz). Next, bicyclo[6.1.0]nonyne-modified glycol chitosan nanoparticles (BCN-CNPs) were prepared as imageable nanoparticles to deliver different imaging agents. Cy5.5, iron oxide nanoparticles and gold nanoparticles were conjugated or encapsulated to BCN-CNPs for optical, MR and CT imaging, respectively. These imageable nanoparticles bound chemical receptors on the Ac4ManNAz-treated stem cell surface specifically via bioorthogonal copper-free click chemistry. Then they were rapidly taken up by the cell membrane turn-over mechanism resulting in higher endocytic capacity compared non-specific uptake of nanoparticles. During in vivo animal test, BCN-CNP-Cy5.5-labeled stem cells could be continuously tracked by non-invasive optical imaging over 15 days. Furthermore, BCN-CNP-IRON- and BCN-CNP-GOLD-labeled stem cells could be efficiently visualized using in vivo MR and CT imaging demonstrating utility of our stem cell labeling method using chemical receptors. These results conclude that our method based on metabolic glycoengineering and bioorthogonal copper-free click chemistry can stably label stem cells with diverse imageable nanoparticles representing great potential as new stem cell imaging technology.

Anticancer activity of PEGylated matrix metalloproteinase cleavable peptide-conjugated adriamycin against malignant glioma cells.

Although matrix metalloproteinases (MMPs) play a crucial role in the invasion and growth of malignant gliomas, their increased activity in tumor environment can be used as a specific target for chemotherapy. We investigated whether polymer-drug conjugates formed via MMP-cleavable peptide linkages could provide MMP-responsive tumor targeting and cytotoxicity for malignant glioma cells. One end of an MMP-cleavable peptide was attached to the end of methoxy polyethylene glycol (MPEG) while the other end was attached to adriamycin (ADR). The release of drugs in the presence of conditioned media of U87MG cells was investigated. The cytotoxicities of the MMP-cleavable MPEG-peptide-ADR (PPA) conjugates and non-cleavable MPEG-ADR (PA) conjugates were investigated using U87MG cells. The (1)H nuclear magnetic resonance (NMR) spectra confirmed the conjugation of the two ends of the peptide to the ends of MPEG and ADR, respectively. Gelatin zymography showed that MMP-2 was strongly expressed in the media of U87MG cells. The PA conjugate did not release ADR either in the phosphate buffered saline (PBS) or conditioned media of U87MG cells. The PPA conjugate released ADR in the presence of the conditioned media of U87MG cells, but not in PBS only. In the cytotoxicity test using U87MG cells, ADR and PPA conjugate showed similar anti-proliferative activities, while the cytotoxicity of PA conjugate was lower than that of ADR. Considering that the cytotoxicity of the PPA conjugate was similar to that of ADR, MMP-cleavable polymer-drug conjugates can be used as targeting carriers for the purpose of inhibiting the proliferation of malignant glioma cells.