Caspase Sensitive Gold Nanoparticle for Apoptosis Imaging in Live Cells

We developed a new apoptosis imaging probe with gold nanoparticles (AuNPs). A near-infrared fluorescence dye was attached to AuNP surface through the bridge of peptide substrate (DEVD). The fluorescence was quenched in physiological conditions due to the quenching effect of AuNP, and the quenched fluorescence was recovered after the DEVD had been cleaved by caspase-3, the enzyme involved in apoptotic process. The adhesion of DEVD substrates on AuNP surface was accomplished by conjugation of the 3,4-dihydroxy phenylalanine (DOPA) groups which are adhesive to inorganic surface and rich in mussels. This surface modification with DEVD substrates by DOPA groups resulted in increased stability of AuNP in cytosol condition for hours. Moreover, the cleavage of substrate and the dequenching process are very fast, and the cells did not need to be fixed for imaging. Therefore, the real-time monitoring of caspase activity could be achieved in live cells, which enabled early detection of apoptosis compared to a conventional apoptosis kit such as Annexin V-FITC. Therefore, our apoptosis imaging has great potential as a simple, inexpensive, and efficient apoptosis imaging probe for biomedical applications

Detection of Active Matrix Metalloproteinase‑3 in Serum and Fibroblast-Like Synoviocytes of Collagen-Induced Arthritis Mice

The activity of rheumatoid arthritis (RA) correlates with the expression of proteases. Among several proteases, matrix metalloproteinase-3 (MMP-3) is one of the biological markers used to diagnose RA. The active form of MMP-3 is a key enzyme involved in RA-associated destruction of cartilage and bone. Thus, detection of active MMP-3 in serum or <i>in vivo</i> is very important for early diagnosis of RA. In this study, a soluble MMP-3 probe was prepared to monitor RA progression by detecting expression of active MMP-3 in collagen-induced arthritis (CIA) mice <i>in vivo</i> in both serum and fibroblast-like synoviocytes (FLSs). The MMP-3 probe exhibited strong sensitivity to MMP-3 and moderate sensitivity to MMP-7 at nanomolecular concentrations, but was not sensitive to other MMPs such as MMP-2, MMP-9, and MMP-13. In an optical imaging study, the MMP-3 probe produced early and strong NIR fluorescence signals prior to observation of erythema and swelling in CIA mice. The MMP-3 probe was able to rapidly and selectively detect and monitor active MMP-3 in diluted serum from CIA mice. Furthermore, histological data demonstrated that activated FLSs in arthritic knee joints expressed active MMP-3. Together, our results demonstrated that the MMP-3 probe may be useful for detecting active MMP-3 for diagnosis of RA. More importantly, the MMP-3 probe was able to detect active MMP-3 in diluted serum with high sensitivity. Therefore, the MMP-3 probe developed in this study may be a very promising probe, useful as a biomarker for early detection and diagnosis of RA

DNA Amplification in Neutral Liposomes for Safe and Efficient Gene Delivery

In general, traditional gene carriers contain strong cationic charges to efficiently load anionic genes, but this cationic character also leads to destabilization of plasma membranes and causes severe cytotoxicity. Here, we developed a PCR-based nanofactory as a safe gene delivery system. A few template plasmid DNA can be amplified by PCR inside liposomes about 200 nm in diameter, and the quantity of loaded genes highly increased by more than 8.8-fold. The liposome membrane was composed of neutral lipids free from cationic charges. Consequently, this system is nontoxic, unlike other traditional cationic gene carriers. Intense red fluorescent protein (RFP) expression in CHO-K1 cells showed that the amplified genes could be successfully transfected to cells. Animal experiments with the luciferase gene also showed <i>in vivo</i> gene expression by our system without toxicity. We think that this PCR-based nanofactory system can overcome the toxicity problem that is the critical limitation of current gene delivery to clinical application

Prediction of Antiarthritic Drug Efficacies by Monitoring Active Matrix Metalloproteinase‑3 (MMP-3) Levels in Collagen-Induced Arthritic Mice Using the MMP‑3 Probe

Active matrix metalloproteinase-3 (MMP-3) is a prognostic marker of rheumatoid arthritis (RA). We recently developed an MMP-3 probe that can specifically detect the active form of MMP-3. The aim of this study was to investigate whether detection and monitoring of active MMP-3 could be useful to predict therapeutic drug responses in a collagen-induced arthritis (CIA) model. During the period of treatment with drugs such as methotrexate (MTX) or infliximab (IFX), MMP-3 mRNA and protein levels were correlated with fluorescence signals in arthritic joint tissues and in the serum of CIA mice. Also, bone volume density and erosion in the knee joints and the paws of CIA mice were measured with microcomputed tomography (micro-CT), X-ray, and histology to confirm drug responses. In joint tissues and serum of CIA mice, strong fluorescence signals induced by the action of active MMP-3 were significantly decreased when drugs were applied. The decrease in RA scores in drug-treated CIA mice led to fluorescence reductions, mainly as a result of down-regulation of MMP-3 mRNA or protein. The micro-CT, X-ray, and histology results clearly showed marked decreases in bone and cartilage destruction, which were consistent with the reduction of fluorescence by down-regulation of active MMP-3 in drug-treated CIA mice. We suggest that the MMP-3 diagnostic kit could be used to detect and monitor the active form of MMP-3 in CIA mice serum during a treatment course and thereby used to predict the drug response or resistance to RA therapies at an earlier stage. We hope that monitoring of active MMP-3 levels in arthritis patients using the MMP-3 diagnostic kit will be a promising tool for drug discovery, drug development, and monitoring of drug responses in RA therapy

Cell-Permeable and Biocompatible Polymeric Nanoparticles for Apoptosis Imaging

Here, we report for the first time cell-permeable and biocompatible polymeric nanoparticles consisting of a polymer conjugated to a near-infrared (NIR) fluorescence (Cy5.5)-linked effector caspase-specific peptide. The close spatial proximity of the NIR fluorochromes in polymeric nanoparticles results in an autoquenched state, but polymer nanoparticles give rise to strong NIR fluorescence signal under apoptotic cells. Thus, the smart polymeric nanoparticle developed here is an attractive probe for real-time imaging of apoptosis in single cells

Dark Quenched Matrix Metalloproteinase Fluorogenic Probe for Imaging Osteoarthritis Development <i>in Vivo</i>

The early detection of osteoarthritis (OA) is currently a key challenge in the field of rheumatology. Biochemical studies of OA have indicated that matrix metalloproteinase-13 (MMP-13) plays a central role in cartilage degradation. In this study, we describe the potential use of a dark-quenched fluorogenic MMP-13 probe to image MMP-13 in both in vitro and rat models. The imaging technique involved using a MMP-13 peptide substrate, near-infrared (NIR) dye, and a NIR dark quencher. The results from this study demonstrate that the use of a dark-quenched fluorogenic probe allows for the visual detection of MMP-13 in vitro and in OA-induced rat models. In particular, by targeting this OA biomarker, the symptoms of the early and late stages of OA can be readily monitored, imaged, and analyzed in a rapid and efficient fashion. We anticipate that this simple and highly efficient fluorogenic probe will assist in the clinical management of patients with OA, not only for early diagnosis but also to assess individual patient responses to new drug treatments

Precise Targeting of Liver Tumor Using Glycol Chitosan Nanoparticles: Mechanisms, Key Factors, and Their Implications

Herein, we elucidated the mechanisms and key factors for the tumor-targeting ability of nanoparticles that presented high targeting efficiency for liver tumor. We used several different nanoparticles with sizes of 200–300 nm, including liposome nanoparticles (LNPs), polystyrene nanoparticles (PNPs) and glycol chitosan-5β-cholanic acid nanoparticles (CNPs). Their sizes are suitable for the enhanced permeation and retention (EPR) effect in literature. Different <i>in vitro</i> characteristics, such as the particle structure, stability, and bioinertness, were carefully analyzed with and without serum proteins. Also, pH-dependent tumor cell uptakes of nanoparticles were studied using fluorescence microscopy. Importantly, CNPs had sufficient stability and bioinertness to maintain their nanoparticle structure in the bloodstream, and they also presented prolonged circulation time in the body (blood circulation half-life <i>T</i>_1/2 = about 12.2 h), compared to the control nanoparticles. Finally, employing liver tumor bearing mice, we also observed that CNPs had excellent liver tumor targeting ability <i>in vivo</i>, while LNPs and PNPs demonstrated lower tumor-targeting efficiency due to the nonspecific accumulation in normal liver tissue. Liver tumor models were produced by laparotomy and direct injection of HT29 tumor cells into the left lobe of the liver of athymic nude mice. This study provides valuable information concerning the key factors for the tumor-targeting ability of nanoparticles such as stability, bioinertness, and rapid cellular uptake at targeted tumor tissues

Smart Nanocarrier Based on PEGylated Hyaluronic Acid for Cancer Therapy

Tumor targetability and site-specific drug release of therapeutic nanoparticles are key factors for effective cancer therapy. In this study, poly(ethylene glycol) (PEG)-conjugated hyaluronic acid nanoparticles (P-HA-NPs) were investigated as carriers for anticancer drugs including doxorubicin and camptothecin (CPT). P-HA-NPs were internalized into cancer cells (SCC7 and MDA-MB-231) via receptor-mediated endocytosis, but were rarely taken up by normal fibroblasts (NIH-3T3). During in vitro drug release tests, P-HA-NPs rapidly released drugs when incubated with cancer cells, extracts of tumor tissues, or the enzyme Hyal-1, which is abundant in the intracellular compartments of cancer cells. CPT-loaded P-HA-NPs (CPT-P-HA-NPs) showed dose-dependent cytotoxicity to cancer cells (MDA-MB-231, SCC7, and HCT 116) and significantly lower cytotoxicity against normal fibroblasts (NIH-3T3) than free CPT. Unexpectedly, high concentrations of CPT-P-HA-NPs demonstrated greater cytotoxicity to cancer cells than free CPT. An in vivo biodistribution study indicated that P-HA-NPs selectively accumulated into tumor sites after systemic administration into tumor-bearing mice, primarily due to prolonged circulation in the blood and binding to a receptor (CD44) that was overexpressed on the cancer cells. In addition, when CPT-P-HA-NPs were systemically administrated into tumor-bearing mice, we saw no significant increases in tumor size for at least 35 days, implying high antitumor activity. Overall, P-HA-NPs showed promising potential as a drug carrier for cancer therapy

Matrix Metalloproteinase Sensitive Gold Nanorod for Simultaneous Bioimaging and Photothermal Therapy of Cancer

Herein, we developed matrix metalloprotease (MMP) sensitive gold nanorods (MMP-AuNR) for cancer imaging and therapy. It was feasible to absorb NIR laser and convert into heat as well as visualize MMP activity. We showed the possibility of gold nanorods as a hyperthermal therapeutic agent and MMP sensitive imaging agent both in vitro and in vivo condition. The results suggested potential application of MMP-AuNR for simultaneous cancer diagnosis and therapy

Tumor Targeting Chitosan Nanoparticles for Dual-Modality Optical/MR Cancer Imaging

We report tumor targeting nanoparticles for optical/MR dual imaging based on self-assembled glycol chitosan to be a potential multimodal imaging probe. To develop an optical/MR dual imaging probe, biocompatible and water-soluble glycol chitosan (Mw = 50 kDa) were chemically modified with 5β-cholanic acid (CA), resulting in amphiphilic glycol chitosan-5β-cholanic acid conjugates (GC-CA). For optical imaging near-infrared fluorescence (NIRF) dye, Cy5.5, was conjugated to GC-CA resulting in Cy5-labeled GC-CA conjugates (Cy5.5-GC-CA). Moreover, in order to chelate gadolinium (Gd(III)) in the Cy5.5-GC-CA conjugates, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was directly conjugated in Cy5.5-GC-CA. Finally, the excess GdCl3 was added to DOTA modified Cy5.5-GC-CA conjugates in distilled water (pH 5.5). The freshly prepared Gd(III) encapsulated Cy5.5-GC-CA conjugates were spontaneously self-assembled into stable Cy5.5 labeled and Gd(III) encapsulated chitosan nanoparticles (Cy5.5-CNP-Gd(III)). The Cy5.5-CNP-Gd(III) was spherical in shape and approximately 350 nm in size. From the cellular experiment, it was demonstrated that Cy5.5-CNP-Gd(III) were efficiently taken up and distributed in cytoplasm (NIRF filter; red). When the Cy5.5-GC-Gd(III) were systemically administrated into the tail vein of tumor-bearing mice, large amounts of nanoparticles were successfully localized within the tumor, which was confirmed by noninvasive near-infrared fluorescence and MR imaging system simultaneously. These results revealed that the dual-modal imaging probe of Cy5.5-CNP-Gd(III) has the potential to be used as an optical/MR dual imaging agent for cancer treatment