TMT-based quantitative proteomic analysis reveals the underlying mechanisms of glycidyl methacrylate-induced 16HBE cell malignant transformation.

Glycidyl methacrylate (GMA) has been widely used as tackifying/crosslinking copolymer monomer in the industrial section. Occupational and environmental exposure to GMA is inevitable. GMA is classified as a Group 2 A carcinogen. However, it still lacks a sufficient understanding of its carcinogenicity at the protein level. The major pathways and players during the malignant transformation process remain unknown. In this study, we first established and characterized a malignant transformation model using human bronchial epithelial (16HBE) cells exposed to 8 µg/mL GMA. Then the proteomics approach, western-blot analysis as well as quantitative PCR (qPCR) analysis were employed to investigate its underlying mechanisms of carcinogenicity. Our results showed that the 16HBE cells exposed to GMA and passaged to the 40th generation had undergone a malignant transformation. Proteomic analysis revealed that 123 proteins were significantly up-regulated while 160 proteins were down-regulated during the process of malignant transformation. Importantly, further pathway analysis identified the extracellular matrix-receptor (ECM-receptor) interaction pathway to be one of the major players mediating the process and most of the differentially expressed proteins (DEPs) were up-regulated, including two vital proteins, CD44 and MMP14, as well as members from integrin family. These results provide direct proteomic evidence that DEPs related to the ECM-receptor interaction pathway play an active role in reinforcing the carcinogenicity of GMA. The findings of this study might deepen our understanding of the underlying mechanisms of GMA carcinogenicity and thus facilitate the risk assessment of GMA.

Antifouling poly(PEGMA) grafting modified titanium surface reduces osseointegration through resisting adhesion of bone marrow mesenchymal stem cells.

As an alternative strategy to achieve the desired bone augmentation, tenting screw technology (TST) has considerably broadened the indications for implant treatment. Titanium tenting screws are typically used in TST to maintain the space for bone regeneration. However, a high degree of osteogenic integration complicate titanium tenting screw removal and impact the bone healing micro-environment. Previous efforts have been focused on modifying titanium surfaces to enhance osseointegration while ignoring the opposite process. Due to the vital role of bone marrow mesenchymal stem cells (BMSCs) in bone regeneration, it might be feasible to reduce osseointegration around titanium tenting screws by resisting the adhesion of BMSCs. Herein, poly(ethylene glycol)methyl ether methacrylate (poly(PEGMA)) with an optimal length of PEG chain was incorporated with a Ti surface in terms of surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET ATRP). The cell apoptosis analysis showed that the new surface would not induce the apoptosis of BMSCs. Then, the adhesive and proliferative behaviors of BMSCs on the surface were analyzed which indicated that the poly(PEGMA) surface could inhibit the proliferation of BMSCs through resisting the adhesion process. Furthermore, in vivo experiments revealed the presence of the poly(PEGMA) on the surface resulted in a lower bone formation and osseointegration compared with the Ti group. Collectively, this dense poly(PEGMA) surface of Ti may serve as a promising material for clinical applications in the future. STATEMENT OF SIGNIFICANCE: The poly(ethylene glycol)methyl ether methacrylate (poly(PEGMA)) with an optimal length of PEG chain was grafted onto a Ti surface by surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET ATRP). The PEGMA surface could reduce the osteogenic integration by preventing the adhesion of cells, resulting in a lower pullout force of the modified implant and thereby desirable and feasible applications in dental surgery.

2-hydroxyethyl methacrylate-derived reactive oxygen species stimulate ATP release via TRPA1 in human dental pulp cells.

Extracellular ATP (adenosine triphosphate) and transient receptor potential ankyrin 1 (TRPA1) channels are involved in calcium signaling in odontoblasts and dental pain. The resin monomer 2-hydroxyethyl methacrylate (HEMA), used in dental restorative procedures, is related to apoptotic cell death via oxidative stress. Although the TRPA1 channel is highly sensitive to reactive oxygen species (ROS), the effect of HEMA-induced ROS on ATP release to the extracellular space and the TRPA1 channel has not been clarified in human dental pulp. In this study, we investigated the extracellular ATP signaling and TRPA1 activation by HEMA-derived ROS in immortalized human dental pulp cells (hDPSC-K4DT). Among the ROS-sensitive TRP channels, TRPA1 expression was highest in undifferentiated hDPSC-K4DT cells, and its expression levels were further enhanced by osteogenic differentiation. In differentiated hDPSC-K4DT cells, 30 mM HEMA increased intracellular ROS production and ATP release, although 3 mM HEMA had no effect. Pretreatment with the free radical scavenger PBN (N-tert-butyl-α-phenylnitrone) or TRPA1 antagonist HC-030031 suppressed HEMA-induced responses. These results suggest that ROS production induced by a higher dose of HEMA activates the TRPA1 channel in human dental pulp cells, leading to ATP release. These findings may contribute to the understanding of the molecular and cellular pathogenesis of tertiary dentin formation and pain in response to dental biomaterials.

Competitive binding and molecular crowding regulate the cytoplasmic interactome of non-viral polymeric gene delivery vectors.

In contrast to the processes controlling the complexation, targeting and uptake of polycationic gene delivery vectors, the molecular mechanisms regulating their cytoplasmic dissociation remains poorly understood. Upon cytosolic entry, vectors become exposed to a complex, concentrated mixture of molecules and biomacromolecules. In this report, we characterise the cytoplasmic interactome associated with polycationic vectors based on poly(dimethylaminoethyl methacrylate) (PDMAEMA) and poly(2-methacrylolyloxyethyltrimethylammonium chloride) (PMETAC) brushes. To quantify the contribution of different classes of low molar mass molecules and biomacromolecules to RNA release, we develop a kinetics model based on competitive binding. Our results identify the importance of competition from highly charged biomacromolecules, such as cytosolic RNA, as a primary regulator of RNA release. Importantly, our data indicate the presence of ribosome associated proteins, proteins associated with translation and transcription factors that may underly a broader impact of polycationic vectors on translation. In addition, we bring evidence that molecular crowding modulates competitive binding and demonstrate how the modulation of such interactions, for example via quaternisation or the design of charge-shifting moieties, impacts on the long-term transfection efficiency of polycationic vectors. Understanding the mechanism regulating cytosolic dissociation will enable the improved design of cationic vectors for long term gene release and therapeutic efficacy.

In Vitro Evaluation and Biodistribution Studies of HPMA Copolymers Targeting the Gastrin Releasing Peptide Receptor in Prostate Cancer.

PURPOSE: The development of diagnostic and therapeutic agents utilizing small peptides (e.g., bombesin (BBN)) to target the overexpression of the gastrin-releasing peptide receptor (GRPR) in cancers has been widely investigated. Herein, we examine the capabilities of BBN-modified HPMA copolymers to target the GRPR. METHODS: Four positive, four negative, and two zwitterionic BBN HPMA copolymer conjugates of varying peptide content and charge were synthesized. In vitro and in vivo studies were conducted in a GRPR-overexpressing prostate cancer cell line (PC-3) and a normal CF-1 mouse model, respectively. RESULTS: Cellular uptake of the conjugates were found to be charge and BBN density dependent. The positively-charged conjugates illustrated a direct relationship between the extent of cellular internalization, ranging from 0.7 to 20%, and BBN-incorporation density. The negative and zwitterionic conjugates showed low PC-3 uptake values. Blocking studies confirmed the GRPR-targeting effect of the positively-charged constructs. In vivo studies of the positively-charged copolymers resulted in rapid blood clearance by the mononuclear phagocyte system (MPS)-associated tissues (e.g., liver and spleen). CONCLUSION: Positively-charged BBN-HPMA copolymer conjugates demonstrated good GRPR-targeting and internalization in vitro. However, the impact of peptide density and charge on in vivo MPS recognition are parameters that must be optimized in future agent development.

Poly (ethylene glycol) hydrogel scaffolds with multiscale porosity for culture of human adipose-derived stem cells.

Three-dimensional (3 D) hydrogel scaffolds are an attractive option for tissue regeneration applications because they allow for cell migration, fluid exchange, and can be synthesized to closely mimic the physical properties of the extracellular matrix environment. The material properties of hydrogels play a vital role in cellular migration and differentiation. In light of this, in-depth understanding of material properties is required before such scaffolds can be used to study their influence on cells. Herein, various blends and thicknesses of poly (ethylene glycol) dimethacrylate (PEGDMA) hydrogels were synthesized, flash frozen, and dried by lyophilization to create scaffolds with multiscale porosity. Environmental scanning electron microscopy (ESEM) images demonstrated that lyophilization induced microporous voids in the PEGDMA hydrogels while swelling studies show the hydrogels retain their innate swelling properties. Change in pore size was observed between drying methods, polymer blend, and thickness when imaged in the hydrated state. Human adipose-derived stem cells (hASCs) were seeded on lyophilized and non-lyophilized hydrogels to determine if the scaffolds would support cell attachment and proliferation of a clinically relevant cell type. Cell attachment and morphology of the hASCs were evaluated using fluorescence imaging. Qualitative observations in cell attachment and morphology of hASCs on the surface of the different hydrogel spatial configurations indicate these multiscale porosity hydrogels create a suitable scaffold for hASC culture. These findings offer another factor of tunability in creating biomimetic hydrogels for various tissue engineering applications including tissue repair, regeneration, wound healing, and controlled release of growth factors.

Impact of antimycin A and myxothiazol on cadmium-induced superoxide, hydrogen peroxide, and nitric oxide generation in barley root tip.

In order to gain more insight into the involvement of mitochondrial complex III in the Cd-induced stress, we studied the effect of complex III inhibitors, antimycin A (AA), and myxothiazol (MYXO), on the Cd-induced ROS and NO generation in the barley root tip. Short-term exposure of barley roots to either MYXO or AA provoked a dose-dependent increase in both H2O2 and NO formation. In contrast to H2O2 generation, an enhanced superoxide formation in the transition zone of the root was a characteristic feature of AA-treated roots. MYXO and AA co-treatment had an additive effect on the amount of both H2O2 and NO formed in roots. On the other hand, AA-induced superoxide formation was markedly reversed in roots co-treated with MYXO. Both AA and MYXO exacerbated the Cd-mediated H2O2 or NO generation in the root tip. On the contrary, while AA also exacerbated the Cd-induced superoxide generation, MYXO dose-dependently attenuated it. These data provide strong evidence that ROS generation, a very early symptom of Cd toxicity in roots, is originated in mitochondria. Cd, similarly to AA, generates superoxide by blocking the mitochondrial electron transport chain (ETC) at complex III. In turn, the site of Cd-induced NO generation is not associated with complex III, but ROS formed in mitochondria at this third complex of ETC are probably responsible for enhanced NO generation in barley root under Cd stress.

3D-Printed Biodegradable Microswimmer for Theranostic Cargo Delivery and Release.

Untethered mobile microrobots have the potential to leverage minimally invasive theranostic functions precisely and efficiently in hard-to-reach, confined, and delicate inner body sites. However, such a complex task requires an integrated design and engineering, where powering, control, environmental sensing, medical functionality, and biodegradability need to be considered altogether. The present study reports a hydrogel-based, magnetically powered and controlled, enzymatically degradable microswimmer, which is responsive to the pathological markers in its microenvironment for theranostic cargo delivery and release tasks. We design a double-helical architecture enabling volumetric cargo loading and swimming capabilities under rotational magnetic fields and a 3D-printed optimized 3D microswimmer (length = 20 µm and diameter = 6 µm) using two-photon polymerization from a magnetic precursor suspension composed from gelatin methacryloyl and biofunctionalized superparamagnetic iron oxide nanoparticles. At normal physiological concentrations, we show that matrix metalloproteinase-2 (MMP-2) enzyme could entirely degrade the microswimmer in 118 h to solubilized nontoxic products. The microswimmer rapidly responds to the pathological concentrations of MMP-2 by swelling and thereby boosting the release of the embedded cargo molecules. In addition to delivery of the drug type of therapeutic cargo molecules completely to the given microenvironment after full degradation, microswimmers can also release other functional cargos. As an example demonstration, anti-ErbB 2 antibody-tagged magnetic nanoparticles are released from the fully degraded microswimmers for targeted labeling of SKBR3 breast cancer cells in vitro toward a potential future scenario of medical imaging of remaining cancer tissue sites after a microswimmer-based therapeutic delivery operation.

Zwitterionic shielded polymeric prodrug with folate-targeting and pH responsiveness for drug delivery.

Zwitterionic polymers are a class of polymers that acts as both Lewis base and Lewis acid in solution. These polymers not only have excellent properties of hydration, anti-bacterial adhesion, charge reversal and easy chemical modification, but also have characteristics of long-term circulation and suppress nonspecific protein adsorption in vivo. Here, we describe a novel folate-targeted and acid-labile polymeric prodrug under the microenvironment of tumor cells, abbreviated as FA-P(MPC-co-PEGMA-BZ)-g-DOX, which was synthesized via a combination of reversible addition-fragmentation chain transfer (RAFT) copolymerization, Schiff-base reaction, Click chemistry, and a reaction between the amine group of doxorubicin (DOX) and aldehyde functionalities of P(MPC-co-PEGMA-BZ) pendants, wherein MPC and PEGMA-BZ represent 2-(methacryloyloxy)ethyl phosphorylcholine and polyethylene glycol methacrylate ester benzaldehyde, respectively. The polymeric prodrug could self-assemble into nanoparticles in an aqueous solution. The average particle size and morphologies of the prodrug nanoparticles were observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. We also investigated the in vitro drug release behavior and observed rapid prodrug nanoparticle dissociation and drug release under a mildly acidic microenvironment. The methyl thiazolyl tetrazolium (MTT) assay verified that the P(MPC-co-PEGMA-BZ) copolymer possessed good biocompatibility and the FA-P(MPC-co-PEGMA-BZ)-g-DOX prodrug nanoparticles showed higher cellular uptake than those prodrug nanoparticles without the FA moiety. The results of cytotoxicity and the intracellular uptake of non-folate/folate targeted prodrug nanoparticles further confirmed that FA-P(MPC-co-PEGMA-BZ)-g-DOX could be efficiently accumulated and rapidly internalized by HeLa cells due to the strong interaction between multivalent phosphorylcholine (PC) groups and cell membranes. This kind of multifunctional FA-P(MPC-co-PEGMA-BZ)-g-DOX prodrug nanoparticle with combined target-ability and pH responsiveness demonstrates promising potential for cancer chemotherapy.

Transport and delivery of interferon-α through epithelial tight junctions via pH-responsive poly(methacrylic acid-grafted-ethylene glycol) nanoparticles.

Whereas significant advancements have been made in our fundamental understanding of cancer, they have not yet translated into effective clinical cancer treatments. One of the areas that has the potential to improve the efficacy of cancer therapies is the development of novel drug delivery technologies. In particular, the design of pH-sensitive polymeric complexation hydrogels may allow for targeted oral delivery of a wide variety of chemotherapeutic drugs and proteins. In this work, poly(methacrylic acid-grafted-ethylene glycol) hydrogel nanoparticles were synthesised, characterised, and studied as matrix-type, diffusion-controlled, pH-responsive carriers to enable the oral delivery of the chemotherapeutic agent interferon alpha (IFN-α). The biophysical mechanisms controlling the transport of IFN-α were investigated using a Caco-2/HT29-MTX co-culture as a gastrointestinal (GI) tract model. The synthesised nanoparticles exhibited pH-responsive swelling behaviour and allowed the permeation of IFN-α through the tight junctions of the developed cellular GI epithelium model. These studies demonstrate the capabilities of these particles to contribute to the improved oral delivery of protein chemotherapeutics.

Drug carriers with star polymer structures.

In this review we summarize several synthetic approaches to the advanced synthesis of star-like polymer-based drug carriers. Moreover, their application as nanomedicines for therapy or the diagnosis of neoplastic diseases and their biodistribution are reviewed in detail. From a broad spectrum of star-like systems, we focus only on fully water-soluble systems, mainly based on poly(ethylene glycol) or N-(2-hydroxypropyl)methacrylamide polymer and copolymer arms and polyamidoamine dendrimers serving as the core of the star-like systems.

Water-soluble fluorescent unimolecular micelles: ultra-small size, tunable fluorescence emission from the visible to NIR region and enhanced biocompatibility for in vitro and in vivo bioimaging.

Fluorescent unimolecular micelles (FUMs) with multicolor emission acting as fluorescent nanoagents for optical fluorescence imaging have, for the first time, been reported. The FUMs show good water-solubility, ultra-small size, and enhanced biocompatibility, which endow the FUMs with versatile applications including organelle labeling, multicolor markers and high tumor accumulation, revealing that our design can serve as a rational strategy for the development of UM-based fluorescent nanoagents for bioprocess monitoring.

Beyond Gene Transfection with Methacrylate-Based Polyplexes-The Influence of the Amino Substitution Pattern.

Methacrylate-based polymers represent promising nonviral gene delivery vectors, since they offer a large variety of polymer architectures and functionalities, which are beneficial for specific demands in gene delivery. In combination with controlled radical polymerization techniques, such as the reversible addition-fragmentation chain transfer polymerization, the synthesis of well-defined polymers is possible. In this study we prepared a library of defined linear polymers based on (2-aminoethyl)-methacrylate (AEMA), N-methyl-(2-aminoethyl)-methacrylate (MAEMA), and N,N-dimethyl-(2-aminoethyl)-methacrylate (DMAEMA) monomers, bearing pendant primary, secondary, and tertiary amino groups, and investigated the influence of the substitution pattern on their gene delivery capability. The polymers and the corresponding plasmid DNA complexes were investigated regarding their physicochemical characteristics, cytocompatibility, and transfection performance. The nonviral transfection by methacrylate-based polyplexes differs significantly from poly(ethylene imine)-based polyplexes, as a successful transfection is not affected by the buffer capacity. We observed that polyplexes containing a high content of primary amino groups (AEMA) offered the highest transfection efficiency, whereas polyplexes bearing tertiary amino groups (DMAEMA) exhibited the lowest transfection efficiency. Further insights into the uptake and release mechanisms could be identified by fluorescence and transmission electron microscopy, emphasizing the theory of membrane-pore formation for the time-efficient endosomal release of methacrylate-based vectors.

Cationic polymers for non-viral gene delivery to human T cells.

The clinical success of chimeric antigen receptor (CAR) T cell immunotherapy in treating multiple blood cancers has created a need for efficient methods of ex vivo gene delivery to primary human T cells for cell engineering. Here, we synthesize and evaluate a panel of cationic polymers for gene delivery to both cultured and primary human T cells. We show that a subset of comb- and sunflower-shaped pHEMA-g-pDMAEMA polymers can mediate transfection with efficiencies up to 50% in the Jurkat human T cell line with minimal concomitant toxicity (>90% viability). We then optimize primary human T cell transfection conditions including activation time, cell density, DNA dose, culture media, and cytokine treatment. We demonstrate transfection of both CD4+ and CD8+ primary human T cells with messenger RNA and plasmid DNA at efficiencies up to 25 and 18%, respectively, with similarly high viability.

Long-term biodistribution study of HPMA-ran-LMA copolymers in vivo by means of 131I-labeling.

BACKGROUND: For the evaluation of macromolecular drug delivery systems suitable pre-clinical monitoring of potential nanocarrier systems is needed. In this regard, both short-term as well as long-term in vivo tracking is crucial to understand structure-property relationships of polymer carrier systems and their resulting pharmacokinetic profile. Based on former studies revealing favorable in vivo characteristics for 18F-labeled random (ran) copolymers consisting of N-(2-hydroxypropyl)methacrylamide (HPMA) and lauryl methacrylate (LMA) - including prolonged plasma half-life as well as enhanced tumor accumulation - the presented work focuses on their long-term investigation in the living organism. METHODS: In this respect, four different HPMA-based polymers (homopolymers as well as random copolymers with LMA as hydrophobic segment) were synthesized and subsequent radioactive labeling was accomplished via the longer-lived radioisotope 131I. In vivo results, concentrating on the pharmacokinetics of a high molecular weight HPMA-ran-LMA copolymer, were obtained by means of biodistribution and metabolism studies in the Walker 256 mammary carcinoma model over a time-span of up to three days. Besides, a direct comparison with the 18F-radiolabeled polymer was drawn. To consider physico-chemical differences between the differently labeled polymer (18F or 131I) on the critical micelle concentration (CMC) and the size of the polymeric micelles, those properties were determined using the 19F- or 127I-functionalized polymer. Special emphasis was laid on the time-dependent correlation between blood circulation properties and corresponding tumor accumulation, particularly regarding the enhanced permeability and retention (EPR) effect. RESULTS: Studies revealed, at first, differences in the short time (2h) body distribution, despite the very similar properties (molecular structure, CMC and size of the micellar aggregates) of the non-radioactive 19F- and 127I-functionalized polymers. Long-term investigations with the 131I-labeled polymer demonstrated that, despite a polymer clearance from the blood within 72h, there was still an increase in tumor uptake observed over time. Regarding the stability of the 131I-label, ex vivo biodistribution experiments, considering the uptake in the thyroid, indicated low metabolism rates. CONCLUSION: The observed in vivo characteristics strongly underline the EPR effect. The findings illustrate the need to combine information of different labeling approaches and in vivo evaluation techniques to generate an overall pharmacokinetic picture of potential nanocarriers in the pre-clinical setting. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENTS: The in vivo behavior of the investigated HPMA-ran-LMA copolymer demonstrates great potential in terms of an effective accumulation in the tumor.

HPMA-Copolymer Nanocarrier Targets Tumor-Associated Macrophages in Primary and Metastatic Breast Cancer.

Polymeric nanocarriers such as N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers deliver drugs to solid tumors and avoid the systemic toxicity of conventional chemotherapy. Because HPMA copolymers can target sites of inflammation and accumulate within innate immune cells, we hypothesized that HPMA copolymers could target tumor-associated macrophages (TAM) in both primary and metastatic tumor microenvironments. We verified this hypothesis, first in preliminary experiments with isolated bone marrow macrophage cultures in vitro and subsequently in a spontaneously metastatic murine breast cancer model generated from a well-established, cytogenetically characterized 4T1 breast cancer cell line. Using our standardized experimental conditions, we detected primary orthotopic tumor growth at 7 days and metastatic tumors at 28 days after orthotopic transplantation of 4T1 cells into the mammary fat pad. We investigated the uptake of HPMA copolymer conjugated with Alexa Fluor 647 and folic acid (P-Alexa647-FA) and HPMA copolymer conjugated with IRDye 800CW (P-IRDye), following their retroorbital injection into the primary and metastatic tumor-bearing mice. A significant uptake of P-IRDye was observed at all primary and metastatic tumor sites in these mice, and the P-Alexa647-FA signal was found specifically within CD11b+ TAMs costained with pan-macrophage marker CD68. These findings demonstrate, for the first time, a novel capacity of a P-Alexa647-FA conjugate to colocalize to CD11b+CD68+ TAMs in both primary and metastatic breast tumors. This underscores the potential of this HPMA nanocarrier to deliver functional therapeutics that specifically target tumor-promoting macrophage activation and/or polarization during tumor development. Mol Cancer Ther; 16(12); 2701-10. ©2017 AACR.

HPMA copolymer-phospholipase C and dextrin-phospholipase A2 as model triggers for polymer enzyme liposome therapy (PELT).

'Polymer Enzyme Liposome Therapy' (PELT) is a two-step anticancer approach in which a liposomal drug and polymer-phospholipase conjugate are administered sequentially to target the tumour interstitium by the enhanced permeability and retention effect, and trigger rapid, local, drug release. To date, however, the concept has only been described theoretically. We synthesised two polymer conjugates of phospholipase C (PLC) and A2 (PLA2) and evaluated their ability to trigger anthracycline release from the clinically used liposomes, Caelyx® and DaunoXome®. N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer-PLC and a dextrin-PLA2 were synthesised and their enzymatic activity characterised. Doxorubicin release from polyethyleneglycol-coated (PEGylated) Caelyx® was relatively slow (<20%, 60 min), whereas daunomycin was rapidly released from non-PEGylated DaunoXome® (∼87%) by both enzymes. Incubation with dextrin-PLA2 triggered significantly less daunomycin release than HPMA copolymer-PLC, but when dextrin-PLA2 was pre-incubated with α-amylase, the rate of daunomycin release increased. DaunoXome®'s diameter increased in the presence of PLA2, while Caelyx®'s diameter was unaffected by free or conjugated PLA2. Dextrin-PLA2 potentiated the cytotoxicity of DaunoXome® to MCF-7 cells to a greater extent than free PLA2, while combining dextrin-PLA2 with Caelyx® resulted in antagonism, even in the presence of α-amylase, presumably due to steric hindrance by PEG. Our findings suggest that in vivo studies to evaluate PELT combinations should be further evaluated.

Investigation into the Biological Impact of Block Size on Cathepsin S-Degradable HPMA Copolymers.

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymers have been studied as an efficient carrier for drug delivery and tumor imaging. However, as with many macromolecular platforms, the substantial accumulation of HPMA copolymer by the mononuclear phagocyte system (MPS)-associated tissues, such as the blood, liver, and spleen, has inhibited its clinical translation. Our laboratory is pursuing approaches to improve the diagnostic and radiotherapeutic effectiveness of HPMA copolymers by reducing the nontarget accumulation. Specifically, we have been investigating the use of a cathepsin S (Cat S)-cleavable peptidic linkers to degrade multiblock HPMA copolymers to increase MPS-associated tissue clearance. In this study, we further our investigation into this area by exploring the impact of copolymer block size on the biological performance of Cat S-degradable HPMA copolymers. Using a variety of in vitro and in vivo techniques, including dual labeling of the copolymer and peptide components, we investigated the constructs using HPAC pancreatic ductal adenocarcinoma models. The smaller copolymer block size (S-CMP) demonstrated significantly faster Cat S cleavage kinetics relative to the larger system (L-CMP). Confocal microscopy demonstrated that both constructs could be much more efficiently internalized by human monocyte-differentiated macrophage (hMDM) compared to HPAC cells. In the biodistribution studies, the multiblock copolymers with a smaller block size exhibited faster clearance and lower nontarget retention while still achieving good tumor targeting and retention. Based on the radioisotopic ratios, fragmentation and clearance of the copolymer constructs were higher in the liver compared to the spleen and tumor. Overall, these results indicate that block size plays an important role in the biological performance of Cat S-degradable polymeric constructs.

TiO2-based Mitoxantrone Imprinted Poly (Methacrylic acid-co-polycaprolctone diacrylate) Nanoparticles as a Drug Delivery System.

BACKGROUND: Light delivery in photodynamic therapy is a challenging issue in deep cancer treatment. To solve this problem, photosensitizers are conjugated to X-ray luminescent nanoparticles. When the complexes are stimulated by X-rays during radiotherapy, the nanoparticles generate light and activate the photosensitizers. METHOD: Core-shell molecularly imprinted polymers (MIPs) were prepared against mitoxantrone (MX) in which TiO2 nanoparticles were applied as a core, diacrylated polycaprolctone as a biodegradable cross-linker and methacrylic acid (MAA) or 4-vinylpyridin (4-VP) as the functional monomer. TiO2 was selected as a scintillator, MX as a photosensitizer and MIP as a drug delivery system in order to evaluate the possibility of using photodynamic therapy (PDT) during radiotherapy in the next studies. Binding properties of polymers and drug release profile were studied and the optimized MIP was characterized by SEM, TEM, EDS, FT-IR and XRD. Also, cytotoxicity and free radical production were also studied in vitro. RESULTS: Data indicated that MAA-based MIP had superior binding properties compared to its non-imprinted polymer (NIP) and higher imprinting factor value than MIP-4VP. Drug release experiments indicated higher MX released amount from MAA-based MIP than the other polymers. MAA-based MIP was selected as an optimized carrier for MX delivery system. According to the results, the size of MX-MIP@TiO2 was reported to be less than 75 nm. The free radical production and cytotoxicity of nanoparticles were also evaluated in vitro. CONCLUSION: The results of the present work proposed the possibility of applying MIP layer as a drug delivery system around TiO2 nanoparticles.

The lower alkyl methacrylates: Genotoxic profile of non-carcinogenic compounds.

All of the lower alkyl methacrylates are high production chemicals with potential for human exposure. The genotoxicity of seven mono-functional alkyl esters of methacrylic acid, i.e. methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, n-, i- and t-butyl methacrylate and 2 ethyl hexyl methacrylate, as well as methacrylic acid itself, the acyl component common to all, is reviewed and compared with the lack of carcinogenicity of methyl methacrylate, the representative member of the series so evaluated. Also reviewed are the similarity of structure, chemical and biological reactivity, metabolism and common metabolic products of this group of compounds which allows a category approach for assessing genotoxicity. As a class, the lower alkyl methacrylates are universally negative for gene mutations in prokaryotes but do exhibit high dose clastogenicity in mammalian cells in vitro. There is no convincing evidence that these compounds induce genotoxic effects in vivo in either sub-mammalian or mammalian species. This dichotomy of effects can be explained by the potential genotoxic intermediates generated in vitro. This genotoxic profile of the lower alkyl methacrylates is consistent with the lack of carcinogenicity of methyl methacrylate.