Zwitterionic Strategy to Stabilize Self-Immolative Polymer Nanoarchitecture under Physiological pH for Drug Delivery In Vitro and In Vivo

The major bottleneck in using polymer nanovectors for biomedical application, particularly those based on self-immolative poly(amino ester) (PAE), lies in their uncontrolled autodegradation at physiological pH before they can reach the intended target. Here, an elegant triblock-copolymer strategy is designed to stabilize the unstable PAE chains via zwitterionic interactions under physiological pH (pH 7.4) and precisely program their enzyme-responsive biodegradation specifically within the intracellular compartments, ensuring targeted delivery of the cargoes. To achieve this goal, biodegradable polycaprolactone (PCL) platform is chosen, and structure-engineered several di- and triblock architectures to arrive the precise macromolecular geometry. The hydrophobic-PCL core and hydrophilic anionic-PCL block at the periphery shield PAEs against autodegradation, thereby ensuring stability under physiological pH in PBS, FBS, cell culture medium and bloodstream. The clinical anticancer drug doxorubicin and deep-tissue penetrable near-infrared IR-780 biomarker is encapsulated to study their biological actions by in vitro live cancer cells and in vivo bioimaging in live animals. These zwitterions are biocompatible, nonhemolytic, and real-time in vitro live-cell confocal studies have confirmed their internalization and enzymatic biodegradation in the endo-lysosomal compartments to deliver the payload. In vivo bioimaging establishes their prolonged blood circulation for over 72 h, and the biodistribution analysis reveals the accumulation of nanoparticles predominantly in the excretory organs.

Structural Engineering of Star Block Biodegradable Polymer Unimolecular Micelles for Drug Delivery in Cancer Cells

The present investigation reports the structural engineering of biodegradable star block polycaprolactone (PCL) to tailor-make aggregated micelles and unimolecular micelles to study their effect on drug delivery aspects in cancer cell lines. Fully PCL-based star block copolymers were designed by varying the arm numbers from two to eight while keeping the arm length constant throughout. Multifunctional initiators were exploited for stepwise solvent-free melt ring-opening polymerization of ε-caprolactone and γ-substituted caprolactone to construct star block copolymers having a PCL hydrophobic core and a carboxylic PCL hydrophilic shell, respectively. A higher arm number and a higher degree of branching in star polymers facilitated the formation of unimolecular micelles as opposed to the formation of conventional multimicellar aggregates in lower arm analogues. The dense core of the unimolecular micelles enabled them to load high amounts of the anticancer drug doxorubicin (DOX, ∼12-15%) compared to the aggregated micelles (∼3-4%). The star unimolecular micelle completely degraded leading to 90% release of the loaded drug upon treatment with the lysosomal esterase enzyme in vitro. The anticancer efficacies of these DOX-loaded unimolecular micelles were tested in a breast cancer cell line (MCF-7), and their IC₅₀ values were found to be much lower compared to those of aggregated micelles. Time-dependent cellular uptake studies by confocal microscopy revealed that unimolecular micelles were readily taken up by the cells, and enhancement of the drug concentration was observed at the intracellular level up to 36 h. The present work opens new synthetic strategies for building a next-generation biodegradable unimolecular micellar nanoplatform for drug delivery in cancer research.

Cardiac magnetic resonance relaxometry compared to left ventricular ejection fraction in the identification of anthracycline related cardiac changes: a systematic review and meta-analysis

Background

Anthracyclines are associated with cancer therapeutics related cardiac dysfunction (CTRCD). The identification of CTRCD currently uses a change in left ventricular ejection fraction (LVEF). Myocardial damage associated with anthracyclines include myocardial inflammation and oedema. This can be assessed using cardiac magnetic resonance (CMR) relaxometry techniques; T1 and T2 mapping and extracellular volume (ECV) fraction.

Purpose

In this meta-analysis, we compared the magnitude of the changes in LVEF and CMR relaxometry techniques wihtin a month of anthracycline therapy completion.

Methods

We performed a structured literature review as per the PRISMA guidelines across three databases (EMBASE, MEDLINE, and SCOPUS) for studies evaluating CMR relaxometry parameter at baseline and soon after completion of anthracycline therapy (3–5 months post baseline). CMR parameters pre and post anthracycline-based chemotherapy were abstracted. A random effects model was used to pool mean difference (MD) in LVEF and ECV given standardisation in imaging acquisition techniques. A random effects model was used to pool standardized mean difference (SMD) in LVEF, T1, T2 and ECV after anthracycline to adjust for variations in imaging techniques and comparison between techniques.

Results

A total of 174 patients were included from seven studies. 91% were female with a mean age of 55.6 years. The pooled MD in LVEF and ECV was −3.15% [95% CI −4.99, −1.31] and 1.61% [0.90, 2.32], respectively. The pooled SMD in LVEF, T1, T2 and ECV was −0.61 [−0.96, −0.25] 0.34 [0.04, 0.63], 0.67 [0.12,1.21], 0.6 [0.31, 0.89], respectively (Table 1).

Conclusions

T2 mapping, ECV and LVEF can identify early myocardial changes better than T1 mapping. These changes suggest there is marked oedema in the myocardial injury from anthracycline therapy. Whilst these findings support the role of CMR relaxometry in identifying CTRCD, further studies are required.

Funding Acknowledgement

Type of funding sources: None.

Self-Reporting Polysaccharide Polymersome for Doxorubicin and Cisplatin Delivery to Live Cancer Cells

We report self-reporting fluorescent polysaccharide polymersome nanoassemblies for enzyme-responsive intracellular delivery of two clinical anticancer drugs doxorubicin (DOX) and cisplatin to study the real-time drug-releasing aspects by fluorescent resonance energy transfer (FRET) bioimaging in live cancer cells. Fluorescent polymersomes were tailor-made by tagging an aggregation-induced emission (AIE) optical chromophore, tetraphenylethylene (TPE), and a plant-based vesicular directing hydrophobic unit through enzyme-biodegradable aliphatic ester chemical linkages in the polysaccharide dextran. The blue-luminescent polymersome self-assembled in water and exhibited excellent encapsulation capability for the red-luminescent anticancer drug DOX. FRET between the AIE polymersome host and DOX guest molecules resulted in a completely turn-off probe. At the intracellular level, the lysosomal enzymatic disassembly of the polymersome restored the dual fluorescent signals from DOX and TPE at the nucleus and the lysosomes, respectively. Live-cell confocal microscopy coupled with selective photoexcitation was employed to study the real-time polymersome disassembly by monitoring the turn-on fluorescent signals in human breast cancer cell lines. Alternatively, carboxylic acid-functionalized AIE polymersomes were also tailor-made for cisplatin stitching to directly monitor Pt drug delivery. The polymersome nanoassemblies exhibited excellent structural tolerance for the chemical conjugation of the Pt drugs, and the fluorescence signals were unaltered. An in vitro drug release study confirmed that the cisplatin-stitched fluorescent polymersomes were very stable under physiological conditions and underwent lysosomal enzymatic degradation to inhibit the cancer cell growth. A lysosomal colocalization experiment using confocal microscopy substantiates the enzyme-responsive degradation of these polymersomes to release both the encapsulated and conjugated drugs at the intracellular level. The present design provides a unique opportunity to deliver more than one anticancer drug from a single polymersome platform in cancer research.

Influence of silver grain size, roughness, and profile on the extraordinary fluorescence enhancement capabilities of grating coupled surface plasmon resonance

Silver gratings with different metal film properties and structures were examined to determine their effect on metal enhanced fluorescence.

The genetics of NOD-like receptors in Crohn's disease

The first Crohn's disease (CD) susceptibility gene identified was CARD15, which is a member of the emerging NOD-like receptor (NLR) family. These function as intracellular cystosolic pattern recognition receptors (PRRs) and play a central role in the innate immune response. We studied other members of the NLR family using a gene-wide haplotype tagging approach in a well-characterised collection of 547 CD patients and 465 controls. Four single nucleotide polymorphisms (SNPs) in NLRP3 had P values < 0.05 and are in high linkage disequilibrium (LD) with each other (r(2) > 0.90 for all four SNPs). rs4925648 and rs10925019 were the most strongly associated with CD susceptibility (P = 0.001, odds ratio (OR) 1.62, 95% CI 1.2-2.18; and P = 6.5 x 10(-4), OR 1.65, 95% CI 1.23-2.19, respectively). rs1363758 located in NLRP11 was associated with CD susceptibility [P = 0.002 (1.64, 1.19-2.25)], which was weakly confirmed in an independent case-cohort collection on joint analysis [P = 0.05, (1.28, 1-1.64)]. On sub-phenotype analysis, an interesting association between NLRP1 and skin extra-intestinal manifestations and colonic, inflammatory CD was identified. None of these results was replicated in the Wellcome Trust Case Control Consortium study and therefore need replication in a further large cohort.

Paget-Schroetter syndrome

A case of primary upper-extremity deep vein thrombosis (UEDVT) or Paget-Schroetter syndrome is reported. It is effort thrombosis usually affecting young healthy individuals and is a rare condition. Our patient was an elderly male with history of exertion using the left upper limb. He responded to limb elevation and anticoagulation. No other cause for thrombosis was found.

Mapping QTLs for root morphology of a rice population adapted to rainfed lowland conditions

In the rainfed lowlands, rice ( Oryza sativa L.) develops roots under anaerobic soil conditions with ponded water, prior to exposure to water stress and aerobic soil conditions that arise later in the season. Constitutive root system development in anaerobic soil conditions has been reported to have a positive effect on subsequent expression of adaptive root traits and water extraction during progressive water stress in aerobic soil conditions. We examined quantitative trait loci (QTLs) for constitutive root morphology traits using a mapping population derived from a cross between two rice lines which were well-adapted to rainfed lowland conditions. The effects of phenotyping environment and genetic background on QTLs identification were examined by comparing the experimental data with published results from four other populations. One hundred and eighty-four recombinant inbred lines (RILs) from a lowland indica cross (IR58821/IR52561) were grown under anaerobic conditions in two experiments. Seven traits, categorized into three groups (shoot biomass, deep root morphology, root thickness) were measured during the tillering stage. Though parental lines showed consistent differences in shoot biomass and root morphology traits across the two seasons, genotype-by-environment interaction (GxE) and QTL-by-environment interaction were significant among the progeny. Two, twelve, and eight QTLs for shoot biomass, deep root morphology, and root thickness, respectively, were identified, with LOD scores ranging from 2.0 to 12.8. Phenotypic variation explained by a single QTL ranged from 6% to 30%. Only two QTLs for deep root morphology, in RG256-RG151 in chromosome 2 and in PC75M3-PC11M4 in chromosome 4, were identified in both experiments. Comparison of positions of QTLs across five mapping populations (the current population plus populations from four other studies) revealed that these two QTLs for deep root morphology were only identified in populations that were phenotyped under anaerobic conditions. Fourteen and nine chromosome regions overlapped across different populations as putative QTLs for deep root morphology and root thickness, respectively. PC41M2-PC173M5 in chromosome 2 was identified as an interval that had QTLs for deep root morphology in four mapping populations. The PC75M3-PC11M4 interval in chromosome 4 was identified as a QTL for root thickness in three mapping populations with phenotypic variation explained by a single QTL consistently as large as 20-30%. Three QTLs for deep root morphology were found only in japonica/indica populations but not in IR58821/IR52561. The results identifying chromosome regions that had putative QTLs for deep root morphology and root thickness over different mapping populations indicate potential for marker-assisted selection for these traits.

Polyvalent cationic metals induce the rate of transferrin-independent iron acquisition by HL-60 cells

The trivalent metals iron, aluminum, and gallium greatly increase the rate of iron acquisition from low molecular weight chelates by human myeloid cells. The present study explores the mechanism responsible. Gallium-induced iron acquisition was shown to lead to stable cellular association of iron, the magnitude of which varied with the chelate to which the iron was bound. The majority of this iron initially associated with the plasma membrane. Cellular depletion of ATP did not affect the response to gallium nor did it require the continued presence of extracellular gallium. However, continued cell association of gallium was needed as subsequent cellular exposure to metal chelators resulted in a rapid loss of the "induced" phenotype. Other trivalent metals (lanthanum and gadolinium) and tetravalent metals (tin and zirconium) but not divalent metals also induced iron acquisition. Neither enhanced iron reduction nor protein kinase C or tyrosine kinases appeared involved in gallium-mediated induction of iron acquisition. Exposure of HL-60 cells to polyvalent cationic metals results in a dramatic and sustained increase in the rate of iron acquisition from low molecular weight chelating agents. This could be important for the rapid clearance of iron by phagocytes from the extracellular environment at sites of local tissue damage.