A PEGylated liposomal formulation of prochlorperazine that limits brain exposure but retains dynamin II activity: A potential adjuvant therapy for cancer patients receiving chemotherapeutic mAbs.

Anti-cancer monoclonal antibodies often fail to provide therapeutic benefit in receptor-positive patients due to rapid endocytosis of antibody-bound cell surface receptors. High dose co-administration of prochlorperazine (PCZ) inhibits endocytosis and sensitises tumours to mAbs by inhibiting dynamin II but can also introduce neurological side effects. We examined the potential to use PEGylated liposomal formulations of PCZ (LPCZ) to retain the anti-cancer effects of PCZ, but limit brain uptake. Uncharged liposomes showed complete drug encapsulation and pH-dependent drug release, but cationic liposomes showed limited drug encapsulation and lacked pH-dependent drug release. Uncharged LPCZ showed comparable inhibition of EGFR internalisation to free PCZ in KJD cells. After IV administration to rats, LPCZ reduced the plasma clearance and brain uptake of PCZ compared to IV PCZ. The results suggest that LPCZ may offer some benefit over PCZ as an adjunct therapy in cancer patients receiving mAb treatment.

Dose-Dependent Effect of Phenothiazines as Dynamin II Inhibitors on the Uptake of PEGylated Liposomes by Endocytic Cells and In Vivo Pharmacokinetics of PEGylated Liposomal Doxorubicin in Rats.

Dynamin II (dynII) plays a significant role in the internalization pathways of endocytic cells, by allowing membrane invaginations to "bud off". An important class of dynII inhibitors that are used clinically are phenothiazines, such as prochlorperazine (PCZ). PCZ is an antipsychotic drug but is also currently in clinical trials at higher concentrations as an adjuvant in cancer patients that increases the efficacy of monoclonal antibodies at high intravenous doses. It is unknown, however, whether high-dose dynII inhibitors have the potential to alter the pharmacokinetics of co-administered chemotherapeutic nanomedicines that are largely cleared via the mononuclear phagocyte system. This work therefore sought to investigate the impact of clinically relevant concentrations of phenothiazines, PCZ and thioridazine, on in vitro liposome endocytosis and in vivo liposome pharmacokinetics after PCZ infusion in rats. The uptake of fluorescently labeled PEGylated liposomes into differentiated and undifferentiated THP-1 and RAW246.7 cells, and primary human peripheral white blood cells, was investigated via flow cytometry after co-incubation with dynII inhibitors. The IV pharmacokinetics of PEGylated liposomes were also investigated in rats after a 20 min infusion with PCZ. Phenothiazines and dyngo4a reduced the uptake of PEGylated liposomes by THP-1 and RAW264.7 cells in a concentration-dependent manner in vitro. However, dynII inhibitors did not alter the mean uptake of liposomes by human peripheral white blood cells, but endocytic white cells from some donors exhibited sensitivity to phenothiazine exposure. When a clinically relevant dose of PCZ was co-administered with PEGylated liposomal doxorubicin (Caelyx/Doxil) in rats, the pharmacokinetics and biodistribution of liposomes were unaltered. These data suggest that while clinically relevant doses of dynII inhibitors can inhibit the uptake of liposomes by endocytic cells in vitro, they are unlikely to significantly affect the pharmacokinetics of long-circulating, co-administered liposomes.

Nitroxide-functional PEGylated nanostars arrest cellular oxidative stress and exhibit preferential accumulation in co-cultured breast cancer cells.

The limited application of traditional antioxidants to reducing elevated levels of reactive oxygen species (ROS) is potentially due to their lack of stability and biocompatibility when tested in a biological milieu. For instance, the poor biological antioxidant performance of small molecular nitroxides arises from their limited diffusion across cell membranes and their significant side effects when applied at high doses. Herein, we describe the use of nanostructured carriers to improve the antioxidant activity of a typical nitroxide derivative, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). Polymers with star-shaped structures were synthesised and were further conjugated to TEMPO moieties via amide linkages. The TEMPO-loaded stars have small hydrodynamic sizes (<20 nm), and are better tolerated by cells than free TEMPO in a breast cancer-fibroblast co-culture, a system exhibiting elevated ROS levels. At a well-tolerated concentration, the polymer with the highest TEMPO-loading capacity successfully downregulated ROS production in co-cultured cells (a significant decrease of up to 50% vs. basal ROS levels), which was accompanied by a specific reduction in superoxide anion generation in the mitochondria. In contrast, the equivalent concentration of free TEMPO did not achieve the same outcome. Further investigation showed that the TEMPO-conjugated star polymers can be recycled inside the cells, thus providing longer term scavenging activity. Cell association studies demonstrated that the polymers can be taken up by both cell types in the co-culture, and are found to co-locate with the mitochondria. Interestingly the stars exhibited preferential mitochodria targeting in the co-cultured cancer cells compared to accompanying fibroblasts. The data suggest the potential of TEMPO-conjugated star polymers to arrest oxidative stress for various applications in cancer therapy.

The pharmacokinetics of PEGylated liposomal doxorubicin are not significantly affected by sex in rats or humans, but may be affected by immune dysfunction.

PEGylated liposomal doxorubicin (PLD, Caelyx®, Doxil®) has been suggested to show significant sex-based differences in plasma clearance, as well as high inter-individual variability that may be driven by monocyte counts in cancer patients. This study aimed to establish if these differences are similarly observed in rats, which exhibit similar liposome clearance mechanisms to humans, and to use this model to identify sources of inter-individual and sex-based pharmacokinetic variability. The plasma and lymphatic pharmacokinetics of PLD were evaluated in male and female rats by quantifying doxorubicin as well as the 3H-labelled liposome. In general, the pharmacokinetics of doxorubicin and the 3H-liposome did not differ significantly between male and female rats when corrected for body surface area. Female rats did, however, show significantly higher doxorubicin concentrations in lymph compared to male rats. With the exception of serum testosterone concentrations in males, none of the physiological parameters evaluated correlated with plasma clearance. Further, reanalysis of published human data that formerly reported sex-differences in PLD plasma clearance similarly revealed no significant differences in PLD plasma clearance between males and females with solid tumours, but increased plasma clearance in patients with Kaposi's sarcoma (generally HIV+/immunocompromised). These data suggest that with the exception of lymphatic exposure, there are unlikely to be significant sex effects in the pharmacokinetics of liposomes, but immune function may contribute to inter individual variability.

Monocytes Do Not Contribute to Sex Differences Seen in the Pharmacokinetics of Pegylated Liposomal Doxorubicin.

Pegylated liposomal doxorubicin (PLD) is widely utilised in cancer chemotherapy, but exhibits large inter-individual pharmacokinetic variability and sex differences in plasma clearance. Population pharmacokinetic modelling has suggested PLD plasma clearance correlates with peripheral monocyte counts, while sex hormones are known to affect endocytosis and phagocytosis in mononuclear cells. This study investigated whether sex hormones affect the uptake of PLD by human monocytes and macrophages in vitro. 17ß-estradiol, but not testosterone, inhibited the uptake of PLD in a concentration dependent manner in undifferentiated (but not differentiated) THP-1 cells, and primary monocytes obtained from women, but not men. Effects of estradiol were only evident at very high concentrations seen during pregnancy. No differences were observed in monocyte count or monocyte subtypes between males and females. These data show that monocytes do not contribute to sex differences seen in PLD clearance in humans of reproductive age.

Depolymerization of hyaluronan using PEGylated human recombinant hyaluronidase promotes nanoparticle tumor penetration.

Aim: Delivery of nanoparticles (NPs) to tumors can be impeded by high levels of hyaluronan (HA) in the stroma. Enzymatic depolymerization of HA with PEGylated hyaluronidase (PEGPH20) improves the delivery of antibodies to tumors. However, it is unknown whether NP delivery is enhanced by this strategy. Methods: The impact of PEGPH20 pretreatment on the uptake and tumor penetration of model PEGylated polystyrene NPs was studied in mice with orthotopic breast cancers. Results: Tumor oxygenation and NP penetration, but not overall tumor uptake, of 50 nm NPs, was significantly enhanced by PEGPH20 pre-administration. Conclusion: PEGPH20 has the potential to improve intratumoral penetration of NP-based drug delivery systems and enhance access to cancer cells in poorly vascularized regions of the tumor.

Trisulfide linked cholesteryl PEG conjugate attenuates intracellular ROS and collagen-1 production in a breast cancer co-culture model.

The progression of cancer has been closely-linked with augmentation of cellular reactive oxygen species (ROS) levels and ROS-associated changes in the tumour microenvironment (TME), including alterations to the extracellular matrix and associated low drug uptake. Herein we report the application of a co-culture model to simulate the ROS based cell-cell interactions in the TME using fibroblasts and breast cancer cells, and describe how novel reactive polymers can be used to modulate those interactions. Under the co-culture conditions, both cell types exhibited modifications in behaviour, including significant overproduction of ROS in the cancer cells, and elevation of the collagen-1 secretion and stained actin filament intensity in the fibroblasts. To examine the potential of using reactive antioxidant polymers to intercept ROS communication and thereby manipulate the TME, we employed H2S-releasing macromolecular conjugates which have been previously demonstrated to mitigate ROS production in HEK cells. The specific conjugate used, mPEG-SSS-cholesteryl (T), significantly reduced ROS levels in co-cultured cancer cells by approximately 50%. This reduction was significantly greater than that observed with the other positive antioxidant controls. Exposure to T was also found to downregulate levels of collagen-1 in the co-cultured fibroblasts, while exhibiting less impact on cells in mono-culture. This would suggest a possible downstream effect of ROS-mitigation by T on stromal-tumour cell signalling. Since fibroblast-derived collagens modulate crucial steps in tumorigenesis, this ROS-associated effect could potentially be harnessed to slow cancer progression. The model may also be beneficial for interrogating the impact of antioxidants on naturally enhanced ROS levels, rather than relying on the application of exogenous oxidants to simulate elevated ROS levels.

Trisulfide-Bearing PEG Brush Polymers Donate Hydrogen Sulfide and Ameliorate Cellular Oxidative Stress.

A potential approach to combat cellular dysfunction is to manipulate cell communication and signaling pathways to restore physiological functions while protecting unaffected cells. For instance, delivering the signaling molecule H2S to certain cells has been shown to restore cell viability and re-normalize cell behavior. We have previously demonstrated the ability to incorporate a trisulfide-based H2S-donating moiety into linear polymers with good in vitro releasing profiles and demonstrated their potential for ameliorating oxidative stress. Herein, we report two novel series of brush polymers decorated with higher numbers of H2S-releasing segments. These materials contain two trisulfide-based monomers co-polymerized with oligo(ethylene glycol methyl ether methacrylate) via reversible addition-fragmentation chain-transfer polymerization. The macromolecules were characterized to have a range of trisulfide densities with similar, well-defined molecular weight distribution, good H2S-releasing profiles, and high cellular tolerance. Using an amperometric technique, the H2S liberated and total sulfide release were found to depend on concentrations and chemical nature of triggering molecules (glutathione and cysteine) and, importantly, the position of reactive groups within the brush structure. Notably, when introduced to cells at well-tolerated doses, two macromolecular donors which have the same proportion as of the H2S-donating monomer (30%) but differ in releasing moiety location show similar cellular H2S-releasing kinetics. These donors can restore reactive oxygen species levels to baseline values, when polymer pretreated cells are exposed to exogenous oxidants (H2O2). Our work opens up a new aspect in preparing H2S macromolecule donors and their application to arresting cellular oxidative cascades.

Lymph-directed immunotherapy - Harnessing endogenous lymphatic distribution pathways for enhanced therapeutic outcomes in cancer.

The advent of immunotherapy has revolutionised the treatment of some cancers. Harnessing the immune system to improve tumour cell killing is now standard clinical practice and immunotherapy is the first line of defence for many cancers that historically, were difficult to treat. A unifying concept in cancer immunotherapy is the activation of the immune system to mount an attack on malignant cells, allowing the body to recognise, and in some cases, eliminate cancer. However, in spite of a significant proportion of patients that respond well to treatment, there remains a subset who are non-responders and a number of cancers that cannot be treated with these therapies. These limitations highlight the need for targeted delivery of immunomodulators to both tumours and the effector cells of the immune system, the latter being highly concentrated in the lymphatic system. In this context, macromolecular therapies may provide a significant advantage. Macromolecules are too large to easily access blood capillaries and instead typically exhibit preferential uptake via the lymphatic system. In contexts where immune cells are the therapeutic target, particularly in cancer therapy, this may be advantageous. In this review, we examine in brief the current immunotherapy approaches in cancer and how macromolecular and nanomedicine strategies may improve the therapeutic profiles of these drugs. We subsequently discuss how therapeutics directed either by parenteral or mucosal administration, can be taken up by the lymphatics thereby accessing a larger proportion of the body's immune cells. Finally, we detail drug delivery strategies that have been successfully employed to target the lymphatics.

Cetuximab Exhibits Sex Differences in Lymphatic Exposure after Intravenous Administration in Rats in the Absence of Differences in Plasma Exposure.

PURPOSE: The aim of this work was to identify whether biochemical and physiological sources of mAb pharmacokinetic sex-effects could be identified in the rat model where target-mediated disposition is avoided. METHODS: Plasma and lymphatic pharmacokinetics of the humanised anti-EGFR antibody cetuximab, along with potential physiological and biochemical drivers of pharmacokinetic sex differences, were examined in male and female rats. Cetuximab was used as a model mAb since plasma clearance is slower in female patients. RESULTS: When plasma concentrations were normalised to dose, female rats displayed slower plasma clearance than males, but no significant differences were observed in liver and spleen biodistribution. Sex differences in apparent plasma clearance, however, were abolished after normalisation to body weight, surface area or fat-free mass. Significant sex differences were observed in plasma testosterone, endogenous IgG and fat free mass, but did not correlate with apparent clearance. Females did, however, show two-fold higher lymphatic exposure compared to males. CONCLUSIONS: These data suggested that mAbs more efficiently access lymph in females, but this does not affect plasma pharmacokinetics or biodistribution. Further, the data suggest that sex differences observed in humans could be a function of antigen density.

Aerosol Pirfenidone Pharmacokinetics after Inhaled Delivery in Sheep: a Viable Approach to Treating Idiopathic Pulmonary Fibrosis.

PURPOSE: Inhaled delivery of pirfenidone to the lungs of patients with idiopathic pulmonary fibrosis holds promise to eliminate oral-observed side effects while enhancing efficacy. This study aimed to comprehensively describe the pulmonary pharmacokinetics of inhaled aerosol pirfenidone in healthy adult sheep. METHODS: Pirfenidone concentrations were evaluated in plasma, lung-derived lymph and epithelial lining fluid (ELF) with data subjected to non-compartmental pharmacokinetic analysis. RESULTS: Compartmental pharmacokinetic evaluation indicated that a 49 mg lung-deposited dose delivered an ELF Cmax of 62 ± 23 mg/L, and plasma Cmax of 3.1 ± 1.7 mg/L. Further analysis revealed that plasma pirfenidone reached Tmax faster and at higher concentrations than in lymph. These results suggested inhaled pirfenidone was cleared from the alveolar interstitium via blood faster than the drug could equilibrate between the lung interstitial fluid and lung lymphatics. However, the data also suggested that a 'reservoir' of pirfenidone feeds into lung lymph at later time points (after it has largely been cleared from plasma), prolonging lung lymphatic exposure. CONCLUSIONS: This study indicates inhaled pirfenidone efficiently deposits in ELF and is cleared from the lungs by initial absorption into plasma, followed by later equilibrium with lung interstitial and lymph fluid.

Drug formulation and nanomedicine approaches to targeting lymphatic cancer metastases.

Lymphatic metastasis plays an important role in cancer progression and prognosis. However, conventional small-molecule chemotherapy drugs inefficiently access the lymphatic system, making the effective eradication of lymphatic metastases difficult without dose-limiting toxicity. Various formulation and nanomedicine-based approaches can be used to significantly enhance the trafficking of small-molecule, peptide and protein drugs toward the lymphatic system to enhance drug exposure at sites of lymphatic cancer growth. However, a number of obstacles exist in translating improved lymphatic exposure into improved chemotherapeutic outcomes. This review highlights the opportunities and challenges inherent in employing formulation and nanomedicinal approaches to improve chemotherapeutic drug activity within the lymphatic system and, importantly, at sites of lymphatic cancer metastasis.

Local inflammation alters the lung disposition of a drug loaded pegylated liposome after pulmonary dosing to rats.

The development of inhalable 'nanomedicines' based on biocompatible lipids and polymers is attracting increasing interest worldwide. Our understanding of how pulmonary inflammation impacts on lung distribution and clearance kinetics however, is limited. Similarly, there is limited information on how the inhaled delivery of biocompatible nanomaterials affects existing respiratory disease. We have addressed these knowledge gaps by describing and comparing the pulmonary pharmacokinetic behaviour of a 3H-labelled PEGylated liposome loaded with a model drug (ciprofloxacin) after intratracheal administration to healthy rats and rats with bleomycin-induced lung inflammation by following both 3H label and drug. Cell- and cytokine-based markers of lung inflammation were used to evaluate the response of healthy and inflamed lungs to the liposome. Liposomes were initially cleared more rapidly from inflamed lungs than from healthy lungs, but exhibited similar rates of lung clearance after 3 days. This was interesting given that mucociliary clearance was more efficient from healthy lungs, despite evidence of higher mucus retention in inflamed lungs and reduced association of the liposome with lung tissue. Although the plasma pharmacokinetics of ciprofloxacin did not differ between rats with healthy or inflamed lungs after pulmonary administration, the plasma pharmacokinetics of 3H-phosphatidylcholine suggested higher liposome bioavailability and more prolonged absorption from inflamed lungs. Concentrations of the pro-inflammatory cytokine IL-1ß were increased in bronchoalveolar lavage fluid after a single pulmonary dose of liposomes to rats with inflamed lungs, but no other significant changes in lung inflammatory markers were identified in healthy or bleomycin-challenged rats.

A 30 kDa polyethylene glycol-enfuvirtide complex enhances the exposure of enfuvirtide in lymphatic viral reservoirs in rats.

HIV therapy with anti-retroviral drugs is limited by the poor exposure of viral reservoirs, such as lymphoid tissue, to these small molecule drugs. We therefore investigated the effect of PEGylation on the anti-retroviral activity and subcutaneous lymphatic pharmacokinetics of the peptide-based fusion inhibitor enfuvirtide in thoracic lymph duct cannulated rats. Both the peptide and the PEG were quantified in plasma and lymph via ELISA. Conjugation to a single 5 kDa linear PEG decreased anti-HIV activity three-fold compared to enfuvirtide. Whilst plasma and lymphatic exposure to peptide mass was moderately increased, the loss of anti-viral activity led to an overall decrease in exposure to enfuvirtide activity. A 20 kDa 4-arm branched PEG conjugated with an average of two enfuvirtide peptides decreased peptide activity by six-fold. Plasma and lymph exposure to enfuvirtide, however, increased significantly such that anti-viral activity was increased two- and six-fold respectively. The results suggest that a multi-enfuvirtide-PEG complex may optimally enhance the anti-retroviral activity of the peptide in plasma and lymph.

Microfluidic preparation of drug-loaded PEGylated liposomes, and the impact of liposome size on tumour retention and penetration.

Understanding the effect of liposome size on tendency for accumulation in tumour tissue requires preparation of defined populations of different sized particles. However, controlling the size distributions without changing the lipid composition is difficult, and differences in compositions itself modify distribution behaviour. Here, a commercial microfluidic format as well as traditional methods was used to prepare doxorubicin-loaded liposomes of different size distributions but with the same lipid composition, and drug retention, biodistribution and localization in tumour tissues were evaluated. The small (∼50 nm diameter) liposomes prepared by microfluidics and large (∼75 nm diameter) liposomes displayed similar drug retention in in vitro release studies, and similar biodistribution patterns in tumour-bearing mice. However, the extent of extravasation was clearly dependent on size of the liposomes, with the small liposomes showing tissue distribution beyond the vascular area compared to the large liposomes. The use of microfluidics to prepare smaller size distribution liposomes compared to sonication methods is demonstrated, and allowed preparation of different size distribution drug carriers from the same lipid composition to enable new understanding of tissue distribution in compositionally consistent materials is demonstrated.

Reducing Dendrimer Generation and PEG Chain Length Increases Drug Release and Promotes Anticancer Activity of PEGylated Polylysine Dendrimers Conjugated with Doxorubicin via a Cathepsin-Cleavable Peptide Linker.

PEGylation typically improves the systemic exposure and tumor biodistribution of polymeric drug delivery systems, but may also restrict enzyme access to peptide-based drug linkers. The impact of dendrimer generation (G4 vs G5) and PEG length (570 vs 1100 Da) on the pharmacokinetics, tumor biodistribution, drug release kinetics, and anticancer activity of a series of PEGylated polylysine dendrimers conjugated with doxorubicin via a cathepsin-B cleavable valine-citrulline linker was therefore investigated in rodents. Although the smallest G4 PEG570 dendrimer showed the most efficient cathepsin-mediated doxorubicin release, systemic exposure and tumor uptake were limited. The largest G5 PEG1100 dendrimer showed good tumor uptake and retention but restricted drug liberation and therefore limited anticancer activity. Superior anticancer activity was achieved using an intermediate sized dendrimer that showed better drug release kinetics, systemic exposure, tumor uptake, and retention. The data suggest that balancing PEG molecular weight and dendrimer size is critical when designing chemotherapeutic dendrimers.

Doxorubicin Conjugation and Drug Linker Chemistry Alter the Intravenous and Pulmonary Pharmacokinetics of a PEGylated Generation 4 Polylysine Dendrimer in Rats.

PEGylated polylysine dendrimers have demonstrated potential as inhalable drug delivery systems that can improve the treatment of lung cancers. Their treatment potential may be enhanced by developing constructs that display prolonged lung retention, together with good systemic absorption, the capacity to passively target lung tumors from the blood and highly selective, yet rapid liberation in the tumor microenvironment. This study sought to characterize how the nature of cathepsin B-cleavable peptide linkers, used to conjugate doxorubicin (Dox) to a PEGylated (PEG570) G4 polylysine dendrimer, affects drug liberation kinetics and intravenous and pulmonary pharmacokinetics in rats. The construct bearing a self-emolative diglycolic acid-V-Citrulline linker exhibited faster Dox release kinetics compared to constructs bearing self-emolative diglycolic acid-glycine-leucine-phenylalanine-glycine (GLFG), or non-self-emolative glutaric acid-GLFG linkers. The V-Citrulline construct exhibited slower plasma clearance, but faster absorption from the lungs than a GLFG construct, although mucociliary clearance and urinary elimination were unchanged. Dox-conjugation enhanced localization in the bronchoalveolar lavage fluid compared to lung tissue, suggesting that projection of Dox from the dendrimer surface reduced tissue uptake. These data show that the linker chemistry employed to conjugate drugs to PEGylated carriers can affect drug release profiles and systemic and lung disposition.

Distribution of therapeutic proteins into thoracic lymph after intravenous administration is protein size-dependent and primarily occurs within the liver and mesentery.

Therapeutic proteins can facilitate the targeting and treatment of lymphatic diseases (such as cancer metastases, infections and inflammatory diseases) since they are cleared via the lymphatics following interstitial (SC or IM) administration. However, therapeutic proteins are often administered intravenously (IV). Recently therapeutic proteins have been found to access the thoracic lymph in surprisingly high quantities after IV administration. The aim of this study was to determine, for the first time, the major sites of thoracic lymph access of therapeutic proteins, and the protein properties that enhance lymph access, after IV administration. In order to achieve this, novel methods were developed or optimized to collect hepatic, mesenteric or thoracic lymph from male SD rats. Four different sized PEGylated or non-PEGylated therapeutic proteins (native interferon α2b (IFN, 19kDa), PEGylated interferon α2b (IFN-PEG12, 31kDa), PEGylated interferon α2a (IFN-PEG40, 60kDa) or trastuzumab (150kDa)) were then administered via short IV infusion, and plasma and lymph concentrations of the proteins determined via ELISA. The recovery of the therapeutic proteins in the thoracic lymph duct, which collects lymph from most of the body, was significantly greater for trastuzumab, IFN-PEG40 and IFN-PEG12 (all >3% dose over 8h) when compared to native IFN (0.9% dose). Conversely, the thoracic lymph/plasma (L/P) concentration ratio and thus efficiency of extravasation and transport through the interstitium to lymph was highest for the smaller proteins IFN and IFN-PEG12 (at 90-100% vs 15-30% for trastuzumab and IFN-PEG40). The lower total recovery of IFN and IFN-PEG12 in thoracic lymph reflected more rapid systemic clearance and thus lower systemic exposure. For all therapeutic proteins, the majority (>80%) of lymph access occurred via the hepatic and mesenteric lymphatics. This lymphatic distribution pattern was supported by quantitative imaging of the lymph node distribution of IV administered Cy5 labelled trastuzumab. Optimizing the properties of IV administered therapeutic proteins represents a viable approach to better target and treat pathological states involving the lymphatics, particularly in the liver and mesentery. This includes cancer metastases, infections and inflammatory diseases. Successful development of the novel technique to collect hepatic lymph will also enable future work to evaluate tissue-specific lymph transport in health and disease.

Linker chemistry dictates the delivery of a phototoxic organometallic rhenium(i) complex to human cervical cancer cells from core crosslinked star polymer nanoparticles.

We have investigated core-crosslinked star polymer nanoparticles designed with tunable release chemistries as potential nanocarriers for a photoactive Re(i) organometallic complex. The nanoparticles consisted of a brush poly(oligo-ethylene glycol)methyl ether acrylate (POEGA) corona and a cross-linked core of non-biodegradable N,N'-methylenebis(acrylamide) (MBAA) and either pentafluorophenyl acrylate (PFPA), 3-vinyl benzaldehyde (VBA) or diacetone acrylamide (DAAM). Each star was modified with an amine functionalized photodynamic agent (i.e. a rhenium(i) organometallic complex) resulting in the formation of either a stable amide bond (POEGA-star-PFPA), or hydrolytically labile aldimine (POEGA-star-VBA) or ketimine bonds (POEGA-star-DAAM). These materials revealed linker dependent photo- and cytotoxicity when tested in vitro against non-cancerous lung fibroblast MRC-5 cells and HeLa human cervical cancer cells: the toxicity results correlated with final intracellular Re concentrations.

Influence of Size and Shape on the Biodistribution of Nanoparticles Prepared by Polymerization-Induced Self-Assembly.

Polymerization-induced self-assembly (PISA) is a facile one-pot synthetic technique for preparing polymeric nanoparticles with different sizes and shapes for application in a variety of fields including nanomedicine. However, the in vivo biodistribution of nanoparticles obtained by PISA still remains unclear. To address this knowledge gap, we report the synthesis, cytotoxicity, and biodistribution in an in vivo tumor-bearing mouse model of polystyrene micelles with various sizes and polystyrene filomicelles with different lengths prepared by PISA. First, a library of nanoparticles was prepared comprised of poly(glycidyl methacrylate)-b-poly(oligo(ethylene glycol) methyl ether methacrylate)-b-polystyrene polymers, and their size and morphology were tuned by varying the polystyrene block length without affecting the surface chemistry. The 3H) ethanolamine, and a biodistribution study was carried out in nude mice bearing HT1080 tumor xenografts 48 h after intravenous delivery. In this model, we found that small spherical polystyrene core nanoparticles with a PEG corona (diameter 21 nm) have the highest tumor accumulation when compared to the larger spherical nanoparticles (diameter 33 nm) or rodlike (diameter 37 nm, contour length 350-500 nm) or wormlike counterparts (diameter 45 nm, contour length 1-2 µm). This finding has provided critical information on the biodistribution of polystyrene core nanoparticles with a PEG corona of different sizes and shapes prepared by the PISA technique and will inform their use in medical applications.