Synthesis and evaluation of [177 Lu]Lu-labeled porphyrin loaded PAMAM dendrimer: Impact on tumor uptake and pharmacokinetics.

The objective of the present work is to evaluate the ability of the radiolabeled PAMAM dendrimers (polyamidoamine) towards facilitating the delivery of an in-house synthesized porphyrin derivative in the tumorous lesions to evaluate their candidature for possible application in endo-radionuclide therapy. For this, PAMAM particles were conjugated with a porphyrin derivative namely, 5,10,15,20-tetrakis-(4-carboxymethyleneoxyphenyl)porphyrin (STAP), synthesized in-house following a two-step reaction. The average number of porphyrin molecules loaded per PAMAM particle was evaluated using ultraviolet-visible spectrophotometry and was found to be approximately 2. STAP conjugated PAMAM particles were further conjugated with p-NCS-benzyl-DOTA (subsequently referred as DOTA) to facilitate radiolabeling with 177 Lu. On an average, two p-NCS-benzyl-DOTA molecules were observed to be attached per PAMAM-STAP particle. DOTA-PAMAM-STAP conjugate was radiolabeled with 177 Lu with a final radiochemical purity of >95%, which was determined by paper chromatography using two different mobile phases viz. 0.1 M sodium citrate buffer (pH 5.0) and 10 mM DTPA. Biological behavior of [177 Lu]Lu-DOTA-PAMAM-STAP conjugate was investigated in fibrosarcoma bearing Swiss mice model wherein accumulation of radiolabeled particles was observed in liver, GIT, spleen, and kidneys at 3 h post-administration. However, accumulated activity exhibited rapid clearance from majority of the organs at 24 h post-administration. [177 Lu]Lu-DOTA-PAMAM-STAP conjugate exhibited an appreciable uptake in tumor mass [6.09 ± 1.22 percentage injected activity/organ (% IA/organ)] at 3 h post-administration (p.i.) which was found to reduce to 1.05 ± 0.13 % IA/organ at 24 h post-administration. The results obtained in biodistribution studies were further corroborated through scintigraphic imaging performed in the same animal model. Despite of an appreciable accumulation in tumor mass, the lower retention of the [177 Lu]Lu-DOTA-PAMAM-STAP conjugate therein, at longer time point (24 h p.i.) may limit its possible potential as a radio-therapeutic agent and indicates towards need for further structural manoeuvring to attain favorable in vivo performance.

Dual-Responsive Alginate Hydrogel Constructed by Sulfhdryl Dendrimer as an Intelligent System for Drug Delivery.

Intelligent stimulus-triggered release and high drug-loading capacity are crucial requirements for drug delivery systems in cancer treatment. Based on the excessive intracellular GSH expression and pH conditions in tumor cells, a novel glutathione (GSH) and pH dual-responsive hydrogel was designed and synthesized by conjugates of glutamic acid-cysteine dendrimer with alginate (Glu-Cys-SA) through click reaction, and then cross-linked with polyethylene glycol (PEG) through hydrogen bonds to form a 3D-net structure. The hydrogel, self-assembled by the inner disulfide bonds of the dendrimer, is designed to respond to the GSH heterogeneity in tumors, with a remarkably high drug loading capacity. The Dox-loaded Glu-Cys-SA hydrogel showed controlled drug release behavior, significantly with a release rate of over 76% in response to GSH. The cytotoxicity investigation indicated that the prepared DOX-loaded hydrogel exhibited comparable anti-tumor activity against HepG-2 cells with positive control. These biocompatible hydrogels are expected to be well-designed GSH and pH dual-sensitive conjugates or polymers for efficient anticancer drug delivery.

Quantitative Evaluation of Dendritic Nanoparticles in Mice: Biodistribution Dynamics and Downstream Tumor Efficacy Outcomes.

A physiologically based pharmacokinetic model was developed to describe the tissue distribution kinetics of a dendritic nanoparticle and its conjugated active pharmaceutical ingredient (API) in plasma, liver, spleen, and tumors. Tumor growth data from MV-4-11 tumor-bearing mice were incorporated to investigate the exposure/efficacy relationship. The nanoparticle demonstrated improved antitumor activity compared to the conventional API formulation, owing to the extended released API concentrations at the site of action. Model simulations further enabled the identification of critical parameters that influence API exposure in tumors and downstream efficacy outcomes upon nanoparticle administration. The model was utilized to explore a range of dosing schedules and their effect on tumor growth kinetics, demonstrating the improved antitumor activity of nanoparticles with less frequent dosing compared to the same dose of naked APIs in conventional formulations.

Linear-Dendritic Polymer-Platinum Complexes Forming Well-Defined Nanocapsules for Acid-Responsive Drug Delivery.

Polymeric nanocapsules hold considerable applications in cancer drug delivery, but the synthesis of well-defined nanocapsules with a tunable drug release property remains a significant challenge in fabrication. Herein, we demonstrate a supramolecular complexation strategy to assemble small molecular platinum (Pt) compounds into well-defined nanocapsules with high drug loading, acidity-sensitivity, and tunable Pt releasing profile. The design utilizes poly(ethylene glycol)-dendritic polylysine-G4/amides to complex with Pt compounds, forming stable nanocapsules with diameters approximately ∼20 nm and membrane thickness around several nanometers. The stability, drug content, and release profiles are tunable by tailoring the dendritic structure. The designated polymer-Pt nanocapsules, PEG-G4/MSA-Pt, showed sustained blood retention, preferential tumor accumulation, enhanced cellular uptake, lysosomal drug release, and nuclear delivery capability. PEG-G4/MSA-Pt showed enhanced antitumor efficacy compared to free cisplatin and other nanocapsules, which stopped the progression of both A549 cell xenografts and patient-derived xenografts (PDXs) of hepatocellular carcinoma on a mice tumor model. Thus, we believe this strategy is promising for developing Pt-based nanomedicine for cancer drug delivery.

Novel G-CSF conjugated anionic globular dendrimer: Preparation and biological activity assessment.

The most crucial role of granulocyte colony-stimulating factor (G-CSF) in the body is to increase the strength of immune system. In recent years, research on the use of nanoparticles in pharmaceuticals has been considered, most of which have been for drug-loading purposes. In this study, a novel G-CSF conjugated dendrimer was synthesized and characterized using different techniques. In vitro cytotoxicity was assessed on A549 and L929 cells, while abnormal toxicity was studied in mice. In vitro and in vivo biological activities were assessed in NFS60 cells and rats, respectively. In addition, in vivo distribution, plasma half-life, and histopathological effect were studied in rat. The characterization tests confirmed the successful conjugation. There was no difference between G-CSF cytotoxicity before and after conjugation, and no difference with the control group. No mice showed abnormal toxicity. Although in vitro biological activity revealed both conjugated and free G-CSF promote proliferation cells, biological activity decreased significantly after conjugation about one-third of the unconjugated form. Nonetheless, in vivo biological activity of conjugated G-CSF increased by more than 2.5-fold relative to the unconjugated form, totally. Fortunately, no histopathologic adverse effect was observed in vital rat tissues. Also, in vivo distribution of the conjugate was similar to the native protein with an enhanced terminal half-life. Our data revealed that G-CSF conjugated dendrimer could be considered as a candidate to improve the in vivo biological activity of G-CSF. Moreover, multivalent capability of the dendrimer may be used for other new potentials of G-CSF in future perspectives.

Mechanism of Anticancer Action of Novel Imidazole Platinum(II) Complex Conjugated with G2 PAMAM-OH Dendrimer in Breast Cancer Cells.

Transition metal coordination compounds play an important role in the treatment of neoplastic diseases. However, due to their low selectivity and bioavailability, as well as the frequently occurring phenomenon of drug resistance, new chemical compounds that could overcome these phenomena are still being sought. The solution seems to be the synthesis of new metal complexes conjugated with drug carriers, e.g., dendrimers. Numerous literature data have shown that dendrimers improve the bioavailability of the obtained metal complexes, solving the problem of their poor solubility and stability in an aqueous environment and also breaking down inborn and acquired drug resistance. Therefore, the aim of this study was to synthesize a novel imidazole platinum(II) complex conjugated with and without the second-generation PAMAM dendrimer (PtMet2-PAMAM and PtMet2, respectively) and to evaluate its antitumor activity. Cell viability studies indicated that PtMet2-PAMAM exhibited higher cytotoxic activity than PtMet2 in MCF-7 and MDA-MB-231 breast cancer cells at relatively low concentrations. Moreover, our results indicated that PtMet2-PAMAM exerted antiproliferative effects in a zebrafish embryo model. Treatment with PtMet2-PAMAM substantially increased apoptosis in a dose-dependent manner via caspase-9 (intrinsic pathway) and caspase-8 (extrinsic pathway) activation along with pro-apoptotic protein expression modulation. Additionally, we showed that apoptosis can be induced by activating POX, which induces ROS production. Furthermore, our results also clearly showed that the tested compounds trigger autophagy through p38 pathway activation and increase Beclin-1, LC3, AMPK, and mTOR inhibition. The high pro-apoptotic activity and the ability to activate autophagy by the imidazole platinum(II) complex conjugated with a dendrimer may be due to its demonstrated ability to reverse multidrug resistance (MDR) and thereby increase cellular accumulation in breast cancer cells.

Chemical characterization (LC-MS-ESI), cytotoxic activity and intracellular localization of PAMAM G4 in leukemia cells.

Generation 4 of polyamidoamine dendrimer (G4-PAMAM) has several biological effects due to its tridimensional globular structure, repetitive branched amides, tertiary amines, and amino-terminal subunit groups liked to a common core. G4-PAMAM is cytotoxic due to its positive charges. However, its cytotoxicity could increase in cancer cells due to the excessive intracellular negative charges in these cells. Furthermore, this work reports G4-PAMAM chemical structural characterization using UHPLC-QTOF-MS/MS (LC-MS) by electrospray ionization to measure its population according to its positive charges. Additionally, the antiproliferative effects and intracellular localization were explored in the HMC-1 and K-562 cell lines by confocal microscopy. The LC-MS results show that G4-PAMAM generated multivalent mass spectrum values, and its protonated terminal amino groups produced numerous positive charges, which allowed us to determine its exact mass despite having a high molecular weight. Additionally, G4-PAMAM showed antiproliferative activity in the HMC-1 tumor cell line after 24 h (IC50 = 16.97 µM), 48 h (IC50 = 7.02 µM) and 72 h (IC50 = 5.98 µM) and in the K-562 cell line after 24 h (IC50 = 15.14 µM), 48 h (IC50 = 14.18 µM) and 72 h (IC50 = 9.91 µM). Finally, our results showed that the G4-PAMAM dendrimers were located in the cytoplasm and nucleus in both tumor cell lines studied.

A Radiolabeled Self-assembled Nanoparticle Probe for Diagnosis of Lung-Metastatic Melanoma.

Melanoma is a highly malignant skin cancer that frequently metastasizes to the lung, bone, and brain at an early phase. Therefore, noninvasive detection of metastasized melanoma could be beneficial to determine suitable therapeutic strategies. We previously reported a biocompatible ternary anionic complex composed of plasmid DNA (pDNA), polyethyleneimine (PEI), and γ-polyglutamic acid (γ-PGA) based on an electrostatic interaction, which was highly taken up by melanoma cells (B16-F10), even if it was negatively charged. Here, we developed a radiolabeled γ-PGA complex by using indium-111 (111In)-labeled polyamidoamine dendrimer (4th generation; G4) instead of pDNA and iodine-125 (125I)-labeled PEI instead of native PEI, and evaluated its effectiveness as a melanoma-targeted imaging probe. This ternary complex was synthesized at a theoretical charge ratio; carboxyl groups of 111In-diethylenetriaminepentaacetic acid (DTPA)-G4 : amino groups of 125I-PEI : carboxyl groups of γ-PGA was 1 : 8 : 16, and the size and zeta potential were approximately 29 nm and -33 mV, respectively. This complex was taken up by B16-F10 cells with time. Furthermore, a biodistribution study, using normal mice, demonstrated its accumulation in the liver, spleen, and lung, where macrophage cells are abundant. Almost the same level of radioactivity derived from both 111In and 125I was observed in these organs at an early phase after probe injection. Compared with the normal mice, significantly higher lung-to-blood ratios of radioactivity were observed in the B16-F10-lung metastatic cancer model. In conclusion, the radiolabeled γ-PGA complex would hold potentialities for nuclear medical imaging of lung metastatic melanoma.

Design and optimisation of dendrimer-conjugated Bcl-2/xL inhibitor, AZD0466, with improved therapeutic index for cancer therapy.

Dual Bcl-2/Bcl-xL inhibitors are expected to deliver therapeutic benefit in many haematological and solid malignancies, however, their use is limited by tolerability issues. AZD4320, a potent dual Bcl-2/Bcl-xL inhibitor, has shown good efficacy however had dose limiting cardiovascular toxicity in preclinical species, coupled with challenging physicochemical properties, which prevented its clinical development. Here, we describe the design and development of AZD0466, a drug-dendrimer conjugate, where AZD4320 is chemically conjugated to a PEGylated poly-lysine dendrimer. Mathematical modelling was employed to determine the optimal release rate of the drug from the dendrimer for maximal therapeutic index in terms of preclinical anti-tumour efficacy and cardiovascular tolerability. The optimised candidate is shown to be efficacious and better tolerated in preclinical models compared with AZD4320 alone. The AZD4320-dendrimer conjugate (AZD0466) identified, through mathematical modelling, has resulted in an improved therapeutic index and thus enabled progression of this promising dual Bcl-2/Bcl-xL inhibitor into clinical development.

Genetically Encoded and Biologically Produced All-DNA Nanomedicine Based on One-Pot Assembly of DNA Dendrimers for Targeted Gene Regulation.

All-DNA nanomedicines have emerged as potential anti-tumor drugs. DNA nanotechnology provides all-DNA nanomedicines with unlimited possibilities in controlling the diversification of size, shape, and loads of the therapeutic motifs. As DNA is a biological polymer, it is possible to genetically encode and produce the all-DNA nanomedicines in living bacteria. Herein, DNA-dendrimer-based nanomedicines are designed to adapt to the biological production, which is constructed by the flexible 3-arm building blocks to enable a highly efficient one-pot DNA assembly. For the first time, a DNA nanomedicine, D4-3-As-DzSur, is successfully genetically encoded, biotechnologically produced, and directly self-assembled. The performance of the biologically produced D4-3-As-DzSur in targeted gene regulation has been confirmed by in vitro and in vivo studies. The biological production capability will fulfill the low-cost and large-scale production of all-DNA nanomedicines and promote clinical applications.

MALDI-MS Imaging Analysis of Noninflammatory Type III Rotaxane Dendrimers.

Rotaxane dendrimers with hyperbranched macromolecular interlocked structures and size modulation capacity demonstrate drug binding and release ability upon external stimuli. Mass spectrometry imaging (MSI) can offer the high-throughput screening of endogenous/exogenous compounds. Herein, we reported a novel method to display the in situ spatial distribution of label-free monodispersed type III rotaxane dendrimers (RDs) G1 (first generation, size ∼1.5 nm) and G2 (second generation, size ∼5 nm) that were explored as potential drug vehicles in spleen tissue by using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-MSI). Experimental results indicated that the trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB) matrix exhibited the best performance for monodispersed type III RDs G1 and G2. The optimized method was successfully applied to map the in vivo spatial distribution of type III RDs G1 and G2 in the spleen from intraperitoneally injected mice. The MALDI-MSI images revealed that RDs G1 and G2 were relatively stable in the spleen within 24 h after administration. It was found that the identified type III RDs G1 and G2 penetrated through the tunica serosa and were predominantly localized in red pulp regions of spleens. They were also mapped in a marginal zone of spleens simultaneously. There was almost no toxicity of type III RDs G1 and G2 to mice spleens from the H&E results. Furthermore, the type III RDs did not induce the expression of inflammatory cytokines from peripheral blood mononuclear cells (PBMCs) or THP-1 monocytes. The MSI analysis not only demonstrated its ability to image select rotaxane dendrimers in a rapid and efficient manner but also provided tremendous assistance on the applications of the further treatment of cancerous tissue as safe drug carriers. Furthermore, the new strategy demonstrated in this study could be applied on other label-free mechanically interlocked molecules, molecular machines, and macromolecules, which opened a new path to evaluate the toxicological and pharmacokinetic characteristics of these novel materials at the suborgan level.

Sorafenib-Loaded Nanoparticles Based on Biodegradable Dendritic Polymers for Enhanced Therapy of Hepatocellular Carcinoma.

PURPOSE: In spite of its enhanced efficacy and reduced side effects in clinical hepatocellular carcinoma (HCC) therapy, the therapeutic efficacy of antitumor angiogenesis inhibitor sorafenib (SFB) is still restricted due to short in vivo half-life and drug resistance. Here, a novel SFB-loaded dendritic polymeric nanoparticle (NP-TPGS-SFB) was developed for enhanced therapy of HCC. METHODS: NP-TPGS-SFB was fabricated by encapsulating SFB with biodegradable dendritic polymers poly(amidoamine)-poly(γ-benzyl-L-Glutamate)-b-D-α-tocopheryl polyethylene glycol 1000 succinate (PAM-PBLG-b-TPGS). RESULTS: NP-TPGS-SFB exhibited excellent stability and achieved acid-responsive release of SFB. It also exhibited much higher cellular uptake efficiency in HepG2 human liver cells than PEG-conjugated NP (NP-PEG-SFB). Furthermore, MTT assay confirmed that NP-TPGS-SFB induced higher cytotoxicity than NP-PEG-SFB and free SFB, respectively. Lastly, NP-TPGS-SFB significantly inhibited tumor growth in mice bearing HepG2 xenografts, with negligible side effects. CONCLUSION: Our result suggests that NP-TPGS-SFB may be a novel approach for enhanced therapy of HCC with promising potential.

PEGylated nanocarriers: A promising tool for targeted delivery to the brain.

Targeted drug delivery across the blood-brain barrier is an extremely challenging quest in the fight with fatal brain ailments, with the major hurdles being short circulation time, reticuloendothelial system (RES) uptake, and excretion of nanocarriers. PEGylation has emerged as a boon for targeted drug delivery to the brain. It is well established that PEGylation can increase the circulation time of nanocarriers by avoiding RES uptake, which is indispensable for increasing the brain's uptake of nanocarriers. PEGylation also acts as a linker for ligand molecules to achieve active targeting to the brain. Using PEGylation, novel approaches are being investigated to facilitate ligand-receptor interactions at the brain endothelium to ease the entry of therapeutic drugs into the brain. In addition, PEGylation made it simpler to assess the brain tissue for delivering diagnostic molecules and theranostic nanocarriers. The potential of PEGylated nanocarriers is being investigated vastly to boost the therapeutic effect several fold in the treatment of brain diseases. This review sheds light on the contribution of PEGylated nanocarriers, especially liposomes, polymeric nanoparticles, and dendrimers for brain-specific delivery of bioactives.

Overcoming multidrug resistance in cancer: Recent progress in nanotechnology and new horizons.

Multidrug resistance (MDR), defined as the ability of cancer cells to gain resistance to both conventional and novel chemotherapy agents, is an important barrier in treating malignancies. Initially, it was discovered that cellular pumps dependent on ATP were the cause of resistance to chemotherapy, and further studies have found that other mechanisms such as increased metabolism of drugs, decreased drug entry, and defective apoptotic pathways are involved in this process. MDR has been the focus of numerous initiatives and countless studies have been undertaken to better understand MDR and formulate strategies to overcome its effects. The current review highlights various nano-drug delivery systems including polymeric/solid lipid/mesoporous silica/metal nanoparticles, dendrimers, liposomes, micelles, and nanostructured lipid carriers to overcome the mechanism of MDR. Nanoparticles are novel gateways to enhance the therapeutic efficacy of anticancer agents at the target site of action due to their tumor-targeting abilities, which can limit the unwanted systemic effects of chemotherapy agents and also reduce drug resistance. Additionally, other innovative strategies including RNA interference as a biological process used to inhibit or silence specific gene expression, natural products as MDR modulators with little systemic toxic effects, which interfere with the functions of proteins involved in drug efflux, and physical approaches such as combination of conventional drug administration with thermal/ultrasound/photodynamic strategies are also highlighted.

Carboxyl-, sulfonyl-, and phosphate-terminal dendrimers as a nanoplatform with lymph node targeting.

The development of drug delivery vehicles to cancer and/or immune cells in lymph nodes is important for cancer diagnosis, therapy, and immunotherapy. We previously reported that anionic carboxyl-terminal dendrimers were accumulated in lymph nodes. In this study, three anionic dendrimers with carboxyl-, sulfonyl-, and phosphate-terminal groups were prepared to examine the lymph node targeting and the association with immune cells in the lymph nodes. These anionic dendrimers were accumulated in the lymph node by intradermal injection. Although the carboxyl- and sulfonyl-terminal dendrimers were diffused from the injection site, the phosphate-terminal dendrimers were mostly retained. The phosphate-terminal dendrimer was recognized by the macrophages, dendritic cells, and B cells in the lymph node, whereas the carboxyl- and sulfonyl-terminal dendrimers were not. Our results show that these anionic dendrimers were accumulated in the lymph node where the association with immune cells could be controlled by the terminal structure of the dendrimer. The phosphate-terminal dendrimer can be used as a nanoplatform for the delivery of some bioactive molecules to some immune cells, including B cells, in the lymph node.

Intratumor Performance and Therapeutic Efficacy of PAMAM Dendrimers Carried by Clustered Nanoparticles.

In recent years, small nanoparticles (NPs) with a diameter of less than 10 nm have aroused considerable interest in biomedical applications. However, their intratumor performance, as well as the antitumor efficacy, has not been well understood due to their size-dependent pharmacokinetics, which presents a formidable challenge for delivering a comparable amount of different small NPs to tumor tissues. Utilizing the multistage delivery strategy, we construct G3-, G5-, and G7-iCluster delivery systems by using poly(amidoamine) (PAMAM) dendrimers of different generations (G3-, G5-, and G7-PAMAM) as building blocks. The iCluster nanoparticles showed comparable pharmacokinetics and similar initial tumor deposition due to their similarity in size and surface chemistry. After accumulating at a tumor site, individual small dendrimers were released, and thus, their intratumor performance was comparatively investigated. Our results indicated that a subtle change in generation markedly affects their intratumor activities. G5-iCluster outperformed G3-iCluster and G7-iCluster in the treatment efficacy in an orthotopic pancreatic tumor model. The mechanistic study revealed that G3-PAMAM showed reduced particle retention in tumor tissue due to its small size and weak cell internalization, while G7-PAMAM was much less penetrative because of its relatively large size and strong particle-cell interaction. In contrast, G5-PAMAM exhibited balanced tumor penetration, cell internalization, and tumor retention. Our finding highlights the huge influence of the subtle difference of small NPs in their intratumor performance.

dendPoint: a web resource for dendrimer pharmacokinetics investigation and prediction.

Nanomedicine development currently suffers from a lack of efficient tools to predict pharmacokinetic behavior without relying upon testing in large numbers of animals, impacting success rates and development costs. This work presents dendPoint, the first in silico model to predict the intravenous pharmacokinetics of dendrimers, a commonly explored drug vector, based on physicochemical properties. We have manually curated the largest relational database of dendrimer pharmacokinetic parameters and their structural/physicochemical properties. This was used to develop a machine learning-based model capable of accurately predicting pharmacokinetic parameters, including half-life, clearance, volume of distribution and dose recovered in the liver and urine. dendPoint successfully predicts dendrimer pharmacokinetic properties, achieving correlations of up to r = 0.83 and Q2 up to 0.68. dendPoint is freely available as a user-friendly web-service and database at http://biosig.unimelb.edu.au/dendpoint . This platform is ultimately expected to be used to guide dendrimer construct design and refinement prior to embarking on more time consuming and expensive in vivo testing.

Transformable nanoparticles triggered by cancer-associated fibroblasts for improving drug permeability and efficacy in desmoplastic tumors.

Cancer-associated fibroblasts (CAFs) are important barriers for nanoparticles (NPs) to deeply penetrate into tumors and severely limit the antitumor efficacy of nanomedicines. Herein, we proposed a CAF-triggered transformable drug delivery system based on a cleavable peptide responsive to fibroblast activation protein-α (FAP-α) specifically overexpressed on the surface of CAFs. The NPs were composed of cationic poly(amidoamine) (PAMAM) dendrimers cross-linked by our designed peptide, a chemotherapeutical drug was incorporated onto PAMAM using disulfide bonds and finally, hyaluronic acid (HA) was conjugated to improve the tumor targetability as well as biocompatibility through electrostatic interactions. These NPs had an initial size of ∼200 nm and negative zeta potential favorable for stable blood circulation; however, after docking with CAFs, they dissociated into smaller NPs and exposed the relative positive surface charge to facilitate penetration and enter the tumor cells together with CAFs. An interesting finding was that this system intracellularly released different levels of drugs in these two kinds of cells, which was beneficial for the disruption of the stromal barrier and increasing the local drug accumulation. Our investigation confirmed that the constructed system could alleviate the biological barriers and hold promising therapeutic efficiency for desmoplastic solid tumors.

Hepatocyte-Targeted Delivery of siRNA Polyplex with PEG-Modified Lactosylated Dendrimer/Cyclodextrin Conjugates for Transthyretin-Related Amyloidosis Therapy.

Targeted drug delivery system (DDS) is required for RNA interference (RNAi) therapy to increase the therapeutic effect and to reduce the adverse effect. Especially in transthyretin (TTR)-related amyloidosis, hepatocyte specific delivery is desired because TTR mainly expresses in hepatocyte. Herein, we report on a hepatocyte-specific small interfering RNA (siRNA) delivery system using polyethylene glycol (PEG)-modified lactosylated dendrimer (generation 3; G3) conjugates with α-cyclodextrin (PEG-LαCs (G3)) for TTR-related amyloidosis therapy, and investigated the in vitro and in vivo gene silencing effect of PEG-LαCs (G3)/siRNA polyplexes. PEG-LαC (G3, average degree of substitution of PEG (DSP) 2)/TTR siRNA (siTTR) polyplex exhibited the asialoglycoprotein receptor (ASGPR)-mediated cellular uptake, high endosomal escaping ability and localization of the siRNA in cytoplasm, resulting in significant TTR silencing in HepG2 cells. In vivo studies showed that PEG-LαC (G3, DSP2)/siTTR polyplex led to a significant TTR silencing effect in liver after systemic administration to mice. Furthermore, safety evaluation revealed that PEG-LαC (G3, DSP2)/siTTR polyplex had no significant toxicity both in vitro and in vivo. These findings suggest the utility of PEG-LαC (G3, DSP2) as a promising hepatocyte-specific siRNA delivery system both in vitro and in vivo, and as a therapeutic approach for TTR-related amyloidosis.

Biodistribution and Biosafety of a Poly(Phosphorhydrazone) Dendrimer, an Anti-Inflammatory Drug-Candidate.

Dendrimers are nanosized, arborescent polymers of which size and structure are perfectly controlled. This is one reason why they are widely used for biomedical purposes. Previously, we showed that a phosphorus-based dendrimer capped with anionic azabisphosphonate groups (so-called ABP dendrimer) has immuno-modulatory and anti-inflammatory properties towards human immune cells in vitro. Thereafter, we have shown that the ABP dendrimer has a promising therapeutic efficacy to treat models of chronic inflammatory disorders. On the way to clinical translation, the biodistribution and the safety of this drug-candidate has to be thoroughly assessed. In this article, we present preliminary non-clinical data regarding biodistribution, hematological safety, genotoxicity, maximal tolerated doses, and early cardiac safety of the ABP dendrimer. One of the genotoxicity assays reveals a potential mutagen effect of the item at a concentration above 200 µM, i.e., up to 100 times the active dose in vitro on human immune cells. However, as the results obtained for all the other assays show that the ABP dendrimer has promising biodistribution and safety profiles, there is no red flag raised to hamper the regulatory pre-clinical development of the ABP dendrimer.