Endocytic Uptake, Transport and Macromolecular Interactions of Anionic PAMAM Dendrimers within Lung Tissue

Pharmaceutical Research, Jun 2017

Purpose Polyamidoamine (PAMAM) dendrimers are a promising class of nanocarrier with applications in both small and large molecule drug delivery. Here we report a comprehensive evaluation of the uptake and transport pathways that contribute to the lung disposition of dendrimers. Methods Anionic PAMAM dendrimers and control dextran probes were applied to an isolated perfused rat lung (IPRL) model and lung epithelial monolayers. Endocytosis pathways were examined in primary alveolar epithelial cultures by confocal microscopy. Molecular interactions of dendrimers with protein and lipid lung fluid components were studied using small angle neutron scattering (SANS). Results Dendrimers were absorbed across the intact lung via a passive, size-dependent transport pathway at rates slower than dextrans of similar molecular sizes. SANS investigations of concentration-dependent PAMAM transport in the IPRL confirmed no aggregation of PAMAMs with either albumin or dipalmitoylphosphatidylcholine lung lining fluid components. Distinct endocytic compartments were identified within primary alveolar epithelial cells and their functionality in the rapid uptake of fluorescent dendrimers and model macromolecular probes was confirmed by co-localisation studies. Conclusions PAMAM dendrimers display favourable lung biocompatibility but modest lung to blood absorption kinetics. These data support the investigation of dendrimer-based carriers for controlled-release drug delivery to the deep lung.

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Endocytic Uptake, Transport and Macromolecular Interactions of Anionic PAMAM Dendrimers within Lung Tissue

Endocytic Uptake, Transport and Macromolecular Interactions of Anionic PAMAM Dendrimers within Lung Tissue Christopher J. Morris 0 1 2 Ghaith Aljayyoussi 0 1 2 Omar Mansour 0 1 2 Peter Griffiths 0 1 2 Mark Gumbleton 0 1 2 Christopher J. Morris 0 1 2 0 Department of Pharmaceutical, Chemical and Environmental Science, University of Greenwich , Medway Campus, Kent ME4 4TB , UK 1 Cardiff School of Pharmacy & Pharmaceutical Sciences , Redwood Building, Cardiff CF10 3NB , UK 2 School of Pharmacy, University of East Anglia , Norwich Research Park NR4 7TJ , UK Purpose Polyamidoamine (PAMAM) dendrimers are a promising class of nanocarrier with applications in both small and large molecule drug delivery. Here we report a comprehensive evaluation of the uptake and transport pathways that contribute to the lung disposition of dendrimers. Methods Anionic PAMAM dendrimers and control dextran probes were applied to an isolated perfused rat lung (IPRL) model and lung epithelial monolayers. Endocytosis pathways were examined in primary alveolar epithelial cultures by confocal microscopy. Molecular interactions of dendrimers with protein and lipid lung fluid components were studied using small angle neutron scattering (SANS). Results Dendrimers were absorbed across the intact lung via a passive, size-dependent transport pathway at rates slower than dextrans of similar molecular sizes. SANS investigations of concentration-dependent PAMAM transport in the IPRL confirmed no aggregation of PAMAMs with either albumin or dipalmitoylphosphatidylcholine lung lining fluid components. Distinct endocytic compartments were identified within primary alveolar epithelial cells and their functionality in the rapid uptake of fluorescent dendrimers and model macromolecular probes was confirmed by co-localisation studies. Conclusions PAMAM dendrimers display favourable lung biocompatibility but modest lung to blood absorption kinetics. These data support the investigation of dendrimer-based carriers for controlled-release drug delivery to the deep lung. dendrimer; endocytosis; lung; polymer; scattering; transport; uptake - * Mark Gumbleton ABBREVIATIONS BSA Bovine serum albumin DPPC 1,2-dipalmitoyl-sn-glycero-3-phosphocholine IPRL Isolated perfused rat lung MRI Magnetic resonance imaging PAMAM Polyamidoamine INTRODUCTION Dendrimers represent an important uniform and nanosized polymer architecture for biomedical and clinical applications and display a variety of synthetic approaches, chemistries, and an ability to carry cargo either by encapsulation, complexation or as pendant groups on the polymer surface. Dendrimers retain promise as nanosized drug carriers displaying a narrow polydispersity and an ease of control in the modification of surface functional groups. The first full family of dendrimer molecules, spanning a number of growth generations were the poly(amidoamine) (PAMAM) dendrimers synthesised by the divergent approach with the iterative addition of methyl acrylate and ethylenediamine to a polymer core and modified with hydroxyl (neutral), amine (positive) or carboxyl (negative) surface functionalities (Scheme 1). The polyamidoamine (PAMAM) class of dendrimers have been the most widely studied as carriers for low molecular Scheme 1 (a) Structure of exemplar anionic PAMAM generation 1.5. Iterative branching of each generation is highlighted by concentric circles. (b) Molecular mass (Mw) and the number of surface functional groups for the PAMAM generations tested here. weight drugs, for MRI contrast agents, and as carriers of biomacromolecules including vaccines, peptides, antibodies and DNA. A number of groups have used cationic PAMAM dendrimers to enhance drug delivery across cell membranes, including avoidance of efflux transporters (1), or for example enhancing cytoplasmic delivery of nucleic acid therapeutics (2) or vaccines (3). However, cell membrane disruption and compromise of tight junction integrity is a significant concern for the exploitation of cationic dendrimers, although approaches have been developed to mitigate the biocompatibility issues associated with the use of these platforms (4). The dendrimer-enhanced delivery of drugs with low oral bioavailability has been of particular interest with many studies (5) reporting dendrimer permeation of cultured intestinal epithelial cell monolayers, although fewer investigations of transport in the fully intact ex vivo or in vivo tissue have been evidenced. Using an everted gut sac model Wiwatanapatapee et al. (6) reported the effect of dendrimer generation and surface functionality (anionic and cationic) upon the association of PAMAM dendrimers with intestinal tissue and upon dendrimer mucosal to serosal transport. In an in-vivo rat model Florence and co-workers (7) administered by oral solution gavage a poly(lysine)15 dendrimer bearing at the surface covalently linked C12 alkyl chains and studied the subsequent intestinal and whole body tissue accumulation. In co (...truncated)


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Christopher J. Morris, Ghaith Aljayyoussi, Omar Mansour, Peter Griffiths, Mark Gumbleton. Endocytic Uptake, Transport and Macromolecular Interactions of Anionic PAMAM Dendrimers within Lung Tissue, Pharmaceutical Research, 2017, pp. 1-15, DOI: 10.1007/s11095-017-2190-7