Dissertation
Endocytosis and distribution of nanoparticles across the nasal mucosal tissues
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2021
DOI: 10.17077/etd.005791
Abstract
The nasal cavity is an attractive site for drug delivery because of the ease of access for drug administration; the rapid absorption of many drugs; the opportunity to provide both local and systemic drug effects; the ability to avoid the harsh gastrointestinal environment and first-pass hepatic metabolism; and the potential to deliver drugs directly to the brain. Nanoparticles may provide unique therapeutic opportunities when included in nasal drug delivery systems, yet the primary uptake and transfer pathways for these particles in the nasal mucosa are not well understood. The objectives of this research were to identify the endocytic pathways involved in the uptake of fluorescently-labeled, carboxylate-modified, polystyrene nanoparticles (CM-PSNPs) and fluorescently-
labeled solid lipid nanoparticles (SLNs) in the nasal mucosa. CM-PSNPs (100 nm) were obtained commercially from Invitrogen® (ThermoFisher Scientific, Carlsbad, CA) and SLNs of different size ranges (~30, 60, and 150 nm) were prepared using solvent emulsification/evaporation or phase inversion temperature methods. Both nanoparticle types were loaded with fluorescent dyes to allow for their measurement following recovery from the nasal tissues.
Nanoparticle transport studies were carried out ex vivo using bovine nasal tissues. Tissue explants were mounted in a Navicyte® diffusion chamber system and incubated with nanoparticle dispersions for up to 60 min. To investigate the endocytic uptake pathways available to the nanoparticles in the nasal olfactory and respiratory mucosal tissues, pharmacological inhibitors of specific endocytic pathways were also included in the incubation media. Chlorpromazine, amiloride, and methyl-ß-cyclodextrin or filipin were used to investigate clathrin-mediated endocytosis, macropinocytosis, and caveolae-mediated endocytosis, respectively. Sodium azide and 2, 4-dinitrophenol, both inhibitors of ATP-synthesis, were also utilized to evaluate the general contribution of endocytosis to the uptake of the nanoparticles. The concentrations of nanoparticles both in the epithelial cell layer and the associated submucosal region were measured individually to evaluate the mucosal distribution of nanoparticles following their mucosal uptake.
The results showed that a single, prevailing endocytic pathway responsible for the uptake of the CM-PSNPs and SLNs in the nasal tissues could not be identified, but macropinocytosis appeared to be preferentially involved in the uptake of the largest nanoparticles (≥ 100 nm) while clathrin-mediated and caveolae-mediated endocytosis mechanisms were highly active in the uptake of the smaller particles (≤ 60 nm). Our findings also indicate that multiple endocytic pathways were available for the uptake of all of the nanoparticles investigated.
High loading of the hydrophobic fluorescent dye, Nile Red, into the SLNs was accomplished and the nanoparticles were found in both the epithelial and submucosal tissues after only 15 min of incubation. The uptake of the smaller SLNs (30 nm) was greater in the olfactory tissues compared to the respiratory tissues with more of the nanoparticles in the olfactory tissues utilizing non-energy dependent pathways for their uptake. The uptake of the nanoparticles was found to be continuous for up to at least a 60 min period. However, the overall efficiency of the nanoparticle uptake was limited (< 2.5%) in both nasal tissue types.
SLNs are promising drug carriers for intranasal drug delivery. They can encapsulate high levels of drug, protecting the drug from local enzymatic metabolism and avoiding solubility limited absorption. The results of these studies show that the SLNs can be found in both the epithelial and submucosal regions within the nasal tissues suggesting the feasibility of using these nanoparticles as drug carriers for local and systemic nasal drug delivery.
Details
- Title: Subtitle
- Endocytosis and distribution of nanoparticles across the nasal mucosal tissues
- Creators
- Ammar Sahib Abdulameer Al Khafaji
- Contributors
- Maureen D Donovan (Advisor)Dale E Wurster (Committee Member)Aliasger K Salem (Committee Member)Lewis L Stevens (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Pharmacy
- Date degree season
- Spring 2021
- DOI
- 10.17077/etd.005791
- Publisher
- University of Iowa
- Number of pages
- xxiv, 200 pages
- Copyright
- Copyright 2021 Ammar Sahib Abdulameer Al Khafaji
- Language
- English
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 165-176)
- Public Abstract (ETD)
The nasal cavity is an attractive site for drug delivery because of its ease of access for drug administration; the rapid absorption of many drugs; the opportunity to provide both local and systemic drug effects; the ability to avoid the harsh gastrointestinal environment and first-pass hepatic metabolism; and the potential to deliver drugs directly to the brain. Nanoparticles may provide unique therapeutic opportunities when incorporated into nasal drug delivery systems, but it is important to understand the mechanisms responsible for nanoparticle uptake into the nasal mucosa Fluorescently-labeled, carboxylate-modified, polystyrene nanoparticles (CM-PSNPs) and fluorescently-labeled solid lipid nanoparticles (SLNs) were used in these studies to investigate available uptake pathways for nanoparticles in the nasal mucosa. Endocytic mechanisms were investigated in the nasal olfactory and respiratory mucosal tissues by incorporating pharmacologic inhibitors along with the nanoparticles. The uptake experiments were carried out using excised bovine nasal olfactory and respiratory tissues.
The results showed that the nasal mucosa uses multiple endocytic processes for the uptake of nanoparticles of a variety of sizes (≤ 150 nm) and materials (CM-PSNPs and SLNs), but the efficiency of uptake was found to be quite low (≤ 2.5%). The smaller SLNs (30 nm) were found in higher numbers in the olfactory tissues than in the nasal respiratory tissues. The nanoparticles were found to be widely distributed within both nasal tissue types and within a relatively short period of uptake (15 min). The results demonstrate that SLNs are promising delivery systems for nasal administration, and both further investigations of their uptake and development of drug-loaded SLNs are needed to produce successful drug therapies.
- Academic Unit
- Pharmacy; Craniofacial Anomalies Research Center
- Record Identifier
- 9984097277002771
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