Dissertation
Evaluation of poly D, L lactic-co-glycolic acid (PLGA) nanoparticle uptake pathways across the nasal mucosa
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Summer 2019
DOI: 10.17077/etd.31jl-wmzf
Abstract
<p>The nasal mucosa provides a non-invasive route for drug administration to the systemic circulation and potentially directly to the CNS. Nanoparticles made from biodegradable polymers, including PLGA, are of great interest for use in drug delivery systems due to their relative safety and ease of surface modification. Owing to their small size, nanoparticles may provide enhanced targeting and transport through the nasal mucosa. An improved understanding of the mechanisms and pathways of nanoparticle transfer across the nasal mucosa is needed to design effective new nasal delivery systems. This study focuses on the preparation of PLGA nanoparticles in various diameters and with varying surface characteristics followed by the in vitro investigation of the mechanisms of endocytosis and exocytosis of PLGA nanoparticles in the nasal mucosa.</p>
<p>PLGA nanoparticles (60 nm or 125 nm) containing the lipophilic fluorescent dye, Nile Red, were prepared using a surfactant-free nanoprecipitation method. In one investigation, the inherent negative surface charge of 60 nm PLGA nanoparticles was modified to a positive charge using a 5th generation polyamidoamine dendrimer (PAMAM) during preparation of nanoparticles. In addition, 60 nm PLGA nanoparticle surfaces were coated by adding 5 % (w/v) bovine serum albumin (BSA) to the nanoparticle dispersion and allowing protein adsorption on the particle surface. Nile Red-loaded PLGA nanoparticles were transported into the epithelial layer and reached the sub-mucosal connective tissues, yet only < 5% of the PLGA nanoparticle load was transferred into the nasal mucosa. Total uptake was size dependent, where the uptake of 60 nm unmodified PLGA nanoparticles was significantly higher than uptake of 125 nm nanoparticles. The amount of Nile Red measured in the tissues after expose to the 125 nm nanoparticles was double the amount from the 60 nm nanoparticles due to differences in the carrying capabilities of the 60 and 125 nm PLGA nanoparticles. Modification of the nanoparticle surface with PAMAM or BSA decreased the uptake of 60 nm PLGA nanoparticles into the nasal mucosa.</p>
<p>Endocytic mechanisms involved in the uptake of PLGA nanoparticles were studied using chemical inhibitors. Nanoparticle uptake in the nasal respiratory mucosa involved energy-dependent processes utilizing multiple known mechanisms, including clathrin-mediated endocytosis and macropinocytosis. In the olfactory mucosa, significant energy-independent nanoparticle uptake was also observed.</p>
<p>In order to investigate how nanoparticles exit epithelial cells for further distribution to distant tissues, the exocytosis of 60 nm Nile Red-loaded PLGA nanoparticles was evaluated using three different epithelial cell line models, RPMI-2650 (nasal), Calu-3 (lung) and MDCK-II wild type (kidney) cells. Following a 30 min exposure to a 60 nm PLGA nanoparticles dispersion, nanoparticle exocytosis into a protein-free medium was evaluated for additional 30 or 60 min. Only a limited number of NP (~ 20 % of the endocytosed NP) underwent exocytosis into the medium after 60 min, while the majority of the internalized nanoparticles remained within the cells.</p>
<p>The measurable transfer of PLGA nanoparticles into the nasal mucosal tissues indicates that they may be useful drug carriers for nasal administration. However, the limited exocytosis of 60 nm NP and the resulting potential for intracellular accumulation may raise toxicity concerns and result in potential cellular injury. While PLGA nanoparticles provide promising drug delivery systems for nasal administration, only with careful design of the nanoparticles, including their size and surface characteristics, will efficient and effective, safe drug delivery be accomplished.</p>
Details
- Title: Subtitle
- Evaluation of poly D, L lactic-co-glycolic acid (PLGA) nanoparticle uptake pathways across the nasal mucosa
- Creators
- Mohammed Abdulhussein Handooz Albarki - University of Iowa
- Contributors
- Maureen D. Donovan (Advisor)Aliasger K. Salem (Committee Member)Lewis L. Stevens (Committee Member)Ramprakash Govindarajan (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Pharmacy
- Date degree season
- Summer 2019
- DOI
- 10.17077/etd.31jl-wmzf
- Publisher
- University of Iowa
- Number of pages
- xxi, 208 pages
- Copyright
- Copyright © 2019 Mohammed Albarki
- Comment
This thesis has been optimized for improved web viewing. If you require the original version, contact the University Archives at the University of Iowa: https://www.lib.uiowa.edu/sc/contact/.
- Language
- English
- Date submitted
- 11/06/2019
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 195-208).
- Public Abstract (ETD)
The nasal mucosa provides a noninvasive route for drug administration to the systemic circulation and potentially to the brain. Nanoparticles made from biodegradable polymers, including PLGA, are promising as drug delivery systems due to PLGA’s relative safety and ease of modification. Due to their small size, nanoparticles may provide improved delivery and targeting through the nasal mucosa. This study focuses on the preparation of small (60 or 125 nm) PLGA nanoparticles and investigation of their uptake after intranasal administration. Understanding their uptake pathways, will provide a much-needed understanding of nanoparticle trafficking and will contribute to the design of effective particulate delivery system to deliver drugs or vaccines intranasally.
In this study, PLGA nanoparticles (average diameter of 60 nm or 125 nm) were prepared. Nanoparticle uptake into the nasal mucosa was determined by exposing excised tissues or cultured cell models to nanoparticle dispersions for 30 or 60 minutes. The 60 nm, negatively-charged PLGA nanoparticle showed the highest uptake, yet <5 % of the nanoparticle load was found to translocate into the nasal tissues. Investigation of the endocytic mechanisms involved in nanoparticle internalization revealed that nanoparticle uptake is an energy-dependent process using multiple endocytic mechanisms. Using in cell-line models, it was shown that a limited fraction of the endocytosed nanoparticles underwent further exocytosis from the cell. This study provided an insight of cellular mechanisms that govern the nanoparticle internalization. Furthermore, it demonstrated that internalized nanoparticles remain in the nasal epithelium for periods longer than typically associated with the nasal absorption of drug molecules.
- Academic Unit
- Pharmacy; Craniofacial Anomalies Research Center
- Record Identifier
- 9983777058702771
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