Development of Enzyme-Responsive Polymersomes as a Drug Delivery System for GM1 Gangliosidosis
Date of Award
Doctor of Philosophy (PhD)
Chemical and Biomolecular Engineering
Dr. Jessica Larsen
Dr. Marc Birtwistle
Dr. Christopher Kitchens
Dr. Angela Alexander-Bryant
GM1 gangliosidosis is a lysosomal storage disorder caused by deficiency of β-galactosidase (βgal) and subsequent accumulation of GM1 ganglioside in lysosomes. The rare nature of this disorder presents challenges with prognosis and treatment. Enzyme replacement therapy (ERT) can effectively treat systemic deficiencies, but the intravenously administered enzyme cannot cross the blood-brain barrier (BBB) to treat the central nervous system. A delivery system to encapsulate and deliver the enzyme can facilitate enzyme transport across the BBB with suitable surface modifications. One of the pathological aspects of GM1-affected cells is the upregulation of the lysosomal enzyme hexosaminidase A (HexA). In this dissertation, I evaluate a biohybrid poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) polymersome system as an enzyme-responsive fluorescence probe to monitor the disease progression during the treatment. The polymersomes are synthesized using the solvent injection method and self-assembled in a size range of < 200 nm. The effect of synthesis parameters such as infusion rate and needle gauge on PEG-PLA polymersome properties was studied and shown to be negligible. I also designed a hyaluronic acid-b-polylactic acid (HA-PLA) polymersome system as a therapeutic tool that can achieve an enzyme-responsive and controlled delivery of βgal in response to upregulated HexA in diseased cells. HexA can degrade the hyaluronic acid in polymersomes and induce a higher drug release. HA-PLA polymersomes were synthesized with an average diameter of 138.0 ± 17.6 nm and ζ-potential of -18.0 ± 3.8 mV. βgal was encapsulated in polymersomes with an efficiency of 77.7 ± 3.4 %. In the presence of model enzyme hyaluronidase, HA-PLA polymersomes demonstrate an enzyme-specific degradation and a two-fold higher release of encapsulant than without cognate enzyme.
Another pathological aspect of GM1 gangliosidosis, among other lysosomal storage disorders, is impaired autophagy, i.e., a reduced fusion of autophagosomes and lysosomes to degrade cellular waste. Reduced autophagy in a cellular model of GM1 Gangliosidosis (GM1SV3) compared to healthy cells was demonstrated using immunofluorescence. Upon treating the GM1SV3 cells with βgal-loaded polymersomes, autophagy was enhanced in a controlled manner. Most notably, the fusion of lysosomes and autophagosomes in GM1SV3 cells returned to normal levels comparable to healthy cells after 24 hours of polymersome treatment as opposed to the 6 hours of treatment with the free enzyme. The studies in my dissertation demonstrate that HA-PLA polymersomes can potentially deliver βgal in response to disease pathology and provide a promising delivery system to treat GM1 Gangliosidosis.
Paruchuri, Bipin Chakravarthy, "Development of Enzyme-Responsive Polymersomes as a Drug Delivery System for GM1 Gangliosidosis" (2022). All Dissertations. 3246.
Author ORCID Identifier
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