(L-453) Characterizing Exosomes for Potential Drug Delivery Across the Blood Brain Barrier

Saturday, October 14, 2023

9:30 AM – 10:30 AM PDT

Location: Exhibit Hall - Row L - Poster # 453

Presenting Author(s)

NM

Nitya Mirle

Undergraduate Researcher
UT TEWH
Austin, Texas, United States
DP

David Park

Undergraduate Researcher
UT TEWH, United States
AK

Adithya Karthik

Undergraduate Researcher
UT TEWH, United States

Co-Author(s)

MG

Maanas Gupta

Undergraduate Researcher
UT TEWH, United States

Primary Investigator(s)

TP

Tyrone Porter

University of Texas at Austin Biomedical Engineering Department Chair
University of Texas at Austin Biomedical Engineering Department, United States

Introduction:: Exosomes are small extracellular vesicles that are released by cells and play a crucial role in intercellular communication. They have garnered attention as potential drug delivery vehicles in the treatment of diseases due to their ability to cross the blood brain barrier. Exosomal engineering can pose benefits in certain drug delivery methods as the surface of exosomes can be mutable and demonstrate tissue and cell specificity. The ability of exosomes to be biocompatible and produce low levels of immunogenicity favors the potential of modification, especially with the use of liposomes. The fusing of liposomes with exosomes offers greater control over membrane lipid composition while also allowing for encapsulation of small molecules. These engineered hybrids can then be used as drug delivery vehicles.

Materials and Methods:: In this study, Human Endothelial Kidney (HEK) cells were used to isolate and characterize exosomes. Dynamic Light Scattering (DLS) was used to confirm the successful formation of exosomes, and DiI, a dye that fluoresces under specific wavelengths, was used to stain exosomes for further experimentation. The study also explored a membrane-engineering approach by fusing exosome membranes with liposomes through co-extrusion to develop hybrid exosomes. The formation of these hybrids was confirmed using FRET analysis between lipid dyes, and the vesicles’ small-molecule loading efficiency was measured using a fluorescence assay. The drug delivery capability of the hybrids was tested with a blood-brain barrier transwell model against free drug in solution. A small dye was used to simulate small-molecule delivery across the blood-brain barrier.

Results, Conclusions, and Discussions:: By exploiting the inherent capabilities of exosomes and augmenting them through hybridization experiments, this study demonstrates the exciting prospect of engineering vesicles with tunable membrane composition and the ability to encapsulate small molecules, including drugs. DLS was utilized to check the integrity of the isolated exosomes. The results demonstrated peaks at both 32.33 nm and 223.9 nm; the former peak corresponds to the size of exosomes, while the latter peak corresponds to larger particles. The polydispersity (PdI) index is 0.513. This index value exhibits a less broad size distribution for the exosomes, keeping the overall error low. With regards to DiI staining, results from a spectrophotometer show that exosomes without DiI peak at 550 nm, while exosomes that are stained with DiI have one peak at 550 nm and another peak at 570 nm. From the results of the DLS, we can conclude that the exosomes were successfully isolated as the particle sizes correspond to each other. In addition, since DiI has an excitation peak at 550 nm and an emission peak at 570 nm, the spectrophotometer results of the DiI stained exosomes show that DiI has successfully been incorporated into the exosomes. The FRET analysis indicated higher fluorescence of the coextruded hybrid exosomes compared to controls, indicating successful formation of hybrid vesicles. The small-molecule loading efficiency of the nanoparticles was measured using a dye, where the supernatant after dye encapsulation was measured against a fluorescence-concentration calibration curve. The imaging indicated relatively effective dye encapsulation. The drug delivery study also showed significant dye fluorescence in the basolateral side of the blood-brain barrier model compared to a control of free drug, indicating the drug-loaded hybrid vesicles were successfully able to cross the barrier. Since the hybrid vesicles were found to effectively cross the blood-brain barrier model, they are good candidates for future study as drug delivery vehicles for brain-related diseases, such as glioblastomas. The BBB poses significant challenges to drug delivery for treating neurological disorders, but the hybrid exosomes, with their modified surface and optimized membrane, demonstrate the ability to traverse this restrictive barrier efficiently.

Acknowledgements (Optional): :

References (Optional): :

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