(L-480) Optimizing protocell uptake in mature adipocytes based on surface charge

Saturday, October 14, 2023

9:30 AM – 10:30 AM PDT

Location: Exhibit Hall - Row L - Poster # 480

Presenting Author(s)

EF

Evelyn Fernandez

Undergraduate Student
The University of Texas at San Antonio
Humble, Texas, United States

Primary Investigator(s)

MG

Maria Gonzalez Porras

Assistant Professor
University of Texas at San Antonio, United States

Co-Author(s)

DZ

David Zhang

Graduate researcher
The University of Texas at San Antonio, United States
AN

Achraf Noureddine

Research Assistant Professor
University of New Mexico, United States

Introduction:: The prevalence of obesity has been steadily increasing, and it poses a substantial burden on public health, healthcare systems, and the overall well-being of the U.S. population. As we strive to address this issue, engineering a targeted delivery system to cells in the adipose tissue that can deliver nucleic acids or molecules, presents potential opportunities to treat obesity and its comorbidities. To address this need, we are using mesoporous silica nanoparticle coated with a lipid bilayer (protocells). Protocells are designed to mimic natural cells and offer a protective environment by encapsulating cargo within their membrane- bound compartments. Moreover, these protocells can be engineered to specifically target tissues or cells, enabling localized delivery of therapeutic cargos, and enhancing treatment effects. The goal of this study is to evaluate the uptake of different lipid encapsulation membrane characteristics in mature adipocytes, specifically surface charge.

Materials and Methods::

Human adipose-derived stem cells (hADSCs) were differentiated into mature adipocytes before nanoparticle treatment. Fluorescently labeled protocells lipids were selected to obtain three different z potentials: positively, negatively, and neutrally charged. 50 mg/ml nanoparticles were add to cell media for 24-hour. Cells were fixed with paraformaldehyde, permeabilized with Triton X-100, and then stained with DAPI (nuclei) and Bodipy (lipids). We then used confocal microscopy to image the cells and nanoparticles and utilized the LSAX software for image analysis.

Results, Conclusions, and Discussions::

We were able to observe protocells surrounding lipids indicating uptake. To quantify the amount of protocells per cell we obtained the intensity profiles of nanoparticles per cell. The determination of the values involved acquiring the pixel sum within a region of interest (ROI) which was selected based on Bodipy staining as singular cells. From the analyzed data, we were able to determine that neutrally charged nanoparticles exhibit higher uptake efficiency compared to negatively charged and positively charged nanoparticles. hADSC were successfully differentiated to mature adipocytes based on the lipid loading observed. After 24 hours of treatment there was more uptake of neutrally charged protocells compared to positively charge and negatively charge protocells, indicating that neutrally charged protocells could be a delivery system for nucleic acids to adipocytes. Future studies will analyze the uptake of protocells at other time points and the endocytosis mechanism. It is possible that positively charged nanoparticles are attracted to the membrane of the adipocytes faster, but the internalization process differs. This finding is valuable as it opens new possibilities for designing nanomedicine that can specifically target and treat obesity and other metabolic disorders, which are growing public health concerns. The ability to deliver therapeutics directly to mature adipocytes, which play a crucial role in fat storage and metabolism, could lead to more targeted and effective treatments. Our findings also provide a potential pathway for the development of therapies that tackle obesity at the cellular level.

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