Yarelis Gonzalez-Vargas
BME PhD Defense Presentation
Date: 2024-07-12
Time: 10:00 AM - 12:00 PM
Location / Meeting Link: EBB CHOA Room / Zoom: https://gatech.zoom.us/j/97231409903
Committee Members:
Brandon Dixon, PhD (Advisor) Andres J. Garcia, PhD Jennifer M. Spangle, PhD Rudolph Gleason, PhD C. Matthew Hawkins, MD
Title: Bioengineered 3D In Vitro Strategies To Investigate Phenotypic And Genotypic Differences In Lymphatic Network Sprouting
Abstract:
This dissertation investigates the development and application of bioengineered 3D in vitro models to study lymphatic network sprouting and lymphatic malformations (LMs). The lymphatic system plays a crucial role in maintaining tissue fluid homeostasis, immune cell trafficking, and fat absorption, processes governed by intricate lymphangiogenic mechanisms influenced by biochemical and biomechanical cues. While traditional in vivo studies have limitations, reproducible tissue-engineered models using primary lymphatic cells offer promising alternatives. Initially, tissue engineering models were established by embedding lymphatic cells from diverse sources in poly(ethylene glycol) (PEG)-based hydrogels to mimic the lymphatic microenvironment. These models elucidated mechanisms underlying lymphatic endothelial cell (LEC) sprouting and the impact of external factors such as extracellular matrix composition and mechanical compression. The findings underscore the potential of these models to replicate in vivo conditions and serve as platforms for testing therapeutic interventions. Building on this groundwork, the study advances towards precision management of LMs through patient-derived organoids (PDOs). Lymphatic malformations, rare vascular anomalies predominantly caused by somatic mutations in PIK3CA, result in lymphatic dysfunction and cyst formation, affecting 1 in 4000 live births. Due to their developmental origins, symptoms are typically evident at birth. Existing treatment options are limited without a standardized regimen. This research aims to overcome these limitations by employing tissue engineering strategies with patient-derived tissues. Cultured tissue samples from LM patients in PEG hydrogels yielded patient-derived cells (PDCs) and organoids (LMOs). Genetic fidelity was confirmed through single-cell RNA sequencing and whole exome sequencing. LMO responses to varying hydrogel stiffnesses revealed insights into LM heterogeneity, suggesting potential for personalized treatment strategies. The final phase assesses the efficacy of PI3K/AKT/MTOR pathway inhibitors, notably the selective PI3K inhibitor alpelisib, on LMOs. The study reveals significant variability in drug responses among LMOs from different patients, with gene expression analyses indicating upregulation of pro-apoptotic genes post-treatment. These results underscore the potential of targeted therapies and highlight the value of patient-derived models in advancing understanding of LM biology and developing precision medicine approaches. Overall, this dissertation underscores the innovative use of bioengineered 3D in vitro models in investigating lymphatic network sprouting and managing lymphatic malformations. The findings emphasize the importance of accounting for tissue heterogeneity and genetic variability in developing effective in vitro models and designing targeted therapeutic interventions.
