BioE PhD Defense Presentation- Alejandro de Janon Gutierrez

Advisor: Shuichi Takayama, Ph.D. (Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech)

Douglas K. Graham, MD Ph.D. (Aflac Cancer & Blood Disorders Center, Emory University School of Medicine)

Committee Members:

Mark Styczynski, Ph.D. (School of Chemical and Biomolecular Engineering, Georgia Tech)

Melissa Kemp, Ph.D. (Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech)

Sunil Raikar, MD Ph.D. (Aflac Cancer & Blood Disorders Center, Emory University School of Medicine)

Developing High Throughput and Long-Term Human Bone Marrow Organoids for Modeling Acute Myeloid Leukemia 

Acute myeloid leukemia (AML) is an aggressive blood cancer caused by the uncontrolled growth of hematopoietic stem and progenitor cells (HSPCs) that are arrested at early stages of development. Despite therapeutic advances, relapse persists, driven in part by the bone marrow (BM) microenvironment, which provides hematopoietic niches essential for AML survival and expansion. Leukemic cells hijack these niches to establish a disease-permissive tumor microenvironment (TME). To address these challenges and improve therapeutic outcomes, there is a growing need for representative in vitro models that can faithfully recapitulate the human BM microenvironment. Organoids which are scaffold-free 3D structures formed from self-organizing cells, represent a promising platform due to their ability to replicate native tissue architecture and functionality.

This thesis presents the development of a physiologically relevant 3D BM organoid system to study AML, its interaction with TME, and use as a drug screening platform. We established vascularized mesenchymal organoids (VMOs) as a foundational platform by co-culturing human umbilical vein endothelial cells (HUVECs) with mesenchymal stromal/stem cells (MSCs) in a minimal Matrigel-based scaffold (Aim1). Then, we expanded this platform into a full tri-culture AML BM organoid model by directly co-seeding AML cells derived from cell lines, primary patient samples, and patient-derived xenografts (PDXs), with ECs and MSCs and characterized the TME (Aim2). Finally, we applied organoid model to evaluate therapeutic responses against chemotherapy and small molecule drug response (Aim3). 

Together, this system offers a scalable and biologically relevant platform that captures the structural and functional complexity of the TME for studying AML-microenvironment interactions and for evaluating therapeutic response within a humanized, multicellular bone marrow context.