Developing tissue-engineered disease models using extracellular matrix-based cell-instructive scaffolds

Abstract

As the debate over the validity of animal models intensifies, advanced three-dimensional (3D) biomimetic strategies such as organoids and microphysiological system (MPS) are emerging as promising alternatives to traditional animal experiments for disease modeling. Incorporating appropriate biomaterials that replicate extracellular matrix (ECM) scaffolds in 3D tissue models significantly enhances the physiological relevance of in vitro experimental models. This is because the ECM exhibits distinct specificity and dynamically varies depending on the type and severity of diseases. However, commonly used ECM scaffolds, based on mixtures of individual ECM proteins and animal tumor-derived ECM proteins like Matrigel, fail to fully represent the tissue-specific or disease-specific features of the ECM. To mimic the complex ECM-mediated biochemical signals specific to tissues, decellularized ECM (dECM) scaffolds, created by removing cellular components from tissues, have been extensively researched. These dECM scaffolds retain the protein composition and bioactive molecules of the original tissue ECM. In this study, I developed novel 3D tissue models that are highly dependent on ECM-mediated signals by employing dECM technology to better recapitulate pathological properties. Firstly, I developed a human intracranial myeloid sarcoma (IMS) model based on brain dECM hydrogel scaffold. Leukemia often leads to various complications through the bloodstream, occasionally accumulating in non-bone marrow tissues to form myeloid sarcomas (MS). IMS occurs when leukemia cells manifest in the brain parenchyma, a rare condition infrequently reported in clinical literature. The scarcity of IMS tissue samples hinders the understanding of phenotypic changes arising from leukemia cells within the brain environment and complicates the development of effective treatment strategies for IMS. In response to this clinical need, this study introduces a novel 3D in vitro model mimicking IMS by embedding leukemia cells within a porcine brain tissue-derived dECM hydrogel scaffold. This model demonstrates significant phenotypic changes in leukemia cell survival, proliferation, differentiation, and cell cycle regulation. Particularly, the emergence of imatinib resistance due to increased dormant leukemia stem cell ratios and upregulation of multidrug resistance genes reflects the pathological characteristics of IMS tissues. Furthermore, the identification of ferroptosis inhibition as a crucial feature of IMS offers valuable insights for the development of targeted therapeutic strategies. Secondly, to appropriately mimic the pathological characteristics of disease cells in vitro, the utilization of disease-specific ECM is necessary. Therefore, I introduced a disease model using primary obese adipocytes and ECM derived from obese adipose tissue, which quickly lose their physiological-pathological characteristics in vitro, limiting their use. Remodeling of white adipose tissue (AT) associated with obesity is a significant contributor to various metabolic syndromes. Yet, the absence of intermediate models impedes the development of medications targeting adipose restoration. Here, I introduce a novel MPS designed to study the pathophysiology of obesity in AT, serving as a new research tool. The AT MPS comprises mature adipocytes embedded in ECM hydrogels interfaced with AT microvascular endothelium and continuously perfused with fresh media. The distinct biochemical signals resulting from ECM remodeling in obesity are encapsulated using decellularized AT ECM (AT dECM) hydrogels, ensuring that mature primary adipocytes maintain their function and morphology without dedifferentiation for up to one week. Through the utilization of AT MPS, I successfully replicated inflammation-induced dysfunction of AT microvasculature, immune cell recruitment due to the upregulation of cell adhesion molecules, and heightened cancer cell adhesion observed in obese individuals, which are indicative of metastasis. Thus, AT MPS offers a promising platform for comprehending the dynamic cellular interactions involved in obesity-induced AT remodeling and validating the efficacy of drugs targeting AT in obesity. In summary, this research highlights the crucial role of ECM in disease modeling and advances the creation of more precise and physiologically relevant in vitro models by capturing the unique and dynamic changes of ECM. These studies focused on developing 3D cell culture techniques using decellularization technology and disease modeling. This methodology enables the examination of cell behavior under various disease conditions by mimicking specific tissue microenvironments in vitro. These models not only deepen our understanding of specific diseases but also serve as invaluable tools for devising new treatment strategies and confirming drug effectiveness. Specifically, by employing models of intracranial myeloid sarcoma and simulating the remodeling of white adipose tissue linked with obesity, I showcased the ability to replicate intricate physiological and pathological processes in vitro, thus contributing to the exploration of innovative therapeutic avenues.