Visualizing vasculature and its response to therapy in the tumor microenvironment

Abstract

Tumor vasculature plays a critical role in the progression and metastasis of tumors, antitumor immunity, drug delivery, and resistance to therapies. The morphological and functional changes of tumor vasculature in response to therapy take place in a spatiotemporal-dependent manner, which can be predictive of treatment outcomes. Dynamic monitoring of intratumor vasculature contributes to an improved understanding of the mechanisms of action of specific therapies or reasons for treatment failure, leading to therapy optimization. There is a rich history of methods used to image the vasculature. This review describes recent advances in imaging technologies to visualize the tumor vasculature, with a focus on enhanced intravital imaging techniques and tumor window models. We summarize new insights on spatial-temporal vascular responses to various therapies, including changes in vascular perfusion and permeability and immune-vascular crosstalk, obtained from intravital imaging. Finally, we briefly discuss the clinical applications of intravital imaging techniques.

Recent advances in understanding the immune microenvironment in ovarian cancer

“…The TME consists of cancer cells, the extracellular matrix (ECM), cancer-associated fibroblasts (CAFs), a complex network of blood vessels, and diverse immune cells, including T-cells, B-cells, and cells linked to tumor progression (TACs). Cancer cells recruit and activate immune cells and stromal components, like lymphocytes, tumor-associated macrophages (TAMs), natural killer (NK) cells, dendritic cells (DCs), tumor-associated neutrophils (TANs), and myeloid-derived suppressor cells (MDSCs) ( 21 – 23 ), collectively establishing an anti-tumor inflammatory microenvironment during early tumor colonization or expansion; thus, impeding tumor growth ( 24 , 25 ). However, prolonged exposure to tumor antigens and immune activation can deplete or alter effector cells, resulting in an immunosuppressive microenvironment that fosters tumor aggressiveness ( 26 , 27 ).…”

Preclinical multi‐physiologic monitoring of immediate‐early responses to diverse treatment strategies in breast cancer by optoacoustic imaging

“…However, tumor vessels differ from normal vessels in structure and function and are unable to provide sufficient oxygen and nutrients for rapidly proliferating tumor cells, which will lead to the exacerbation of the oxygen‐poor state of the tumor microenvironment, forming a vicious cycle [23]. The tumor microenvironment plays a pivotal role in tumor progression, growth, and metastasis, and is also an important reason affecting the therapeutic effect [24–26]. Physiological processes, including vascular perfusion and oxygenation status as well as metabolism, determine the breast cancer progression following diverse treatment strategies [27, 28].…”