Tumor-associated macrophages (TAMs) have been identified as an important component for tumor growth, invasion, metastasis, and resistance to cancer therapies. However, tumor-associated macrophages can be harmful to the tumor depending on the tumor microenvironment and can reversibly alter their phenotypic characteristics by either antagonizing the cytotoxic activity of immune cells or enhancing anti-tumor response. The molecular actions of macrophages and their interactions with tumor cells (e.g., phagocytosis) have not been extensively studied. Therefore, the interaction between immune cells (M1/M2-subtype TAM) and cancer cells in the tumor microenvironment is now a focus of cancer immunotherapy research. In the present study, a live cell coculture model of induced M1 macrophages and mouse mammary 4T1 carcinoma cells was developed to assess the phagocytic activity of macrophages using a time-lapse video feature using phase-contrast, fluorescent, and differential interference contrast (DIC) microscopy. The present method can observe and document multipoint live-cell imaging of phagocytosis. Phagocytosis of 4T1 cells by M1 macrophages can be observed using fluorescent microscopy before staining 4T1 cells with carboxyfluorescein succinimidyl ester (CFSE). The current publication describes how to coculture macrophages and tumor cells in a single imaging dish, polarize M1 macrophages, and record multipoint events of macrophages engulfing 4T1 cells during 13 h of coculture.
This study promotes the use of nanobiochar (NBC) as an environmentally friendly substitute to conventional fillers to improve various properties of biopolymers such as their mechanical strength, thermal stability and crystallization properties. TGA analysis showed a slight increase in onset thermal degradation temperature of the composites by up to 5 °C with the addition of 4 wt% NBC. Non-isothermal DSC analysis determined that the addition of NBC into PHBHHx increases the crystallization temperature and degree of crystallinity of PHBHHx while isothermal DSC analysis demonstrated higher crystallization rate in PHBHHx/NBC composited by up to 54%. PHBHHx incorporated with NBC also exhibited superior tensile strength and modulus versus neat PHBHHx. Increase in mechanical strength was further proven via DMA where PHBHHx/NBC composites maintained higher storage modulus at higher temperatures when compared to neat PHBHHx. PHBHHx/NBC also exhibited no cytotoxicity effect against HaCat cells. This study demonstrates the ability of biochar to act as both nucleating agents and reinforcing agents in biodegradable polymers such as PHBHHx, which could be suitable for packaging application.