Comparison of bone marrow-derived macrophages grown in M-CSF vs. GM-CSF

Alveolar macrophages (AMs) are the primary immune cell type responsible for phagocytizing inhaled particles and initiating the inflammatory response. Crystalline silica and multi-walled carbon nanotubes (MWCNT) are two particles shown to have deleterious effects on lung macrophages. Silica is an environmental and occupational hazard, inhalation being associated with systemic inflammation, lung fibrosis, and autoimmune disease. MWCNT are an emerging concern and present unique challenges in toxicity evaluation due to numerous variables contributing to bioactivity. The exact mechanisms by which both silica and MWCNT exert their toxic effects are unknown, creating the need for a high-throughput in vitro model for analysis.

Because of low AM numbers in naïve mice, bone marrow-derived macrophages (BMdM) are the predominant model used for in vitro assessments. BMdM are able to be cultured in large quantities and allow for the creation of a homogenous population. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) are important for differentiation of myeloid progenitors into different macrophage populations. Often times M-CSF is used in vitro to differentiate bone marrow monocytes into macrophages, however, studies have shown that GM-CSF is the necessary factor in the development of alveolar macrophages.

This project will test the hypothesis that BMdM grown in GM-CSF more closely model the response of AMs to MWCNT and silica, than BMdM cultured with M-CSF. For this project, BMdMs will be cultured with GM-CSF and M-CSF, respectively, and the responses of these two populations to silica and MWCNT will be compared to primary murine AMs. Over the summer the student will learn isolation of primary murine alveolar macrophages, sterile technique, cell culture, cytokine measurement via ELISA, viability assays, and analysis of cell populations via flow cytometry.