Dr Quesenberry's research initially focused on cytokine modulation of hematopoiesis and bone marrow stem cells, and more recently on the basic nature of bone marrow stem cells with a particular emphasis on the relationship of this to cell cycle status. Additionally, he has also extensively studied endotoxin effects on hematopoiesis and extracellular vesicle effects on cell fate with an emphasis on tissue restoration of different injuries. He has also looked at extracellular vesicles for an ability to reverse malignant phenotype. On a clinical level investigations have gone forward on the capacity of injection of marrow stem cells to reverse refractory acute leukemia and lymphoma, probably by altering host response to cancer. In addition, work is ongoing to characterize salivary extracellular vesicles as biomarkers for sub concussion brain injury.