The mammalian blood system is a complex tissue that regulates multiple physiological processes including oxygen and nutrient delivery, wound clotting, and defense against infection and other physiological insults via the specialized cells of the immune system. All lineages of blood cells, including those of the immune system, are produced by rare hematopoietic stem cells (HSCs) lodged in the bone marrow, which first generate the blood system during embryonic development and subsequently provide for lifelong blood homeostasis.
While much is known about the processes that shape the blood system during homeostasis, less is understood about how this complex tissue responds dynamically to stress conditions such as blood loss, injury or infection, as well as the identity of the signals that ‘awaken’ normally dormant HSCs to produce blood under these conditions. Dr. Pietras’ research focuses on understanding how inflammation, the physiological process initiated by these insults, shapes the blood system by impacting the fate decisions made by HSCs. He is also interested in the functional consequences, both for HSCs and the blood system at large, of long-term exposure to pro-inflammatory factors in the context of chronic inflammatory diseases and malignancy. The goal of his research is to understand how these factors may reprogram HSCs to make blood in a deregulated fashion that could affect disease severity and outcome, and to identify potential therapeutic targets that can restore normal HSC function in human patients.