Modulation of Oxygen Tensions via Microfabricated Devices

Oxygen is a key modulator of many cellular pathways and plays an important role in a number of cellular behaviors. The hypoxic inducible factor 1α (HIF-1α) is often considered the master regulator of the cellular response to oxygen tension (1). HIF-1α is a transcription factor involved in angiogenesis, glucose transport and glycolysis, apoptosis, migration, and differentiation, among many other functions (2). Unfortunately devices permitting in vitro oxygen modulation fail to meet the needs of biomedical research due to the inability to effectively mimic conditions found in vivo. The gold standard for hypoxia work is the hypoxic chamber, but the tool requires hours for equilibration and is not effective at generating very low oxygen levels (3). As an example demonstrating this disadvantage, cancer tumor oxygenation can change in the span of minutes (4). Intermittent hypoxia, or the changing of oxygen over time, has been shown to be important in heart attack, stroke, and sleep apnea as well. Other microfluidic approaches, although offering more oxygen control, are often difficult to disseminate to other labs due to the requirement of specialized methods and equipment for their operation. In this work, a microfabricated technology has been developed to grant precise control the temporal and spatial oxygen concentration exposed to both cell monolayers in the multiwell plate as well as with 3-D cell-seeded constructs. The concept is adaptable to both pre-established and novel experiments depending on the needs of the researcher. The devices are simple to use and require minimal additional equipment beyond what is available to a standard cell culture lab.