Instead of trying to replicate natural conditions, a new strategy employs engineered devices, called Ducted Respiratory Chamber (DRC) bioreactors. Celartia’s Petaka® G3, instead of attempting to impose “normal” gas conditions on the cells through active incubator controls, passively allows cells to maintain their own oxygen, carbon dioxide, and humidity levels.
These levels are maintained automatically and independently from the laboratory or incubator conditions. Because the DRC devices act passively, they are inherently far simpler, more reliable, and less expensive than traditional methods of active gas control.
While the passively controlled gas environments within the DRC are far simpler than the active interventions required by today’s incubators, they are actually far more dependable, as they are driven exclusively by natural laws.
The Petaka G3 DRC design is shown in Figure 1. The cell culture chamber is isolated on the injection side from the atmosphere by a self-sealing silicone injection port that allows the closed introduction of media and cells, including most eukaryotic cells types, small early-stage embryos, tissue fragments, and even needle biopsies.
On the venting side, the culture chamber is partially isolated from the atmosphere by an engineered, semi-closed respiratory duct having two major portions. Closest to the reaction chamber, a series of small chambers act as water vapor condensers blocking evaporation, preventing alterations in media osmolarity, even at 37ºC for 10 to 20 days at 10% RH.
The chambers also act as a capillary breaker to prevent media flow into the second portion, the respiratory duct that controls internal gas levels. The length and cross-section of the respiratory duct is engineered to partially restrict the diffusion of oxygen from the high levels of ambient air to create lower, physiologic levels of dissolved oxygen in the reaction chamber.
Observing Fick’s Law, as oxygen is consumed inside the culture chamber, decreasing the partial pressure of oxygen in the media, oxygen diffuses from the outside atmospheric (higher) partial pressure, through the respiratory duct, to the lower partial pressure inside.