Cellular functions are highly responsive to temperature which can also affect cell viability.
CO₂ gas changes pH in the medium. In the improper pH conditions, cells stop growing and lose viability and it may produce morphological changes of cells.
Low humidity causes evaporation of water from the media. Evaporation leaves too-high concentrations of salts, minerals, etc., resulting in toxicity and cell death.
Preventing contamination is the key to apply the printed tissue in vivo.
Replicating the temperature, CO₂ and humidity with in vivo conditions is important to replicate tissues and organs.