The Physical Environment

Abstract

The essential idea of the entire panoply of the chemical solution and mechanical apparatus surrounding the cell in in vitro culture is to recreate the physical, nutritional, and hormonal environment of the cell in vivo. This includes controlling the temperature, pH, osmolality, and gaseous environment; providing a supporting surface; and protecting the cell from chemical, physical, and mechanical stress. The mammalian body has evolved to do this over billions of years. We are still learning the correct requirements for different cells to function optimally and normally in vitro. This chapter will deal with the control of the physical environment. Chapter 4 on media and the section on serum-free media will deal with the nutrient and hormonal environment. It should be recognized, however, that these are interrelated and by necessity inseparable. Thus, the level of nutrients present determines the response to hormones, as does the surface on which the cell is grown. The energy source supplied may alter the osmolality and the temperature will alter the rate of energy use. Again, an understanding of how these basic elements interrelate will allow the cell biologist to alter and even design cell culture systems that are optimal for a specific function, whether supporting the function of a highly differentiated cell such as a neuron or providing the simplest environment possible for the production of recombinant proteins. We will deal with each of the aspects of the physical environment separately.