Cells = Organisms?

I just finished reading this brief article about the history and (somewhat) current state of cell culture engineering. My academic background has been almost entirely focused in the physical sciences, so I am continuously amazed by the body of common knowledge that exists in the life sciences.

The article states that the methods used to maintain cell cultures are very consistent and reproducible. However, one of the main limitations to maintaining cell cultures over a long period of time is that the individual cells adapt to their artificial environment and begin to take on traits that are different from the primary cultures. I was not expecting this; normally, I am used to the idea that organisms adapt to external stimuli. Of course, an adaption by an organism could be argued as being caused by changes at the (sub)cellular level, but still I am amazed that the individual and basic units of life behave much like the larger organisms they conspire to form, despite their much smaller degree of complexity.

I also found it interesting that massive vats of cultures are used to produce many therapeutic drugs and biochemicals. This too could be considered common sense, but for a humble physicist who remains naive on the subject of biology and medicine it is very much different than the common image of drugs being harvested by dutiful lab technicians from individual Petri dishes.