Tripping Up Trypsinization With CD Cell Cultures
April 11, 2013

New Method Of Growing Laboratory Cells Could Lead To Safer Drug Trials

redOrbit Staff & Wire Reports - Your Universe Online

Researchers from the University of Southern Denmark (SDU) have discovered a method which they claim will lead to safer, more accurate laboratory testing of novel drugs on humans.

While cells occurring normally in a person´s body are capable of exchanging vital information with one another, cells isolated for research purposes lose their ability to communicate, the investigators explain.

However, because of this, those laboratory cells believe that they are alone and thus behave differently than they would if they were aware that they were surrounded by other cells. Rather than performing their advanced functions, they spend nearly all of their energy multiplying.

If a cell line is left together inside of a container and fed, overcrowding will result, preventing the bottom cells from getting oxygen and nutrients and this will eventually kill them. Typically, an enzyme known as trypsin is added to the cells in order to help keep them alive.

The process is known as trypsinization, and according to the researchers, it detaches the cells from one another so that they can be dispersed into conditions that are less crowded. Adding trypsin will help keep the laboratory cells alive, but will kill their ability to communicate, thus altering their behavior.

“Cells grown in normal laboratory conditions do not react like natural cells in the human body, and therefore they all-too-often give erroneous messages about how a drug works in the human organism,” lead researcher Stephen Fey, an associate professor in the university´s Department of Biochemistry and Molecular Biology, said in a statement.

“When you are testing the toxicity of a substance — which you always do because of the possible dangers — there is a risk that the trypsin-treated cells report back that they can tolerate the substance, but when one tests the substance on a real person, the effect can actually be fatal,” he added.

Such was the case in 1993, when five out of 15 liver patients participating in a medical trial following US Federal Drug Administration (FDA) guidelines died while testing a drug intended to treat hepatitis B. That substance, fialuridin, had been tested on laboratory cells and animals and had been deemed safe for human trials.

However, it turned out to be acutely lethal to humans and led to extensive liver failure. In addition to the five trial participants who died, two other survived only after receiving liver transplants.

Writing in the journal Toxicology Research, Fey and his colleagues describe a new method that does away with trypsinization and instead tests drugs on cells grown as 3D structures.

“With our 3D culture method, cells mimic cells in the human body better and thus we get more appropriate results,” the lead author explained. “By avoiding trypsinizing cells, they keep their ability to communicate. To avoid using trypsin, cells are grown in small round 3D structures, called spheroids, in a solution, which is constantly being turned. This tricks them into thinking that they are in a tissue surrounded by blood in a natural human body.”

Fey refers to cells grown using this method as 3D cell cultures because they live in three-dimensional spaces instead of traditional methods that grow cells on a two-dimensional surface (the bottom of a container). He and his SDU colleagues have managed to use their methods to grow human liver cells that are far more similar to the actual liver cells in the human body than trypsinized cells typically used by the pharmaceutical industry.

“Our research shows that we can now predict the dose at which a substance becomes toxic for humans more accurately than before and thus reduce the risk of poisoning test persons,” Fey added.