Robotics Allows Rapid Compound Testing

The high-throughput screening (HTS) laboratory that recently opened at the Life Science Research Laboratory on KU's west campus has once again put the Kansas City area on the biomedical research map. The high-throughput screening lab was established with support from the National Institutes of Health COBRE grant to Gunda Georg, director of HBC's Drug Discovery Program and KU Distinguished Professor of Medicinal Chemistry. The 1,500-square-foot facility is the first of its kind in the state and the greater Kansas City area. Following installation of the equipment this fall, the lab will provide services that regional researchers have never before been able to access locally.

The director of the new lab and a research professor at HBC, Qizhuang Ye, marvels at the relatively recent and yet revolutionary changes in drug discovery. Little more than a decade ago, before the development of high-throughput screening methods, pharmaceutical researchers still had to use test tubes for compound evaluation, manually inserting one compound at a time to determine its biological activity when introduced to a therapeutic target. Since that time there has been a virtual explosion of discoveries of chemical methods for generating libraries of compounds that can be tested as potential therapeutic drugs. There has also been a rapid development of high-throughput screening technology that uses robotics to expedite the compound screening process. The combination of compound libraries and high-throughput screening technology has led to lightning-quick advances in the identification of novel compounds as potential therapeutic agents, as well as basic research tools for academic study. "With high-throughput screening, instead of testing one compound at a time, now researchers can test many, many compounds a day - a phenomenal increase and an enabling technology," says Ye.

The high-throughput screening lab includes a liquid handling system and plate readers that can detect biological activity. High-throughput screening begins with microplates, each containing either 96, 384, or 1586 individual wells for testing compounds. The liquid handling workstation can deliver liquid from 0.5 to 200 micro liters to individual wells of the microplates using a 96-channel pipetting head to transfer liquid to all wells simultaneously. In the liquid handling phase of the test, a uniform amount of testing compounds, a specific protein target and other necessary reagents are delivered into each well. The equipment's rail-mounted robotic arm picks up the plate and transfers it to a plate reader for detecting signals, which could be light absorption, fluorescence, time-resolved fluorescence, fluorescence polarization, or luminescence. The reader determines the varying levels of biological activity represented by the strength of signals coming from each well. All of the liquid transfer, signal detection, and data analysis can automatically be handled by computers.

In the case of kinetic monitoring of an enzymatic reaction, every few seconds the plate reader records the UV absorption level in each well. "If a specific well is exhibiting a significantly higher or lower signal than that in control wells, then that means the compound in that specific well could have a specific effect on the target under evaluation," Ye says.

The high-throughput capability will not compromise data quality. However, Ye says there are several things he and a researcher can do to ensure that the information gathered is accurate. For example, researchers put blanks and controls or known enzyme inhibitors in the microplate to ensure that the assay and the equipment are working properly. "From the blanks, you can anticipate observing a fairly standard slope of UV absorption change in an enzvmatic reaction," Ye explains. "Similarly, in the control wells where you have put compounds with known effects, if you see expected slopes, you know that the assay is working. Then you can safely conclude that inhibition of enzymatic activity in wells with unknown compounds could indicate that these are potential agents with effects on the specific protein target and the candidates for further biological testing."

A 1988 graduate of KU's medicinal chemistry department Ph.D. program, Ye was among the first wave of people to use high-throughput screening when it was developed nearly a decade ago. Following postdoctoral work at Harvard Medical School, he used the new technology for pharmaceutical research at Parke-Davis. In 1997, he returned to his home country of China to set up a high-throughput screening facility for the Chinese Academy of Sciences at the Shanghai Institute of Materia Medica.

The purpose of setting up the high-throughput screening laboratory at KU is to bring the technology to biomedical researchers in this region and serve the research community in this area. Now we have the powerful research tools available at KU, says Ye, and he is eager to assist anyone who has the need to use the technology for research.