It's easy to focus on the kit and forget the really important part of the system — the cell. Cells of most interest with respect to ion channels include neurons and heart cells, which cannot be grown for long in culture and do not divide.

Cellular Dynamics International: James Thomson (right), Timothy Kamp (left) and Craig January. Credit: B. FRITZ

Many of the cell lines used in ion-channel work are, therefore, stem cells and cell lines engineered to express specific channels. These include human embryonic kidney (HEK293) and Chinese hamster ovary (CHO) lines. bSys of Basel, Switzerland, offers a wide range of screening techniques, but chief executive officer Daniel Konrad believes that one of the company's chief advantages is their skill in selecting and fine-tuning cells.

“Each clone of cells is subtly different, and only trialling with many different sources can show which expression system is ideal,” he says. bSys also works hard to find the right suspension protocol. This can make the difference between cells that generate 200 picoamp currents and those that can generate 500–1,000 picoamps and can be used in robotic screening systems, says Konrad.

A new company moving into the designer-cell niche is Cellular Dynamics International (CDI) of Madison, Wisconsin, founded by noted human embryonic stem-cell researchers James Thomson, Craig January and Timothy Kamp of the University of Wisconsin. CDI will initially focus on developing HEK cell and cardiomyocyte-based screening services to the pharmaceutical and biotechnology industries, and plans to have a drug-screening service running by the first quarter of 2006.

On the other side of the Atlantic, in Edinburgh, UK, the European arm of Stem Cell Sciences, founded by Peter Mountford in Melbourne, Australia, is developing neural stem (NS) cell lines from the Universities of Edinburgh and Milan. These cells are thought to be phenotypically similar to the NS cells found in vivo. Derived from human and animal embryonic stem (ES) cells and from fetal and adult brain tissue, NS cells have great potential in biomedical research because of their homogeneity, their ability to self-renew indefinitely, and their relative ease of manipulation. Stem Cell Sciences is establishing a service for generating specifically mutated NS cells from engineered ES cells and transgenic animals. NS cells are attractive candidates for in vitro drug screening and may also be useful for cellular therapy for conditions such as Parkinson's disease and epilepsy.

R&D Systems of Minneapolis, Minnesota offer ready-to-use primary cortical stem cells derived from rat embryos and the kits to grow them. The cells are validated for differentiation into astrocytes, neurons and oligodendrocytes.

P.M.