LA JOLLA -- Imagine if the milk you poured on your breakfast cereal cost $500 per bottle.

To supply the human embryonic stem cells they are studying with nutrients and hormones, the participants in a laboratory class at UC San Diego dribble red fluid over the cells, which are bunched in tiny clumps on plastic dishes.

Taped above their equivalent of the kitchen table is a chart that lists the cost of each squirt of fluid.

The value of stem cells lies in their ability to become any other kind of cell in the body. The fluid keeps the cells growing, but it also helps to prevent them from changing into something else -- perhaps muscle, skin or nervous tissue.

"There's still a lot of mythology surrounding how stem cells should be grown," instructor Karl Willert said. "Each lab has a different way of doing things."

At the beginning of class, Willert passes out recipes sent to him by scientists at various universities, along with the latest tips on keeping the cells healthy.

The half-dozen people in the class are learning basic techniques for growing and sorting human stem cells. Soon, they'll move on to projects of their own at UC San Diego and research institutes nearby.

They all applied for and obtained training grants from the California Institute for Regenerative Medicine, which was created after voters approved $3 billion for human stem cell research in 2004. One of the institute's first pulses of money funded the training grants.

It's difficult to call them students because some already have doctorates or medical degrees. But they aren't yet the directors of their own labs, and they still have some freedom to explore.

One student in the class, pediatric endocrinologist Carla Demeterco, said the training grant allowed her to stay in the United States rather than return to her native Brazil. She said she wants to be able to transplant insulin-secreting cells back into her young diabetic patients one day.

"This is something we owe to the people that approved it (the 2004 stem cell measure)," she said.

Toward that end, she wants to study how scientists can make insulin-secreting cells by starting with stem cells and nudging them to change in the direction they want, she said.

Another student, Justin Voog, started graduate school in 2003 after finishing college in Minnesota.

He joined Leanne Jones' research group at the Salk Institute, which studies fruit fly development. He said he's looking ahead to when he starts his own lab, and wants to translate what he learns about stem cells in the fruit fly to mammals.

"It's been great," he said, adding that a key benefit of the class is talking with people from different research backgrounds.

While waiting for a piece of equipment called a centrifuge, Demeterco and Stina Mui, both clinical fellows, swapped stories about how many patients they saw that morning.

The laboratory class meets in the afternoons, after the group has discussions on the latest research papers and ethical and legal issues connected with stem cell work.

"If they look a little tired, that's why," co-instructor Zoe Vomberg said.

In one recent class session, the group was trying out a new technique for checking if stem cells have changed by being grown in a dish for too long.

Specifically, the cells could divide unevenly and end up with extra chromosomes, Vomberg said.

"We've learned that if the cells look too good, they might have a chromosomal abnormality," she said.

Each of a normal cell's 46 chromosomes carries genetic information, and extra chromosomes can push them into becoming tumor cells. That's bad news if someone wants to inject them into patients.

Willert said the class uses one of the stem cell lines approved by the federal government in 2001 and one derived from embryos by Doug Melton and his co-workers at Harvard University after 2001.

Because they use the Harvard cells, which weren't federally approved, they have to avoid using federal grants for their work.

"The whole building has to be separate," Willert said.

In the class, both kinds of stem cells are grown on top of mouse cells. In the microscope, they look like a layer of spikes on a plastic dish.

The cells, which come from connective tissue, are blasted with radiation first to stop them from growing, too.

Scientists say that eventually stem cells for clinical applications will need to be grown without mouse "feeder" cells, which might carry viruses.

Several research groups around the world are trying to figure out how to replace mouse cells with proteins or hormones to keep the stem cells in line.

By direct contact, the mouse cells keep the human cells from changing into other types.

One of the class's exercises is to grow stem cells without the mouse cells, Willert said. After a few weeks, the tiny clumps change shape and include several different kinds of cells.

"That's how you know they have the potential," he said.

Contact staff writer Quinn Eastman at (760) 740-5412 or qeastman@nctimes.com.