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The San Diego Union-Tribune

Petri dishes may hold the future

Exhibit gives public a look at living stem cells


July 27, 2005

Amid the clamor of exhibits at San Francisco's Exploratorium, something very quiet is beating: the heart cells of a mouse.

That may not seem all that unusual – except they're not inside a mouse. It died long ago. Its offspring have probably passed on, as well.

These heart cells – pulsing and throbbing in a petri dish, magnified and visible on an overhead screen – are alive because they just emerged from a culture of embryonic stem cells, also on display, that have grown in a petri dish for years – and, as long as they are fed and nurtured, will continue to thrive.

The exhibit is the first of its type in the nation. While research labs around the world are racing to isolate and grow such cells, the work is done out of view from the public.

"Our idea is to mirror the research," said the Exploratorium's Charles C. Carlson, who conceived the new interactive stem cell exhibit.

Immortality is just one of the fascinating features of embryonic stem cells. "They just keep going and going," Carlson said.

They're also valued for their versatility. Given the right cues, they can mature into any cell of the body.

The cells on display have been prompted to grow into heart cells. Also on exhibit are their progenitors – the small translucent dots of embryonic stem cells. Visitors can use a "joy stick" to scan the colonies of cells.

And while it is not yet possible to build an entire mouse, the museum hopes in the future to make other living cells, such as neurons.

Simple display

Since their discovery 20 years ago, embryonic stem cells have become one of medicine's great hopes – and one of science's greatest political and ethical dilemmas.

A growing body of research supports the tantalizing potential of these cells to create tissue and build organs. Recent studies have found the ability of the cells to form everything from new blood vessels to brain tissue.

But because they are found in very young embryos, the cells are as controversial as they are interesting. That's because an embryo must be destroyed to harvest the cells. In mice, that's no big deal. In humans, it stirs debate.

The Exploratorium steers clear of the ethical minefields. "At this juncture, we're not set up to do that. It would be a different kind of exhibit," said Carlson. "We'd want to do it right and don't want to be cavalier."

Its goal, instead, is to simply put the cells on display.

"We want to get the science out there and let people see it," said Carlson. "Everybody hears and reads about these cells – but who actually gets to see them? Only the scientists.

"It's the power of the image that holds so much potential. Once people see them, and understand them, they can make up their own minds."


The small exhibit succeeds in posing some of biology's biggest questions: What is life? When does it start? How does it change? What supports it?

Maintaining the cells is no small task. They are finicky creatures, with far more complicated needs than the Exploratorium's conventional exhibits.

Project developer Kristina Yu is responsible for their welfare. She's learned to maintain their plastic habitat at a mouselike temperature, keeping the requisite 7 percent concentration of carbon dioxide. She ensures that a nutritional soup is to their liking. When they breed and get too crowded, she separates them.

Finally, she is careful not to mix cultures of critters. A nearby yeast colony, needed for another exhibit, is a nuisance because it so readily contaminates other cultures.

She pats an incubator affectionately, as if it were alive.

"They have to coexist peacefully," said Yu. "It is a little zoo in here."

Because cells are alive, the exhibit is a process, not a fixture. In a way, it is its own type of experiment, filled with trial, error and innovation.

That's the whole point, said Carlson.

"This is biology. You never know from day to day what you'll have. Cells change all the time."

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