I got a call from old Jim the other day. He's another absentee ranchette owner in my neighborhood that I manage for. He's 91, lives in town now, and can't remember things straight any more. Actually, he seems to remember the long ago past just fine, but loses track of more current things. He may be inventing that past he speaks of so clearly for all I know, but it seems like he's lost the ability to make new memories, as if at some point his head got full and new stuff goes in one ear and overflows out the other. He calls me Jake and no amount of correction sticks. Maybe there was some Jake in his past that I remind him of. His daughter, a grandmother herself, handles his affairs for the most part and sealed the deal with me. Someone in the clan has it straight, so I go with the flow.

He wanted me to fill his pond with water. It was already full, and it's the rainy season when you don't have to work to keep a pond full, but I said I'd see to it for him. Then he told me about how he grew up on a Kansas wheat farm, but had to pay more for tractor fuel than the wheat was worth. The crops were good, but the prices were low. I allowed as how this was still a problem today for many, and one of the reasons I worked all the time even though I was too old for that stuff. He reminded me that he had shoes, and children, older than I am, and that I should be careful not to lose my teeth since that was the worst part of being old for him. He can't crack nuts with his false teeth.

It may be that my future won't be so toothless.

Japanese researchers have successfully reconstituted two bioengineered organs -- teeth and whiskers -- from individual cells in mice, according to a report out this week in Nature Methods. . .

Teeth develop during embryogenesis via the interplay of epithelial and mesenchymal cells. During the study, Takashi Tsuji of Tokyo University of Science and colleagues recapitulated that process by isolating these cell types from embryonic mouse incisor tooth germ. The researchers dissociated the tissues into single cells and injected large numbers of each type separately into adjacent regions of a drop of collagen gel, creating a three-dimensional tooth germ culture. The team then either cultured the drops for two weeks, or implanted them into a mouse kidney after two days in culture. . .

What the authors of the current study have not done, however, is demonstrate that these growing teeth can properly erupt from the gums, Smith added. They also provide little detail about how they achieved the shape of the tooth's crown or how well it is attached to the periodontal ligament, which both positions the tooth and protects it from breaking during chewing, Smith said.

More to the point, the authors used embryonic cells, which are not available in adult humans. "One of the problems with reengineering an organ like a tooth is where you're going to get your cells from," Smith explained. "You either need cells that are already programmed to have a dental fate, or you need other cells that you then program to achieve a dental fate."

Tomooka said he and his co-authors are now searching for adult murine cells that can replace the embryonic tissues used in this study. "The adult brain has stem cells making neurons. Maybe somewhere in your mouth we can find such cells." Indeed, he said he has a manuscript in preparation describing one possible candidate. "With high possibility there are such cells in the adult mouth," he said.

There's still a long way to go, but the idea that adult stem cells might be used to regenerate worn out body parts, even teeth and hair, is pretty interesting, even to a fellow that isn't as old as Jim's shoes. And maybe when my mind is full like Jim's there will be some help for that too.

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Tracked: February 19, 2007 07:16 PM