This story marks the first time I've had to use a pseudynm to protect the identity of a horse.

"Disney's" owner's desire for privacy only underscores the stakes here. Performance horses at his level can be worth $60,000 and more. Training, too, is an enormous investment. "Gretchen," as we call her in the piece, has spent years training Disney in English dressage (which, incidentally, makes for some very entertaining YouTube viewing if you have some time to kill). And so when she noticed that her horse's gait had started to suffer, she jumped to find a treatment.

Speed is key here, it was explained to me, because the smaller the injury, the better a horse's chance for recovery. Emphasizing that point is one of the main reasons Gretchen agreed to take part in this program. She says too many owners treat their horses' injuries with ever-greater doses of painkillers, delaying real treatment until it's too late. Gretchen estimated that, including all the preliminary visits and tests, Disney's treatment may reach $7,000.

Davis vets couldn't provide statistics on whether this treatment – injecting a horse's mesenchymal stem cells, drawn from the marrow of the animal's sternum, into the same animal's torn tendon – succeeds in producing new tendon tissue. (Part of the problem is that it's hard to distinguish tendon tissue from scar tissue, seen through an ultrasound.) But if it works, they believe humans may one day have another option for treating our torn ligaments, too.

Listen to the Stem Cells and Horses radio report online, and watch our Web Extra Slideshow.

Soon after Barack Obama is sworn in as President next week, he is expected to reverse George Bush’s executive order limiting embryonic stem cell research. Scientists say their research has been stifled by restricting them to existing stem cell lines. The resulting boom in this cutting-edge medical technology will benefit California's research institutes in a big way.

Researchers call stem cell technology a "revolution" in medicine, along the lines of the development of antibiotics in the 1940s, or the manufacturing of insulin and other therapies from recombinant DNA breakthroughs.

But why do stem cells offer such promise?

Robert Klein, chair of the governing board for the California Institute of Regenerative Medicine (the state stem-cell agency created by Proposition 71), says that the recombinant DNA revolution in the 1970s saved the life of his son, and that the potential for saving lives is even greater with stem cell work.

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Stem cell technology has only existed for a decade. And despite the Presidential ban on use of new lines of embryonic stem cells, the advances in research have happened quickly. And, according to Deepak Srivastava, Director of Cardiovascular Research at the UCSF Gladstone Institute, the many possible applications of stem cell work will be seen in the short term (over the next few years) and long term (regeneration of damaged organs could happen in 7 to 10 years, he says).

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Dr. Srivastava says, in the case of one of his patients, five-month-old Ryder Ortiz, stem cell technology could have been a godsend. And it might still BE a godsend, he adds. Ryder was born without a left ventricle, the heart chamber that shoots blood into the body. With stem cell technology, it may become possible to grow a new ventricle, and that would’ve been a huge boon to the infant Ryder.

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But here's the thing: Doctors jerry-rigged Ryder's circulatory system, and it's a process that works – until the patient hits his teen years. In many cases, that’s when the re-worked circulatory system fails. Now, if Dr. Srivastava's estimate is correct, and the technology develops in the next 7 to 10 years, that will be just in time for Ryder Ortiz, who will be inching nearer to adolescence at that time.

Listen to the New Life for Embryonic Stem Cell Research radio report online.

ABC, Yahoo! and others ran a story about a woman who had a liver transplant whose blood type ended up changing. I love stories like this.

Not because of the change itself. Most likely, stem cells traveled from the new liver to the patient’s bone marrow. There, the stem cells set up shop and gave her a new blood type.

What intrigues me is what these types of stories mean for solving crimes. Because changed blood type usually means changed blood DNA. In other words, her blood cells now have different DNA from the other cells in her body. This can really confound an investigation if the police aren’t careful.

Of course this was a very rare event. But bone marrow transplants aren’t. And every bone marrow transplant results in blood cells with different DNA compared to the rest of the recipient’s cells.

Imagine that someone who has had a bone marrow transplant does something wrong and leaves blood behind at the crime scene. The police do a cheek swab to gather DNA evidence and check it against the police DNA database as well as likely suspects (including our bone marrow recipient).

The police don’t catch our bone marrow recipient because his cheek DNA is different than his new blood DNA. So he is off the hook (as long as the police don’t check the blood too). But they do get a match and arrest someone—the donor.

Sounds weird but something almost like this complicated a case in Alaska a few years ago. There was a serious crime and a semen sample from the crime scene matched a known criminal’s DNA. But the person whose DNA matched the DNA from the crime scene had a strong alibi…he was in jail at the time! So what happened?

A little further investigation showed that the guy in jail had received a bone marrow transplant from his brother. And his brother was the one who committed the crime.

This one worked out all right in the end. But what would have happened to the brother if he weren’t in jail at the time? Would an overworked public defender have figured something like this out? The guy was lucky he was already in jail!

So people with bone marrow transplants need to be careful. And the police need to be careful about what sample they take from suspects.

Dr. Barry Starr is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA.

latitude: -33.8027, longitude: 150.988