Does anyone need more proof that stem cells are not going to serve as universal repair kits for Alzheimer’s disease, Parkinson’s disease, Lou Gehrig’s disease and spinal cord injury any time soon? Here is what counts as a big breakthrough in stem-cell research these days: producing cells that can then be studied for clues to what drugs will work against a particular disease.

I don’t mean to be cynical. Scientists today are announcing what is truly a milestone: they have taken skin cells from two elderly women—ages 82 and 89—who have Lou Gehrig’s disease, or amyotrophic lateral sclerosis (ALS), and used a technique that was announced less than a year ago to make the cells go backward in time, so to speak, and become embryonic stem cells. The researchers then made the stem cells morph into spinal motor neurons, the very ones that die in ALS. It’s a milestone because earlier studies had generated these induced stem cells from healthy donors, but no one knew if it would work on cells from elderly patients with a serious genetic disease.

So kudos all around. But the achievement is not, as the press release puts it, “an important step toward the goal of using induced pluripotent stem cells . . . to treat disease”—except if the step is small and the goal is decades away.

Just to recap what scientists led by Kevin Eggan of the Harvard Stem Cell Institute and Christopher Henderson of Columbia are reporting online today in Science. They started with skin cells from the two women, who had an inherited form of ALS in which one gene is mutated (this mutation is the cause of only about 2 to 5 percent of ALS cases, however, something to keep in mind). They then followed the recipe discovered last year, introducing four genes into the skin cells to “reprogram” them, essentially causing the cells to revert to embryonic stem-cell status. They then bathed the "pluripotent" cells in a stew of molecules that caused them to morph into motor neurons. Voila: motor neurons with the exact same genetic make-up as the women.

Not too long ago, that possibility was hailed as a technique for producing “patient-specific cells” that could then be returned to the patient to cure what ailed her. But think about it. The cells carry the same mutation that causes these women’s ALS in the first place. Transplanting them into the women would be like putting a cirrhotic liver into an alcoholic whose own liver was kaput.

Sure, maybe the cells could be used to generate genetically-matched healthy neurons to replace the diseased ones. But in a press conference, the scientists were quite clear about the more likely next step. “Because the cells contain the genes that produced the disease [in these women],” Eggan said, “you can study them in a Petri dish.” Henderson added, “we don’t understand the disease process, and that is preventing us from developing cures. But we now have in a culture dish cells with the same genetic make-up as the ALS patients in the very cells that are affected by the disease. We’ll see if they degenerate and die faster than normal cells, and will try to understand the mechanism of the degeneration process, since it is the mechanism that is the key to a cure, and will test chemical compounds that might stop the degeneration.”

That may sound like something that should have been done before, but in fact it has been impossible to isolate the diseased motor neurons from ALS patients, of which there areabout 30,000 in the United States. With a limitless supply of those neurons thanks to the iPS technique, scientists can both study the disease process and try everything they can think of to stop it.

Eggan had originally hoped to produce patient-specific stem cells using human eggs, in the process called therapeutic cloning, or somatic-cell nuclear transfer. In this technique, scientists remove all the genetic material from the ovum and replace it with the DNA from the skin cell of a patient. The fertilized ovum undergoes several cell divisions, yielding stem cells that the scientists then extract and induce to differentiate into the motor neurons they want to study.

But despite blanketing the Boston area with ads asking women to donate, he had no takers: women were eager to help, but when they learned that Massachusetts law prohibits the scientists from compensating them in any way—not for lost time at work, not for transportation—they had second thoughts. Women can, of course, be paid thousands of dollars for donating eggs to infertile couples. “Over the last two years we’ve done everything we could within the law to recruit women to donate ova,” Eggan said. “We were never able to recruit enough donors because we were legally prevented from providing the same sort of compensation that these women would receive for donating their ova for in vitro fertilization.”

Move over, steroids. Take a hike, human growth hormone. If scientists are right, a simple pill can enhance and even mimic the beneficial effects of exercise. At least in mice. But some people may not be waiting for research to show that the compounds work in people as well. The scientist who discovered the drugs, which are a cinch for chemists to synthesize, believes they may already be in athletes’ equipment bags—since anti-doping agencies had no idea they should even be on the lookout for them.

The drugs, called AICAR and GW1516, work by genetically reprogramming muscle fibers. The result is that the fibers use energy more efficiently, allowing them to contract repeatedly without tiring. Mice given the drugs ran faster and—this is where marathoners should prick up their ears—44 percent longer on the treadmill than un-drugged mice without flagging, Ronald Evans, a Howard Hughes Medical Institute investigator at the Salk Institute for Biological Studies in La Jolla, and colleagues are reporting today in an advance online publication in the journal Cell. The drugs also retool the muscles, with the result that there are more slow-twitch fibers (the kind used for endurance exercises) and fewer fast-twitch fibers (which let you put on bursts of speed, as in a sprint).

The drugs differ in just how much you—by which I mean a mouse, of course—can get away with. GW1516 had a dramatic impact on endurance, but to get the benefit the mice had to exercise. AICAR, on the other hand, really does seem like the proverbial exercise in a pill: no exertion required.

The work builds on research that Evans reported in 2004, when he created genetically-engineered “marathon mice” that had altered muscle composition and enough physical endurance to run twice as far as normal mice. The genetic engineering basically flipped a switch so that a gene called PPAR-delta was permanently “on.” PPAR-delta is more prevalent in slow-twitch muscle fibers than in fast-twitch ones, so keeping the gene turned on “increase[d] the amount of non-fatiguing muscle fibers,” Evans said. The result was a mouse able to run up to twice the distance of a normal littermate without training.

Despite whisperings that genetic engineering will be the next Olympic doping scandal, it’s obviously easier to get the benefits of the marathon mouse through a pill rather than gene splicing. But this genetic switch was flipped when the animals were still embryos. That raised the question, “what about reprogramming in an adult?” Evans said. “When all the muscles are in place, can you give a drug that washes over the muscle for a few hours at a time and reprograms existing muscle fibers? That’s a very different question.”

And it’s the question the new study answers with a resounding “yes.” GW1516 acts in concert with exercise: Evans had two groups of mice run on a treadmill for 30 minutes five days a week for a total of four weeks. All of the mice, as expected, became more fit, able to run longer and faster than when they were couch potatoes. But the animals that also got GW1516 ran 68 percent longer than un-drugged mice. “The dramatic effect of the drug was stunning,” Evans said.

The second drug, AICAR, wowed them even more: even in the absence of exercise, it activated many of the genes in muscle that are turned on by exercise. After four weeks of swallowing the drug, mice were able to run 44 percent longer than un-drugged mice—despite never having set paw into the treadmill. “The mice were behaving as if they’d exercised,” said Evans. Even better, actually: mice on the drug ran longer and farther than mice that had dutifully taken to the treadmill every day. Who said life was fair?

Both drugs trigger a suite of changes that underlie the improved endurance. They increase the number of mitochondria (structures that produce energy) in muscle cells, and increase blood flow. Evans suspects there were also beneficial changes to the heart and lungs. That suggests that the drugs could give even sedentary people the benefits of exercise. “Almost no one gets the recommended 40 minutes to an hour per day of exercise,” Evans says. “If there was a way to mimic exercise, it would make the quality of exercise that they do much more efficient.”

And for people who already walk, jog or run? “If you like exercise, you like the idea of getting more bang for your buck,” which GW1516 can provide, he says. “If you don’t like exercise, you love the idea of getting the benefits from a pill,” as with AICAR.