Miracles That May Keep You Going

RIGHT NOW THE BEST WAYS OF ADDING A FEW YEARS TO YOUR life involve a lot of hard work. But medical science has a knack for making quantum leaps, as it did with vaccines andantibiotics. You shouldn't start gorging on pork rinds, or count on some future quick fix, but there are some potential "miracles" already visible on the horizons of medical research.

Chromosomes, the tight bundles of DNA that store genetic 'information, are capped at the ends by stabilizing sections called telomeres. Every time a cell reproduces, its telomeres get a little bit shorter, which had led some scientists to speculate that telomeres regulate overall life span. That turned out not to be the case, but telomeres do play a role in cells' aging. They seem to regulate how many times a cell can divide before it shuts down. If a way could be found to lengthen telomeres, this might prevent a host of age-related problems like atherosclerosis, immune disorders and fragile skin. Telomeres are also involved in cancer research. Cancer cells reproduce uncontrollably, and their telomeres don't shorten. At least one company, Geron, is working on inhibiting the enzyme that rebuilds telomeres.

One theory of how aging takes place is that the body's normal metabolism-taking in oxygen and nutrients and converting them to usable materials and energy-produces harmful byproducts. These molecules, called free radicals, oxidize other molecules in the body, changing their structure in damaging ways. Over time, this damage mounts. But the body produces enzymes that act as antioxidants. In 1994 Rajindar Sohal and William Orr of Southern Methodist University genetically engineered fruit flies to make more of these enzymes. The flies lived about one third longer than they were supposed to and were more vigorous. If genes for the enzymes could be inserted into the right locations in human chromosomes, people, too, could conceivably gain this extra resistance.

Since 1935 researchers have known that when laboratory rats and mice are fed a very-low-calorie diet-30 to 50 percent of their normal intake-they live about 30 percent longer than their well-fed confreres, as long as they get sufficient nutrition. Again, free radicals seem to be responsible: the less food consumed, the fewer free radicals are produced-possibly because on a low-calorie regimen cells' power-generating machinery operates at high efficiency, as it does during exercise. There haven't been solid studies on how caloric restriction affects human beings, but researchers speculate that someday drugs may enhance cellular efficency without diets, Consuming fewer calories while maintaining a healthy level of nutrients isn't easy... so don't quit eating just yet.

If researchers can't arrest the aging process, they might be able to take an automotive-repair approach, slotting in new parts when the originals wear out. When an organ transplant fails, it's usually because the recipient's immune system has rejected the new organ. But an organ grown in a lab might be cloned from the recipient's own cells so it wouldn't be rejected. Alternatively, researchers are trying to eliminate the proteins in animal cells that provoke immune response. These engineered cells could then be cloned and grown into a fetus. Tissue from this fetus--neurons at first, possibly whole organs later-could be used for transplant into humans. Others are working on building organs from scratch, fabricating skin and bone and culturing livers on artificial "scaffolds."