Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, February 7, 1991 TAG: 9102060235
SECTION: EXTRA PAGE: E-1 EDITION: METRO
SOURCE: NATALIE ANGIER/ THE NEW YORK TIMES
DATELINE: LENGTH: Long
Only hair could be that ornery.
A hair and its follicle together make up one of the most complex and baffling systems in the body.
But now, increasing numbers of scientists are beginning to understand that system by analyzing it in extraordinary detail from the base of the root to the tip of the shaft.
They are applying new tools of biochemistry and molecular biology to probe the fine structure of hair. And they are beginning to identify the key cells, proteins and genes that control the growth, death and regrowth of hair and its sometimes frustrating distribution across the body.
Beyond wish-list spinoffs like a baldness cure, the new insights are making significant contributions to understanding some of the basic processes of body cells.
"Hair is one of the most complicated and interesting systems in biology," said Dr. Elaine Fuchs, a molecular geneticist at the University of Chicago. "It's also an excellent model for how cells throughout the body differentiate. If you can really understand the developing hair follicle and how it communicates with the matrix of cells around it, you could understand cell-to-cell interactions throughout the body."
Many of the latest results were presented at a recent meeting, "The Molecular and Structural Biology of Hair," held in Arlington, Va., by the New York Academy of Sciences. It was the first international meeting devoted solely to the basic biochemistry of hair.
Among the findings reported:
Some researchers proposed that the growth of hair is reminiscent of the growth of a tumor. Hair is the only part of the human body that is periodically destroyed and replenished throughout adulthood, they said, and each time the hair structure is preparing to grow again, a fresh follicle must invade the scalp, rather as a tumor burrows into surrounding tissue.
Researchers have discovered that the same growth-promoting proteins in the body that trigger cancer are also involved in the normal hair regeneration cycle.
Other researchers have detected evidence that the body may kill off the follicle at the end of the hair cycle by using the same "soldier cells" of the immune system that attack microbes and reject foreign tissue.
Scientists are also picking apart the genetic events underlying the changes in hair growth that occur throughout adulthood. They are beginning to understand why the male sex hormone, testosterone, works in early adolescence to enlarge the follicles on a man's face and thus allow a beard to grow, but has the opposite effect on the scalp years later, prompting the follicles to shrink and cause baldness.
Still other researchers are mastering the difficult art of growing complete human hairs in the test tube. Scientists from Cambridge University in England announced that when they plucked out human hairs along with adjoining sebaceous glands at a particular point in the hair cycle, the hairs would continue to grow in culture dishes for up to 10 days.
Many biologists are isolating and cultivating the papilla cells clustered below the root of the hair. These cells send signals to the tissue of the follicle, telling it either that it is time to grow or to retrench. These cells are the most important part of the entire hair structure, scientists said, because they seem to be in command of hair growth and death.
The new advances in technology are fast attracting researchers who might once have scorned any "science" of hair growth as something best left to cosmetologists.
"This was a non-field a few years ago," said Dr. Stuart Yuspa of the National Cancer Institute in Bethesda, Md. "The fact that there are now a few hundred people doing really fine work is astonishing."
Yet even the most devout basic scientists are not ignorant of the possible payoffs should their work result in a genuine cure for baldness. Much of the new research is supported by pharmaceutical companies like Unilever and Upjohn.
Dr. Kurt Stenn, a dermatologist at Yale University School of Medicine and one of the conference organizers, complained that some researchers tried to hoard their results with the hope of winning big patents.
"If we're going to understand hair growth, we're going to do it through solid, methodical science," he said. "It's not going to come out in splashy, commercialized miracle cures."
Challenging problem
Whether they are working for love or money, scientists say hair is a challenging problem.
The complete hair follicle is composed of seven different types of cells, and it further interacts with a variety of connective cells, nerve cells, blood vessels and other tissues.
And during the growth of a hair, six different genetic programs are required to assure that all the parts of the system mature at the proper time.
What is more, every one of the 100,000 or so hairs on the scalp is at a different stage of the hair cycle, growing for 4 to 6 years, withering at its base over a period of three weeks, and then resting for another three months before rousing itself once again.
The process of renewal begins when precursor skin cells, located in a little bulge extending from the stump of the old follicle, increase to form a fresh follicle, which then pokes down 3 millimeters into the skin.
Once the follicle has reached its full length, dividing cells at its base are pushed upward to create a sheath inside the follicle, made of several concentric rings of cells.
"They're like the rings of a tree," Stenn said.
Depending on their position within the sheath, the cells are more or less hardened by differing concentrations of structural proteins known as keratins.
The sheath serves to protect the follicular pocket and to help mold the new hair strand that eventually grows up from the root. The strand is also constructed of cells containing keratin. When it moves through the sheath it is both pressed into shape and made increasingly stiffer, as the keratins within the cells become ever more tightly linked together by being squeezed up through the scalp.
As a general rule, said Stenn, Asian people have round sheaths, and thus their hair strands grow out shaped like tubes. Blacks have flat sheaths, and their hair emerges ribbon-shaped. In whites, the sheath is oval, and so is the cross-section of their hair.
Whatever its shape, the hair shaft that finally extends out into the world is so densely packed with keratin that it is essentially dead tissue. The hair falls out at the end of the cycle, when the follicle begins to regress to half of its full-length size.
Growing follicles
All hairs on the body grow at about the same rate of one-half inch a month, but the hairs on, say, the eyelashes and the arms have a much shorter growth stage before follicular death begins, and therefore never get very long.
Scientists believe papilla cells are the masterminds of hair growth. These cells remain unscathed in a little cluster right outside the bottom of the follicle and are not destroyed when the old follicle dies by half.
Only very recently have scientists learned to manipulate the dermal papilla cells, and in so doing they are learning how vital the cells are to hair growth.
In one report at the meeting, researchers from the University of Durham in England showed that they could take dermal papilla cells from the coat of a mouse and inject them into the skin of the mouse's paw pad, which normally is as hair-free as the palm of the human hand. Within days, the papilla cells had stimulated a crop of fur follicles where none belonged.
"This is the first time that we've been able to grow a follicle . . . in skin where hair has never grown before," said Dr. Amanda Reynolds, who did much of the new work. "It demonstrates quite clearly how much information is conveyed by the dermal cells."
Dr. Walter T. Gibson at Colworth Laboratory in Britain has found evidence that the cells responsible for degrading the old follicle tissue may be the same white blood cells that help attack invaders and scavenge stray cancer cells.
He noted that people with immune deficiency disorders and those who take immune-suppressant drugs to prevent graft rejection often become hairy.
Gibson's findings suggest one possible cure for baldness: an immune-suppressant drug that could be topically applied to the scalp.
But he emphasized that his work was "at the most preliminary stages," and little more than an experimental observation not yet proving cause and effect.
Until that or some other hair-loss potion pans out, balding men will have to be content with such familiar standbys as that used by Stenn, who admits to mourning his own loss of crown hair. Whenever he goes out, he says, he simply wears a hat.
by CNB