That's because with no functioning immune system until transplanted bone marrow begins to "take" and grow, patients could sicken and die from common microbes or even fungus infections.
The new transplantation center will include an imperceptible, one-mile-an- hour "breeze" to waft germs away from the vulnerable patients during the month or so it takes for enough of the bone marrow to grow back so that patients can go home.
Hahnemann has been a pioneer in bone-marrow transplantation since the mid- 1970s, when the procedure was "just a wild idea," said Dr. Isadore Brodsky, chairman of Hahnemann's department of neoplastic diseases and an expert on the procedure.
Now, he said, the cure rate of Hahnemann's transplant program approaches 50 percent in certain types of leukemia, lymphoma and Hodgkin's disease cases and ranges up to about 80 percent in other treated diseases, such as aplastic anemia and several inherited blood or immune-system diseases.
The techniques being used at Hahnemann, which says it is the only medical center doing adult bone-marrow transplants in the area, were developed at Hahnemann and Johns Hopkins University in the last five years. (Children's Hospital of Philadelphia performs some pediatric bone-marrow transplants.)
But it has only been in the last year or two that bone-marrow transplants have moved beyond the experimental state and have been used to treat people.
Last month, Hahnemann was selected as one of 12 medical centers around the country to take part in a national bone-marrow donation registry that will
serve as a kind of blood bank for frozen bone marrow.
The centers will also be available - if ever necessary - to treat the kind of massive, lethal radiation injuries that killed dozens of people after the Soviet Union's Chernobyl nuclear-plant accident and the resulting radiation leakage into the atmosphere.
Bone-marrow transplantation is the only therapy available for such severe radiation injuries, both Soviet and American doctors found after the disaster.
Bone marrow, the spongy tissue found inside bones, is the body's factory for producing infection-fighting blood cells. It is the heart of the body's defense system, and without an immune system, humans quickly die.
The theory of bone-marrow transplantation in treating leukemia and several other forms of cancer is simple - if not stark.
The treatment begins with massive doses of chemicals or radiation to destroy all cancer cells in the body.
The doses are so huge that they kill not only the cancer cells but also all the bone-marrow cells. Because marrow cells grow faster than other cells in the body, they are more sensitive to chemotherapy or radiation. So a dose that kills the bone marrow leaves other cells healthy.
Bone-marrow transplants offer a major advantage over other cancer therapies for one major reason: They allow the use of far higher doses of chemotherapy or radiation than could be used before.
"Basically, we give a dose of chemotherapy from which no human being could ever recover (without a bone-marrow transplant) . . . the bone marrow is wiped out," Brodsky said.
Generally, the transplanted bone marrow regenerates within several weeks and grows to replace the marrow destroyed by the cancer treatment. In many cases, the patient is cured - and apparently stays cured.
"I know I've had a second chance at life," said one former Hahnemann patient, Joseph Connor, 23, of Colwyn, Delaware County, who was told in 1985 that he suffered from incurable Hodgkin's disease, a type of cancer of the body's lymph system.
"In February of this year, after I went through all the conventional treatments available, I went to Johns Hopkins University, where they told me I would not survive 30 days.
"Well, I guess they didn't know me. I had a bone-marrow transplant at Hahnemann and I'm still here, with a new lease on life."
In recent years, researchers have even developed ways for patients to have their own bone marrow transplanted.
In the "self-donation" process - called autologous transplantation - some of the patient's own bone marrow is removed and frozen. Next, the patient is treated with massive doses of chemotherapy or radiation to destroy the cancer cells - also destroying the remaining bone marrow in the process. Then, the removed bone marrow can be treated to kill any cancer cells in it before being reinfused into the body.
The ideal marrow donation is from an identical twin. About one-quarter of the time, however, a brother or sister has identically matching bone marrow, Brodsky said.
Suitable "matches" are based on a comparison of certain biochemicals on the surface of blood cells.
In the general public, Brodsky said, the odds of finding an unrelated person with an identical genetic match is only about one in 20,000. The new National Bone Marrow Donor Registry, however, with about 14,000 potential donors so far, is designed to increase the chances of finding a match.
In addition to the diseases already being treated by transplantation, Brodsky said, the use of bone-marrow transplantation in other forms of cancer - including lung and breast cancer - is being researched now and shows therapeutic promise.
"For example, if I had cancer of the lung and it had been removed surgically, we might fear that it might not be entirely gone," Brodsky explained.
"So, the idea is that my own bone marrow would be harvested and then frozen. Then I could be given massive doses of chemotherapy or radiation, far higher than any human immune system could stand. Then, my own bone marrow would be thawed and given back to me and this would 'rescue' me, the idea being that I'd received enough chemotherapy and radiation to effect a cure," he said.
The hospital's new marrow transplantation center, scheduled to be operating by the spring, is designed to prevent infection among marrow transplantation patients waiting for the transplants to "take."
A key component of the center's design is an air-circulation system that gently pushes filtered and purified air from its walls, past the patients and toward doctors and visitors - ensuring that nurses, doctors and visitors are ''downwind" of the patients and will not be able to infect them with common germs and bacteria that a healthy immune system routinely fights off.
Any bacteria or other undesirable organisms carried by the visitors will be wafted away from the patients, out the door and into an air-filtration system, which purifies the air before it enters the patient center again.
For routine patient care, doctors and nurses will stand behind a transparent screen and work on the patient with flexible gloves, although they will also be able to enter the rooms when necessary.