Explore Current Stem Cell Treatments

By Lawrence S.B. Goldstein and Meg Schneider

Part of the Stem Cells For Dummies Cheat Sheet

Scientists have been working with human adult stem cells — the stem cells found in specific tissues — for more than 40 years, compared to only a dozen years for human embryonic stem cells. As a result, the only stem cell treatments that have been proven to work well so far involve tissue stem cells, mainly those found in bone marrow and skin.

Researchers are sketching out all kinds of possible uses for stem cells on the drawing boards, and some of these potential uses are in or preparing to enter clinical trials — experiments to see whether these treatments really work in people. So far, though, the only proven stem cell therapies are for burns and blood disorders; everything else is experimental or theoretical, at least for the moment (no matter what you may read in ads or marketing brochures).

Transplanting bone marrow

Bone marrow transplants have been used since the 1950s to treat leukemia and other blood disorders. Bone marrow is the spongy material found in the center of your bones. Bone marrow, which resides mainly in the large bones like the hip bone and shoulder blade, holds caches of hematopoietic (blood-forming) stem cells that can give rise to all the cell types in the blood:

Red blood cells, which pick up oxygen from the lungs and distribute it to the body’s tissues, and take carbon dioxide and other waste products from the tissues and return them to the lungs for expulsion.
White blood cells, which roam through the bloodstream looking for and attacking foreign invaders like bacteria.
Platelets, which induce the blood to clot.

Doctors use bone marrow transplants to replace the blood and immune systems of patients with certain blood cancers or other disorders. Transplanted blood-forming stem cells “home in” to the bone marrow and, once settled, begin rebuilding the patient’s supply of blood cells. Depending on the disease and the method used to harvest blood-forming stem cells, the stem cells begin producing new blood cells within 10 days to 6 weeks.

Healing burns with skin grafts

Skin grafts have been used for centuries, although no one knew exactly why they worked until fairly recently. Skin is particularly rich in stem cells because so much skin is lost through normal wear and tear; you shed thousands, or even millions, of dead skin cells every day. In mild cuts and burns, these stem cells work to repair the damaged tissue. In severe burns, though, the stem cells in the burn area are destroyed, so doctors have to take skin from an undamaged area.

The main obstacle in skin grafts is that, currently, only the burn patient’s own skin works reliably. If doctors try to use skin from another person, the patient’s immune system eventually rejects the graft. Scientists are working on ways to grow skin that’s genetically compatible with the patient so that, even if the patient doesn’t have enough undamaged skin to use, the burns can still be treated effectively.