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STEM CELL THERAPIES TODAY


STEM CELL THERAPIES TODAY


Did you know that several stem cell therapies are routinely used to treat disease today?

These include:

  • Adult Stem Cell Transplant: Bone Marrow Stem Cells
  • Adult Stem Cell Transplant: Peripheral Blood Stem Cells
  • Umbilical Cord Blood Stem Cell Transplant

Adult Stem Cell Transplant: Bone Marrow Stem Cells

Perhaps the best-known stem cell therapy to date is the bone marrow transplant, which is used to treat leukemia and other types of cancer, as well as various blood disorders.

Why is this a stem cell therapy?

Leukemia is a cancer of white blood cells, or leukocytes. Like other blood cells, leukocytes are made in the bone marrow through a process that begins with multipotent adult stem cells. Mature leukocytes are released into the bloodstream, where they work to fight off infections in our bodies.

Leukocytes

Leukemia results when leukocytes begin to grow and function abnormally, becoming cancerous. These abnormal cells cannot fight off infection, and they interfere with the functions of other organs.

Successful treatment for leukemia depends on getting rid of all the abnormal leukocytes in the patient, allowing healthy ones to grow in their place. One way to do this is through chemotherapy, which uses potent drugs to target and kill the abnormal cells. When chemotherapy alone can't eliminate them all, physicians sometimes turn to bone marrow transplants.

In a bone marrow transplant, the patient's bone marrow stem cells are replaced with those from a healthy, matching donor. To do this, all of the patient's existing bone marrow and abnormal leukocytes are first killed using a combination of chemotherapy and radiation. Next, a sample of donor bone marrow containing healthy stem cells is introduced into the patient's bloodstream.

If the transplant is successful, the stem cells will migrate into the patient's bone marrow and begin producing new, healthy leukocytes to replace the abnormal cells.

Adult Stem Cell Transplant: Peripheral Blood Stem Cell Transplant

Blood donation


While most blood stem cells reside in the bone marrow, a small number are present in the bloodstream. These multipotent peripheral blood stem cells, or PBSCs, can be used just like bone marrow stem cells to treat leukemia, other cancers and various blood disorders. Since they can be obtained from drawn blood, PBSCs are easier to collect than bone marrow stem cells, which must be extracted from within bones. This makes PBSCs a less invasive treatment option than bone marrow stem cells. PBSCs are sparse in the bloodstream, however, so collecting enough to perform a transplant can pose a challenge.


Umbilical Cord Blood Stem Cell Transplant

Umbilical cord blood

Newborn infants no longer need their umbilical cords, so they have traditionally been discarded as a by-product of the birth process. In recent years, however, the multipotent-stem-cell-rich blood found in the umbilical cord has proven useful in treating the same types of health problems as those treated using bone marrow stem cells and PBSCs.

Umbilical cord blood stem cell transplants are less prone to rejection than either bone marrow or peripheral blood stem cells. This is probably because the cells have not yet developed the features that can be recognized and attacked by the recipient's immune system. Also, because umbilical cord blood lacks well-developed immune cells, there is less chance that the transplanted cells will attack the recipient's body, a problem called graft versus host disease.

Both the versatility and availability of umbilical cord blood stem cells makes them a potent resource for transplant therapies.


NCRR/SEPA

Supported by a Science Education Partnership Award (SEPA) [No. 1 R25 RR16291-01] from the National Center for Research Resources, a component of the National Institutes of Health, Department of Health and Human Services. The contents provided here are solely the responsibility of the authors and do not necessarily represent the official views of NCRR or NIH.
"I heard that scientists are growing human organs in lab dishes."

"Is this true?"
Mad scientist growing organs

Is it possible to grow a replacement organ from stem cells in the lab, like growing a plant from a seed? Let's consider all of the things you would need to make an organ - say, a kidney - in a lab dish.

  1. First, you need to obtain a type of stem cell that can ultimately become a kidney. Would this be an embryonic stem cell? A fetal stem cell? Will an adult stem cell do the job? How do you know? Where will you get the cells?

  2. Next, you have to coax the stem cells to grow and divide in a lab dish. Which nutrients will help them grow? Do they need other types of cells around to encourage them to divide? If so, can you obtain them?

  3. After you have enough stem cells, you must simulate the physical environment required for them to differentiate into a functional kidney. How do you make the cells begin differentiating? Can you simulate the physical environment they need? Can you create a physical scaffold, or foundation, upon which the cells can shape themselves into a kidney? How will you help the developing kidney grow blood vessels to supply oxygen and nutrients to cells on the interior?

Scientists are still years away from growing whole human organs in lab dishes - but not for lack of trying. Research groups around the world have convinced various types of stem cells to grow, divide and even differentiate in lab dishes. Most of this research is performed in stem cells obtained from other organisms, such as mice, rats and frogs.

The final step, creating a functional organ out of differentiating stem cells, is more challenging. Obstacles to success include the problem of delivering oxygen and nutrients to cells on the inside of the organ, as well as creating physical scaffolds upon which to grow and differentiate cells.

Scientists are working closely with engineers to build and test different scaffolds. Early in 2002, University of Utah bioengineers earned applause from around the world for their imaginative nerve cell scaffold. Have a look.