Bone Marrow Stem Cells May Provide Source of Nerve Cells for Brain Repair

August 3, 2000

Experimental Neurology/MedscapeWire

Cells deep within the bone may one day yield a readily available source of neurons to treat Parkinson’s disease, stroke, and other neurodegenerative disorders, a University of South Florida College of Medicine study found.

The study, which was published in the August issue of Experimental Neurology, demonstrated that both mouse and human stem cells that produce bone marrow can be reprogrammed in the laboratory to become immature nerve cells.

"It’s striking that we can generate new kinds of cells from deep within the bone, including cells with the potential to become neurons for brain repair," said lead investigator Juan Sanchez-Ramos, MD, a professor in Parkinson’s disease research at the University of South Florida.

Neuroscientists continue to seek alternatives to human embryonic neurons as a source of therapeutic cells for brain repair, said Paul Sanberg, PhD, director of the University of South Florida neurosciences program. Bone marrow stem cells are readily accessible because they are already collected from bone marrow donors for certain cancer treatments. And stem cells can be extracted from a patient’s own bone marrow, so they are less likely to be rejected than neural cells from other sources.

Stem cells are primitive cells that can multiply indefinitely, migrate to different parts of the body, and develop into any kind of tissue. Bone marrow retains the ability to generate stem cells throughout life. Left to their own devices, these bone marrow stem cells typically give rise to bone, blood, and cartilage.

But the researchers found that when a certain type of bone marrow stem cell (a stromal cell) is cultured in the laboratory with retinoic acid and growth factor, the cells lose their bone marrow characteristics and begin to resemble immature neurons. When these transformed bone marrow cells were combined with fetal rat brain tissue in a petri dish, the number of neuron- like cells doubled.

More studies are needed to determine whether the bone marrow–derived stem cells triggered to resemble early nerve cells can actually develop into functioning neurons, Dr. Sanchez-Ramos said. The researchers have begun cloning the stem cells and transplanting them into an animal model for stroke to see if they can replace damaged brain tissue.