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Transplanted Brain Stem Cells Display Abnormal Proliferation, Report Researchers in Cloning and Stem Cells

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    Transplanted Brain Stem Cells Display Abnormal Proliferation, Report Researchers in Cloning and Stem Cells

    Transplanted Brain Stem Cells Display Abnormal Proliferation, Report Researchers in Cloning and Stem Cells

    LARCHMONT, N.Y.--(BUSINESS WIRE)--April 22, 2002--Neural stem cells transplanted into the brains of adult mice migrated to the lateral ventricle, replicated, and formed tumor-like structures that attached to the ventricular wall.

    Raising questions about the safety of therapeutic strategies that would use adult stem cells to treat neurodegenerative disorders, these findings are reported in a study published in the Spring 2002 (Volume 4, Number 1) issue of Cloning and Stem Cells (formerly Cloning, a peer-reviewed journal published by Mary Ann Liebert, Inc. (
    The paper, entitled "Transplantation of an Indigenous Neural Stem Cell Population Leading to Hyperplasia and Atypical Integration," may be viewed free online at The authors, Tong Zheng, Ph.D., Dennis A. Steindler, Ph.D., and Eric D. Laywell, Ph.D., are affiliated with the Departments of Neuroscience and Neurosurgery, McKnight Brain Institute, the University of Florida College of Medicine, in Gainesville.

    They had previously identified a cell type found in the mature brain, called an astrocyte, that appears to be a multipotent, naturally occurring neural stem cell. When transplanted into adult mice, some of these astrocytes behaved as they normally would and migrated into the olfactory bulb.

    Others, however, "made hyperplastic structures that looked a bit like brain tumors," said Dr. Steindler, co-author of the study and Professor of Neuroscience and Neurosurgery. These structures resolved over time, with the cells penetrating the ventricular wall and dispersing within the surrounding brain tissue. "The bottom line is that we need to be cautious even when using natural brain stem cells as potential therapeutics."

    "The idea of using patients' own stem cells to treat themselves, remains, at least in my mind, the best avenue for treatment," says Byron E. Petersen, Ph.D., the newly named Associate Editor of Cloning and Stem Cells. "However, before we start putting stem cells (adult or embryonic) into patients, we need more of a basic understanding of stem cell biology. A few politicians and medical researchers have already decided that adult stem cells will be the 'golden parachute' in treating patients. I feel this maybe the case, but there is still a long road ahead of us in determining the correct cell type to be used in patient treatment protocols. This study goes to show that funding for all aspects of stem cell research should be continued until all of the kinks have been worked out."

    Cloning and Stem Cells is an authoritative peer-reviewed journal published in print and online that focuses on understanding and manipulating developmental plasticity and defining the molecular mechanisms that regulate differentiation or dedifferentiation of nuclei and cells. Edited by Ian Wilmut, Ph.D., the Journal publishes papers for researchers working in the fields of stem cell biology, cloning, and developmental and molecular biology. A complete table of contents and a free sample issue may be viewed online at
    Mary Ann Liebert, Inc., is a privately-held, fully integrated media company known for establishing authoritative peer-reviewed journals in many promising areas of science and biomedical research, including the Human Gene Therapy, Tissue Engineering, e-biomed: The Journal of Regenerative Medicine, and Biotechnology Law Report. Its biotechnology trade magazine, Genetic Engineering News (GEN), was the first in its field and is today the industry's most widely read publication worldwide. A complete list of the firm's 60 journals, books, and newsletters is available at

    Mary Ann Liebert, Inc.,

    Vicki Cohn, 914/834-3100, ext. 617;

    SOURCE: Mary Ann Liebert, Inc.

    Unfortunately, this work is not yet available online. Note that the study was carried out in mice and the news article above does indicate the strain of mice used. Mice differ considerably in their immune response to transformed cells. Animals use their immune system to eliminate cancerous cells. If this is a mouse that does not have an aggressive immune system response to transplantation, overgrowth and perhaps even cancerous looking growths may result.

    The article also does not indicate whether the cells were treated with retinoic acid or other differentiating agents that tend to suppress tumor formation. For example, embryonic stem cells or the human teratoma cells will definitely form tumors if they were directly transplanted into the brain or spinal cord. However, if the cells are treated with retinoic acid, they do not form tumors.

    Over the past year or so, we have transplanted a variety of cells into rat spinal cord. The response of different strains of rats to these cells can vary from vigorous rejection of cells (within 2 weeks), to slow or partial rejection (4-5 weeks), and complete acceptance of the cells. The last often is associated with formation of tumors from the transplanted cells.

    So much depends on how the cells are treated before transplantation and the immune response of the animals to the cells. This should not be regarded as a reason not to go ahead with such transplants. It just reminds us that even adult stem cells will form tumors and that we need to look at these issues carefully.