Stem cell transplants are now being used to treat a variety of neurodegenerative diseases, cancers and brain injury. The stem cells used for such therapy are normally derived from embryos or fetuses, either obtained through termination of pregnancy, or from embryos grown in the lab or leftover from in-vitro fertilization.
Recently, stem cells from cord blood have been used as the blood of a newborn has a very high content of stem cells. They can also be harvested from bone marrow.
There have been lots of studies conducted that show success in treating immune system failure, cancer and other conditions, but the technique is still very much experimental and scientists aren’t completely sure of its safety or effectiveness.
There have been documented cases of embryonic stem cells causing cancer in the recipient, rather than helping, because these cells are prone to forming into tumors rather than helping as they were intended.
For example, a boy with ataxia telangiectasia had fetal stem cells injected into his brain and spine to try to improve the outcome of his condition. Four years later he began having headaches and after medical investigation was found to have brain and spinal tumors at the sites where he was injected. After removal of the spinal tumor, it was found that the tissue did not match his DNA so could have only come from the embryonic cells.
The authors of the case report wrote, "A boy with ataxia telangiectasia (AT) was treated with intracerebellar and intrathecal injection of human fetal neural stem cells. Four years after the first treatment he was diagnosed with a multifocal brain tumor. Studies showed that the tumor was of nonhost origin suggesting it was derived from the transplanted neural stem cells. Further work is urgently needed to assess the safety of these therapies."
The Nature Medicine journal has raised the concern that stem cells can be unstable and have the ability to grow into anything, including cancer, after it caused tumors in rats.
"The goal of replacing dying cells in Parkinson's disease with stem cells is now brought a step closer to the clinic. A new protocol eases symptoms in a rat model of the disease, but also raises the concern that poorly differentiated cells have the potential to become tumorigenic," the article stated.
Other research published in the same journal found that embryonic stem cells were very similar in their make up to cancer cells.
"Findings, reported recently by researchers at Stanford University in California support the still-controversial hypothesis that embryonic stem cells and at least some cancer stem cells share a common genetic program."
They added that they could potentially create cancer using embryonic stem cells.
"Practically, this means that epithelial cancer stem cells can potentially be generated at will rather than sorted from heterogeneous sources."
A safer and more ethical alternative is to use cord blood, preferably stored after being taken from the person’s own cord so that no foreign cells are used. Adult stem cells are also thought to be more stable than embryonic ones and more limited at what they can develop into.
Sources:
1. Amariglio N, Hirshberg A, Scheithauer BW, Cohen Y, Loewenthal R, et al. (2009) Donor-Derived Brain Tumor Following Neural Stem Cell Transplantation in an Ataxia Telangiectasia Patient. PLoS Med 6(2): e1000029. doi:10.1371/journal.pmed.1000029.
2. Nature Medicine - 12, 1237 - 1238 (2006)
doi:10.1038/nm1106-1237
3. 3. Wong, D. J. et al. Module map of stem cell genes guides creation of epithelial cancer stem cells. Cell Stem Cell 2, 333–344 (2008).
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting, in addition to running a charity for people damaged by vaccines or medical mistakes.