I find that the PloS Editor's summary in the article itself is an excellent popularized explanation of what the study means so I present it as is (except some added parentheses).
Editor's Summary
Most of the cells in the human body are highly specialized (‘‘differentiated’’). The brain and the spinal cord, for example, contain two main cell types—neurons, which transmit electrical signals to and from the brain, and glial cells, which support and protect the neurons. If these essential neural cells become damaged or diseased, the body cannot replace them. Scientists think, however, that it might be possible to use ‘‘neural stem cell’’ transplants to replace the neural cells that are lost in neurodegenerative diseases (for example, Parkinson’s disease) or damaged by strokes or trauma. Stem cells are undifferentiated cells that replicate indefinitely and that have the potential to develop into many different specialized cells. Pluripotent stem cells (which are able to develop into any kind of specialized cell) can be isolated from early human embryos; ‘‘multipotent’’ stem cells (which develop into only a few cell types) can be isolated from many differentiated tissues, including the brain. Human fetuses (unborn offspring from the end of the 8th week after conception) are thought to be a particularly good source of neural stem cells because many new neural cells are made in fetal brains.
Although stem cell transplantation might provide treatments for many debilitating diseases, some concerns have been raised over its safety (added: especially when unmatched embryonic or fetal stem cells are being used after donation). In particular, some experts fear that tumors might sometimes develop from (added: donated) transplanted stem cells. Tumor cells actually behave very much like stem cells—they divide indefinitely and they tend to be undifferentiated. It is very important, therefore, that every patient who receives a (added: donated, that is a non-self) human stem cell transplant is carefully followed up to see whether any tumors develop as a result. In this study, the researchers describe a case in which multiple, slow-growing, donor-derived brain tumors formed in a patient after the transplantation of (added: donated) human fetal neural stem cells.
What Did the Researchers Do and Find?
Beginning in 2001, (added: donated) fetal neural stem cells were injected several times into the brain and the fluid surrounding it of a boy with ataxia telangiectasia at a Moscow hospital. Ataxia telangiectasia*, a rare disorder characterized by degeneration of the brain region that controls movement and speech, occurs when both copies of the ATM gene (human cells contain two copies of most genes) contain a genetic change that stops the production of functional ATM protein. In 2005, the boy had a magnetic resonance imaging scan at the Sheba Medical Center (Israel) because of recurrent headaches. The scan revealed abnormal growths in his brain and spinal cord. In September 2006, when the boy was 14, the spinal cord growth was surgically removed. This growth has never reappeared but the mass in the boy’s brain has continued to grow slowly. The material removed from the boy’s spinal cord contained both neurons and glial cells, the researchers
report, and resembled a glioneuronal tumor. In addition, it contained both XX (female) and XY (male) cells and the tumor cells had two normal copies of the ATM gene (added: meaning it could not be derived from the recipient since the gene was normal). Finally, a technique called HLA typing showed that the tumor contained cells from at least two donors.
What Do These Findings Mean?
These findings indicate that the growth in the patient’s spinal cord was donor-cell derived and contained cells from two or more donors, at least one of whom was female. Although the growth in the patient’s brain has not been examined, the multiple masses seen in this patient probably arose independently from transplanted cells injected at different sites, suggest the researchers. Importantly, the slow growth of the tumors and the well-differentiated appearance of the cells removed from the patient suggest that the tumors are relatively benign. Donor-derived cells might have been able to establish tumors in this particular patient because people with ataxia telangiectasia often have an impaired immune system and the immune system normally helps to reject tumor cells. Nevertheless, this first example of a donor-derived brain tumor developing after fetal neural cell transplantation is worrying and suggests that further work should be done to assess the safety of this therapy.
This very important study highlights that we know as yet very little about embryonic and fetal stem cells and that their behavior when injected in human tissues is highly unpredictable. Treatments in humans are as yet not advisable but similar uncontrolled experiments are continuously occurring in uncontrolled centers and in desperate situations.
Everyone must be advised, patients and doctors equally that donor embryonic and/or fetal stem cells carry unknown risks. Embryonic and/or fetal stem cell treatment may in the future be a solution to many of today's untreatable diseases but must first be studied in well planned experiments, performed in specialized centers in animal models and must not be ill advised solutions in desperate human patients.
Important for readers to note the difference:
We also need to remember that this is about fetal stem cells obtained from unborn offsprings from the end of the 8th week after conception and not about current approved treatments as bone marrow transplantation using own or matched adult stem cells from cord blood, bone marrow or peripheral blood.
References
1. Amariglio N et al. Donor-Derived Brain Tumor Following Neural Stem Cell Transplantation in an Ataxia Telangiectasia Patient. PloS Medicine 2009; 6(2): e1000029
*More information on Ataxia Telangiectasia from the NIH Neurological Disorders Site
What is Ataxia Telangiectasia?
Ataxia-telangiectasia is a rare, childhood neurological disorder that causes degeneration in the part of the brain that controls motor movements and speech. Its most unusual symptom is an acute sensitivity to ionizing radiation, such as X-rays or gamma-rays. The first signs of the disease, which include delayed development of motor skills, poor balance, and slurred speech, usually occur during the first decade of life. Telangiectasias (tiny, red "spider" veins), which appear in the corners of the eyes or on the surface of the ears and cheeks, are characteristic of the disease, but are not always present and generally do not appear in the first years of life. About 20% of those with A-T develop cancer, most frequently acute lymphocytic leukemia or lymphoma. Many individuals with A-T have a weakened immune system, making them susceptible to recurrent respiratory infections. Other features of the disease may include mild diabetes mellitus, premature graying of the hair, difficulty swallowing, and delayed physical and sexual development. Children with A-T usually have normal or above normal intelligence.
Is there any treatment?
There is no cure for A-T and, currently, no way to slow the progression of the disease. Treatment is symptomatic and supportive. Physical and occupational therapy may help maintain flexibility. Speech therapy may also be needed. Gamma-globulin injections may be given to help supplement a weakened immune system. High-dose vitamin regimens may also be used.
What is the prognosis?
The prognosis for individuals with A-T is poor. Those with the disease usually die in their teens or early 20s.
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1 comment:
very interesting post. thank you, stefan
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