Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Brain stem cells are not rejected when transplanted

14.07.2003


Findings could improve retinal and other nervous system transplants



For the first time scientists have shown that brain stem cells are immune privileged, which means that they are invisible to a transplant recipient’s immune system and do not trigger the immune system to reject them. These results, published in the July issue of Stem Cells, indicate that using central nervous system stem cells in transplants for diseases of the eye (which is part of the brain), brain, and spinal cord, may eliminate the need for tissue typing before, and immunosuppressive drugs after, transplantation. Ultimately these findings promise to improve the success of retinal transplantation to regenerate vision for millions with macular degeneration, retinitis pigmentosa and diabetic retinopathy and brain transplants to restore functioning for patients with disorders such as Parkinson’s disease.

"These findings are very exciting," says Michael Young, PhD, the lead author of the study and an assistant scientist at Schepens Eye Research Institute and assistant professor at Harvard Medical School. "Though we suspected brain stem cells might be protected in this way, this is the first documented evidence."


Most tissues when transplanted from one body to another are seen by the recipient as foreign and attacked by the immune system. This is because the transplanted tissue has molecules on its surface called antigens that are recognized by the immune system as "not self." If the immune response goes unchecked by drugs to inhibit the attack, it will eventually destroy the transplanted tissue and reject it.

There are sites in the body that do not mount attacks against foreign tissue because to do so would be too self-destructive. For instance, in the eye an all out immune attack would cause inflammation that would destroy delicate tissue and, with it, vision. These sites, which are known as "immune privileged," include the eye, the brain, the digestive system, and the reproductive system.

Young, who in previous research found that brain and retinal stem cells transplanted into the eyes of mice and rats seemed to survive longer and integrate more easily into damaged retinas than other cells, suspected that these "neural stem cells" might be immune privileged. The only way for him to learn the true nature of their immune properties was to transplant these neural stem cells to a part of the recipients body that, unlike the eye, was not immune privileged already.

He and his colleagues chose a part of the body that always rejects transplanted tissue without immunosuppressant drugs and without close tissue typing – the kidney capsule, the pouch in which the kidney is located. This pouch is commonly used to determine whether transplants can survive. Over the years scientists have tested skin, cornea and other tissues in the kidney capsule to evaluate their transplant potential.

Young and his colleagues took brain stem cells from green mice (mice in which the gene for green protein found in jellyfish has been inserted) and placed them under the kidney capsule in other normal non-green mice. After 4 weeks, the team examined the mice and found that the stem cells had not been rejected in any of the mice, and, in fact, had grown into neural tissue.

They concluded that these neural stems cells did not induce an immune response and must be invisible to the immune system, at least initially. The next step was to determine if the cells possessed the antigens that most other tissues had. To test this theory, the team took other brain cells (not stem cells) from the green mice and implanted them in the normal non-green mice. These cells were rejected, and when brain stem cells were then again implanted in the normal non-green mice, they, too were rejected. The team concluded, therefore, that the brain stem cells did possess antigens, but unless the recipient was primed or pre-immunized, the antigens were not visible to the immune system of the recipient and not rejected.

"Understanding the immune properties of these stem cells could have an enormous effect on how we perform brain or retinal transplantations in the future. Stem cells already have the advantage of being able to transform or differentiate into various types of cells and can be reproduced endlessly outside the body. Now we know that at least brain stem cells are immune privileged and can be used without the same worry about tissue matching or immunosuppression that is true for other types of tissue. Young is the director of Schepens Eye Research Institute’s Minda de Gunzburg Retinal Transplantation Research Center. The center is committed, with a focus on retinal regeneration, to unlocking the mysteries of vision and finding the cures for blinding eye diseases that devastate millions in the United States and around the world.

The study, titled "Neural progenitor cells lack immunogenicity and resist destruction as allografts" can be obtained at the Stems Cells website at http://stemcells.alphamedpress.org/ or by emailing pattijacobs@hotmail.com or mikey@vision.eri.harvard.edu.

Other members of the research team include Junko Hori, Tat Fong Ng, Marie Shatos, and J. Wayne Streilein of Schepens Eye Research Institute of Boston and Henry Klassen of the Stem Cell Research Program at Children’s Hospital of Orange County in Orange, California.


###
Schepens Eye Research Institute is an affiliate of Harvard Medical School and is the largest independent eye research institute in the world.


Patti Jacobs | EurekAlert!
Further information:
http://www.eri.harvard.edu/
http://stemcells.alphamedpress.org/

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>