A multinational team of researchers report that the adult human brain harbors a new type of stem cells called multipotent perivascular mesenchymal stem cells. Perivascular stem cells have not been identified before in the human adult brain. The researchers isolated and characterized these stem cells from two different regions in the adult human brain.
The research report was recently published in the peer-reviewed journal PLoS ONE.
Stem cells have the potential to develop into many different cell types. All tissues contain stem cells that contribute to tissue maintenance and repair. These stem cells reside in special niches, called “stem cell niches.” Stem cell niches consist of blood vessels and adjacent cells. In these niches, “pericytes”- perivascular cells lining blood vessels- and the respective tissue-specific stem cells reside in close proximity.
Recently, the perivascular cells lining the blood vessels themselves have been found to possess features of stem cells –called mesenchymal stem cells that are usually isolated from the bone marrow. These cells seem to be able to contribute to tissue repair in some tissues.
The image on the left shows perivascular stem cells (green) around blood vessels (red) and
the image on the right shows that sorted isolated cells have the ability to become neurons. Image Credit: Dr. Gesine Paul-Visse.
In the adult brain, it was believed that new nerve cells arise from specific neural stem cells in mainly two regions of the brain. “We have now, for the first time identified, isolated and characterized a new stem cell that is lining small blood vessels from two different regions of the adult human brain,” Dr. Gesine Paul, the first author in the paper told SciGuru.com. They observed that these cells co-express markers for both, pericytes and mesenchymal stem cells. “That is why we call this cell population “Perivascular mesenchymal stem cell”, Dr. Paul added. Brain tissue used in the study was obtained from individuals undergoing brain surgery.
One isolated cell can renew itself into a large number of new cells and adopt the phenotype of different cell types, such as fat, cartilage and bone cells. Intriguingly, the researchers found that human brain-derived perivascular mesenchymal stem cells can not only become the above cell types, but can also become neurons and glial cells. Glial cells provide support and protection to neurons in the brain.
The perivascular progenitor cell isolated has never been characterized in the adult human brain. The fact that the brain-derived perivascular mesenchymal stem cell can become neurons suggests that these stem cells exhibit some degree of tissue-specificity and may have specific function depending on the tissue they reside in.
According to the researchers, the potential of perivascular mesenchymal stem cells is far greater than previously believed. Their results are likely to have a major impact on the understanding of the plasticity of perivascular cells in the human brain and open up the possibility that, under certain circumstances, perivascular mesenchymal stem cells adopt a different role in the adult brain and contribute to tissue repair or maintenance. “If we can stimulate these adult stem cells, they may be utilized in therapies to promote brain repair,” said Dr. Paul. The findings, nevertheless, open up completely new avenues of research brain injury, repair and neurodegenerative diseases.
Paul G, Özen I, Christophersen NS, Reinbothe T, Bengzon J, et al. (2012) The Adult Human Brain Harbors Multipotent Perivascular Mesenchymal Stem Cells. PLoS ONE 7(4): e35577. doi:10.1371/journal.pone.0035577.