Health,Stem Cells, and Technology

Wednesday, June 20, 2012

Adult Human Brain: Multipotent Perivascular Mesenchymal Stem Cells

A new stem cell type has been discovered in the adult brain that can proliferate and form several different cell types, including new brain cells.  This discovery will help to develop methods that can repair diseases and injury to the brain.

Analyzing brain tissue from biopsies, scientists at the University of Lund, Sweden, including lead authors Dr. Gesine Paul and Dr. Ilknur Özen,  for the first time found stem cells located around small blood vessels in the brain. The cell’s specific function is still unclear, but its plastic properties suggest great potential. A similar cell type has been identified in several other organs where it can promote regeneration of muscle, bone, cartilage and adipose tissue. Blood vessels and adjacent cells form perivascular stem cell niches in adult tissues other than the brain. In this perivascular niche, a stem cell with mesenchymal characteristics was recently identified in some adult somatic tissues. These cells are pericytes that line the microvasculature, express mesenchymal markers and differentiate into mesodermal lineages but might even have the capacity to generate tissue-specific cell types. In the present study, researchers isolated, purified and characterized a previously unrecognized progenitor population from two different regions in the adult human brain, the ventricular wall and the neocortex. They show that these cells co-express markers for mesenchymal stem cells and pericytes in vivo and in vitro, but do not express glial, neuronal progenitor, hematopoietic, endothelial or microglial markers in their native state. Furthermore, they demonstrate at a clonal level that these progenitors have true multilineage potential towards both, the mesodermal and neuroectodermal phenotype. They can be epigenetically induced in vitro into adipocytes, chondroblasts and osteoblasts but also into glial cells and immature neurons. This progenitor population exhibits long-term proliferation, karyotype stability and retention of phenotype and multipotency following extensive propagation. Thus, we provide evidence that the vascular niche in the adult human brain harbors a novel progenitor with multilineage capacity that appears to represent mesenchymal stem cells and is different from any previously described human neural stem cell. Future studies will elucidate whether these cells may play a role for disease or may represent a reservoir that can be exploited in efforts to repair the diseased or traumatized human brain.

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

Tuesday, June 19, 2012

Telomerase Gene Therapy In Mice Delays Aging, Increases Longevity Without Cancer

Major goals in aging research are to improve health during aging and to increase lifespan. Studies have shown that genetic manipulations leading to shortened or lengthened telomeres result, respectively, in decreased or increased longevity. Based on this, Dr. Maria Blasco, PhD at the Spanish National Cancer Institute tested the effects of a telomerase gene therapy in adult (1 year of age) and old (2 years of age) mice. Dr. Blasco and her team observed that treatment of 1- and 2-year old mice with an adeno associated virus (AAV) of wide tropism (i.e. effecting many types of cells) expressing mouse TERT (telomerase reverse transcriptase) had remarkable beneficial effects on health and fitness, including insulin sensitivity, osteoporosis, neuromuscular coordination, and several molecular biomarkers of aging. Importantly, telomerase-treated mice did not develop more cancer than their control littermates, suggesting that the known tumorigenic activity of telomerase is severely decreased when expressed in adult or old organisms using AAV vectors. Finally, telomerase-treated mice, both at 1-year and at 2-year of age, had an increase in median lifespan of 24 and 13%, respectively. These beneficial effects were not observed with a catalytically inactive TERT (a control measure), demonstrating that the positive effects shown in the studies require telomerase activity. The  results of this study provide proof-of-principle for a role of TERT in delaying physiological aging and extending longevity in normal mice through a telomerase-based treatment, and demonstrate the possibility of anti-aging gene therapy for humans.

Friday, June 15, 2012

Light-Field Photography

And now a camera that lets you adjust the focus of an image after you've taken the picture! This March brought the first major update to camera design since the dawn of cheap digital photography. Sold for $399 and up by Lytro, a startup based in Mountain View, CA, that plans to use its technology to offer much more than the refocusing trick, with options such as making 3-D images at home.
All consumer cameras create images using a flat plate for detection of the light, whether chemical film or a digital sensor, to record the position, color, and intensity of the light that comes through a lens. Lytro's camera performs similarily, but it also records the angle at which rays of light arrive. The resulting files aren't images but mini-databases capturing the three-dimensional pattern of light, called a light field, at a particular moment. Software can mine that database to produce many different possible photos and visual effects from just one captured image.
Lytro has wrapped its technology in a consumer-friendly package, making this new form of photography more likely to catch on. 
Light-field cameras existed before, but they had limited industrial uses and were never cheap enough for consumers. Lytro founder Dr. Ren Ng, who worked on light-field technology for his PhD at Stanford University, made this one affordable by simplifying the design. Instead of using multiple lenses that made previous light-field cameras expensive and delicate, Ng showed that laying a low-cost plastic film patterned with tiny microlenses on top of a regular digital sensor could enable the detector to measure the direction of incoming light.
Recording the entire light field entering the camera means that images can be focused after the fact: a user can choose near, far, or any focus in between.
Refocusing images after they are shot is just the beginning of what Lytro's cameras is capable of performing. A downloadable software update will soon enable the camera to capture everything in a photo in sharp focus regardless of the object's distance from the lens, which is practically impossible with a conventional camera. Another update scheduled for this year will use the data in a Lytro snapshot to create a 3-D image. Dr. Ng is also exploring a video camera that could be focused after shots were taken, potentially giving home movies a much-needed boost in production values.
Images from Lytro cameras can be shared on websites and social media in a way that allows other people to experiment with changing the focus to explore what the photographer captured. Can't wait to try it out!

Thursday, June 14, 2012

Stem Cells Can Be Harvested After Death

Some stem cells can lay dormant for more than two weeks in a dead person and then be revived to divide into new, functioning cells. The research, published in the journal Nature Communications, reveals more about the versatility of adult stem cells, a current means to replenish damaged tissue.
Remarkably, skeletal muscle stem cells can survive postmortem for 17 days in humans and 16 days in mice. The stem cells retained their ability to differentiate into perfectly functioning muscle cells. This discovery could form the basis of a new source, and more importantly new methods of conservation, for stem cells used to treat a number of conditions.
The study led by Dr. Fabrice Chretien, MD, PhD of France's Pasteur Institute found that to survive in adverse conditions, skeletal muscle stem cells lower their metabolism to enter a dormant state, using less energy.The team then also looked at stem cells taken from bone marrow, where blood cells are produced. These cells remained viable for four days after death in lab mice and retained their ability to reconstitute tissue after a bone marrow transplant. By harvesting and banking stem cells from the body of consenting donors post mortem, the shortage of tissues and cells for human therapy may be ameliorated.