Using skin cells from adult siblings with schizophrenia and a genetic mutation linked to major mental illnesses, Johns Hopkins researchers have created induced pluripotent stem cells (iPS cells) using a new and improved “clean” technique.
Reporting online February 22 in Molecular Psychiatry, the team confirms the establishment of two new lines of iPS cells with mutations in the gene named Disrupted In Schizophrenia 1, or DISC1. They made the cells using a nonviral “epiosomal vector” that jumpstarts the reprogramming machinery of cells without modifying their original genetic content with foreign DNA from a virus.
The stem cells from these two new lines, the scientists say, can be coaxed to become brain cells such as neurons. Because they have the DISC1 mutation, they stand to play an important role in the screening of drugs for treatments of major mental illnesses such as schizophrenia, bipolar disorder and major depression, as well as provide clues about the causes of these diseases.
“Most people think of stem cells only as potential transplant therapy to replace damaged cells or tissue, but for psychiatric diseases, which have proven a challenge to scientific understanding just as a sheer cliff challenges a climber, these cells provide a toehold,” says Russell L. Margolis, M.D., professor of psychiatry and neurology, and director of the Johns Hopkins Schizophrenia Program. “Nature put in only a few little grab holds, and now we are generating our own so we can scale the cliff of mental illness faster.”
The benefit of maintaining the original genome of cells being reprogrammed outweighs the fact that the episomal vector approach is both time- and labor-intensive, says Guo-li Ming, Ph.D., associate professor of neurology, Institute for Cell Engineering, Johns Hopkins University School of Medicine.
“The efficiency of the new technique is very, very low,” Ming reports, citing a rate of 0.0006 percent or less and comparing it to the rate of efficiency of virally infected reprogrammed cells, which hovers at about 0.001 percent. “Human cells grow slowly, and this kind of reprogramming takes time.”
However, the episomal vector method solves tricky problems associated with the more efficient viral approach, which involves inserting foreign genes into the cell’s genome and potentially interrupting or influencing other genes that can change cell behavior. It also relieves worry about weird cell behavior later due to reactivation of introduced genes that remain in the genome, the researchers say.
The skin biopsy samples used in the study came from an American family first reported 25 years ago to have multiple family members affected with schizophrenia. A genetic analysis conducted by Margolis and colleagues six years ago discovered that a mutation in the DISC1 gene was common to all members of the family with severe mental illness. Two years ago, Margolis and Christopher A. Ross, M.D., Ph.D., director of the division of neurobiology, collected the skin samples and delivered them to Ming’s team, which thus far has successfully reprogrammed two of those samples into the new iPS cell lines. Skin cell samples from the remaining family members, as well as from unrelated individuals with schizophrenia, are still works in progress in the Ming lab, potentially becoming additional stem cell lines, according to Ming.
First, using the cultured skin cells, the team delivered a package of so-called reprogramming factors into the cytoplasm — as opposed to the nucleus, where the cell’s genetic material resides — via bits of DNA (episomal vectors) that are serially diluted during cell division after making their special delivery. These cells then were grown in culture while the scientists monitored them for changes.
It took a wildly variable window of time — anywhere between three weeks and three months — for the elongated and single-layered skin cells to begin to change shape and cluster together, a telling sign that they were on the path to becoming stem cells, Ming explains.
“Seeing the colonies was heartening evidence of reprogramming, but not proof of ground state of pluripotent stem cells,” Ming says. “We had to go through a series of characterization process, which generally takes about six months or more, depending on your rigor, to prove that.
The team then conducted a series of tests to verify not only that the genes they used to introduce the reprogramming factors were undetectable from the transformed cells, but also to prove their pluripotency. First, they confirmed that these cells could generate differentiated cells from all three germ layers — the endoderm, mesoderm and ectoderm — which eventually give rise to all of an animal’s tissues and organs. By changing the recipe of the culture media in which the cells were growing, the team coaxed the cells to become not only neurons, but also fat cells and bone and muscle tissue, for instance. To confirm these were bona fide iPS cells with the ability to differentiate into all different cells types, the researchers performed a stringent test that involved injecting the presumed stem cells into mice whose immune systems were suppressed and noted that cells from three germ layers were present in the tumors that formed.
“The hard work of generating and characterizing these iPS cells is a prelude for future studies,” Ming says. “Now, we can look at neural cells differentiated from these iPS cells in order to investigate the mechanisms and functions of the DISC1 gene in the nervous system, and understand the role it may play in diseases such as schizophrenia. These future studies may lead to the identification of new molecules that might serve as drug targets.”
This research was supported by the National Institutes of Health, the Maryland Stem Cell Research Fund, the National Alliance for Research on Schizophrenia and Depression, and the International Mental Health Research Organization.
Johns Hopkins authors on the paper, in addition to Ming and Margolis, are Cheng-Hsuan Chiang, Yijing Su, Zhexing Wen, Nadine Yoritomo, Christopher A. Ross and Hongjun Song, all of Johns Hopkins.On the Web:
Molecular Psychiatry: http://www.nature.com/mp/index.html
Maryalice Yakutchik | Newswise Science News
Further reports about: > DISC1 gene > DNA > Margolis > Molecular Psychiatry > Stem cell innovation > brain cell > cell death > family members > health services > iPS cells > immune system > mental illness > methanol fuel cells > pluripotent stem > pluripotent stem cells > psychiatric disease > schizophrenia > skin cell > stem cells
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses