Induced Pluripotent Stem Cells to be Tested in Parkinson’s Disease Study

Stem cell researchers from the United Kingdom are preparing a study to examine the ability of induced pluripotent stem cells iPSCs to improve the condition of patients afflicted with Parkinson’s disease. Oxford University will host the study and this group will take skin cells from Parkinson’s patients, transform them into iPSCs, differentiate these iPSCs into neurons, and then surgically introduce these new cells into the brains of Parkinson’s patients.

Parkinson’s disease is caused by the degeneration of a specific group of neurons. Neurons are those cells in the brains that are able to conduct nerve impulses. However, neurons transmit these nerve impulses by means of small molecules called “neurotransmitters.” Neurons release distinct neurotransmitters and some use acetylcholine, others glutamine, others dopamine, and still others norepinephrine. Think of it as neurons speaking different languages to talk to each other. Some speak acetylcholine, while others use dopamine, and so on. In a portion of the brain called midbrain, there is a small, black group of neurons that speak dopamine. This group of neurons is collectively called the “substantia nigra,” which simply means “black stuff.” These dopamine-using neurons are the ones that degenerate during Parkinson’s disease.

Patients who suffer from Parkinson’s disease have problems with motor skills, speech, and other functions as well. Parkinson’s disease patients also have movement disorders that include stiffness of the muscles, tremors, a slowing and eventual loss of physical movements.

This stem cell research team at Oxford University is carrying out the first iPSC clinical study ever. It will also not involve the destruction of human embryos. The group hopes to take skin cells from at least 1,000 Parkinson’s patients, and transform them into neurons. These experiments will be challenging because iPSCs, to date, do not usually form neurons in culture very effectively. These experiments, however, will provide researchers with large quantities of experimental neurons for experimental purposes. These experimental neurons will be used to treat patients, and also to test Parkinson’s disease treatments in culture.

According to Richard Wade-Martins, the head of the Oxford Parkinson’s Disease Centre: “Parkinson’s disease is the second most common neurodegenerative disease in the UK and is set to become increasingly common as we live longer. Once we have neurons from patients we can compare the functioning of cells taken from patients with the disease and those without to better understand why dopamine neurons die in patients with Parkinson’s.”

This a very exciting study and it is a shame that it did not happen in the US first.

Scientists Make Tumor-Seeking and Cancer-Killing Immune Cells

The Jonsson Comprehensive Cancer Center on the campus of the University of California, Los Angeles (UCLA) houses a research group that created tumor-seeking, cancer-killing immune cells. This same group used positron emission tomography (PET) to observe these engineered cells in real time as they traveled throughout the body to locate and attack dangerous skin tumors called melanomas. The immune cells were made by means of genetic engineering. They used an HIV-like virus as the means to endow these immune cells with the genes for T-cell receptors that caused the lymphocytes to become specific killers of cancerous cells. They also gave the engineered lymphocytes with a “reporter gene” that allows scientists to track them during a PET scan. After they were injected into the bloodstream, the genetically engineered lymphocytes made their way to the lungs and lymph nodes, and then specifically homed in on the tumors wherever they were located in the body.

Dr. Antoni Ribas, an associate professor of hematology–oncology and a researcher at UCLA’s Jonsson Comprehensive Cancer Center put it this way: “We’re trying to genetically engineer the immune system to become a cancer killer and then image how the immune system operates at the same time. We knew this approach of arming the lymphocytes with T-cell receptors showed significant anti-tumor activity based on studies in humans. Now, by tracking the immune system’s reaction to cancer and imaging it in real time, we can project how the same process that succeeded in mice might behave in people.”
“The novelty of our work is that we were able to pack together the cancer-specific T-cell receptor and the PET reporter genes in a single vector and use it in mice with an intact immune system that closely resembles what we would see in real patients,” said Dr. Richard Koya, an assistant professor of surgical oncology at the David Geffen School of Medicine at UCLA and first author of the study. “We were also gladly surprised to see the targeted tumors literally melt away and disappear, underscoring the power of the combined approach of immune and gene therapy to control cancer.”

Typically, the immune system fails to recognize cancer cells in the body as foreign entities. By inserting an antigen-specific T-cell receptor that was engineered to seek out a tumor antigen on the surface of melanoma cells, the researchers effectively “uncloaked” the malignant cells and designated them as the deadly invaders they are. When viewed with a PET scan, these genetically engineered T cells appeared to seek out and attack the cancer. This technique, in fact, this technique might provide oncologists with better ways to fight malignancies and monitor responses to therapy in cancer patients.

In this study, after the engineered T cells found the tumors and began to fight them within two the three days after their injection into the bloodstream of the mice. These mice were routinely examined with PET scans for ten days to ensure the lymphocytes were indeed killing the cancer. Such a process would almost certainly take longer in people. Some 1 million genetically engineered lymphocytes were created and injected into a mouse in this study, but it would take about one billion tumor-seeking cells to fight cancer in humans.

Ribas and his team are working now on inventing ways to insert T-cell receptor and reporter genes into the lymphocytes in a way that is safe for use in humans. Human studies of the process could conceivably begin in about a year, according to Ribas. This study appears July 12 in the early online edition of the journal Proceedings of the National Academy of Sciences.

National Institutes of Health Rejects Forty-Seven New Embryonic Stem Cell Lines

The human embryonic stem cell registry was created by the National Institutes of Health (NIH) after a March 2009 executive order by President Barak Obama that called for the federal funding of responsible stem cell research that uses ethically obtained hESCs.  Recently, the NIH rejected a request to make 47 human embryonic stem cell (hESC) lines available for federally-funded stem-cell researchers.  The organization cited ethical concerns as the main reasons why they rejected these cell lines.  These cell lines would have provided scientists with potential models to study several different genetic diseases like cystic fibrosis, Huntington’s disease, and others. 

These hESC lines were from embryos donated by couples who were treated for infertility at the Reproductive Genetics Institute (RGI).  RGI is a private infertility clinic in Chicago, IL, and this institute made all their hESC lines available to researchers by means of their London-based affiliate Stemride International, Ltd.  However, the NIH rejected these hESC lines because the donor waivers were “too vague” and contained exculpatory language that limited the donor’s right to sue the clinic.  Francis Collins, director of the NIH said, “It was frankly rather painful for my expert advisory committee to recommend against approval of 47 additional lines from RGI because of a consent problem, but rigorous guidelines are only meaningful if they are rigorously applied.” 

Privately-funded scientists can still use these hESC lines, and RGI can resubmit them the appropriate consent forms signed by the donors.  However, since these donations were anonymous, this is probably not impossible. 

NIH did approve 8 other stem cell lines, which brings the total number of lines in the agency’s hESC registry to 75.

It is noteworthy that President Bush was routinely lambasted for not allowing federal funding for new hESC lines.  Some of this criticism was certainly warranted, since the number of available hESC lines was vastly exaggerated, and there was no recourse provided to re-examine the list of federally-funded hESCs.  However, President Obama’s policy was hailed as a new path for stem cell research, but we still have large numbers of hESC lines being rejected for federal funding.  Could be that rejection of previous hESC lines was not completely political?  If improper paperwork can cause the rejection of hESC lines for federal funding, then what about the way in which they were derived?  It seems as though the rejection of hESC lines for federal funding is not just a pro-life thing.  Then why the outrage when a pro-life president did it, but not when a pro-choice president does it?

Neural stem cells hunt down brain tumors

Brain tumors are one of the biggest bummers in medicine.  Brain tumors are typically inoperable and because the drugs that are used to treat cancers must cross the blood-brain barrier, this greatly limits the available drugs that can be used to treat these tumors.  Now, research from lab in Germany indicates that our own brain-specific stem cells might actively seek out and destroy particular types of brain cancers.

Scientists from the Max Delbrück Center for Molecular Medicine (MDC) in Berlin, Germany, have demonstrated how the brain’s own stem cells and precursor cells control the growth of particular brain tumors called glioblastomas.  Glioblastomas are among the most common and aggressive of all brain tumors.  They typically form in adults in their mid-fifties or early sixties.  The causes for their development are not yet known, but researchers have reasonably good reasons to believe that misdirected neural stem cells / precursor cells mutate into cancer cells and form glioblastomas.

Several years ago researchers from the MDC and Charité (Berlin) showed that normal stem cell/ precursor cells of the brain can attack glioblastomas.  Apparently, the tumor itself entices these stem cells to migrate over relatively long distances from the stem cell niches of the brain.  How?

These used cell culture and other techniques to show that neural stem cells and neural precursor cells release a protein that belongs to the family of the BMP proteins (bone morphogenetic protein).  BMPs received their names because they are able to induce bone and cartilage tissue formation, but they are quite active in the brain.  Neural stem cells release BMP-7 in the brain in the vicinity of the glioblastoma cells. The protein influences a small population of cancer cells, the so-called tumor stem cells.  These tumor stem cells seem to be the actual cause for the continuous tumor self-renewal in the brain, but a fraction of these cells is sufficient to form new tumors again even after surgery. BMP-7 induces signaling in the tumor stem cells, causing them to differentiate, which makes them tumor stem cells no longer.

However, the activity of stem cells in the brain and thus of the body’s own protective mechanism against glioblastomas diminishes with increasing age. This could explain why the tumors usually develop in older adults and not in children and young people.

These discoveries could lead to new concepts in the therapy of glioblastomas.  “Normal cancer cells” can be destroyed using conventional therapies (surgery, radiation, chemotherapy), which are seldom successful in tumor stem cells.  The aim is therefore to develop therapy concepts to destroy these tumor stem cells.  Findings from the mouse experiments could point to a new approach: reprogramming tumor stem cells into less harmful cells, which could then be destroyed with a therapy.

X chromosomal inactivation creates variation in embryonic stem cell cultures

Human embryonic stem cells (hESCs) might provide the material for regenerative medicine. However, one of the biggest challenges for getting these cells from the bench to the clinic is ensuring their safety and quality while mass producing them.

However, several hurdles must be scaled before these cells can come into the clinic, and one of these hurdles is embryonic stem cell instability.  Even though the original publications of the original derivation of embryonic stem cells showed that they were stable in culture over long periods of time, subsequent studies have called into question the stability of these cells.  Another is the cell-to-cell variation  that exists in a single embryonic stem cell culture.

Now scientists at the UCLA Broad Stem Cell Research Center have shown that female hESCs show variation that might be be a result of X chromosome inactivation.  All female cells have two X chromosomes and in early development, one X chromosome is permanently inactivated. The X chromosome inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell and that the cells develop normally. If the second X chromosome is not inactivated, the result could be disease development, including some cancers in which two active X chromosomes can be found in the malignant cells.

Chromosomal and genetic variations found in human embryonic stem cells lines have been attributed to the various culture conditions in which they’re grown.  However, work by Tamar Dvash and her colleagues at the Broad Stem Cell Research Center scientists reveals that very early in their growth, female human embryonic stem cells already show variation in the inactivation of the X chromosome.

Guoping Fan, an associate professor of human genetics and senior author of the study stated, “It suggests that culture conditions and methods in the derivation of human embryonic stem cells could be further improved to achieve a uniform pattern of X chromosome inactivation.”

Previously, what scientists knew about human embryonic development was gleaned from studying mouse embryos. However, the advent of human embryonic stem cell research has allowed researchers to closely study early human development.  Dvash, Fan and other scientists, including collaborator Neta Lavon of Cedars-Sinai Medical Center, were examining the process of inactivation of the X chromosome when they made their observation.

The creation of a stem cell line includes many steps.  The donated, frozen blastocysts are thawed and the inner cell mass—the 20 to 50 cells that are fully pluripotent in the blastocyst—is placed in culture with cells that support its growth. After a time, a small piece of the developing stem cell colony, or group of cells, is cut away and placed into a culture dish to further expand, a process called passaging.

The cells studied by Dvash and Fan were passaged only five to ten times instead of the usual more than 20 times, meaning the culture in which they were grown should have had less influence on any variation found in the cells. However, even at the first five passages, the resulting cells showed variations in X chromosome inactivation, meaning some cells had inactivated one X chromosome and some had not.

“People are looking at these cells as having great potential for transplantation and possible cures for diseases,” Dvash said. “What this study proves is that we need to monitor X chromosome inactivation closely in cells being considered for therapeutic use. We need to make sure they’re undergoing normal inactivation to ensure they will be stable when they begin to differentiate.”

Going forward, the scientists will also examine induced pluripotent stem cells, adult stem cells that have been reprogrammed to have all the qualities of embryonic stem cells, which can become any cell in the body. They will study skin cells taken from females, which would already have undergone inactivation of one X chromosome because they are already differentiated. The cells will be programmed into embryonic-like cells with two active X chromosomes so they can more closely study the process of inactivation.