Category Archives: Gene therapy

Sacramento, Calif. (PRWEB) December 22, 2014

Using modified human stem cells, a team of UC Davis scientists has developed an improved gene therapy strategy that in animal models shows promise as a functional cure for the human immunodeficiency virus (HIV) that causes AIDS. The achievement, which involves an improved technique to purify populations of HIV-resistant stem cells, opens the door for human clinical trials that were recently approved by the U.S. Food and Drug Administration.

We have devised a gene therapy strategy to generate an HIV-resistant immune system in patients, said Joseph Anderson, principal investigator of the study and assistant professor of internal medicine. We are now poised to evaluate the effectiveness of this therapy in human clinical trials.

Anderson and his colleagues modified human stem cells with genes that resist HIV infection and then transplanted a near-purified population of these cells into immunodeficient mice. The mice subsequently resisted HIV infection, maintaining signs of a healthy immune system.

The findings are now online in a paper titled Safety and efficacy of a tCD25 pre-selective combination anti-HIV lentiviral vector in human hematopoietic stem and progenitor cells, and will be published in the journal Stem Cells.

Using a viral vector, the researchers inserted three different genes that confer HIV resistance into the genome of human hematopoietic stem cells cells destined to develop into immune cells in the body. The vector also contains a gene which tags the surface of the HIV-resistant stem cells. This allows the gene-modified stem cells to be purified so that only the ones resistant to HIV infection are transplanted. The stem cells were then delivered into the animal models, with the genetically engineered human stem cells generating an HIV-resistant immune system in the mice.

The three HIV-resistant genes act on different aspects of HIV infection one prevents HIV from exposing its genetic material when inside a human cell; another prevents HIV from attaching to target cells; and the third eliminates the function of a viral protein critical for HIV gene expression. In combination, the genes protect against different HIV strains and provide defense against HIV as it mutates.

After exposure to HIV infection, the mice given the bioengineered cells avoided two important hallmarks of HIV infection: a drop in human CD4+ cell levels and a rise in HIV virus in the blood. CD4+ is a glycoprotein found on the surface of white blood cells, which are an important part of the normal immune system. CD4+ cells in patients with HIV infection are carefully monitored by physicians so that therapies can be adjusted to keep them at normal level: If levels are too low, patients become susceptible to opportunistic infections characteristic of AIDS. In the experiments, mice that received the genetically engineered stem cells and infected with two different strains of HIV were still able to maintain normal CD4+ levels. The mice also showed no evidence of HIV virus in their blood.

Although other HIV investigators had previously bioengineered stem cells to be resistant to HIV and conducted clinical trials in human patients, efforts were stymied by technical problems in developing a pure population of the modified cells to be transplanted into patients. During the process of genetic engineering, a significant percentage of stem cells remain unmodified, leading to poor resistance when the entire population of modified cells is transplanted into humans or animal models. In the current investigation, the UC Davis team introduced a handle onto the surface of the bioengineered cells so that the cells could be recognized and selected. This development achieved a population of HIV-resistant stem cells that was greater than 94 percent pure.

Developing a technique to purify the population of HIV-resistant stem cells is the most important breakthrough of this research, said Anderson, whose laboratory is based at the UC Davis Institute for Regenerative Cures. We now have a strategy that shows great promise for offering a functional cure for the disease.

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New Technique for Bioengineering Stem Cells Shows Promise in HIV Resistance

Scientists at Indiana University and colleagues at Stanford and the University of Texas have demonstrated a technique for "editing" the genome in sperm-producing adult stem cells, a result with powerful potential for basic research and for gene therapy.

The researchers completed a "proof of concept" experiment in which they created a break in the DNA strands of a mutant gene in mouse cells, then repaired the DNA through a process called homologous recombination, replacing flawed segments with correct ones.

The study involved spermatogonial stem cells, which are the foundation for the production of sperm and are the only adult stem cells that contribute genetic information to the next generation. Repairing flaws in the cells could thus prevent mutations from being passed to future generations.

"We showed a way to introduce genetic material into spermatogonial stem cells that was greatly improved from what had been previously demonstrated," said Christina Dann, associate scientist in the Department of Chemistry at IU Bloomington and a co-author of the study. "This technique corrects the mutation, theoretically leaving no other mark on the genome."

The paper, "Genome Editing in Mouse Spermatogonial Stem/Progenitor Cells Using Engineered Nucleases," was published in the online science journal PLOS-ONE.

The lead author, Danielle Fanslow, carried out the research as an IU research associate and is now a doctoral student at Northwestern University. Additional co-authors are from the Stanford School of Medicine and the University of Texas Southwestern Medical Center.

A challenge to the research was the fact that spermatogonial stem cells, like many types of adult stem cells, are notoriously difficult to isolate, culture and work with. It took years of intensive effort by multiple laboratories before conditions were created a decade ago to maintain and propagate the cells.

For the IU research, a primary hurdle was to find a way to make specific, targeted modifications to the mutant mouse gene without the risk of disease caused by random introduction of genetic material. The researchers used specially designed enzymes, called zinc finger nucleases and transcription activator-like effector nucleases, to create a double strand break in the DNA and bring about the repair of the gene.

Stem cells that had been modified in the lab were then transplanted into the testes of sterile mice. The transplanted cells grew or colonized within the mouse testes, indicating the stem cells were viable. However, attempts to breed the mice were not successful.

"Whether the failure to produce sperm was a result of abnormalities in the transplanted cells or the recipient testes was unclear," the researchers write.

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'Genome editing' could correct genetic mutations for future generations

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Newswise Study results of CD19-directed chimeric antigen receptor (CAR) therapy using the Sleeping Beauty non-viral transduction system to modify T cells has demonstrated further promise in patients with advanced hematologic malignancies.

Patients who had acute lymphocytic leukemia (ALL), non-Hodgkin lymphoma (NHL) or chronic lymphocytic leukemia (CLL) were part of clinical trials at The University of Texas MD Anderson Cancer Center, which used the Sleeping Beauty gene transfer system initially discovered at the University of Minnesota.

Results from the study were presented at the 56th Annual Meeting of the American Society of Hematology (ASH) annual conference in San Francisco and were published in the Dec. 5 issue of the ASH journal Blood.

The Sleeping Beauty gene was named for its ability to awaken an extinct transposon DNA that can replicate itself and insert the copy back into the genome. This allows a gene to be transferred into a DNA molecule known as a plasmid. An enzyme called a transposase binds to the plasmid, cuts the transposon and gene out of the plasmid and pastes it into the target DNA sequence. This gene transfer system was the basis for the MD Anderson clinical trials.

Using the Sleeping Beauty gene transfer system, Laurence Cooper, M.D., Ph.D., professor of pediatrics and Partow Kebriaei, M.D., associate professor of stem cell transplantation and cellular therapy, were able to plug a gene into T cells, creating an artificial or chimeric antigen receptor (CAR) on the T cell that recognizes and binds to CD19, a cell surface on B cells. The resultant product known as CAR T cells are produced at MD Anderson and are being employed in the Sleeping Beauty clinical trials.

We are treating patients with advanced CD19 positive hematologic malignancies using CAR T cells in combination with conventional blood stem cell transplantation, said Kebriaei. We are also treating patients who had active disease but had not received blood stem cell transplantation.

Patients were recipients of autologous (patients own cells) or allogeneic (donor cells) stem cell transplantations, which were administered in combination with CAR. Kebriaei reported no acute or long-term toxicity in the 33 patients treated.

Five patients at high risk for relapse were treated with CAR T cells along with autologous stem cell transplant, and four of those patients remain in complete remission with a median follow-up of 12 months, she said. Among 13 patients treated with donor CAR T cells after allogeneic stem cell transplantation, six remain in complete remission with a median follow-up of 7.5 months.

Read this article:
Experimental Gene Therapy Successful in Certain Lymphomas and Leukemia

Stem Cell Cure for "Bubble Baby" Disease (SCID), Pioneered by UCLA #39;s Don Kohn
On November 18th, 2014, a UCLA research team led by Donald Kohn, M.D., announced a breakthrough gene therapy and stem cell cure for "bubble baby" disease, or severe combined ...

By: California Institute for Regenerative Medicine

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Stem Cell Cure for "Bubble Baby" Disease (SCID), Pioneered by UCLA's Don Kohn - Video

A new treatment for children with "bubble baby" conditions means a pair of California twins can finally have their chubby cheeks kissed.

A team at the University of California Los Angeles has combined two techniques gene therapy and stem cell therapy to treat 18 children with a genetically inherited immune condition called ADA-deficient severe combined immunodeficiency or SCID. They think it may be a true cure, but will have to wait a few more years to be sure.

Its made all the difference for two-year-old Evangelina Padilla-Vaccaro, who was diagnosed just weeks after she and her twin sister Annabella were born.

Hearing that news, you just figure your kid is dead, said Alysia Padilla-Vaccaro. Youre supposed to be showing off your kids, not thinking youre going to be burying one, she added, wiping away tears.

A bone marrow transplant can cure the condition, but Annabella wasnt a match for Evangelina. That meant isolation, because with ADA-SCID, even a common cold can kill.

So there was no kissing of our babies, Padilla-Vaccaro said. You just want to bite those chubby cheeks and kiss that face and we didn't get that until they were about 18 months old, she added.

The UCLA medical team at UCLAs Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, led by Dr. Donald Kohn, announced it has cured 18 children with severe combined immunodeficiency.

SCID is really rare and ADA-SCID even rarer affecting maybe one in a million children. Its caused by defective genes and in the case of ADA-SCID its the gene responsible for an immune system component called adenosine deaminase.

Courtesy Padilla-Vaccaro family

Evangelina Padilla-Vaccaro was diagnosed with a "bubble baby" condition just weeks after she and her twin sister Annabella were born.

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New 'bubble baby' treatment means kisses for 18 kids

TIME Health medicine Bubble Boy Disease Cured With Stem Cells Alysia Padilla-Vacarro and daughter Evangelina on the day of her gene therapy treatment. Evangelina, now two years old, has had her immune system restored and lives a healthy and normal life. Courtesy of UCLA Researchers have treated more than two dozen patients with a treatment made from their own bone marrow cells

Alysia Padilla-Vacarro and Christian Vacarro owe their daughters life to stem cells. Evangelina, now two, is alive today because she saved herself with her own bone marrow cells.

Evangelina, a twin, was born with a severe immune disorder caused by a genetic aberration that makes her vulnerable to any and all bacteria and viruses; even a simple cold could be fatal. But doctors at University of California Los Angeles (UCLA) Broad Stem Cell Research Center gave her a new treatment, using her own stem cells, that has essentially cured her disease. Shes one of 18 children who have been treated with the cutting-edge therapy, and the studys leader, Dr. Donald Kohn, says that the strategy could also be used to treat other gene-based disorders such as sickle cell anemia.

Known to doctors as adenosine deaminase (ADA)-deficient severe combined immunodeficiency (SCID), its better known as bubble boy disease, since children born with the genetic disorder have immune systems so weak that they need to stay in relatively clean and germ-free environments. Until Evangelina and her sister Annabella were 11 months old, We were gowned and masked and did not go outside, says their mother Alysia Padilla-Vaccaro. Our children did not physically see our mouths until then because we were masked all the time. We couldnt take them outside to take a breath of fresh air, because there is fungus in the air, and that could kill her.

Both parents wore masks at work to lower the chances they would be exposed to germs that they might bring back home. And they took showers and changed clothes as soon as they entered the house.

MORE: Gene-Therapy Trial Shows Promise Fighting Bubble Boy Syndrome

SCID is caused by a genetic mutation in the ADA gene, which normally produces the white blood cells that are the front lines of the bodys defense against bacteria and viruses. The Vaccaros decided to treat Annabella in the same way that they cared for Evangelina; They were crawling and playing with each other, and every toy they sucked on, they stuck in each others hands and each others mouth, so we couldnt take one outside to have a grand old time and potentially bring something back that could harm her sister, says Padilla-Vaccaro.

The only treatments for SCID are bone marrow transplants from healthy people, ideally a matched sibling; the unaffected cells can then repopulate the immune system of the baby with SCID. But despite being her twin, Annabella wasnt a blood match for her sister, nor were her parents. Padilla-Vaccaro and her husband, Christian, were considering unrelated donors but were concerned about the risk of rejection. We would be trying to fix one problem and getting another, she says.

MORE: Stem Cells Allow Nearly Blind Patients to See

Thats when the doctors at the Childrens Hospital at Orange County, where Evangelina was diagnosed, told her parents about a stem cell trial for SCID babies at UCLA, led by Dr. Donald Kohn. As soon as they said trial, I thought, my kid is dead, says Padilla-Vaccaro of the last resort option. But a dozen children born with other forms of SCIDin which different mutations caused the same weak immune systemswho were successfully treated by Kohn convinced the couple that the therapy was worth trying. Kohn had one spot left in the trial and was willing to hold it for Evangelina until she matured more. Born premature, she was diagnosed at six weeks old and needed more time for what was left of her immune system to catch up to weather the procedure.

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Bubble Boy Disease Cured With Stem Cells

Stem Cells FDA Oversight
Celia Witten, M.D., Ph.D., Director, Office of Cellular, Tissue, Gene Therapy Center for Biologics Evaluation Research, Food Drug Administration (FDA) For more information on the 2014...

By: Alliance for Regenerative Medicine

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Stem Cells & FDA Oversight - Video

A new variation of gene therapy raises hopes for a safe and effective long-term treatment for X-linked severe combined immunodeficiency syndrome (SCID-X1), a life-threatening heritable disorder.

The research was produced by a collaborative research team from Dana-Farber/Boston Children's Cancer and Blood Disorders Center, along with other institutions participating in an international clinical trial that involved boys from the United States and France.

SCID-X1, dubbed bubble boy disease after a patient who lived for 12 years in a sterile bubble, is a rare genetic disorder that hinders the ability of individuals to combat infections. Because the disease is carried in an X-chromosome recessive pattern, the disorder occurs almost only in males. The resulting mutations inactivate a gene called IL-2 receptor gamma (IL2RG), severely weakening immune system functions. Left untreated, individuals who inherit the disorder usually die within a year.

Previous gene therapy trials conducted in Europe over a decade ago promised dramatic progress, until a quarter of patients developed leukemia about two to five years following treatment. Scientists found that the previously used vectorthe device for transporting the correct gene in therapyinadvertently activated oncogenes, which can cause cancer.

In this new study, the vector in use is a self-inactivating gammaretrovirus, which has a specific sequence deleted that basic research had implicated in the process of inappropriate activation of oncogenes, David A. Williams, chief of the hematology/oncology department at Boston Children's Hospital, wrote in an email.

Of the nine patients who underwent the treatment, eight had survived between 12 and 38 months after treatment. One boy died from a severe infection he was fighting at the time he enrolled in the study.

A single round of therapy restored normal disease-fighting T cell count300 cells or more per microliter of bloodin six of the eight patients. One patient underwent a second round of treatment and remains healthy despite a low cell count. The eighth patient received a hematopoietic stem cell transplant after the therapy led to less than optimal uptake of the virus and failed to stimulate T-cell production, according to Williams.

We feel the surrogate assays for safety look excellent and are very encouraged, Williams said. However, because leukemia can take years to develop (and although some of our patients are now approaching 4 years of [follow-up]) we must be cautious and continue to follow these children closely.

Williams noted that the research was the result of positive collaboration between institutions.

Work by Sung-Yun Pai and Gigi Notarangelo, funding from [Boston Childrens Hospital] (and other childrens hospitals) and [the National Institute of Health] were essential for success, he said. This is the first international collaborative trial in stem cell gene therapy, which was critical for success due [to the] rarity of [this] disease.

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With Collaboration, Scientists Test Gene Therapy for 'Bubble Boy Disease'

PHILADELPHIA A new form ofgene therapyfor boys with X-linked severe combined immunodeficiency syndrome (SCID-X1), a life-threatening condition also known as bubble boy disease, appears to be both effective and safe, according to an international clinical trial with sites inBoston, Cincinnati, Los Angeles, London, and Paris.

Early data published in theNew England Journal of Medicinesuggests that the therapy may avoid the late-developing leukemiaseen in a quarter of SCID-X1 patients in previous gene-therapy trials in Europe that took place more than a decade ago. Left untreated, boys with SCID-X1 usually die of infection before their first birthday.

The lab of coauthorFrederic Bushman, PhD, professor of Microbiology, from thePerelman School of Medicine at the University of Pennsylvania, carried out the deep DNA sequencing on patient specimens to track and verify distributions of integration sites of the vector.The vector used in the new trial was engineered to remove molecular signals implicated in cancers in the first trial.

Eight of nine boys recruited to date to the present trial are alive between 12 and 38 months after treatment, with no SCID-X1-associated infections. The gene therapy alone generated functioning immune systems in seven of eight boys. Genetic studies showed that the new viral vector did not lead to vector insertions near known cancer-causing genes, raising cautious hopes about the vector's long-term safety.

We showed that fewer cells accumulated with integration sites near cancer genes in the second trial, suggesting that the adverse properties had indeed been engineered out, explains Bushman So far there are no clinical adverse events in the present trial -- the integration site data has suggested improved safety.

The modified vector created for the current trial is a self-inactivating gammaretrovirus, designed to deliver its payload effectively while minimizing the chance of inadvertently turning on oncogenes that could lead to leukemia.

The core question of the trial was whether the new self-inactivating viral vector could safely and successfully shuttle a gene called theIL-2 receptor gamma(IL2RG) subunit into the patients' hematopoietic stem cells. In boys born with SCID-X1, mutations render theIL2RGgene inactive, robbing the children of the ability to produce a functional immune system.

For more information, see theDana-Farber/Boston Children's Cancer and Blood Disorders Centersnews release.

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Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of theRaymond and Ruth Perelman School of Medicine at the University of Pennsylvania(founded in 1765 as the nation's first medical school) and theUniversity of Pennsylvania Health System, which together form a $4.3 billion enterprise.

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New Gene Therapy for "Bubble Boy" Disease Appears to be Safe, Effective

TIME Health Genetics Gene-Therapy Trial Shows Promise Fighting Bubble Boy Syndrome The immune system-related disease affects about 1 in 100,000 babies each year

A new gene-therapy treatment is showing promise in treating a rare and severe congenital condition that involves extreme immune-system deficiencies.

Bubble boy syndrome, an X-linked condition, takes its name from a famous case in which an affected boy, vulnerable to infection, lived inside a plastic bubble that protected him from the worlds germs. Outside of such sterile environments, babies with the syndrome seldom live longer than a year, the Wall Street Journal reports.

The condition has for decades bested medical researchers, despite occasional bouts of optimism hope for one previous gene-therapy treatment was felled when some recipients developed leukemia.

Gene-therapy treatment works, essentially, by replacing unperforming genes with functional ones. Dysfunctional cells are removed from the childs immune system and exposed to a genetically engineered virus that can reprogram the cells to function properly, explains Reuters. Those cells are then reinserted back into the patient.

In the earlier treatment, the virus to which the cells were exposed apparently activated a part of their genetic code that leads to leukemia, Reuters says.

But initial results reported in the New England Journal of Medicine show that none of the nine babies from the U.S. and Europe who received the latest treatment are exhibiting any signs of cancer.

Of the nine infant participants in the research who were between 4 and 10 months old when they began receiving the therapy eight were still alive 16 to 43 months later, without living in a protective bubble. (The ninth child died four months after treatment began from an earlier infection he had been fighting.)

Out of the eight boys still living, the treatment upped blood T-cell levels, rebuilding the immune system, of seven. In the case of the eighth child, the treatment did not rebuild his immune system, but a successful stem-cell transplant has kept him in improved health, Reuters reports.

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Gene-Therapy Trial Shows Promise Fighting Bubble Boy Syndrome