graft vs host disease

Improving a special kind of cell to help combat immune related problems

/ Yimy Villa / 1 Comment

Regulatory T cells (Tregs) are a type of immune cell that play an extremely important role in maintaining stability in the body and preventing the body’s immune system from attacking its own cells and organs. This unique property makes Tregs extremely valuable to researchers as a potential treatment for immune related issues. One of these is autoimmune disease, which is a disease in which the body’s own immune system attacks healthy cells. Some examples of this are type 1 diabetes, multiple sclerosis, and lupus. Another immune related issue is graft vs. host disease (GvHD), which can occur after receiving a transplantation where the donated bone marrow or stem cells start attacking the recipient.

For this reason, researchers at the La Jolla Institute for Immunology (LJI) and Emory University School of Medicine, partially supported by a CIRM training grant , have been working to generate stable induced Tregs (iTregs) for treating autoimmune diseases and rejection of a transplanted organ. The teams were led by LJI professor Anjana Rao, Ph.D, and Emory instructor Benjamin G. Barwick, Ph.D. The two team study showed evidence that vitamin C and and specific proteins called TET can be combined to give Tregs their life-saving power. Studies have previously found that vitamin C can enhance the activity of TET proteins and prompt the generation of stable iTregs under lab conditions.

For this study, the researchers also analyzed gene expression patterns as well as changes that altered the physical structure of DNA in the induced Tregs. The team found a major modification involving the DNA itself and showed that TET enzymes were also involved. All of these interactions can eventually change how cells “read” the DNA code. They also observed the alteration of DNA accessibility which depends on whether DNA is loosely or tightly coiled. As the DNA coils unwind, regulatory regions become exposed which subsequently influence gene expression.

In a news release, LJI instructor Xiaojing Yue, Ph.D elaborated on the results of this study.

“Vitamin C can be used to stabilize iTregs generated in vitro. We hope that these kinds of induced Tregs can be used in the future for treatment of autoimmune diseases and organ transplantation.”

The full study was published in EMBO reports.

Cord blood transplants help children fighting deadly diseases

/ Kevin McCormack / Leave a comment
Dr. Paul Szabolcs: Photo courtesy of UPMC

A simple blood stem cell transplant is showing tremendous promise in treating a wide range of metabolic, blood and immune disorders such as thalassemia and some leukodystrophies.

These are considered rare diseases – meaning there are fewer than 200,000 people with them in the US – so there is often little funding available to develop new therapies to help people suffering from them. So, researchers at UPMC Children’s Hospital of Pittsburgh set out to develop a therapy that could help several different disorders without having to craft individual approaches for each condition.

The team used blood stem cells from donated umbilical cords and placentas. In a news article, study senior author Dr. Paul Szabolcs, said they then used a combination of chemotherapy and immunotherapy to prepare the patients for the transplant and increase the chance of success.

“We approached the topic with the mindset to design a regimen that carefully balances low-intensity chemo (bringing safety) with sufficiently effective immunotherapy to blast away the patients’ immune system, therefore preventing rejection. Rejection has been a common failure when other centers explored the reduced-intensity conditioning (RIC) approach with cord blood. We are the first to prove the RIC is able to give reliable results in long-term engraftment.”

Szabolcs says another advantage to their approach was that it meant there didn’t need to be a perfect immune system match of donor and recipient.

“That’s huge for ethnic minorities. The probability of a perfect match is very low, but with a cord blood graft, we have a chance to overcome this discrepancy over the course of a couple months and then taper immunosuppressants away.”

Altogether 44 children were treated this way. After undergoing the preparation, they had the blood stem cells transfused into them and, once those cells had integrated into the body they got a second, smaller, transfusion a few weeks later to help kick start their immune system.

Most of the complications from the infusions were mild, and while around 5 percent of children died from viral infection due to the immune suppression this was much lower than in earlier studies. Another encouraging sign was that none of the children suffered severe Graft vs Host disease which can be fatal.

Thirty of the children in the trial suffered from metabolic disorders, meaning their bodies were unable to remove dangerous toxins, and this led to developmental delays in their brains. One year after the treatment all 30 children had normal enzyme levels and their neurological decline had stopped. Some of the children even showed improvements and gained new skills.

Most of the children with metabolic disorders had leukodystrophies. These are usually fatal within a few years of diagnosis. Even with a cord blood transplant the three-year survival rate is only 60 percent. In this trial more than 90 percent of children with leukodystrophies were alive after three years.

Dr. Szabolcs says this approach has a lot of advantages over existing approaches, including cost.

“There has been a lot of emphasis placed on cool new technologies that might address these diseases, but — even if they prove effective — those aren’t available to most centers. The regimen we developed is more robust, readily applicable and will remain significantly less expensive.”

The study was published in the journal Blood Advances.

Donor blood stem cells and T cells could help patients wean off immunosuppressive drugs after organ transplant

/ Yimy Villa / 1 Comment
Dr. Samuel Strober is refining a process that eliminates the need for the many immunosuppresant drugs normally required after a transplant.
Image credit: Stanford Medicine News Center

In 2019, there were over 23,000 kidney transplants in the United States, according to figures from the United Network for Organ Sharing (UNOS). These transplants can be lifesaving, but the donated organ can be perceived as a foreign invader by the patient’s immune system and attacked. In order to protect the organ from attack, transplant recipients are required to take numerous drugs that suppress the immune system, which are referred to as immunosupressive (IS) drugs. Unfortunately, these drugs, while helping protect the organ, can also cause long term problems such as hypertension, diabetes, heart disease, infection, a high concentration of fats in the blood, and cancer.

To address this problem, Dr. Samuel Strober and his team at Stanford University are conducting a CIRM-funded clinical trial that gives patients getting a kidney transplant a mixture of their own blood cells and cells from the kidney donor, a process called mixed chimerism.

Pairing patients and donors for transplants is done via Human Leukocyte Antigen (HLA) matching. HLA are markers on most cells in your body and are used by your immune system to recognize which cells belong to the body. If you are fully HLA matched that means your cells and the donor cells are immunologically compatible, and so less likely to be rejected. If they are HLA haplotypes, it means they are close but not fully matched so rejection is more likely.

In the trial, fifty-one patients with end stage renal failure that had just received a kidney transplant were infused with blood stem cells (cells that can give rise to different kind of blood cells) and T cells (a cell that plays a role in the immune response) obtained from the donor to achieve a mixed chimerism. Of the 51 patients 29 were fully HLA matched, and 22 were HLA haplotype matched.

Standard IS drugs were administered to all the patients after transplantation and the patients were monitored from six to twelve months to ensure there was no organ rejection or graft vs host disease (GVHD), a condition where donated blood stem cells attack the body.

After this period, the patients were taken off the IS drugs and the results of this trial are very promising. Twenty-four of the fully HLA matched patients with a persistent mixed chimerism for at least six months were able to stop taking the IS drugs without evidence of rejection for at least two years. Ten HLA haplotype matched patients with a persistent mixed chimerism for at least twelve months were able to stop taking some of the IS drugs without rejection.

This is encouraging news for patients undergoing any kind of transplant, leading to hope that one day all patients might be able to get a life-saving organ without having to take the IS drugs forever.

The full results of this study were published in Science Translational Medicine.

New hope for stem cell therapy in patients with leukemia

/ Pallavi Penumetcha / 1 Comment

LeukemiaWhiteBloodCell

Leukemia white blood cell

Of the many different kinds of cancer that affect humans, leukemia is the most common in young people. As with many types cancer, doctors mostly turn to chemotherapy to treat patients. Chemotherapy, however, comes with its own share of issues, primarily severe side effects and the constant threat of disease recurrence.

Stem cell therapy treatment has emerged as a potential cure for some types of cancer, with leukemia patients being among the first groups of patients to receive this type of treatment. While exciting because of the possibility of a complete cure, stem cell therapy comes with its own challenges. Let’s take a closer look.

Leukemia is characterized by abnormal white blood cells (also known as the many different types of cells that make up our immune system) that are produced at high levels. Stem cell therapy is such an appealing treatment option because it involves replacing the patient’s aberrant blood stem cells with healthy ones from a donor, which provides the possibility of complete and permanent remission for the patient.

Unfortunately, in approximately half of patients who receive this therapy, the donor cells (which turn into immune cells), can also destroy the patients healthy tissue (i.e. liver, skin etc…), because the transplanted blood stem cells recognize patient’s tissue as foreign. While doctors try to lessen this type of response (also known as graft versus host disease (GVHD)), by suppressing the patient’s immune system, this procedure lessens the effectiveness of the stem cell therapy itself.

Now scientists at the University of Zurich have made an important discovery – published in the journal Science Translational Medicine – that could mitigate this potentially fatal response in patients. They found that a molecule called GM-CSF, is a critical mediator of the severity of GVHD. Using a mouse model, they showed that if the donor cells were unable to produce GM-CSF, then mice fared significantly better both in terms of less damage to tissues normally affected by GVHD, such as the skin, and overall survival.

While exciting, the scientists were concerned about narrowing in on this molecule as a potential target to lessen GVHD, because GM-CSF, an important molecule in the immune system, might also be important for ensuring that the donor immune cells do their jobs properly. Reassuringly, the researchers found that blocking GM-CSF’s function had no effect on the ability of the donor cells to exert their anti-cancer effect. This was surprising because previously the ability of donor cells to cause GVHD, versus protect patients from the development of cancer was thought to occur via the same biological mechanisms.

Most excitingly, however, was that finding that high levels of GM-CSF are also observed in patient samples, and that the levels of GM-CSF correlate to the severity of GVHD. Dr. Burkhard Becher and his colleagues, the authors of this study, now want to run a clinical trial to determine whether blocking GM-CSF blocks GVHD in humans like it does in mice. In a press release, Dr. Becher states the importance of these findings:

“If we can stop the graft-versus-host response while preserving the anti-cancer effect, this procedure can be employed much more successfully and with fewer risks to the patient. This therapeutic strategy holds particular promise for patients with the poorest prognosis and highest risk of fatality.”

Stories that caught our eye: How dying cells could help save lives; could modified blood stem cells reverse diabetes?; and FDA has good news for patients, bad news for rogue clinics

/ Kevin McCormack / Leave a comment

Gunsmoke

Growing up I loved watching old cowboy movies. Invariably the hero, even though mortally wounded, would manage to save the day and rescue the heroine and/or the town.

Now it seems some stem cells perform the same function, dying in order to save the lives of others.

Researchers at Kings College in London were trying to better understand Graft vs Host Disease (GvHD), a potentially fatal complication that can occur when a patient receives a blood stem cell transplant. In cases of GvHD, the transplanted donor cells turn on the patient and attack their healthy cells and tissues.

Some previous research had found that using bone marrow cells called mesenchymal stem cells (MSCs) had some success in combating GvHD. But it was unpredictable who it helped and why.

Working with mice, the Kings College team found that the MSCs were only effective if they died after being transplanted. It appears that it is only as they are dying that the MSCs engage with the individual’s immune system, telling it to stop attacking healthy tissues. The team also found that if they kill the MSCs just before transplanting them into mice, they were just as effective.

In a news article on HealthCanal, lead researcher Professor Francesco Dazzi, said the next step is to see if this will apply to, and help, people:

“The side effects of a stem cell transplant can be fatal and this factor is a serious consideration in deciding whether some people are suitable to undergo one. If we can be more confident that we can control these lethal complications in all patients, more people will be able to receive this life saving procedure. The next step will be to introduce clinical trials for patients with GvHD, either using the procedure only in patients with immune systems capable of killing mesenchymal stem cells, or killing these cells before they are infused into the patient, to see if this does indeed improve the success of treatment.”

The study is published in Science Translational Medicine.

Genetically modified blood stem cells reverse diabetes in mice (Todd Dubnicoff)

When functioning properly, the T cells of our immune system keep us healthy by detecting and killing off infected, damaged or cancerous cells in our body. But in the case of type 1 diabetes, a person’s own T cells turn against the body by mistakenly targeting and destroying perfectly normal islet cells in the pancreas, which are responsible for producing insulin. As a result, the insulin-dependent delivery of blood sugar to the energy-hungry organs is disrupted leading to many serious complications. Blood stem cell transplants have been performed to treat the disease by attempting to restart the immune system. The results have failed to provide a cure.

Now a new study, published in Science Translational Medicine, appears to explain why those previous attempts failed and how some genetic rejiggering could lead to a successful treatment for type 1 diabetes.

An analysis of the gene activity inside the blood stem cells of diabetic mice and humans reveals that these cells lack a protein called PD-L1. This protein is known to play an important role in putting the brakes on T cell activity. Because T cells are potent cell killers, it’s important for proteins like PD-L1 to keep the activated T cells in check.

Cell based image for t 1 diabetes

Credit: Andrea Panigada/Nancy Fliesler

Researchers from Boston Children’s Hospital hypothesized that adding back PD-L1 may prevent T cells from the indiscriminate killing of the body’s own insulin-producing cells. To test this idea, the research team genetically engineered mouse blood stem cells to produce the PD-L1 protein. Experiments with the cells in a petri dish showed that the addition of PD-L1 did indeed block the attack-on-self activity. And when these blood stem cells were transplanted into a diabetic mouse strain, the disease was reversed in most of the animals over the short term while a third of the mice had long-lasting benefits.

The researchers hope this targeting of PD-L1 production – which the researchers could also stimulate with pharmacological drugs – will contribute to a cure for type 1 diabetes.

FDA’s new guidelines for stem cell treatments

Gottlieb

FDA Commissioner Scott Gottlieb

Yesterday Scott Gottlieb, the Commissioner at the US Food and Drug Administration (FDA), laid out some new guidelines for the way the agency regulates stem cells and regenerative medicine. The news was good for patients, not so good for clinics offering unproven treatments.

First the good. Gottlieb announced new guidelines encouraging innovation in the development of stem cell therapies, and faster pathways for therapies, that show they are both safe and effective, to reach the patient.

At the same time, he detailed new rules that provide greater clarity about what clinics can do with stem cells without incurring the wrath of the FDA. Those guidelines detail the limits on the kinds of procedures clinics can offer and what ways they can “manipulate” those cells. Clinics that go beyond those limits could be in trouble.

In making the announcement Gottlieb said:

“To be clear, we remain committed to ensuring that patients have access to safe and effective regenerative medicine products as efficiently as possible. We are also committed to making sure we take action against products being unlawfully marketed that pose a potential significant risk to their safety. The framework we’re announcing today gives us the solid platform we need to continue to take enforcement action against a small number of clearly unscrupulous actors.”

Many of the details in the announcement match what CIRM has been pushing for some years. Randy Mills, our previous President and CEO, called for many of these changes in an Op Ed he co-wrote with former US Senator Bill Frist.

Our hope now is that the FDA continues to follow this promising path and turns these draft proposals into hard policy.

 

One man’s journey with leukemia has turned into a quest to make bone marrow stem cell transplants safer

/ Karen Ring / Leave a comment

Dr. Lukas Wartman in his lab in March 2011 (left), before he developed chronic graft-versus-host disease, and last month at a physical therapy session (right). (Photo by Whitney Curtis for Science Magazine)

I read a story yesterday in Science Magazine that really stuck with me. It’s about a man who was diagnosed with leukemia and received a life-saving stem cell transplant that is now threatening his health.

The man is name Lukas Wartman and is a doctor at Washington University School of Medicine in St. Louis. He was first diagnosed with a type of blood cancer called acute lymphoblastic leukemia (ALL) in 2003. Since then he has taken over 70 drugs and undergone two rounds of bone marrow stem cell transplants to fight off his cancer.

The first stem cell transplant was from his brother, which replaced Wartman’s diseased bone marrow, containing blood forming stem cells and immune cells, with healthy cells. In combination with immunosuppressive drugs, the transplant worked without any complications. Unfortunately, a few years later the cancer returned. This time, Wartman opted for a second transplant from an unrelated donor.

While the second transplant and cancer-fighting drugs have succeeded in keeping his cancer at bay, Wartman is now suffering from something equally life threatening – a condition called graft vs host disease (GVHD). In a nut shell, the stem cell transplant that cured him of cancer and saved his life is now attacking his body.

GVHD, a common side effect of bone marrow transplants

GVHD is a disease where donor transplanted immune cells, called T cells, expand and attack the cells and tissues in your body because they see them as foreign invaders. GVHD occurs in approximately 50% of patients who receive bone marrow, peripheral blood or cord blood stem cell transplants, and typically affects the skin, eyes, mouth, liver and intestines.

The main reason why GVHD is common following blood stem cell transplants is because many patients receive transplants from unrelated donors or family members who aren’t close genetic matches. Half of patients who receive these types of transplants develop an acute form of GVHD within 100 days of treatment. These patients are put on immunosuppressive steroid drugs with the hope that the patient’s body will eventually kill off the aggressive donor T cells.

This was the case for Wartman after the first transplant from his brother, but the second transplant from an unrelated donor eventually caused him to develop the chronic form of GVHD. Wartman is now suffering from weakened muscles, dry eyes, mouth sores and skin issues as the transplanted immune cells slowly attack his body from within. Thankfully, his major organs are still untouched by GVHD, but Wartman knows it could be only a matter of time before his condition worsens.

Dr. Lukas Wartman has to use eye drops every 20 minutes to deal with dry eyes caused by GVHD. (Photo by Whitney Curtis for Science Magazine)

Hope for GVHD sufferers

Wartman along with other GVHD patients are basically guinea pigs in a field where effective drugs are still being developed and tested. Many of these patients, including Wartman, have tried many unproven treatments or drugs for other disease conditions in desperate hope that something will work. It’s a situation that is heartbreaking not only for the patient but also for their families and doctors.

There is hope for GVHD patients however. Science Magazine mentioned two promising drugs for GVHD, ibrutinib and ruxolitinib. Both received breakthrough therapy designation from the US Food and Drug Administration and could be the first approved treatments for GVHD.

Another promising therapy is called Prochymal. It’s a stem cell therapy developed by former CIRM President and CEO, Dr. Randy Mills, at Osiris Therapeutics. Prochymal is already approved to treat the acute form of GVHD in Canada, and is currently being tested in phase 3 trials in the US in young children and adults.

While CIRM isn’t currently funding clinical trials for GVHD, we are funding a trial out of Stanford University led by Dr. Judy Shizuru that aims to improve the outcome of bone marrow stem cell transplants in patients. Shizuru says that these transplants are “the most powerful form of cell therapy out there, for cancers or deficiencies in blood formation” but they come with their own set of potentially deadly side effects such as GVHD.

Shizuru is testing an antibody drug that blocks a signaling protein called CD117, which sits on the surface of blood stem cells and acts as an elimination signal. By turning off this protein, her team improved the engraftment of bone marrow stem cells in mice that had leukemia and removed their need for chemotherapy treatment. The therapy is in a Phase 1 trial for patients with an immune disease called severe combined immunodeficiency (SCID) who receive bone marrow transplants, but Shizuru said that her hope is the drug could also treat patients with certain cancers or blood diseases.

Advocating for better GVHD treatments

The reason the article in Science Magazine spoke to me is because of the power of Wartman’s story. Wartman’s battle with ALL and now GVHD has transformed him into one of the strongest patient voices advocating for the development of new GVHD treatments. Jon Cohen, the author of the Science Magazine article, explained:

“The urgency of his case has turned Wartman into one of the world’s few patients who advocate for GVHD research, prevention, and treatment. ‘Most people it affects suffer quietly,” says Wartman. ‘They’re grateful they’re alive, and they’re beaten down. It’s the paradox of being cured and dying of the cure. Even if you can get past that, you don’t have the energy to advocate, and that’s really tragic.’”

Patients like Wartman are an inspiration not only to other people with GVHD, but also to funding agencies and scientists working to advance GVHD research towards a cure. We don’t want these patients to suffer quietly. Wartman’s story is an important reminder that there’s a lot more work to do to make bone marrow transplants safer – so that they save lives without later putting those lives at risk.