Stanford study successful in transplant of mismatched stem cells, tissue in mice

Dr. Irv Weissman at Stanford University

A transplant can be a lifesaving procedure for many people across the United States. In fact, according to the Health Resources & Services Administration, 36,528 transplants were performed in 2018. However, as of January 2019, the number of men, women, and children on the national transplant waiting list is over 113,000, with 20 people dying each day waiting for a transplant and a new person being added to the list every 10 minutes.

Before considering a transplant, there needs to be an immunological match between the donated tissue and/or blood stem cells and the recipient. To put it simply, a “match” indicates that the donor’s cells will not be marked by the recipient’s immune cells as foreign and begin to attack it, a process known as graft-versus-host disease. Unfortunately, these matches can be challenging to find, particularly for some ethnic minorities. Often times, immunosuppression drugs are also needed in order to prevent the foreign cells from being attacked by the body’s immune system. Additionally, chemotherapy and radiation are often needed as well.

Fortunately, a CIRM-funded study at Stanford has shown some promising results towards addressing the issue of matching donor cells and recipient. Dr. Irv Weissman and his colleagues at Stanford have found a way to prepare mice for a transplant of blood stem cells, even when donor and recipient are an immunological mismatch. Their method involved using a combination of six specific antibodies and does not require ongoing immunosuppression.

The combination of antibodies did this by eliminating several types of immune cells in the animals’ bone marrow, which allowed blood stem cells to engraft and begin producing blood and immune cells without the need for continued immunosuppression. The blood stem cells used were haploidentical, which, to put it simply, is what naturally occurs between parent and child, or between about half of all siblings. 

Additional experiments also showed that the mice treated with the six antibodies could also accept completely mismatched purified blood stem cells, such as those that might be obtained from an embryonic stem cell line. 

The results established in this mouse model could one day lay the foundation necessary to utilize this approach in humans after conducting clinical trials. The idea would be that a patient that needs a transplanted organ could first undergo a safe, gentle transplant with blood stem cells derived in the laboratory from embryonic stem cells. The same embryonic stem cells could also then be used to generate an organ that would be fully accepted by the recipient without requiring the need for long-term treatment with drugs to suppress the immune system. 

In a news release, Dr. Weissman is quoted as saying,

“With support by the California Institute for Regenerative Medicine, we’ve been able to make important advances in human embryonic stem cell research. In the past, these stem cell transplants have required a complete match to avoid rejection and reduce the chance of graft-versus-host disease. But in a family with four siblings the odds of having a sibling who matches the patient this closely are only one in four. Now we’ve shown in mice that a ‘half match,’ which occurs between parents and children or in two of every four siblings, works without the need for radiation, chemotherapy or ongoing immunosuppression. This may open up the possibility of transplant for nearly everyone who needs it. Additionally, the immune tolerance we’re able to induce should in the future allow the co-transplantation of [blood] stem cells and tissues, such as insulin-producing cells or even organs generated from the same embryonic stem cell line.”

The full results to this study were published in Cell Stem Cell.

Stanford and University of Tokyo researchers crack the code for blood stem cells

Blood stem cells grown in lab

Blood stem cells offer promise for a variety of immune and blood related disorders such as sickle cell disease and leukemia. Like other stem cells, blood stem cells have the ability to generate additional blood stem cells in a process called self-renewal. Additionally, they are able to generate blood cells in a process called differentiation. These newly generated blood cells have the potential to be utilized for transplantations and gene therapies.

However, two limitations have hindered the progress made in this field. One problem relates to the amount of blood stem cells needed to make a potential transplantation or gene therapy viable. Unfortunately, it has been challenging to isolate and grow blood stem cells in large quantity needed for these approaches. A part of this reason relates to getting the blood stem cells to self-renew rather than differentiate.

The second problem involves the existing blood stem cells in the patient’s body prior to transplantation. In order for the procedure to work, the patient’s own blood stem cells must be eliminated to make space for the transplanted blood stem cells. This is done through a process known as conditioning, which typically involves chemotherapy and/or radiation. Unfortunately, chemotherapy and radiation can cause life-threatening side effects due to its toxicity, particularly in pediatric patients, such as growth retardation, infertility and secondary cancer in later life. Very sick or elderly patients are unable to tolerate this conditioning process, making them ineligible for transplants.

A CIRM funded study by a team at Stanford and the University of Tokyo has unlocked the code related to the generation of blood stem cells.

The collaborative team was able to modify the components used to grow blood stem cells. By making these modifications, which effects the growth and physical conditions of blood stem cells, the researchers have shown for the first time that it’s possible to get blood stem cells from mice to renew themselves hundreds or even thousands of times within a period of just 28 days. 

Furthermore, the team showed that when they transplanted the newly grown cells into mice that had not undergone conditioning, the donor cells had engrafted and remained functional.

The team also found that gene editing technology such as CRISPR could be used while growing an adequate supply of blood stem cells for transplantation. This opens the possibility of obtaining a patient’s own blood stem cells, correcting the problematic gene, and reintroducing these back to the patient.

The complete study was published in Nature.

In a news release, Dr. Hiromitsu Nakauchi, a senior author of the study, is quoted as saying,

“For 50 years, researchers from laboratories around the world have been seeking ways to grow these cells to large numbers. Now we’ve identified a set of conditions that allows these cells to expand in number as much as 900-fold in just one month. We believe this approach could transform how [blood] stem cell transplants and gene therapy are performed in humans.” 

How a see-through fish could one day lead to substitutes for bone marrow transplants

Human blood stem cells

For years researchers have struggled to create human blood stem cells in the lab. They have done it several times with animal models, but the human kind? Well, that’s proved a bit trickier. Now a CIRM-funded team at UC San Diego (UCSD) think they have cracked the code. And that would be great news for anyone who may ever need a bone marrow transplant.

Why are blood stem cells important? Well, they help create our red and white blood cells and platelets, critical elements in carrying oxygen to all our organs and fighting infections. They have also become one of the most important weapons we have to combat deadly diseases like leukemia and lymphoma. Unfortunately, today we depend on finding a perfect or near-perfect match to make bone marrow transplants as safe and effective as possible and without a perfect match many patients miss out. That’s why this news is so exciting.

Researchers at UCSD found that the process of creating new blood stem cells depends on the action of three molecules, not two as was previously thought.

Zebrafish

Here’s where it gets a bit complicated but stick with me. The team worked with zebrafish, which use the same method to create blood stem cells as people do but also have the advantage of being translucent, so you can watch what’s going on inside them as it happens.  They noticed that a molecule called Wnt9a touches down on a receptor called Fzd9b and brings along with it something called the epidermal growth factor receptor (EGFR). It’s the interaction of these three together that turns a stem cell into a blood cell.

In a news release, Stephanie Grainger, the first author of the study published in Nature Cell Biology, said this discovery could help lead to new ways to grow the cells in the lab.

“Previous attempts to develop blood stem cells in a laboratory dish have failed, and that may be in part because they didn’t take the interaction between EGFR and Wnt into account.”

If this new approach helps the team generate blood stem cells in the lab these could be used to create off-the-shelf blood stem cells, instead of bone marrow transplants, to treat people battling leukemia and/or lymphoma.

CIRM is also funding a number of other projects, several in clinical trials, that involve the use of blood stem cells. Those include treatments for: Beta Thalassemia; blood cancer; HIV/AIDS; and Severe Combined Immunodeficiency among others.

CIRM Board Approves Funding for New Clinical Trials in Solid Tumors and Pediatric Disease

Dr. Theodore Nowicki, physician in the division of pediatric hematology/oncology at UCLA. Photo courtesy of Milo Mitchell/UCLA Jonsson Comprehensive Cancer Center

The governing Board of the California Institute for Regenerative Medicine (CIRM) awarded two grants totaling $11.15 million to carry out two new clinical trials.  These latest additions bring the total number of CIRM funded clinical trials to 53. 

$6.56 Million was awarded to Rocket Pharmaceuticals, Inc. to conduct a clinical trial for treatment of infants with Leukocyte Adhesion Deficiency-I (LAD-I)

LAD-I is a rare pediatric disease caused a mutation in a specific gene that affects the body’s ability to combat infections.  As a result, infants with severe LAD-I are often affected immediately after birth. During infancy, they suffer from recurrent life-threatening bacterial and fungal infections that respond poorly to antibiotics and require frequent hospitalizations.  Those that survive infancy experience recurrent severe infections, with mortality rates for severe LAD-I at 60-75% prior to the age of two and survival very rare beyond the age of five.

Rocket Pharmaceuticals, Inc. will test a treatment that uses a patient’s own blood stem cells and inserts a functional version of the gene.  These modified stem cells are then reintroduced back into the patient that would give rise to functional immune cells, thereby enabling the body to combat infections.  

The award is in the form of a CLIN2 grant, with the goal of conducting a clinical trial to assess the safety and effectiveness of this treatment in patients with LAD-I.

This project utilizes a gene therapy approach, similar to that of three other clinical trials funded by CIRM and conducted at UCLA by Dr. Don Kohn, for X-linked Chronic Granulomatous Disease, an inherited immune deficiency “bubble baby” disease known as ADA-SCID, and Sickle Cell Disease.

An additional $4.59 million was awarded to Dr. Theodore Nowicki at UCLA to conduct a clinical trial for treatment of patients with sarcomas and other advanced solid tumors. In 2018 alone, an estimated 13,040 people were diagnosed with soft tissue sarcoma (STS) in the United States, with approximately 5,150 deaths.  Standard of care treatment for sarcomas typically consists of surgery, radiation, and chemotherapy, but patients with late stage or recurring tumor growth have few options.

Dr. Nowicki and his team will genetically modify peripheral blood stem cells (PBSCs) and peripheral blood monocular cells (PBMCs) to target these solid tumors. The gene modified stem cells, which have the ability to self-renew, provide the potential for a durable effect.

This award is also in the form of a CLIN2 grant, with the goal of conducting a clinical trial to assess the safety of this rare solid tumor treatment.

This project will add to CIRM’s portfolio in stem cell approaches for difficult to treat cancers.  A previously funded a clinical trial at UCLA uses this same approach to treat patients with multiple myeloma.  CIRM has also previously funded two clinical trials using different approaches to target other types of solid tumors, one of which was conducted at Stanford and the other at UCLA. Lastly, two additional CIRM funded trials conducted by City of Hope and Poseida Therapeutics, Inc. used modified T cells to treat brain cancer and multiple myeloma, respectively.

“CIRM has funded 23 clinical stage programs utilizing cell and gene medicine approaches” says Maria T. Millan, M.D., the President and CEO of CIRM. “The addition of these two programs, one in immunodeficiency and the other for the treatment of malignancy, broaden the scope of unmet medical need we can impact with cell and gene therapeutic approaches.”

CIRM & NHLBI Create Landmark Agreement on Curing Sickle Cell Disease

CIRM Board approves first program eligible for co-funding under the agreement

Adrienne Shapiro, co-founder of Axis Advocacy, with her daughter Marissa Cors, who has Sickle Cell Disease.

Sickle Cell disease (SCD) is a painful, life-threatening blood disorder that affects around 100,000 people, mostly African Americans, in the US. Even with optimal medical care, SCD shortens expected lifespan by decades.  It is caused by a single genetic mutation that results in the production of “sickle” shaped red blood cells.  Under a variety of environmental conditions, stress or viral illness, these abnormal red blood cells cause severe anemia and blockage of blood vessels leading to painful crisis episodes, recurrent hospitalization, multi-organ damage and mini-strokes.    

On April 29th the governing Board of the California Institute for Regenerative Medicine (CIRM) approved $4.49 million to Dr. Mark Walters at UCSF Benioff Children’s Hospital in Oakland to pursue a gene therapy cure for this devastating disease. The gene therapy approach uses CRISPR-Cas9 technology to correct the genetic mutation that leads to sickle cell disease. This program will be eligible for co-funding under the landmark agreement between CIRM and the National Heart, Lung and Blood Institute (NHLBI) of the NIH.

This CIRM-NHLBI agreement was finalized this month to co-fund cell and gene therapy programs under the NIH “Cure Sickle Cell” initiative.  The goal is to markedly accelerate the development of cell and gene therapies for SCD. It will deploy CIRM’s resources and expertise that has led to a portfolio of over 50 clinical trials in stem cell and regenerative medicine.     

“CIRM currently has 23 clinical stage programs in cell and gene therapy.  Given the advancements in these approaches for a variety of unmet medical needs, we are excited about the prospect of leveraging this to NIH-NHLBI’s Cure Sickle Cell Initiative,” says Maria T. Millan, M.D., the President and CEO of CIRM. “We are pleased the NHLBI sees value in CIRM’s acceleration and funding program and look forward to the partnership to accelerate cures for sickle cell disease.”

“There is a real need for a new approach to treating SCD and making life easier for people with SCD and their families,” says Adrienne Shapiro, the mother of a daughter with SCD and the co-founder of Axis Advocacy, a sickle cell advocacy and education organization. “Finding a cure for Sickle Cell would mean that people like my daughter would no longer have to live their life in short spurts, constantly having their hopes and dreams derailed by ER visits and hospital stays.  It would mean they get a chance to live a long life, a healthy life, a normal life.”

CIRM is currently funding two other clinical trials for SCD using different approaches.  One of these trials is being conducted at City of Hope and the other trial is being conducted at UCLA.

CIRM-funded therapy helps “bubble babies” lead a normal life

Ja’Ceon Golden; ‘cured” of SCID

At CIRM we are very cautious about using the “c” word. Saying someone has been “cured” is a powerful statement but one that loses its meaning when over used or used inappropriately. However, in the case of a new study from U.C. San Francisco and St. Jude Children’s Research Hospital in Memphis, saying “cure” is not just accurate, it’s a celebration of something that would have seemed impossible just a few years ago.

The research focuses on children with a specific form of Severe Combined Immunodeficiency (SCID) called X-Linked SCID. It’s also known as “bubble baby” disease because children born with this condition lack a functioning immune system, so even a simple infection could be fatal and in the past they were kept inside sterile plastic bubbles to protect them.

In this study, published in the New England Journal of Medicine, researchers took blood stem cells from the child and, in the lab, genetically re-engineered them to correct the defective gene, and then infused them back into the child. Over time they multiplied and created a new blood supply, one free of the defect, which helped repair the immune system.

In a news release Dr. Ewelina Mamcarz, the lead author of the study, announced that ten children have been treated with this method.

“These patients are toddlers now, who are responding to vaccinations and have immune systems to make all immune cells they need for protection from infections as they explore the world and live normal lives. This is a first for patients with SCID-X1.”

The ten children were treated at both St. Jude and at UCSF and CIRM funded the UCSF arm of the clinical trial.

The story, not surprisingly, got a lot of attention in the media including this fine piece by CNN.

Oh, and by the way we are also funding three other clinical trials targeting different forms of SCID. One with UCLA’s Don Kohn,  one with Stanford’s Judy Shizuru, and one with UCSF’s Mort Cowan

Stanford scientist uses CRISPR-Cas9 and stem cells to develop potential “bubble baby” therapy

Dr. Matthew Porteus, professor of pediatrics at Stanford University.
Photo courtesy of Stanford Medicine.

Our immune system is an important and essential part of everyday life. It is crucial for fighting off colds and, with the help of vaccinations, gives us immunity to potentially lethal diseases. Unfortunately, for some infants, this innate bodily defense mechanism is not present or is severely lacking in function.

This condition is known as severe combined immunodeficiency (SCID), commonly nicknamed “bubble baby” disease because of the sterile plastic bubble these infants used to be placed in to prevent exposure to bacteria, viruses, and fungi that can cause infection. There are several forms of SCID, one of which involves a single genetic mutation on the X chromosome and is known as SCID-X1

Many infants with SCID-X1 develop chronic diarrhea, a fungal infection called thrush, and skin rashes. Additionally, these infants grow slowly in comparison to other children. Without treatment, many infants with SCID-X1 do not live beyond infancy.

SCID-X1 occurs almost predominantly in males since they only carry one X chromosome, with at least 1 in 50,000 baby boys born with this condition. Since females carry two X chromosomes, one inherited from each parent, they are unlikely to inherit two X chromosomes with the mutation present since it would require the father to have SCID-X1.

What if there was a way to address this condition by correcting the single gene mutation? Dr. Matthew Porteus at Stanford University is leading a study that has developed an approach to treat SCID-X1 that utilizes this concept.

By using CRISPR-Cas9 technology, which we have discussed in detail in a previous blog post, it is possible to delete a problematic gene and insert a corrected gene. Dr. Porteus and his team are using CRISPR-Cas9 to edit blood stem cells, which give rise to immune cells, which are the foundation of the body’s defense mechanism. In a study published in Nature, Dr. Porteus and his team have demonstrated proof of concept of this approach in an animal model.

The Stanford team was able to take blood stem cells from six infants with SCID-X1 and corrected them with CRISPR-Cas9. These corrected stem cells were then introduced into mice modeled to have SCID-X1. It was found that these mice were not only able to make immune cells, but many of the edited stem cells maintained their ability to continuously create new blood cells.

In a press release, Dr. Mara Pavel-Dinu, a member of the research team, said:

“To our knowledge, it’s the first time that human SCID-X1 cells edited with CRISPR-Cas9 have been successfully used to make human immune cells in an animal model.”

CIRM has previously awarded Dr. Porteus with a preclinical development award aimed at developing gene correction therapy for blood stem cells for SCID-X1. In addition to this, CIRM has funded two other projects conducted by Dr. Porteus related to CRISPR-Cas9. One of these projects used CRISPR-Cas 9 to develop a treatment for chronic sinusitis due to cystic fibrosis and the second project used the technology to develop an approach for treating sickle cell disease.

CIRM has also funded four clinical trials related to SCID. Two of these trials are related to SCID-X1, one being conducted at St. Jude Children’s Research Hospital and the other at Stanford University. The third trial is related to a different form of SCID known as ADA-SCID and is being conducted at UCLA in partnership with Orchard Therapeutics. Finally, the last of the four trials is related to an additional form of SCID known as ART-SCID and is being conducted at UCSF.

Promising start to CIRM-funded trial for life-threatening blood disorder

Aristotle

At CIRM we are always happy to highlight success stories, particularly when they involve research we are funding. But we are also mindful of the need not to overstate a finding. To quote the Greek philosopher Aristotle (who doesn’t often make an appearance on this blog), “one swallow does not a summer make”. In other words, one good result doesn’t mean you have proven something works.  But it might mean that you are on the right track. And that’s why we are welcoming the news about a clinical trial we are funding with Sangamo Therapeutics.  

The trial is for the treatment of beta-thalassemia, (beta-thal) a severe form of anemia caused by a genetic mutation. People with beta-thal require life-long blood transfusions because they have low levels of hemoglobin, a protein needed to help the blood carry oxygen around the body. Those low levels of oxygen can cause anemia, fatigue, weakness and, in severe cases, can lead to organ damage and even death. The life expectancy for people with the more severe forms of the condition is only 30-50 years.

In this clinical trial the Sangamo team takes a patient’s own blood stem cells and, using a gene-editing technology called zinc finger nuclease (ZFN), inserts a working copy of the defective hemoglobin gene. These modified cells are given back to the patient, hopefully generating a new, healthy, blood supply which potentially will eliminate the need for chronic blood transfusions.

Yesterday, Sangamo announced that the first patient treated in this clinical trial seems to be doing rather well.

The therapy, called ST-400, was given to a patient who has the most severe form of beta-thal. In the two years before this treatment the patient was getting a blood transfusion every other week. While the treatment initially caused an allergic reaction, the patient quickly rebounded and in the seven weeks afterwards:

  • Demonstrated evidence of being able to produce new blood cells including platelets and white blood cells
  • Showed that the genetic edits made by ST-400 were found in new blood cells
  • Hemoglobin levels – the amount of oxygen carried in the blood – improved.

In the first few weeks after the therapy the patient needed some blood transfusions but in the next five weeks didn’t need any.

Obviously, this is encouraging. But it’s also just one patient. We don’t yet know if this will continue to help this individual let alone help any others. A point Dr. Angela Smith, one of the lead researchers on the project, made in a news release:

“While these data are very early and will require confirmation in additional patients as well as longer follow-up to draw any clinical conclusion, they are promising. The detection of indels in peripheral blood with increasing fetal hemoglobin at seven weeks is suggestive of successful gene editing in this transfusion-dependent beta thalassemia patient. These initial results are especially encouraging given the patient’s β0/ β0 genotype, a patient population which has proved to be difficult-to-treat and where there is high unmet medical need.” It’s a first step. But a promising one. And that’s always a great way to start.

Gene therapy gives patient a cure and a new lease on life

Brenden Whittaker (left), of Ohio, is a patient born with a rare genetic immune disease who was treated at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center in a CIRM funded gene therapy trial. Dr. David Williams (on right) is Brenden’s treating physician.
Photo courtesy of Rose Lincoln – Harvard Staff Photographer

Pursuing an education can be quite the challenge in itself without the added pressure of external factors. For Brenden Whittaker, a 25 year old from Ohio, the constant trips to the hospital and debilitating nature of an inherited genetic disease made this goal particularly challenging and, for most of his life, out of sight.

Brenden was born with chronic granulomatous disease (CGD), a rare genetic disorder that affects the proper function of neutrophils, a type of white blood cell that is an essential part of the body’s immune system. This leads to recurring bacterial and fungal infections and the formation of granulomas, which are clumps of infected tissue that arise as the body attempts to isolate infections it cannot combat. People with CGD are often hospitalized routinely and the granulomas themselves can obstruct digestive pathways and other pathways in the body. Antibiotics are used in an attempt to prevent infections from occurring, but eventually patients stop responding to them. One in two people with CGD do not live past the age of 40.

In Brenden’s case, when the antibiotics he relied on started failing, the doctors had to resort to surgery to cut out an infected lobe of his liver and half his right lung. Although the surgery was successful, it would only be a matter of time before a vital organ was infected and surgery would no longer be an option.

This ultimately lead to Brenden becoming the first patient in a CGD gene therapy trial at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center.  The trial, lead by UCLA’s Dr. Don Kohn thanks to a CIRM grant, combats the disease by correcting the dysfunctional gene inside a patient’s blood stem cells. The patient’s corrected blood stem cells are then reintroduced, allowing the body to produce properly functioning neutrophils, rebooting the immune system.

It’s been a little over three years since Brenden received this treatment in late 2015, and the results have been remarkable. Dr. David Williams, Brenden’s treating physician, expected Brenden’s body to produce at least 10 percent of the functional neutrophils, enough so that Brenden’s immune system would provide protection similar to somebody without CGD. The results were over 50 percent, greatly exceeding expectations.

Brenden Whittaker mowing the lawn in the backyard of his home in Columbus, Ohio. He is able to do many more things without the fear of infection since participating in the trial. Photo courtesy of Colin McGuire

In an article published by The Harvard Gazette, Becky Whittaker, Brendan’s mother, is quoted as saying, ““Each day that he’s free of infection, he’s able to go to class, he’s able to work at his part-time job, he’s able to mess around playing with the dog or hanging out with friends…[this] is a day I truly don’t believe he would have had beyond 2015 had something not been done.”

In addition to the changes to his immune system, the gene therapy has reinvigorated Brenden’s drive for the future. Living with CGD had caused Brenden to miss out on much of his schooling throughout the years, having to take constant pauses from his academics at a community college. Now, Brenden aims to graduate with an associate’s degree in health sciences in the spring and transfer to Ohio State in the fall for a bachelor’s degree program. In addition to this, Brenden now has dreams of attending medical school.

In The Harvard Gazette article, Brenden elaborates on why he wants to go to medical school saying, ” Just being the patient for so long, I want to give back. There are so many people who’ve been there for me — doctors, nurses who’ve been there for me [and] helped me for so long.”

In a press release dated February 25, 2019, Orchard Therapeutics, a biopharmaceutical company that is continuing the aforementioned approach for CGD, announced that six patients treated have shown adequate neutrophil function 12 months post treatment. Furthermore, these six patients no longer receive antibiotics related to CGD. Orchard Therapeutics also announced that they are in the process of designing a registrational trial for CGD.

Antibody effective in cure for rare blood disorders

3D illustration of an antibody binding to a designated target.
Illustration created by Audra Geras.

A variety of diseases can be traced to a simple root cause: problems in the bone marrow. The bone marrow contains specialized stem cells known as hematopoietic stem cells (HSCs) that give rise to different types of blood cells. As mentioned in a previous blog about Sickle Cell Disease (SCD), one problem that can occur is the production of “sickle like” red blood cells. In blood cancers like leukemia, there is an uncontrollable production of abnormal white blood cells. Another condition, known as myelodysplastic syndromes (MDS), are a group of cancers in which immature blood cells in the bone marrow do not mature and therefore do not become healthy blood cells.

For diseases that originate in the bone marrow, one treatment involves introducing healthy HSCs from a donor or gene therapy. However, before this type of treatment can take place, all of the problematic HSCs must be eliminated from the patient’s body. This process, known as pre-treatment, involves a combination of chemotherapy and radiation, which can be extremely toxic and life threatening. There are some patients whose condition has progressed to the point where their bodies are not strong enough to withstand pre-treatment. Additionally, there are long-term side effects that chemotherapy and radiation can have on infant children that are discussed in a previous blog about pediatric brain cancer.

Could there be a targeted, non-toxic approach to eliminating unwanted HSCs that can be used in combination with stem cell therapies? Researchers at Stanford say yes and have very promising results to back up their claim.

Dr. Judith Shizuru and her team at Stanford University have developed an antibody that can eliminate problematic blood forming stem cells safely and efficiently. The antibody is able to identify a protein on HSCs and bind to it. Once it is bound, the protein is unable to function, effectively removing the problematic blood forming stem cells.

Dr. Shizuru is the senior author of a study published online on February 11th, 2019 in Blood that was conducted in mice and focused on MDS. The results were very promising, demonstrating that the antibody successfully depleted human MDS cells and aided transplantation of normal human HSCs in the MDS mouse model.

This proof of concept holds promise for MDS as well as other disease conditions. In a public release from Stanford Medicine, Dr. Shizuru is quoted as saying, “A treatment that specifically targets only blood-forming stem cells would allow us to potentially cure people with diseases as varied as sickle cell disease, thalassemia, autoimmune disorders and other blood disorders…We are very hopeful that this body of research is going to have a positive impact on patients by allowing better depletion of diseased cells and engraftment of healthy cells.”

The research mentioned was partially funded by us at CIRM. Additionally, we recently awarded a $3.7 million dollar grant to use the same antibody in a human clinical trial for the so-called “bubble baby disease”, which is also known as severe combined immunodeficiency (SCID). You can read more about that award on a previous blog post linked here.