Sickle Cell Disease and blood transfusions

June 17, 2016 at 9:00 am

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Sickle cell disease (SCD) is a chronic genetic blood disorder inherited from both parents. Having sickle cell trait (inheriting the gene from one parent but not the other) is an advantage against malaria, which is why SCD primarily impacts people of African, Mediterranean, Middle Eastern, and Indian descent.

But the disease itself (which happens when someone inherits genes from both parents) is devastating.

When someone has SCD, their red blood cells are shaped like stiff crescents instead of flexible discs. These pointed cells can snag on blood vessel walls, causing blockages that prevent oxygen from reaching tissues, incredible pain (called a crisis), and damage to a patient’s brain, eyes, internal organs, joints, bones, and skin. These complications can be life-threatening.

Approximately 1 in 500 African Americans (100,000 people in the U.S) have SCD, though as many as 1 in 13 African Americans are carriers of sickle cell trait.

Treatment of SCD often includes chronic blood transfusion therapy to increase the number of healthy red blood cells in the bloodstream, even when a patient is not actively sick. Transfusions can reduce the chance of stroke.

Says Bloodworks Research Institute’s Dr. James Zimring,

The more we study the disease, the more we understand that transfusions are needed earlier and more frequently than we have appreciated.

Anyone who receives regular blood transfusions is at risk of developing antibodies against antigens in other people’s blood, called alloimmunization. The more antibodies someone makes, the harder it becomes to find blood they can still receive.

Transfusion for transfusion, patients with SCD are more likely to develop antibodies than someone without it. Although science is working hard on it, no one understands all of the reasons why.

Most of us know that our blood type is either A, B, O or AB, and Rh positive or negative, which correspond to antigens on the red cells, but there are actually hundreds of other antigens in the blood.

Dr. Meghan Delaney, BloodworksNW’s Medical Director for Transfusion Service at Seattle Children’s, says:

When sickle cell pediatric patients get transfusions from our blood bank. they require specially matched red cells. Most patients receive blood that’s matched for ABO and Rh,

Other than matching blood to patients, there is no way to prevent a reaction besides not transfusing. For some patients, this can to lead delays, substandard care, and even death.

BloodworksNW’s Immunohematology & Red Blood Cell Genomics Reference Laboratory performs the extended blood typing and matching for patients in the community. Sickle cell patients also have blood typing done by genotype, or molecular methods, since there tends to be blood group differences in people of different ethnic backgrounds that can make figuring different blood types more complicated.

Dr. Zimring explains:

Antigens tend to be within an ethnic group. You are more likely to be a match to someone who has a similar ancestry as you do. Therefore, the more people who have a similar ancestry that donate blood, the more likely it is that  compatible blood will be available.

Dr. Zimring hopes to uncover why SCD patients are so difficult to transfuse. He and BloodworksNW’s Dr. Krystalyn Hudson are studying the process by which the immune system makes antibodies to transfused red blood cells.

Understanding why sickle cell patients make antibodies at a greater frequency might help scientists understand why any patient might make an antibody.

This awareness will help researchers formulate new therapeutic approaches, which will help both sickle cell patients and others receiving regular transfusions.

One thing is for certain:

Sickle cell disease would benefit from increased resources for delivery of medical care and research.

More donors of all ethnic backgrounds are needed to help patients in our community. Schedule your next donation


Chemical engineering at Bloodworks? You bet!

March 24, 2016 at 2:03 pm

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Chemical engineering isn’t just about chemicals. It can be about blood too, says Bloodworks Research Institute’s Dr. Wei Yang.

It’s related to chemical processes and reactions, but some of us are focused on material and biological applications.

Dr. Yang was exposed to the field at an early age: her parents both work for a chemical factory. She was always good at chemistry and wanted to solve medical problems, so chemical engineering was a natural fit – many chemical engineers have careers related to human health.  She earned her PhD from the University of Washington in 2014, and completed a year-long postdoc with her PhD advisor after completing her degree.

Her advisor introduced her to Dr. José López, whose thrombosis research at BloodworksNW aligns with her interests. She joined the López lab in September, 2015.

Thrombosis is unwanted blood clotting. It can lead to heart attacks, strokes, and other sometimes fatal complications. BloodworksNW is the only research institute in the Northwest dedicated to thrombosis research.

Dr. Yang’s work focuses on reducing blood clots created by medical devices. The body’s natural reactions to bleeding and foreign substances can’t distinguish intruders from devices designed to help, like artificial hearts, dialysis, or ECMO.

When proteins in the blood come in contact with these devices, these proteins unravel into long, sticky chains, cling to the devices, and cause platelets to activate and clot. Von Willebrand factor (VWF) is a particular problem – it’s the key protein involved in platelet adhesion and the biggest, stickiest protein in the body.

Patients can have strokes when these clots break off and make it to the brain, and anticoagulants given to prevent clotting cause other bleeding issues. This is especially a problem for young children on ECMO.

Scientists have attacked this problem for decades. Their solutions often work well in the lab, but not in simulations that mimic actual blood flow.

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Dr. Yang’s solution is a polymer that imitates a protein. Because this zwitterionic material binds to water very well, the water interferes with the binding of proteins to the coated surface, keeping the surface clean – even in a complex fluid like blood. When coated onto a device, the polymer prevents VWF from unraveling, attaching, and forming harmful clots.

So far, devices treated with Dr. Yang’s material have remarkable results compared to uncoated devices, in both the laboratory and in blood flow simulations.

We think that if we can reduce VWF, based on current results, it’s likely we can decrease clotting formation for the ECMO system.

Imagine the difference this life-changing medical breakthrough could make for patients in need and the doctors who treat them.

Research is connected to the gift of life, and we’re fortunate to have early-career scientists like Dr. Yang pushing innovative ideas forward.

Dr. Sherrill Slichter reflects on 45 years of research at BloodworksNW

March 31, 2015 at 2:45 pm

SlichterMany advancements in platelet transfusion would not be possible without Dr. Sherrill Slichter’s 45 years of research at Bloodworks Northwest.

Growing up in Wenatchee, WA, Dr. Slichter had an interest in science in a time where attitudes towards women’s abilities were much different than they are today.

When I was in high school, I took math and physics and chemistry, and our class advisor was the biology teacher in high school and she was sure I was going to flunk out, so I had to take my class card home every semester and have my parents sign it.

She majored in math at Washington State University, but soon realized it wasn’t for her. As a second semester junior, she started taking pre-med classes, and went to medical school as one of five women in a class of 100.

On the first day of medical school, I was sitting at the lunch counter in a pharmacy across the street from the medical school when one of my fellow classmates, who I didn’t know because it was the first day, looked over to me and said, ‘do you understand that you’re taking the place of somebody who could use this education? Raise a family.’

I guess I survived by saying to myself, ‘I can do what you can do, regardless of my gender.’

Dr. Slichter initially wanted to focus on patient care instead of research, but an experience with a woman with hemolytic uremic syndrome, a disease of the red blood cells that causes kidney failure, made her change her mind. The patient, the wife of an army private, was dying of renal failure, but there was only one dialysis machine at the University of Washington hospital and it was in use. The physician in charge refused to treat her because of what Dr. Slichter suspected to be discrimination, and the woman died.

There was a professor in the division of hematology, a physician named Laurie Harker — he was interested in clotting and bleeding disorders — so I went up to Laurie and I said, ‘are you doing any work on hemolytic uremic syndrome?’

Dr. Slichter came to BloodworksNW in 1970 to develop a coagulation laboratory, and her focus has been on platelets.

We didn’t have platelets as a separate transfusion product at [BloodworksNW], so I started research studies trying to determine how to, first of all, spin the blood to separate the blood into its components: platelets, plasma, red cells.

And then once we had platelets for transfusion, we had to figure out how to store them, so I’m still working on improving methods and extending the storage time of platelets.

Once we had platelets to give, patients started to develop antibodies against the donor platelets, so we’ve been working on methods to modify platelets prior to transfusion to prevent them from being recognized as foreign by patients and rejecting them.

Dr. Slichter determined early on that platelets store better at room temperature rather than in the cold, and must be agitated during storage. A colleague says, “The platelet storage system is sort of like her — she doesn’t like to sit still.”

These advancements helped improve the prognosis for cancer patients, and made bone marrow transplantation possible.

Dr. Slichter’s original goal of extending the storage and accessibility of platelets remains. She’s currently working with the U.S. Army on freezing and freeze-drying platelets to provide for situations where fresh platelets are not feasible. Though she initially extended the life of platelets from three to five to seven days, her lab studies now show that platelets can survive for 13 days using special storage conditions. The issue is then reducing pathogens in the platelet product, but she’s working on it.

Our long-term goal is to get extended-stored, pathogen-reduced non-immunogenic platelets, and I think we’re very close potentially in the next 5-10 years to achieving that goal.

A lot has changed in attitude from when Dr. Slichter started.

There are more women medical students than men, so that’s all for good.

One thing that hasn’t changed is a commitment to advancing technology by investing in the next generation of researchers.

We don’t just draw blood, store blood and transfuse blood with established guidelines – we’re very interested in training young people.

HLA testing and organ transplants

April 21, 2014 at 10:08 am

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Have you ever wondered how doctors determine whether a donated organ is the right fit for a patient in need of a transplant? Gary received a new liver in 2005 to overcome a rare autoimmune disease called Primary Sclerosing Cholangitis, but his surgeon couldn’t just put any old liver into his body — it had to meet a number of criteria.

There are three factors that play into matching an organ to a recipient: blood type, human leukocyte antigens (HLA), and antibodies. The donor’s and recipient’s blood type need to be compatible, though HLA and antibodies get tricky — you don’t need to have the exact same HLA, though the better the match the less likely you are to have harmful antibodies against your type.

How do antibodies work?

Most blood donors know their ABO blood type and understand how it works with blood transfusion: O can only receive type O blood; AB can receive blood from any other types; A can receive blood from an A or O donor; and B can receive blood from an O or B donor. If you receive the wrong blood type, a transfusion reaction can occur.

You may not know that this reaction is because of antibodies, proteins that attack specific particles, called antigens, in the body (in this case, on the red blood cells).

O red blood cells have no antigens, but that blood type has antibodies in the serum (the fluid in your blood) against antigens found on A and B red blood cells. AB red blood cells have both A and B antigens, but no antibodies in the serum (because these would attack the person’s own red blood cells). This is why O is the universal whole blood donor, while AB is the universal blood recipient.

HLA works in the same way, on a much larger scale — it’s the most polymorphic (variable) genetic system in humans. For example, there are only four or five alleles (genetic markers) that code for hair or eye color, but there are thousands of HLA alleles.  Each person only expresses a few alleles (inherited from their parents) so the chances of someone not related to you being an exact HLA match is essentially one in a million.

The immune system: HLA and antibodies

HLA and antibodies are part of our immune system: our body’s defense against invaders like bacteria, parasites, and viruses. According to Dr. Paul Warner in our HLA Lab,

The main function of the immune system is to tell what is ‘you’ from what is not ‘you’. Anything that’s not ‘you’ in a part of your body that should be sterile, like your blood, you need to get rid of, because it wants to use your body as a food source.  That’s basically what an infection is.  Because your specific HLA molecules are present on the surface of virtually every cell in your body, it’s a good way for your immune system to tell ‘friend’ from ‘foe’.

Unfortunately, this is a mixed blessing when we are trying to match a donor organ to a recipient. The immune system, designed to protect the body, will attack and reject an organ that it views as being foreign. So,

The main thing that we do is not so much [HLA] matching – we do mismatched transplants all the time. The main thing that we do is make sure that the person receiving that transplant does not have antibodies against the mismatched HLA of the donor, because those antibodies can cause graft rejection.

Detection and identification of antibodies against HLA in a transplant recipient is more important than HLA matching of the donor and recipient, by far. You can be a zero HLA match, as long as you don’t have antibodies against the mismatched HLA of the donor. However, the better the match, the better the long-term outcome – because you don’t make antibodies against your own HLA, so if someone has the same HLA you do, you won’t make antibodies against them, either.

So, what does the testing look like? Click through to see the steps.

After we receive samples of donor and patient blood, we will use these to determine whether the organ is a good fit for a patient.
First, we need to determine the HLA type of the donor and recipient; we use a machine called a thermal cycler and a process called polymerase chain reaction (PCR) which repeatedly heats and cools the samples to amplify specific sequences of DNA. The enzyme used to amplify the DNA has to be able to withstand the heat during this heating/cooling process, so we use an enzyme discovered in bacteria that live in the hot springs of Yellowstone Park. This whole process is quick: we can go from the initial whole blood sample to the person’s HLA type in approximately 2 hours. This testing needs to be done separately from the rest of the testing, as the DNA in the atmosphere (after the PCR amplification) can contaminate other samples!
Then we do a test to see if the recipient has antibodies against the donor HLA. This is called a crossmatch. We mix the serum from the recipient (the part of the blood where the antibodies are) with white blood cells from the donor (which have the donor HLA on them). After incubating the serum and cells to let any potential antibodies bind to their target cells, we wash the cells to get rid of any unbound antibodies (like antibodies against flu viruses, and anything else your body has made an immune response against. Remember, we are only looking for antibodies against the donor HLA, and everyone’s serum has lots of other antibodies present.) After adding an anti-antibody that has a fluorescent marker on it, any donor cells that have antibodies from the recipient’s serum bound to them will light up when exposed to an appropriate light source.
The patient samples are run through a flow cytometer which is a very complex machine that shoots a laser at the cells to detect antibodies. If antibodies bound to the cells are present, they can be detected because of the fluorescence, which the flow cytometer measures. The technologist running the test then compares the patient sample with several controls to determine whether the donor and recipient are compatible (the recipient has no antibodies against the donor), or incompatible (the recipient does have antibodies against the donor).
We also freeze samples of serum and cells from each donor and recipient. The frozen cells are stored in liquid nitrogen-chilled tanks (approximately -350 degrees F. Brrrrr!). This helps with research or if additional testing is needed down the road. For example, if a patient’s transplant starts to go bad five years after transplant, we can get a new serum sample from the patient, and test it against (thawed) donor cells to see if new antibodies have appeared. Then the patient can be treated to try to get rid of the antibodies, and hopefully prevent the organ from being totally rejected.

Because of these tests, Gary and thousands of other transplant recipients in the Pacific Northwest are able to enjoy many more years of doing what they love. In Gary’s case, it’s spending time with his family.

Thrombosis research at Bloodworks Northwest

March 6, 2014 at 12:36 pm

March is Blood Clot Awareness Month, so we sat down with Dr. José A. López, Bloodworks Northwest’s Chief Scientific Officer, to discuss the work his lab is doing in thrombosis (blood clot) research.

What is thrombosis and why is it such a concern?

“Thrombosis” refers to the formation of a clot within a blood vessel in the absence of an injury that causes bleeding. The thrombi [clots] are composed of platelets, red blood cells, and a protein mesh called fibrin.  When a clot blocks a blood vessel, it prevents the tissues served by that vessel from being perfused by blood – the tissue doesn’t get any oxygen or nutrients and if this goes on long enough, the tissue dies.

If you add up all the different types of thrombosis, they kill more people than any other type of disease – AIDS, malaria, or cancer. Almost 100% of heart attacks are caused by thrombosis in the coronary arteries. Similarly, stroke is caused by a thrombus that can start in the heart and be thrown off to the brain or is formed within the artery in the brain. There are also thrombi in the legs – that’s called deep vein thrombosis, and they can get thrown off into the lungs to produce a condition called pulmonary embolism.

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It’s estimated that 20% of cancer patients experience thrombosis. In addition to the diseases we normally think of as caused by thrombosis, there are syndromes where small blood vessels are occluded, like thrombotic thrombocytopenic purpura (TTP). TTP is a disease where thrombi form in small vessels throughout the body—in brain, kidney, heart, liver, pancreas. It’s a catastrophic disease, and if you don’t treat it, people die within a few days. 100%.

Why did you choose thrombosis as an area of research?

It started with a patient actually. Back in the previous millennium, when I was a medical resident, I saw a patient with TTP; I diagnosed her and helped save her life. It was such a rare disease, so I was asked to talk about it and because I had to talk about it, I had to learn about it. That actually interested me in platelets, and how they were involved in producing this dreadful disease.

What specifically are you examining? Any particular types of clots?

YD1C0056We’re really looking at all types of clots. In arteries, the blood is going fast and it’s under pressure. In thrombosis that involves the arteries, it’s generally believed that platelets are more important. They clump and form what are called “aggregates.” We’ve done a lot of work figuring out the mechanisms by which platelets are able to stick to the vessel wall. We have a collaboration with a group in Turkey, where they do this procedure in patients that have had a heart attack — they actually put a wire into the coronary arteries and suck out the clot, and we examine what’s in the clot.

We’re looking for platelet proteins, other blood proteins and other cells, but we’re also looking to see how the proteins get modified. Many of these processes happen because of oxidative stress. We are able to detect the oxidation of proteins; we have research that shows that some blood proteins become more pro-thrombotic when they become oxidized. The von Willebrand factor [a blood protein that sticks platelets to the vessel wall] changes when it becomes oxidized – it gets stickier. One possible implication of this work is that we now have a way to determine if anti-oxidant medications actually have an effect on important oxidant targets.  At present, they are used for a number of disorders but there are few ways to determine if they are having an effect.

We also look at how clots form in the veins of the legs. This is not fast flowing blood. In addition, going back to clots in small vessels, we’re studying how these thrombotic mechanisms are involved in several diseases, including sepsis and malaria. We’re attempting to translate our findings to the care of patients.

Can you tell me about any notable breakthroughs?

YD1C0011I can tell you about ones that I think are very exciting! Von Willebrand factor is made in the cells that line the vessels and is secreted into the blood as long chains. The longer the chain is, the stickier the protein. It turns out von Willebrand factor is related to proteins in mucus – those are also long chains and form in the same way as von Willebrand factor. It’s been known for 50 years that  you can break mucous chains down using a drug called N-acetylcysteine or NAC, which breaks up the chains by breaking up disulfide bonds.

NAC has been used in patients with cystic fibrosis because they accumulate a lot of dense mucous in their lungs and they can’t cough it out. I thought, “well, maybe we can use this stuff to break down von Willebrand factor.”

So, we did a bunch of work based on that idea, and it turns out NAC can break von Willebrand factor down! We did studies on human blood and mice, but not on patients. We published it, and it got a lot of press, and I’ve now heard of patients that had TTP and were refractory to other drugs, and doctors used this to save them. Every patient I’ve heard about woke up and got better. This could be a reporting bias – they only report the ones that are successful, but it is still if it has helped a few people.

I have also worked with engineers at UW to develop and study in vitro systems for making blood vessels. We’ve been able to do that. It’s really exciting. That paper also got a lot of press. We can use human cells to test their functions in small blood vessels. We’ve tested how Von Willebrand factor clogs up the vessels – why it happens at certain sites and not others. We also found using this system that platelets are really potent at helping existing vessels make new vessels. This has implications for new blood vessel formation in cancer and wound healing. When you heal a wound you need to make new blood vessels to serve the new tissue you’re creating. Small blood vessels are affected in many diseases but it isn’t necessarily apparent because the problem is so widespread and systemic.

What sort of equipment, subjects, etc. do you use?

We study living things. We study humans — we don’t generally do experiments on them, though we did one where we gave volunteers fish oil and studied them before and after they took the fish oil to see how well their platelets stick. We found that the ingestion of fish oils makes the platelets less sticky, so that could explain one of the benefits of taking fish oil.

We also study mice that have genetic lesions to test some of our ideas on. With the NAC, for example we demonstrated that we could bust up small vessel thrombi, giving us confidence that the drug probably would work in people. That said, you still have to test it in people to know.

We do a lot of laboratory work – we use a lot of systems where we study the interaction of blood cells with proteins or other components of the vessel wall and we do it under flow. The blood is always moving, so there’s a whole bunch of physics that goes into understanding what’s involved when a blood cell attaches to the vessel. A platelet needs to attach to a vessel wall as it’s going by traveling very fast, and we’ve done a lot of work on this problem and have defined some diseases where this mechanism doesn’t work.

What can you tell me about your team?

PSBC_large_050812The two most senior people are Junmei Chen and Adam Munday – they pretty much run the experiments day to day. We have several technicians, people who really do all the laboratory work, and we also have trainees, post-doc fellows. I work with a couple of students from the University of Washington. There is a lot of training going on – we really consider ourselves to be parts of the UW in terms of training the students, teaching them how to do research, education, etc.

We also have a lot of collaborations, primarily with UW. One of those collaborations is with engineers making the small blood vessels in vitro. We also have a collaboration with a mechanical engineer who make devices that can measure the contractile force of a platelet.  This allows us to determine how platelet contractile force is affected during  certain conditions such as trauma shock or in other diseases. We have a pretty good team.

What’s your research philosophy?

I’m a real believer that, if what you are trying to do is learn how things work, you will discover important things that will help you to manipulate the system, which helps to translate the solution to patient care. Sometimes the inspiration is from a clinical problem, say TTP, but for me that inspiration does not lead to “I’m going to find a cure for it right away.” Instead, I try to learn how the disease works.  If you just try to cure something by attempting different things empirically, if you cure it by accident, you won’t know why you did it, and it may not work on someone else.

What we do is try to understand the problem. In the process of understanding it, you find things that you couldn’t have predicted. And when you don’t have a defined solution, you have the knowledge to make good educated guesses.

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