One drop of blood. From the outside, it’s nothing more than a tiny red speck. Or a spot on the carpet. But on the inside, it’s a red universe brimming with super-powered cells and the very stuff of human life. That’s why scientific scrutiny is bringing more and more of blood’s secrets to the fore . . .
By Rob Whitaker
Could cow’s blood save your life one day? Will scientists be able to generate blood in a test tube? And what about the possibility of doing blood tests without a needle in sight?
It may sound incredible but it’s no more remarkable than a procedure that occurs every day, something we don’t even give a second thought: the miracle of blood tests.
When blood is taken from a vein in your arm and sent to the pathology lab, it’s a fact-finding mission of potentially mammoth proportions. To the pathologist a few millilitres of red fluid in an odd-looking tube is like your book of life. Or your body’s black box.
He doesn’t need a scalpel, X-ray machine or ultrasound. With a few technical tools he can assess how well your immune system and various organs are functioning. He can gauge how stressed you are, what kind of food you’ve eaten, which drugs you’ve taken, the kind of bugs that roam your body and whether any cancer cells are skulking in hidden corners.
He can also tell whether you’re prone to arthritis, are pre-menopausal or pregnant, and what your fertility status is. He can even determine whether you’ve recently suffered a heart attack.
A simple blood test can yield an impressive spread of medical information and now the procedure itself looks set to become even more high-tech. Needle-phobics in particular can take heart that blood tests could soon become non-invasive and needle-free. And it’s all thanks to space travel.
Because researchers need to test blood in space for medical studies, the National Space Biomedical Research Institute is investigating the use of near-infrared light to glean chemical information about blood without the need for a sample. Sounds like a much better kind of blood test, doesn’t it?
Blood is clearly a magical substance. And because this fluid has so many vital functions and carries so much information about a person’s state of health and disease, bloodrelated research is thundering ahead. But where to from here?
Of course HIV/Aids is the headliner act in the current crop of blood (and bodily fluid) transmitted infections. The virus targets white blood cells called helper T-cells and affects the very cells that should coordinate the body’s immune response. It’s no wonder that scientists are mining the secrets in the blood in an attempt to fight this global killer.
In March last year research released from Canada’s University of Montreal revealed that a potent white blood cell protein could offer protection against killer immune diseases like HIV because it works like a “shield” for viral attacks. It’s thought this discovery could help with the development of an HIV vaccine – probably the most globally significant discovery on the horizon.
Some of the most up-and-coming research is also focusing on umbilical cord blood as a source of stem cells, which could ultimately be used to combat various conditions including certain cancers. In fact, more and more parents are “investing” in their newborns’ health by paying to have the umbilical cord blood frozen and stored in a cord blood bank.
Why? To ensure that the child has permanent access to transplantable cells. (These cells could also be transplanted into siblings or family members as a near-perfect match.) The process is still being refined and explored and some scientists think there’s a long way to go. But umbilical cord blood banking is a medical insurance policy that could pay big dividends if the research trends are on track.
In August last year researchers at a US biotech company announced they’d successfully grown tubes of human blood pretty much from scratch. The team used embryonic stem cells (which can differentiate into almost any kind of tissue) to produce 10 to 100 billion blood cells at a time. This futuristic technique could ultimately revolutionise blood transfusions by being used to generate an endless supply of disease-free blood of every blood type.
The need to find donor blood that “matches” that of the potential recipient’s makes transfusions a constant challenge for medical practitioners. The aim is to avoid the rejection that occurs when donor and recipient blood types differ. Of course this limits the number of donors available for any one recipient – especially those with rare blood types (see table below).
Blood-type mismatching is thought to cause at least half of all transfusion-related deaths. That’s why researchers around the globe are working on transfusion-improving technology. Since the late 1990s another American company has been working on a “Universal Blood Machine” that converts type A, B and AB blood into the universal type O that can be safely transfused into people with any blood type.
Last year the company’s Danish research team reported their success in the journal Nature Biotechnology. They managed to identify enzymes that can turn types A and B blood into type O. The result? We could be on our way to an endless supply of universal donor blood.
What’s in one drop of blood?
Try five million red blood cells, 10 000 white blood cells (more if there’s a persistent infection) and 250 000 cell fragments called platelets. These millions of cells only make up half the volume of the diminutive drop. The other half is composed of plasma, a fluid that’s 95 per cent water and five per cent nutrients, proteins and hormones.
Clearly a droplet of blood is so much more than it seems. But so is blood itself. In fact, this amazing element of the human body is the ultimate multi-tasker, performing a range of functions simultaneously as it travels the vascular infrastructure – the vast network of veins, arteries and capillaries so extensive that each person has enough to encircle the earth. Twice.
From birth to death blood undertakes the incessant housekeeping our bodies need. It feeds cells and cleans up, carts away waste and guards against intruders. Plus it’s the only substance that comes into contact with all the tissues in the body, allowing them to communicate with one another. Think of it as a super-efficient networking system with over 100 trillion different users – namely every single cell in the body.
How to decipher your blood-test sheet
Pathology labs can test for more than 200 items in your blood. Depending on your complaint and recent history, your doctor will request specific tests to help with the diagnosis by ticking off the appropriate boxes on a pathology test sheet.
The pathologist will then analyse your blood by looking at three elements:
firstly the blood cells,
secondly the “commuters and hitchhikers” (elements that are naturally present in the blood but may indicate a problem if the concentration goes up or down) and
lastly the “invaders” (viruses or toxins).
1 Checking the blood cells
Red and white blood cells, platelets and other blood products can expose many secrets about your health. On the pathology sheet these tests will be ticked off as haematology tests, which include a full blood count.
Your red cells can show if you’re anaemic or have an iron deficiency, while your platelet count and other clotting proteins can reveal whether your blood is clotting too slowly or fast and why, explains Dr Gerhard Sissolak, head of the clinical division of haematology at Cape Town’s Tygerberg Hospital.
There are a number of different types of white blood cells and their specific counts can reveal infections (bacterial and viral), leukaemia and even whether you’re winning the battle against cancer. Certain white cell counts can also be used to diagnose allergic reactions or the presence of HIV or another infectious disease.
2 Analysing the “commuters and hitchhikers”
Have you had a heart attack? Are you at risk for heart disease or a stroke? Is your cholesterol too high? Do you have diabetes? Tests listed on the sheet under chemistry can reveal all of this as well as how well your kidneys, lungs, heart and pancreas are functioning.
With the tests listed under endocrinology, the pathologist can detect fertility problems and confirm whether a woman has reached menopause. Antenatal tests on the other hand can determine pregnancy and reveal whether you’ve been exposed to German measles or HIV.
The immunology tests ticked on your test sheet will show whether you’re prone to diseases like arthritis and asthma or whether you’re suffering from an acute infection. A blood test can also indicate signs of cancer – these tests are listed under tumour markers on the sheet and include a PSA test for the early detection of prostate cancer.
3 Detecting the invaders
A host of tests – listed under serology and microbiology on the test sheet – is used to seek out bacteria, viruses, parasites and other unwanted attackers that could invade the blood. Hepatitis A, B and C, sexually transmitted diseases, HIV and many other infections from salmonella to bilharzia and Ebola can be detected.
Pharmacology or toxicology tests will show the presence and blood levels of sleeping pills, alcohol, pain killers, antidepressants and a wide variety of other drugs and poisons.
One unit of donated blood can help save the lives of up to three people.
In South Africa, a blood transfusion takes place every 48 seconds but less than one per cent of the local population donates blood regularly.
People with O blood type are universal donors. Their blood can be given to people of all blood types.
People with AB+ blood type are universal donors of plasma, the liquid portion of blood. AB+ plasma is often used in emergencies, for newborns and for patients requiring massive transfusions.
While hip replacement surgery calls for three to four units of blood for transfusion, a stab or gunshot wound can demand six to 12 units. Even worse, an aortic or abdominal aneurysm can require five to 50 units of blood and a liver transplant 30 to 150 units!
For more information and to donate blood visit the South African National Blood Services website www.sanbs.org.za
What's your type?
Some blood types are more common than others – and the more rare the type, the more difficult it may be to find a blood-donor match. See the table below to work out how rare your blood really is . ..
1 person in 3
1 person in 3
1 person in 12
1 person in 14
1 person in 16
1 person in 29
1 person in 67
1 person in 167
Many world-class athletes – like Tour de France cyclists – have been caught trying to perk up their performance by using “blood enhancers”. This sneaky strategy involves exploiting one of the body’s natural processes – namely red blood cell production.
If the red blood cell count falls below a certain level in normal, healthy people, the kidneys release a hormone called erythropoietin (EPO) that stimulates bone marrow stem cells to produce more red cells. But when an athlete with a normal red cell count takes synthetic EPO the increased red blood cell production leaves him with an enhanced oxygen transport system and a competitive edge. More red blood cells mean more oxygen can be carried to the working muscles, which means the body can work harder for longer. And this can make the difference between winning and losing.
But it can also make the difference between health and disease. When used as intended, EPO is an effective treatment for conditions like anaemia. On the other hand, when it’s misused by over-ambitious athletes, it can cause thickening of the blood that could lead to increased risk of heart disease, stroke or blood clots.
Could cow's blood save you?
In an emergency or surgical setting blood is a precious resource. When you consider that there are continually nationwide blood shortages you can understand why healthcare teams are reluctant to waste even a drop of the stuff. Fortunately there could be hope on the horizon.
No, it’s not some new wonder drug or breakthrough medical surgery. In fact, cows could be helping us break new biomedical ground. And South Africa is at the leading edge of the clinical research.
It’s called Hemopure (developed by a company called Biopure) and is based on stabilised bovine (cow) haemoglobin, a synthetic alternative to the human variety.
But is this oxygen-carrying protein as good as the real thing, found naturally in red blood cells? Not quite, as some people could have an adverse reaction to the product. That being said, in some cases it holds significant advantages over stored blood products. According to manufacturers Hemopure is stable for up to 36 months at room temperature, doesn’t require refrigeration or warming and is compatible with all blood types.