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Researchers at the Ontario Cancer Institute, led by John Dick, have found a way to hunt down and isolate the stem cells from which your entire blood supply is derived. Until now, these hematopoietic stem cells (HSC) have been remarkably hard to track and isolate – they represent just one in every 100,000 blood cells. Yet these HSC are remarkably potent – a single cell placed in a mouse was able to differentiate itself into every type of human blood cell – from just one cell essentially came an entire blood supply! John Dick’s team was able to identify the protein code on their surface which marks the HSC as different from other blood cells. With the knowledge of how to find HSC, scientists may be able to create huge quantities of blood stem cells for research, rocketing their work ahead. Doctors may one day be able to use similar techniques to produce vast supplies of blood for patients. After fifty years of stem cell experiments, and twenty three long years of Dr. Dick working with blood stem cells, we’ve finally isolated where they all come from. It’s an exciting time in science.
Full Article here.
Yet another lunchroom poster I made (sorry for the watermark).
The Kleihauer Betke Test:
A peripheral blood smear of the mom’s blood is prepared and fixed in 80% ethanol. It is then treated with acid (McIlvaine’s buffer) and stained with eosin and hematoxylin. Fetal cells will remain in tact and stain bright pink because of the high HbF/fetal hemoglobin content which resists acid elution. Adult hemoglobin in maternal cells will elute out, leaving faintly staining “ghost cells”. The percental of fetal cells per 2000 cells is used to determine how much extra WinRho (in 300mg vials) is required:
Vials = %fetal cells x maternal blood volume (~5000mL)/30mL
Rounded to the nearest whole number + 1 extra. But that one extra is usually the shot they automatically gave her after she gave birth.
The Rosette Test / Screen for fetal-maternal bleeds
After the baby is born, we take their cord blood (which is thick and gross, by the way) and do a forward ABORh on them. If they are D positive or weak D positive and the mother is negative, the hospital will do an onsite rosette test:
A 3% cell suspension of the mother’s blood is incubated with chemically modified anti-D which will bind to any infant cells. Unbound antibody is washed away and indicator cells (O positive cells treated with ficin to increase reactivity) will bind with infant cells to make little microscopic rosettes/clumps which you can look for with an inverted mic:
All eligible mothers will receive another shot of WinRho regardless of the result because the clumps can be hard to see. However, positive screens indicate a fetal bleed over 30mL (which occurs in about 0.3% of pregnancies), in which case, the mother might need a larger dose, determined by a Kleihauer-Betke (in tomorrow’s post). The WinRho is administered within 72hours because once mom’s discharged, it’s really hard to hunt a lady who just gave birth down just to give her another needle!
I’m going to make this week hemolytic disease of the fetus and newborn week here because there’s been lots of baby talk in my home. Lots of babies and blood bank testing to come (you are safe from poop stories once again).
Starting off with a story though that I will come back to over the course of the week: there’s a hospital here that handles most of the complicated pregnancies for the city. One O negative lady in particular wanted a baby really badly, but for reasons I don’t recall, she had been immunized to D (colloquially, “Rh”). She also has been trying for several pregnancies but miscarried on each one because her anti-D titre was through the roof and her body was determined to fight these O positive babies. She needed to come in for an intrauterine transfusion for her baby every three months, and IUTs are just a mess in and of themselves to do, but she had successfully made it to her sixth month this time.
One of my friends was coming into his shift right after her IUT, quite happy that he wasn’t the one who had to do it but also really glad that she was doing so well in her fourth pregnancy (names of blood bank regulars are some of the fastest names you’ll learn).
But then the hospital announces a code Pink (dedicated code for emergencies in the maternity ward) later, and the woman ended up losing the baby once again.
There is an old fashioned Emergency Red Phone in the blood bank in the reference lab, and whenever that phone goes off, the entire lab freezes. Everybody stares at it, pipettes in the air, antisera hanging off the tip of the dropper, afraid to answer. In recent memory (not my own memory), a phonecall could cost the blood bank some 300 units for an aortic aneurysm. At other times, the call ends with a “dead on arrival”.
The STARS emergency copter too has a very distinct smell. It is one that, before the bloodbank, would have made me rub my nose in disgust and move on because the air vent exits right beside the landing pad. Now, much like the screech of the emergency phone, it tells the staff to get ready.
Last week, there was a woman at one of the hospitals some of my friends work at who had gone through 86 units of blood products. Last I heard about her, her massive transfusion was not done yet, she had cleared out the stock of her blood type and had switched over to the O pos packed cells, but she was still fighting.
Product stocks are a very stressful matter in the bloodbank. Sometimes I see a product get close to expiry and stare at it anxiously, hoping it will be used up and not be thrown away and wasted.