Is freeze-dried blood the future?

15 March 2016

Interview with

Dr Krishnaa Mahbubani, The University of Cambridge

What if you could send soldiers to war with a packet of their own blood in theirBlood Donation Sticker backpack? Ready to use at a moments notice? Dr Krishnaa Mahbubani is working on this becoming a possibility and like a Pot Noodle, you just add water. She brought along a selection of foods to help explain...

Krishnaa -   Today, I've brought some freeze dried blood, some actual blood and also some tomatoes and dried pineapples.

Smith - What are you going to make - a pizza?

Krishnaa - Well not exactly.  I'm going to show you how and why I freeze dry blood.  So I've got some tomatoes here that are similar to your red blood cells; they're round, they have a membrane on the outside of them and they're full of liquid inside.

Smith - They're also in a plastic bag!

Krishnaa -   Well that's more just so they're easier to carry around - just like your blood vessels. So, I have some tomatoes there, which I then froze.  As you can see here they're kind of solid.  You can have a little feel...

Smith - They are pretty hard!

Krishnaa - I then allowed them to thaw out and what I had now having frozen and thawed out my tomatoes; they kind of look quite grim and grose and they're...

Smith - If I give these a squeeze, they're quite squiggy.

Krishnaa -   Yes, they're pretty much not going to be there pretty much.  So, this is the problem with trying to freeze thing. If you don't freeze them properly and carefully, when you thaw them out they just turn to mush.

Smith - Why does that happen?

Krishnaa -   Well that's because when water freezes, it actually expands.  So all the water inside your cells expand and cause the membrane on the outside to explode.

Smith - You make big ice crystals inside the cells which busts them open?

Krishnaa - Absolutely.  So that's pretty much what happens when you freeze them and when you thaw them, the same thing happens.  As you thaw them, the water expands when it comes up to about 4 degrees, and that causes any residual cells that hadn 't quite exploded before to explode again.

Smith - So I can see the problem with blood.  If we just took a blood sample from a person and put that in the freezer, all the blood cells would basically bust open and the blood would become useless.

Krishnaa - Absolutely!  All you'll have is the red material inside your blood, which is the haemoglobin, which really does work by absorbing the oxygen onto it but, without the cell around it, it  won't go anywhere in your body, so it's kind of useless.

Smith - Why do we need to freeze blood at all?  Why would that be useful?

Krishnaa - Blood at the moment when we take it, we put it in the fridge and it can only be stored for a very short period of time and that means we can't really store it; we can't move it to places where we need it as well.  So when people are at war and we want to transport blood out to them, we can't really do that because it's very tricky to keep the temperature constant so that the blood stays where you want it to be and in best condition.

Smith - And also, it's better to have your own blood isn't' it, if you can?

Krishnaa - Absolutely!  If you have the opportunity of wandering around with a bag of your own dry blood in your backpack, if anything were to happen to you, you'd just mix the pack together so the liquid mixes with your dried blood and then off you go.  They can, actually medically put the blood back into you and you're good to go.

Smith - Have you got it working?

Krishnaa - Well... not quite there yet.  Chris loves to ask me this question but I'm not a big fan of answering it.  I'm still working on it and it's getting better.

Smith - Okay, so what are you doing to try to make it so that blood can be frozen and what is this in front of us?  Is this examples of it?

Krishnaa - Yes, so here's some examples of it.  So I've got some blood that I tried to freeze dry rather than just freeze alone, which is quite tricky.  What I do is I freeze the in small little vials because, obviously, I don't want to use loads of it initially when I'm doing different tests.  So I freeze small amounts of it and then what I do is I pull the pressure down so I make it very cold and make it very low pressure and what that does, it changes the boiling point of water within the blood.  So, at that pressure I'm able to boil the water out even though the temperature is well below zero.  So, as a result, I can end up with a very dry cake and they use this technique for fruits and vegetables.  I have here some freeze dried pineapple which Chris can have a little taster of.  It's quite crunchy...

Smith - Okay so this is just literally chunks of yellow stuff and they don't look that appetizing but I'll eat it.

Krishnaa - They don't look very tasty but they're actually fine.

Smith - Okay yes, it's pineapple.

Krishnaa - It does taste like pineapple and the idea that I'm using for my freeze dried blood is that you can just add water.  So what we did earlier was add some pineapple into a jar and then we added a bit of water into it and now we just let it re-hydrate again and what you have are swollen up looking like quite regular pineapple....

Smith - It doesn't look great but it does look like pineapple.

Krishnaa -   It does actually look like....

Smith - Does it taste alright?

Krishnaa - Yes. It actually tastes like pineapple.

Smith - Mmm.  But you wouldn't want to inject that into somebody would you? That wouldn't make a good blood transfusion.  So how do you turn the pineapple trick into blood that will work?

Krishnaa - So what have are little cakes of blood and the idea is we'll have two packs next to each other so you can actually just mush the liquid straight into the blood...

Smith - Is that a scientific term - mush?

Krishnaa - Well not really, but the idea is it's going to be in soft packs so you can actually squeeze the two packs together to allow the whole mixture to come together.  What we do is we add it together...

Smith - We've got a little bottle here and it's got... It looks like a big pill actually - a sort of browny red stuff in the bottom - and you just added about half a bottle in this little bottle of water...

Krishnaa - Yes.  So what it is is just a cake of blood because it's effectively just the blood dried up with all the water removed, and now all I've done is add a bit of water to it, and I've shaken it up and it's gone back into its liquid form.  Now here here it looks much darker than the red blood; that's because I haven't oxygenated the water to make it go red which is what makes your blood nice and red.  So it's a bit darker just because it's not much oxygen in it.

Smith - And if I put this reconstituted freeze dried, or previously freeze dried blood, under the microscope, do I actually see blood cells in there or do I just see a mess?

Krishnaa - No.  You'd actually see quite a few blood cells in there...

Smith - Quite a few... or like how many?  What percentage - come on?

Krishnaa - About 8% of blood cells in there compared to the regular - what I started with.

Smith - So there's a little way to go but the fact is, when I spoke to you a few years ago it was much worse than that so you've actually made quite substantial progress.

Krishnaa - 8% is a significant improvement already but I've got a fair way to go.

Smith - And how have you made that difference?  What have you done to mean that you're now getting almost one in ten of the cells you freeze actually coming back to life?

Krishnaa - So what we've done is we've added different materials into it, known as cryoprotectants or lyoprotectants. We add these things to stop the damage happening during the freezing and during the drying process. We're starting to look at different things we can add to the blood that are not toxic and are not bad for us so that when we do transfuse them back into ourselves, we don't have to remove them and that is helping the keep the cells stronger and alive. It's also maintaining the chemical structure within the cells.

Berrow - I've got a very important question and that's how far are we away from being able to freeze dry a whole person?

Krishnaa - We're actually a very, very long way away from that.  And that is very simple. It's because ice, when it forms, is an excellent insulator so when the ice forms on the outside, the inside of you doesn't freeze up fast enough and so, because you're a very large person (you're not a tiny little cell), it's going to take a very long time to get you to freeze all the way down the middle and it's going to take a very, very long time to get all of that water out as well.  So, right now, not really possible.

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