donated blood: is it alive?

I donated blood this morning, and as I was lying there, I started wondering about the fact that blood gets stored for as much as six weeks before being used.

Are the blood cells alive? How do they endure for so long without being refreshed by the usual metabolic processes that take place within the human body (O2/CO2 exchange, pickup of nutrients/energy from the digestive system, etc.)?

They do refrigerate the blood, which helps it last longer. Red blood cells at least don’t have much in the way of metabolic requirements, they aren’t much more than cellular membranes full of hemoglobin.

Dead blood cells wouldn’t do much good.

Try this experiment. Cut yourself. What color is the blood?
Put the blood in two airtight containers, with little air. Refrigerate one; let the other stand at room temperature.

Periodically, note the color. Take a small sample and expose it to fresh air, and note the color change, if any.

Live blood turns bright read when exposed to oxygen. Dead blood does not. The color change is the hemoglobin getting oxygenated, so it can carry it to tissues that need oxygen.

Which do you think would be more useful to a patient?

Are red blood cells alive? Do they fulfill all the criteria that we associate with living cells?

Could what you are describing be ascribed to cell damage, or extraneous factors (e.g. clotting, dehydration or cell lysis due to osmotic pressure)? Is oxygen still binding to haemoglobin, but the haemoglobin, not being contained within cells, but in solution is not in a concentration great enough to effect a chromatic change detectable by eye?

Does haemoglobin in solution change colour in the presence of oxygen, CO or CO2? Is the haemoglobin alive?

Is the definition of life, with regards to RBCs at least, limited to the RBC’s utility to a human? If it is no longer useful, is it dead? If I saturate all the blood cells in a unit of donated blood with CO, is it useful to a patient, are the RBCs dead?

Depends on your definition of “alive”. Mammelian (human) red blood cells lack a nucleus - they expel their nucleus during maturation and are therefore not able to propagate.

Outside of the body, red blood cells go bad (“die”) when their energy supply runs out - as old blood conserves run out of glucose, the membrane potential collapses and even when re-fed, the blood cells are no longer able to power theuptake of glucose into the cell, or to repair oxidized hemoglobin (MetHb).

Oxygen binding and release does not require “live” erythrocyte - it can also be demonstrated with pure solutions of hemoglobin. However, every time a hemoglobin molecule bind oxygen, there is a small probability that the oxygen steals an electron from the heme iron, converting hemoglobin to met-hemoglobin, which is no longer able to transport oxygen. “Live” erythrocytes expend metabolic energy to “repair” this Met-hemoglobin and render it functional again by reducing the iron ion to the Fe2+ state.

As mentioned, RBCs may not be considered “alive”, if being alive requires reproduction.

How about white blood cells? I don’t think blood donation makes use of them, though.

Don’t be ridiculous. If blood weren’t alive if wouldn’t be a useful test for “The Thing” (1982):

http://www.youtube.com/watch?v=hqVbOSEsJNo
(not to mention the original Don A. Stuart/John W. Campbell story Who Goes There?.
Seriously, the point of transfusing whole blood (rather than plasma, or derivatives like clotting factors) is to give the transfusee a supply of fully functioning blood to use in transporting oxygen (and other stuff). There’s not much point in transfusing plasma filled with dead red blood cells that your loiver is going to have to strain out.

[bald-faced hijack, with an explanation]

I was planning to start this as another thread when I saw this as a point d’appui.

One of Lance Armstrong’s doping convictions, if IIRC, was that he had used fresh oxygen-rich blood he had churned out during earlier training, pumping it in when he thought he needed that extra bit of pep.

How is this possible? Does a person have to go through a full-body flush, like a dialysis patient? I’ve heard about that only with the indomitable Kieth Richards, in order to beat a heroin probation violation rap. I don’t know if this is a Paul Bunyan story, or if it is even medically feasible.

So, anyone could make use of such a Breakfast of Champions?

[/bald-faced hijack, with an explanation]

It depends on how you define life.

  1. Taking in energy from the outer environment and using it to fuel processes that ward off entropy in its inner environment. Yes - the blood components that do this inside their native host will continue to do this for some time outside their native host and then inside a recipient. Otherwise they wouldn’t do the recipient any good, as said.

  2. Ability to replicate themselves. No - Blood cells, red and white, don’t do this. Reds not at all, even inside their native host. Whites mostly not, as the vast majority of WBCs in circulation are terminally differentiated. So, by this definition of life, most blood cells are not alive even as they circulate in their native host. However, even those WBCs that might be able to replicate after they are removed are usually inactivated by irradiation before they are transfused. This prevents them from attacking the recipient.

As an aside, whole blood transfusions are uncommon these days, as most blood is separated into its major components - RBCs (usually containing the inactivated WBCs also), plasma with the clotting factors (which may be fractionated further to separate the factors somewhat), and platelets. This allows for more efficient use, as only the component needed is transfused, and the various components have different shelf lifes and different optimum storage conditions.

Highlighting this question, which I find interesting but don’t know the answer to.

White blood cells can easily be called alive or dead - there’s no ‘what does that mean?’ issue.

How long do they live in the bag of blood? Are they centrifuged out before being put in patients?