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Scientists Make Artificial Protein Mimic Blood
Al writes "Researchers at the University of Pennsylvania have created a protein that can carry and deliver oxygen — a useful step towards developing artificial blood. This would avoid the problems involved with donor blood — contamination, limited storage, and short supply — and lead to easier and faster blood transfusions on the battlefield and in trauma cases. The Penn researchers used three amino acids to make a four-helix columned protein structure put a smaller structure, called a heme, inside it. The heme is a large flat molecule that has an iron atom at its center, which oxygen binds to. The researchers also made the protein structure flexible, so that it can open to receive the oxygen and close again without letting any water in. They did this by linking together the helical columns with loops to restrict their motions, giving the final structure a candelabra shape."
... Vampires and Humans can live together in peace.
Conservation of angular momentum makes the world go round.
This sounds extremely cool, and very useful.
Some questions I would have is:
1. How much of this 'blood' can a human take before his/her body rejects it (if it ever does)?
2. How quick and expensive is it to create, say, a liter of blood?
3. Is there any reason that this blood wouldn't be able to combine with certain blood-types?
Either way, this is some great research that UPenn is doing. I'm excited to see where this goes.
This would be a great thing in the ER. Blood type rejection is a major cause of complications and death. If we could develop something as safe as saline solution, that would not be rejected by the body, and would help carry oxygen it would simplify things greatly. It wouldn't even need to carry oxygen as well as blood to be effective. Human blood can be diluted to 10% and still carry enough oxygen, so if this fluid was greater than 5% as effective as blood and the patient had not blead out completely it would be more than enough.
We are the Borg...
They fail to give any meaningful data on its oxygen dissociation curve against pH, so we have no idea how it will perform as an oxygen transporter at physiological conditions. Also missing is any information on whether histidine groups are present above and below the heme which are quite important for regulating the binding and release of O2. While I am suitably impressed with their engineering of a protein from scratch, I will hold off on kudos for creating something useful until I see some hard data.
Remember, hemoglobin is just one part of the red blood cell - that's the 'thing' that delivers blood to tissues. If you just dump straight hemoglobin in the system, it gets chewed up quickly (like most random proteins) and clobbers the kidneys. (see the interesting wikipedia article for some background. Researchers have tried various 'synthetic' hemoglobins to do just that and so far, they haven't worked well.
Interestingly, there is a bovine hemoglobin / albumin conjugate that is approved for dogs. So it's possible that some combination of an oxygen carrying protein sans full red blood cell will work, but we haven't got there yet.
Faster! Faster! Faster would be better!
Not the fault of the Slashdotters, as the MIT Tech Review linked also emphasizes the wrong aspects of this work. If one goes back to the actual paper in Nature, it's immediately apparent that the researchers did not set out to create artificial hemoglobin. Instead, the work is a demonstration of biologically-relevant function occurring in a relatively simple molecule that was *not* explicitly designed for that function. In other words, the protein was designed to ligate a heme and have a hydrophobic core--and that's it. That it behaves much like hemoglobin is coincidental, and that is the point. No design was necessary to incorporate that function. It follows that in nature, life-supporting processes are the natural result of certain molecular properties.
.... This protein was created with absolutely no thought to toxicity or viability inside a biological organism. It was designed to test the hypothesis that biological processes can exist in a biologically-relevant framework (a protein, rather than, say, an inorganic metal complex) without being specifically designed-in or optimizing the framework to support said processes.
If this protein could eventually find application as an artificial hemoglobin, that's great, but the point of the work isn't to announce the creation of same, but to highlight the fact that there are many potential solutions to any given biological problem, and that complexity of form is not an inherent requirement for life-sustaining chemistry.
So, let's answer some "various questions" from above: 1) This has never been put inside a living creature, and it would likely be toxic in its current form. It would probably require significant re-design (changes in surface properties) to become immuno-silent.
2) While it looks like this is a relatively cheap protein to produce (it's expressed in E. coli per the Nature paper, with nothing exotic added to the media), producing and purifying protein is generally an expensive game. That's one reason why peptide-based cancer treatments are exorbitantly expensive.
3) Assuming an immuno-silent variant, blood type would be irrelevant.
4) The components of pretty much any protein are non-toxic, but it's impossible to know a priori if some fragments of such a protein would aggravate the immune system. Probably not, though, provided (again) an immuno-silent design.
5), 6), etc.
Even without a ready-to-use artificial hemoglobin, this work is significant because it implies that evolving biological function is a very simple process, and the solutions nature has found to the problems of biology are not the only possible solutions.