Got blood? continued:

Artificial blood, transfusions and stem cells 

Let's first look at artificial blood....which falls under the category of bioengineering/chemical engineering/materials science rather than stem cells, per se. In emergency situations and very difficult situations like war, fresh blood is not always readily available and can become scarce quickly.  Real human blood from donors needs to be refrigerated and certain blood types are harder to come by than others.  An option is a substance that can help carry oxygen around, and replace blood volume after drastic blood loss. It is also useful if this substance is relatively inexpensive so large amounts can be carried around in ambulances, and of course, will not have antibodies that cross react, which can happen if a person is given the wrong blood type. Let's look at a few options being developed. Recall that human red blood cells contain the molecule hemoglobin which carries iron in its core, which in turn binds to oxygen and transports it around the body.

Scientists at the University of Sheffield, UK are developing a type of "plastic blood".  These chemists are creating a small plastic molecule with a shape similar to natural hemoglobin that would carry iron, bind oxygen in the lungs and then transport it to other parts of the body. The team is currently attempting to create more than a prototype.  This is going to be on display in a new exhibition entitled "Plasticity--100 years of making plastics" at the Science Museum in the UK.

Chemical engineer Joseph DeSimone at the University of North Carolina at Chapel Hill has a different idea.  He has created tiny sacs of polyethylene glycol just 8 micrometers in diameter.  Coincidentally, a human red blood cell is about the same size (in fact, if you ever look at an image of tissues from under a microscope, you can use this handy number to gauge the size of other structures in the image!).  These sacs can deform in order to pass through capillaries that are smaller than 8 micrometers.  He hopes that these tiny sacs could carry a hemoglobin type molecule for transporting oxygen, or even to carry drugs and contrast agents for MRI (magnetic resonance imaging). Polyethylene glycol is biologically benign and work has been done to see the side effects in mice (no adverse effects so far).  I just wonder if the sacs will hold up long enough to make it to their intended destination or if they will liberate their contents when required to.  Also of concern is how the body will process this plastic and eliminate it or could it just stick to the inside of our arteries, gumming everything up.

Lastly, in the artificial blood department, Northwestern University bionanotechnology researchers are working on creating sacs made from peptide amphiphile (a small synthetic molecule created by the lead researcher, Samuel I. Stupp) and hyaluronic acid.  I cannot speak intelligently at all about PA, but I can tell you that hyaluronic acid (now often called hyaluronan) is a very important molecule in the extracellular matrix surrounding cells in the tissues of the body.  It is very good at attracting water and is abundant in joints and cartilage. The researchers hope to be able to make various shaped and sized structures from the membrane which can be put to use carrying biological solutions or even stem cells. to keep them hidden from the body's immune system.

Transfusions 

October 29, 2007, I had a transfusion.  I went one day for a general physical and submitted to a CBC (complete blood count).  A nurse called me a few hours later with a panic in her voice and asked if I had been fainting or dizzy or had trouble breathing. Well, I did notice that when I stood up I would feel weird, and I was having trouble with my usual excellent typing skills...transposing letters and such, and hey, I always felt tired and just assumed I was working too hard on the exterior renovations of this house.  The hematologist was amazed I was standing! He said it would take forever to get my hemoglobin levels up to par via iron infusions or taking supplements, so he suggested a transfusion.  After the initial sense of feeling like I had the flu (presumably an immune reaction) I noticed that I felt SO much better. 

Still, I need to monitor my hemoglobin levels (and a few other levels, too), so I go back occasionally and they take blood back OUT of me.  What is worse, I have to pay for them to give me blood and take it back!!  Anyway, one day I went in to have my blood drawn and there was a very large man, who definitely could have been a football player and has certainly seen his share of tackles and maybe even knives.  He looked quite street wise.  But he would NOT submit to the blood test.  The fear in his eyes and his voice was very clear.  As I sat there, calmly giving back the blood I had already paid for, more and more technologists came in to restrain this guy.  Unfortunately, I had to leave before I could see who won the battle!