Technical
Information (second proposed method)
Using
biological materials is an important avenue to research. The goal
is to be able to modify hemoglobin from a source other than humans. Increasing
its oxygen carrying capacity, prolonging its shelf life, removing all toxins
through sterilization, and ultimately gaining the ability to wholly replace
true blood.
Hemoglobin
can be extracted from blood by removing it from the blood cell membranes
of other animals, which is good in terms of isolating the substance, but
is met with an array of complications when outside of the red blood cell.
Bovine hemoglobin appears to be similar to that of human hemoglobin in
laboratory tests. First, we must create an artificial microencapsulator
that parallels the membrane of actual red blood cells. It is not
important at this point to construct a membrane that functions exactly
like a red blood cell, rather we are looking to give the hemoglobin a basic
surrounding, or neighborhood, that still allows us to access it.
A red blood cell is composed of a polymerase membrane made of lipid vesicles,
so it would be best to use something made of the same material, for instance,
the membrane surrounding the yolk of an egg. Remember we are tying
to imitate the structure of the red blood cell, not the function, so the
similarity in lipid vesicles should suffice. Now that we have encapsulated
our hemoglobin, we can both sterilize it and store it because it has a
longer shelf life than actual hemoglobin. Sterilization is beneficial
because it eliminates any impurities (viruses) such as HIV, that could
potentially be contracted by the recipient of a blood transfusion.
Purification of the hemoglobin is relatively simple and can be in the same
manner used to purify insulin. Also, by creating an artificial membrane,
we have the option of omitting iso-agglutinating
antigens, which obviates blood typing and screening. Our new membrane
surrounding the hemoglobin, without the presence of the antigens, makes
cross-matching blood types unnecessary and thus enables us to transfuse
blood almost immediately to victims of trauma or hemorrhaging.
Another
complication of hemoglobin when outside of the red blood cell is the fact
that the molecule rapidly dissociates from its original tetrameric form
into dimers.
These smaller dimers are excreted by the kidneys and cause renal toxicity
as well as further kidney damage as the fragments are expelled. Moreover,
as a dimer,
hemoglobin no longer binds with plasma, which is essential
in sustaining the life of the red blood cell. We can essentially
kill two birds with one stone in solving the problem of hemoglobin’s direct
association to kidney damage and its inability to bind with plasma by determining
what causes it to dissociate into diamers. Hemoglobin is a protein
and is therefore composed of an intricate network of amino acids.
By altering the native hemoglobin with the addition of a single specific
amino acid, it is possible to covalently bind the dimers, thus preventing
any dissociation.
An
equally large problem is the fact that outside of the red blood cell, hemoglobin
is unable to retain the component that allows it to readily release oxygen,
in which case, the molecule is essentially worthless. In addition,
hemoglobin
does not bind with nitric oxide when outside the confines of the red blood
cell, and therefore does not transfer to the blood vessel. Incorporating
a small amount of manufactured NO(g) into the blood during transfusion
will prevent vasoconstriction
of the blood vessels, which occurs as a result of nitric oxide depletion.
This is a delicate process, however, because an over-infusion of NO(g)
can cause the blood vessels to vasodilate, an equally undesired occurrence.
Ideally,
we would be able to create an artificial blood that is indistinguishable
from true blood. Unfortunately, that kind of technology presently
only exists in science fiction movies and is still years away. Until
then, using the ideas and applications suggested, we are presented with
an opportunity to recreate blood step by step, beginning with the element
that has given scientists the most trouble, the red blood cell.
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