The field of blood substitute technology is developing all the time as scientists around the World continue in their search for an effective alternative to the use of donor blood for the transfusion procedures that are so often necessary for saving lives.
Two exciting prospects include the extraction of haemoglobin from worm blood and the development of 'synthetic red blood cells'.
Haemoglobin from worms
Scientists have recently been researching the possibility of using worm haemoglobin to develop a blood substitute after successfully extracting haemoglobin from two common worms:
The haemoglobin from these species is present as large polymers, which are up to 50 times larger than human haemoglobin. This haemoglobin represents an exciting prospect as a potential blood substitute. Its large size means that it needs no modification to remain stable in the bloodstream long enough to oxygenate the tissues, and will not break down and cause kidney damage.
The worm haemoglobin has performed well in pre-clinical testing, maintaining normal oxygen-carrying capacity and causing no allergic reactions in mice.
Worm haemoglobin is a promising new discovery. However, its suitability as a blood substitute will depend on the ease in which it can be extracted and purified from worms in sufficient quantities that will be required for further safety tests. One worry is that worm haemoglobin may cause the side effect of increased blood pressure, similar to that often observed following injection of cell free haemoglobin into people.
Synthetic red blood cells
The development of synthetic red blood cells involves the encapsulation of haemoglobin inside biodegradable polymer membranes. This stabilises the haemoglobin and prevents its breakdown in the bloodstream, which can cause kidney problems.
Research pioneered by Thomas Chang, (shown left) is currently focusing on the prospect of entrapping natural red blood cell enzymes along with the haemoglobin inside these capsules. This has the potential to create a 'microenvironment' for the haemoglobin, which is very similar to the natural environment within our blood. Such an environment would allow haemoglobin to behave in its natural manner. This would ensure correct oxygen and nitric oxide binding and release, and prevent the problems of blood pressure increases seen with cell-free haemoglobin.
Such technology is very exciting and could soon yield the next, 'third-generation' of blood substitute products for clinical trials. However, such technology is complex and clinical use is not expected for some time yet.
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