•Blood is a special type of connective tissue that is composed of white cells, red cells, platelets, and plasma.
•The average adult has about five litres of blood living inside of their body.
•Blood is made up of three types of cells:-
1. Erythrocytes or RBC - They are shaped like slightly indented, flattened disks. These are the most abundant cells, and contain haemoglobin (Hb or Hgb).
2. Leukocytes or WBC - These are the cells of our immune system; they defend the body against infections and foreign materials.
3. Thrombocytes or Platelets - are involved in the clotting (coagulation) of blood. When we bleed the platelets clump together to help form a clot.
RBC
2
• RBC supplies Oxygen and essential nutrients to various cells
and tissues.
•RBC is also involved with the endocrine System for the
transportation of hormones.
•RBC are also responsible for maintaining the Homeostasis of
the body ( mainly pH levels and body temperature)
•WBC have antibodies which defend us from infection and
foreign bodies.
•Platelets are involved with coagulation of blood when bleeding.3
•The blood flow in our body is generally laminar.
•The flow becomes turbulent in the blood vessels due to
narrowing of the arteries and veins. (Stenosis
of the arteries)
•Turbulence occurs when a critical Reynolds number in
exceeded due to increase in velocity. This can be
mathematically represented by:‐
Where
v
= mean velocity,
D
= vessel
diameter,
ρ
= blood density, and η
=
blood
viscosity 4
• Synthetic compound which can be used as a blood substitute.
•Blood is a complex tissue hence it is very hard to make a compound that performs all the
functions of blood.
•Researchers have mainly focused on two main blood substitute technologies:‐
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1.It can be used to meet the increasing demand of blood required
during major operations
2.It is a disease‐free source of blood hence the risk of diseases like
HIV (Human Immunodeficiency Virus) etc from blood substitutes is
removed.
3.
These blood substitutes do not carry any antigens which
determine blood groups hence it is impossible for immune system
of the body to reject them.
4.The shelf life of artificial blood is around 1‐3 years compared to
the shelf life of normal blood, which is 42 days.
5.The artificial blood can be very useful in battlefield and war
scenarios as it is easy to carry and does not require controlled
conditions.
6
•The first successful human transfusions were done in 1667.
•In 1854, blood in patients was substituted with milk and salt/saline solution.
• In 1868, researchers found that solutions containing haemoglobin
isolated from red blood
cells could be used as blood replacements.
• During World War I, a gum‐saline solution containing galactoso‐gluconic
acid was used to
extend plasma.
•In 1966, experiments with mice suggested a new type of blood substitute,
perfluorochemicals
(PFC).
•In 1968, the idea was tested on rats. The rat's blood was completely removed and replaced
with a PFC emulsion. The animals lived for a few hours and recovered fully after their blood
was replaced.
•Research in this area was further fueled
in 1986 when it was discovered that HIV and
hepatitis could be transmitted via blood transfusions.
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•Increased availability
•Oxygen carrying capacity: equaling
or surpassing that of biological blood
•Volume expansion
•Universal compatibility: elimination of cross matching
•Pathogen free: elimination of blood contained infections
•Minimal side effects
•Survivability:
over a wider range of storage temperatures
•Long shelf life
•Cost efficient8
•The two types(HBOC
and PFC) have dramatically
different chemical structures, but they both work
primarily through
passive diffusion.
•Passive diffusion takes advantage of gasses' tendency to move from areas of greater concentration to areas
lesser concentration until it reaches a state
of
equilibrium.
• In the human body, oxygen moves from the lungs (high
concentration) to the blood (low concentration).
•Then, once the blood reaches the capillaries, the oxygen moves from the blood (high concentration) to
the tissues (low concentration).9
•HBOC vaguely resemble blood.
• They are very dark red or burgundy and are made from real, sterilized haemoglobin
• RBCs
from real, expired human blood
• RBCs
from cow blood
• Genetically modified bacteria that
can produce haemoglobin
• Human placentas
11
• Techniques:
Cross‐linking
portions of the haemoglobin molecule with an
oxygen‐carrying haemoglobin derivative called
diaspirin
Polymerizing
haemoglobin by binding multiple molecules to
one another
Conjugating
haemoglobin by bonding it to a polymer
12
(A,B) Tetrameric
stabilization is accomplished by intramolecular
crosslinking
between
the two a or ß
subunits using a site specific crosslinker. (C) The effective molecular
weight of Hb
can be increased by conjugating it to polyethylene glycol. (D)
Polymerized Hb
of molecular weights greater than the native Hb
tetramer of 64 kDa
may be produced through polyfunctional
crosslinking
agents. (E) Hb
can also be
encapsulated into liposomes
in order to recreate the natural properties of red blood
cells.
13
• Preventing the Hb
tetramer's dissociation is a major concern in order to suppress renal filtration.
• Because the alpha/beta (a‐ß)dimers
are relatively stable, the goal of intramolecular
modification is to
cross‐link the two alpha (a‐a) or beta (ß‐ß) subunits and stabilize the association of the two alpha/beta (a‐
ß) dimers. • The cross‐linking not only prevents tetramer
dissociation, but also reduces the affinity of Hb
for O2
.• The most popular cross‐linkers currently used are
bis(3,5‐dibromosalicyl)fumarate(DBBF) and nor‐2‐ formylpyridoxal 5‐phosphate (NFPLP).
14
•Multiple Hb
proteins are linked together through the use of
dialdehydes, such as glutaraldehyde
and glycoaldeyde.•Increase in size due to formation of oligomers. This also affects the
molecular weight which exceeds 500 Kda(compared
to 64.5 Kda
unpolymerized
Hb).• The increase in size prevents the rapid excretion of the molecule,
prolonging the Hb
plasma half‐life.•Unpolymerized
Hb
tetramers have, however, the unfortunate result of
generating excessive viscosity, oncotic
pressure, and O2
affinity.
15
• Conjugation of Hb
is the covalent binding of Hb
to a biocompatible polymer, such as
polysaccharide, in order to increase its overall size.
• Such a process achieves similar improvements than those made using polymerization.
• The intravascular circulation time of a HBOC is extended by conjugating Hb
with a
macromolecule.
16
• HBOCs
work much like ordinary RBCs.• The molecules of the HBOC float in the blood
plasma, picking up oxygen from the lungs and dropping it off in the capillaries.
• The molecules are much smaller than RBCs, so they can fit into spaces that RBCs
cannot, such as
into extremely swollen tissue or abnormal blood vessels around cancerous tumours.
• Most HBOCs
stay in a person's blood for about a day ‐‐
far less than the 100 days or so that
ordinary RBCs
circulate.
17
• The modified haemoglobin molecules can fit into very small spaces between cells and bond to
nitric oxide,
which is important to maintaining blood pressure. • This can cause a patient's blood pressure to rise to
dangerous levels. • HBOCs
can also cause abdominal discomfort and
cramping that is most likely due to the release of
free radicals, harmful molecules that can damage cells.
• Some HBOCs
can cause a temporary, reddish discoloration of the eyes or flushed skin.
18
• Apart from side effects, haemoglobin can replace only the oxygen transport capacity of whole blood, without the coagulation or immunologic aspects normally
present in blood.• Thus haemoglobin‐based oxygen carriers will not
replace blood, use of these products may be limited to specific applications or in conjunction with specialized techniques, such as cardiopulmonary bypass with
extracorporeal circulation or acute normovolemic hemodilution
with harvesting of autologous
whole
blood for later reinfusion.
19
• Unlike HBOCs, PFCs
are usually white and are entirely
synthetic.
• They're a lot like
hydrocarbons
(chemicals
made entirely of hydrogen and carbon) but they contain
fluorine instead of carbon.
20
• Perfluorochemicals
will not mix with blood, therefore
emulsions
must be made by
dispersing small drops of PFC in
water. This liquid is then mixed with
antibiotics,
vitamins,
nutrients
and
salts, producing a mixture that contains about 80
different components.
21
• Main function is to carry oxygen in blood.
• They can carry between 20 and 30 percent more gas than water or blood plasma, and if more gas is present,
they can carry more of it.
• PFCs, like HBOCs, are extremely small and can fit into spaces that are inaccessible to RBCs. For this reason,
some hospitals have studied whether PFCs
can treat
traumatic brain injury (TBI)
by delivering oxygen
through swollen brain tissue.
22
• PFCs
are oily and slippery, so they have to be
emulsified, or suspended in a liquid, to be
used in the blood.• These emulsifiers eventually break down as they
circulate from the blood.• The liver and kidneys remove them from the
blood, and the lungs exhale the PFCs
the way they would carbon dioxide.
• Sometimes people experience flu‐like symptoms as their bodies digest and exhale the PFCs.
23
• Platelet count is known to decrease, presumably due to opsonization
of platelets by the
perfluorocarbon
and subsequent sequestration and elimination by the reticuloendothelial
system.
• PFCs
are chemically inert, but they are extremely good at carrying dissolved gases.
However, extra
oxygen can cause the release of free radicals in a person's body. Researchers are studying whether PFCs
can work without the additional oxygen.
24
• Restoring oxygen delivery after loss of blood from trauma, especially in emergency and battlefield
situations
• Preventing the need for blood transfusions during surgery
• Maintaining oxygen flow to cancerous tissue, which may make chemotherapy more effective.’
• Treating anemia, which causes a reduction in red blood cells
• Allowing oxygen delivery to swollen tissues or areas of the body affected by sickle‐cell anemia
25
• Artificial blood can be made according to the type of blood required.
• Viscosity of artificial blood can be adjusted by adjusting the concentration, PH and
temperature while designing the material.
27
Attribute Infused HBOCs Transfused Red Cells
Onset of action: Immediate 2,3-DPG dependent
Oxygen affinity: Red cell 2,3 DPG not required for oxygen release
Red cell 2,3 DPG required for oxygen release
Oxygen transport: Red cells plus plasma Red cells only
Risk of disease transmission:
Sterile pharmaceutical; no leukocyte exposure
Risk minimize by improved donor selection; leukocyte exposure
Storage: Room temperature; no loss of efficacy Refrigeration required; progressive loss of efficacy
Shelf life: 36 months 42 days
Compatibility: Universal Type-specific
Preparation: Ready to use Requires typing and cross-matching
Viscosity: Low High
Duration of action: Maximum of 3 days Estimated 60 to 90 days 28
FOUR MAIN TECHNOLOGY CURRENTLY IN PROGRESS:‐
1.STEM CELL CREATIONS
2.SYNTHETIC CELLS
3.POLYMER PLATELETS
4.MASS PRODUCTION
29
Advanced Cell Technology, headquartered in Santa Monica, CA is currently
researching on developing Blood Cells from Embryonic Stem Cells.
•The Company is working on making a large supply
of O‐
blood cells which can be used by any patient.
•They have already produced 10 billion Blood Cells
from Human Embryonic Cells
•The main challenge is producing trillions of these
cells which can be used in blood transfusion. 1cc of
blood contains 5 billion RBCs.
30
Samir
Mitragotri
, a chemical Engineering professor at
University of California, Santa Barbara and University of
Michigan hope to mimic the well defined shape of RBC and
their flexibility using synthetic biocompatible polymers.
•Spheres of biocompatible materials were squeezed and
coated with layers of Hg Protein.
•These cells haven’t matched the ability to bend but these
blood cells coated with haemoglobin can store over 90% of
Oxygen.
•The next step of the research is to test the circulation time
of these cells in Rodents.
•The research team believes that these cells can also be
used to carry drugs or chemicals used for medical imaging.
31
•A group of researchers at the University of North Carolina (UNC)
at Chapel Hill
is looking into mass production of Synthetic Blood.
•They are trying to etch the cell shape in silicon and then use that to create
mould using liquid polymer.
•These moulds are then converted into hydrogel
blood cell replica, which can
then be used as synthetic blood.
•The hydrogel
blood cell are very flexible to pass through mice liver and remain
in circulation. (Flexibility of Mice RBC is six times more compared to human
RBC)
32
This technology does not aim at developing synthetic
alternatives for natural blood but it is trying to keep patients
alive.
A team led by Erin Lavik, a biomedical engineering professor at
Case Western Reserve University, is developing synthetic
platelets to help seal injuries and stop internal bleeding more
quickly.
The team has designed polymer nanoparticles
that bind to
natural platelets, increasing the platelets' ability to stop
bleeding.
Experimental results show that the bleeding time in injured rat’s
thigh arteries was reduced by 50% if the synthetic platelets were
injected before injury and by 23% if it were injected after the
injury.
The team will study its effects on larger animals and then
proceed to clinical trials.
33
Robert M. Winslow. “Haemoglobin –based Red Cell Substitutes”. John Hopkins University Press, 1992.“The Human Heart”. The Franklin Institute, Accessed November, 2011. URL <http://www.fi.edu/learn/heart/blood/blood.html>“Artificial Blood”. Indian Journal of Critical care Medicine, Retrieved from <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2738310/> PMCID: PMC2738310“Artificial Blood: What Is It? Will I Use It?” by Bruce J. Leone, M.D.Associate Professor of Anesthesiology at
Mayo Clinic Jacksonville. Accessed October, 2011. URL<http://www.dcmsonline.org/jax-medicine/1998journals/december98/artificialblood.htm>“Blood Substitutes” Medscape Reference. Accessed October, 2011. URL
<http://emedicine.medscape.com/article/207801-overview>“Artificial Blood: Manufactured Life” Jensen, 2010. Accessed October 2011, URL<http://www.scribd.com/doc/21977473/Artificial-Blood>“Artificial Blood: A Current Review” by Mr. Parag .A. Kulkarni. Accessed October 2011, URL<http://www.pharmainfo.net/reviews/artificial-blood-current-review>“Blood Substitutes” by Dr Pierre Lafolie. Accessed October, 2011. URLhttp://biomed.brown.edu/Courses/BI108/2006-108websites/group09artificialblood/index.htm“You Won't Believe It's Not Blood: 5 Synthetic Substitutes for the Real Thing”. Accessed October, 2011<http://www.popularmechanics.com/science/health/med-tech/5-synthetic-substitutes-for-real-blood-2#fbIndex2>"Artificial Blood." How Products are Made. Ed. Stacey L. Blachford. Gale Cengage, 2002. eNotes.com. 2006. 31 Oct, 2011 <http://www.enotes.com/how-products-encyclopedia/artificial-blood>Wilson, Tracy V. "How Artificial Blood Works" 29 December 2006. HowStuffWorks.com. <httphttp://science.howstuffworks.com/innovation/everyday-innovations/artificial-blood2.htm>
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