MadSci Network: General Biology

Re: Do you think we'll never be able to bring back a naturally dead person?

Date: Wed Apr 3 12:07:59 2002
Posted By: Bernadette Baca, Health Physicist, Division of Reactor Safety
Area of science: General Biology
ID: 1016566008.Gb

It all sounds like science fiction to bring back a dead person through 
organ and tissue transplants or replacement, tissue and organ regeneration, 
or even utilize a machine to perform biological functions.  However, the 
science fiction behind Frankenstein and some Star-Trek episodes may one day 
be reality.  To simply supply the individual with a new or artificial 
heart, lung, or other organ or tissue, or even provide them with an 
infusion of regenerating cells in order to bring them back from the brink 
of death is one of the driving forces behind many of the research and 
medical projects today.  Science has grown by leaps and bounds in this 
area, with many areas are still considered in their infancy, but all 
working to this common goal for simplified organ and tissue replacement and 
regeneration.  Until then, we can only hope for the best with what current 
technology we have.  I believe you may find additional answers through 
researching the current advances and limitations of organ and tissue 
transplants and even bionics.  


First, I'd like to cover "bionics." Bionics is seen as an attempt to 
develop better machines through the understanding of biological design 
principles or imitation of biology and to connect biological systems to 
artificial organs, or other systems.  There have been amazing advances in 
the realm of bionics such that a deaf person can hear, pace makers are 
common place, artificial hearts used to sustain an individual until a 
transplant is available, various joints are replaced with man-made 
materials that incorporate bone then dissolve away, an implanted chip which 
can control artificial limbs, and a blind person that may once again be 
able to see.  There is even talk of nanites or nanodes that would traverse 
the human body making necessary repairs.  It's almost like the science 
fiction of Star-Trek meets the real 20th century.  Even with such fantastic 
advances such as pace makers, artificial joints, and prosthetic technology, 
there is still a lot of work yet to do in understanding the processes of 
the human brain (especially for neuro-related bionics) and how foreign 
materials interact with the human body (artificial limbs) for extended 
periods of time.    In some aspects we are so close but yet so far away.

Even with the most common bionic procedures (e.g. joint replacement and 
pace makers) there are still  obstacles.  As mentioned earlier, we are 
still uncertain about the long term interaction of many of the devices used 
in the human body.  Individuals may not take well to the grafting, be 
allergic to the materials used, not be physically strong enough for the 
medical procedure, or complications (namely secondary infections) from the 
medical procedure arise.  However, it is still all about taking a chance 
that we make in efforts to extend a person's life, or more appropriately 
for many bionic devices, improve a person's quality of life.

So, in considering that may be, just may be, if the stars lined up (an 
artificial organ device is available, the person is well enough to undergo 
the medical procedures to get it, and there is no rejection of the 
artificial organ), one would also need to consider the costs associated in 
receiving this artificial organ or device.  And unfortunately, many of the 
advanced devices are not economically available to the general public and 
often insurances will not cover those devices considered "experimental".  
It's a harsh reality but one that exists.  Currently most insurance 
policies covered various joint replacement procedures but, again, will not 
cover "experimental" procedures.

The current advances seen in bionics today speak of eventually seeing 
machines doing so much for us or becoming an important organ or tissue to 
replace a failing one.  However, we are not there yet.  This is where 
science fiction is becoming reality - SLOWLY. 

For further information on bionics please see the following websites:


Now to answer your question concerning replacing old and worn out human 
parts with other human body parts.  This field of human body part 
replacement also has undergone dramatic advances, but still is considered 
in its infancy in many areas.  Doctors and scientists have been able to 
successfully reattached individuals' fingers, legs, arms, and hands, and 
graft skin for severely injured individuals.  This is great!  Yes, 
individuals have had their limbs reattached, bone marrow transplants, and 
skin grafts performed successfully.  But many times these organs and 
tissues were typically from their own body.  Much, much more comes into 
play when organs and tissues do not come from the individuals themselves.  
And just like for bionic parts, there are draw backs; and for transplants 
there may be more draw backs and considerations.

It is not as easy as it sounds to simply replace a failing or aging organ 
or tissue with another.  There are so many factors to consider.  Even organ 
and tissue donor web sites stress the uncertainty involved with transplants 
and the likelihood for an individual to pass all the medical and 
psychological testing, wait (and often times a LONG wait) for a match, and 
have the transplant procedure be successful.  No doubt that some procedures 
have become commonplace, but many are not and carry much more uncertainty 
in success.


To begin with, most living and viable transplant organs or tissues must be 
compatible to the recipient.  Several tests are performed on the individual 
and organ or tissue for compatibility factors.  The recipient must also be 
strong enough physically and mentally for the procedure before the 
individual can receive the transplant.

First, organs and tissues are "typed" based on blood type and 
histocompatibility (immune system or white blood cell compatibility).  A 
blood type test (characterization of the red blood cells) is the first step 
in determining whether the organ or tissue is a suitable match. This test 
identifies and characterizes the "ABO" of red blood cells and whether or 
not it matches the potential donor.  The following is a table illustrating 
which blood types can be received and donated to respective blood types: 

Blood Type	Can Receive from Type	Can Donate to Type
O	               O	           O, A, B, AB
A	             A, O	              A, AB
B	             B, O	              B, AB
AB	          O, A, B, AB	                AB

Blood type is an important consideration in finding a suitable match, just 
as it is in giving blood for a blood transfusion.  

The next important blood test deals with the immune system or white bloods 
cells. There are basically two tests performed on a transplant patient's 
white cells.  The first test is to characterize the inherited generic 
markers on the surface of the white cells.  These markers are called Human 
Leukocyte Antigens (HLA).  An individual basically inherits one set of 
these markers, or antigens, from each parent.  Even though there are 
multiple combinations of these antigens, it is possible to locate a 
non-related donor that has the same HLA combination.  The second test is 
just as important as any other test and it tests the specific immune 
response between the patient and donor cells.  This second test, 
"crossmatching", measures and characterizes the antibodies the recipient 
and even donor cells create in order to defend against invading or foreign 
materials.  The crossmatching results show whether and to what degree the 
recipient and donor's white blood cells create antibodies which would then 
destroy the other's cells.   More specific information on tissue typing is 
provided in the websites listed toward the end of this section.

Other tests that are run on an individual considered for an organ or tissue 
transplant include and are not limited to the testing of other organs and 
systems that would support the transplant, a psychological evaluation to 
make sure the individual can cope with having the transplant, and test for 
any other medical problems that would make a transplant dangerous, or that 
would cause the transplant to fail.  Some of the other medical tests 
include screening for cancer, HIV or AIDS, an incurable infection (such as 
tuberculosis or Hepatitis C), severe disease in another organ system (such 
as severe coronary heart disease), and emphysema or cirrhosis of the liver.

There are also many other medical and even financial factors that I can not 
even think of that come into play to receive such transplants.  A few that 
I am aware of are if an individual is overweight or elderly are not 
considered the best candidates for transplants.  Being overweight may place 
too much strain on the new transplant causing it fail.  Being older puts 
the individual at greater risk for complications during the medical 
procedure, effects from the medications, and increased risks for cancers to 
develop.  Financially, the individual must have sufficient funds or medical 
insurance coverage to pay for all the medications,  regular blood tests, 
and check ups an individual will need to have for the rest of their life 
once they receive their transplant.  


Today, the harvesting of an individual's own organs and tissues allows them 
to be safely stored and used at a later date.  The most commonly known 
procedure is for cancer treatment patients to have their own or a matched 
donor's bone marrow harvested and later transplanted after the cancer 
treatments.  There is also bone tissue preservation for trauma and surgical 
patients, portions of the parathyroid cryo-preserved for re-implantation, 
and skin tissue preservation for burn, trauma, and surgical patients.  With 
advances in this area, many more individuals are able to get a new lease on 
life through the use of their own organs and tissues; however, this may not 
be an option for the many others in need of a transplant.


So now that we have all these tests run in order to find a tissue "match" 
or have harvested the individual's own tissue or organ, what else is there 
to consider?  Organ and tissue rejection is the single major factor for 
transplants to fail.  Even one's own harvested organs or tissues may be 
seen as foreign and the body attacks it in order to destroy and remove it 
from the body.  An individual's own blood characteristics can change over 
time due the immune response of the many different viruses, bacteria, etc. 
that it encounters.  It can change significantly since the tissues or organ 
was first harvested and any time after the transplant.  This is why the 
tissue typing and blood tests are so important, even for self donated 
tissues.  It is hoped that the immune system is sufficiently characterized 
before and after the transplant to avoid the host turning on the donor 
cells (graft or organ/tissue rejection) and even the donor cells from 
turning on the host (graft-vs-host disease).   

In efforts to minimize an immune response or rejection to the new organ or 
tissue, immunosuppressive drugs are administered.  Another complication 
seen when such drugs are taken is that it opens the door to many other 
infections and risks.  When the immune system is lowered or compromised, 
the risk of cancer and other illnesses increase.  However, with careful 
surveillance and antibiotic drugs, many of these "secondary" infections or 
complications are reduced.

One must also remember that at any time the individual may experience organ 
rejection - even if they take their medications as required.  A transplant 
patient must have regular blood checks for rejection for the rest of their 
life - not mention taking their anti-rejection medications.  A transplant 
is a life long commitment to keep the transplant healthy and avoiding 


Now for science fiction to meet reality, there is on-going research into 
the "regeneration" of organs and tissues.  This section of science has 
recently made significant advances and discoveries but is still in early 
infancy.  In one scenario, a tissue engineer injects or places a given 
molecule, such as a growth factor, into a wound or an organ that requires 
regeneration.  These molecules cause the patient's own cells to migrate 
into the wound site, turn into the right type of cell and regenerate the 
tissue.  In the second more ambitious procedure, the patient receives cells 
(either his or her own or those of a donor) that have been harvested 
previously and incorporated into three-dimensional scaffolds of 
biodegradable polymers, such as those used to make dissolvable sutures.  
The entire structure of cells and scaffolding is transplanted into the 
wound site, where the cells replicate, reorganize and form new tissues.  At 
the same time, the artificial polymers break down, leaving only a 
completely natural final product in the body: a neo-organ.  The creation of 
neo-organs applies the basic knowledge gained in biology only over the past 
few decades to the problems of tissue and organ reconstruction.

Tissue engineering does not yet rival the fictional portrayals seen in 
movies or in books in which some on can simply regenerate or grow complete 
organs and tissues, but a glimpse of the future has arrived.  The creation 
of tissue for medical use is already a fact, to a limited extent, performed 
in hospitals across the U.S.  These groundbreaking applications involve 
fabricated skin, cartilage, bone, ligament and tendon and make musings of 
"off-the-shelf" whole organs seem less than far-fetched.  Scientists must 
surmount a few obstacles, however, before drugs that promote tissue and 
organ formation become commonplace.  To date, only the factors responsible 
for bone and blood vessel growth have been characterized.  To regenerate 
other organs, such as a liver, for example, the specific molecules for 
their development must be identified and then produced reliably.

This specific area of science and medicine is progressing rapidly; but 
unfortunately benefits a selected few areas and needs.  More specifics on 
tissue engineering can be found at the following website:


However, the biggest problem associated with organ and tissue transplants 
is simply "availability".  Many individuals on donor waiting lists die 
because of the shortage of organs and tissues.  Currently, each day about 
63 people receive an organ transplant, but another 16 people on the waiting 
list die because not enough organs are available.  It seems so unfair that 
many individuals die before they get the chance at a donated organ or 
tissue.  However, if the organ and tissue was not compatible, the 
individual may suffer more from the organ/tissue rejection than not having 
it at all. 

The United Network for Organ Sharing (UNOS) has been tracking the number of 
individuals on transplant waiting lists and the number of available organs 
and tissues available.  As of February 28, 2002, the overall number of 
individuals listed on the national transplant waiting list was 78,945 and 
by March 23, 2002, the number increased to 79,165.  In addition, UNOS 
tracks the number of available donor organs and tissues recovered.  In 
2000, a total of only 11,684 available donor organs and tissues recovered.  
The numbers for 2001 and 2002 were not yet available.  Even so, this is a 
far cry from the number of individuals listed on the waiting list.  UNOS 
also estimated that the number of individuals who died while waiting for a 
donor organ/tissue was 5,800 in 2000 and 4,320 in 2001.  So simply waiting 
to find an available and compatible organ or tissue to transplant may be 
the biggest obstacle of all.

Getting and keeping a transplant healthy is not by any means an easy one, 
but there are numerous survivors out there to attest the trails and 
obstacles have paid off for them. 

For additional information on organ and tissue transplants please see the 
following websites:

With as much wishing and dreaming about one simple procedure to replace or 
regenerate failing and worn out body parts, we are still working to make 
dreams and hopes reality and hopefully one day make organ and tissue 
replacement quite commonplace.  But right now and to the extent of bringing 
a dying person back to life, it is going to depend on what organ and tissue 
is failing, the availability of the organ or tissue (or even an artificial 
replacement), the overall health of the individual, the compatibility of 
the individual and the replacement, and current technology and surgeon 
skill to save the person's life.  There always exists the possibly that the 
most remote chance or operation will help, but sometimes even the most 
guaranteed procedures do not end as we hope.  Life is still quite 
unpredictable and uncertain.  Often at times no matter how we look at it or 
how hard try to overcome obstacles, individuals slip away and we can only 
hope to a much better place.

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