XENOTRANSPLANTATIONPART - 1

In recent years, transplantation is the most effective way to cure the functional failure of organs .

Lack of donor is what pinches the most waitlisted recipients, many dying before their turn comes up for transplant

What can we do ?

Use the organs of animals

Concept

XENO- A tissue transplant from one species to another

e.g. from pig/chimps to human.

A procedure in which a human receives cells, tissues, or organs from a nonhuman animal

Timeline of xenotransplantation 1682- 1st documented attempt . Repair of the

skull defect of Russian nobleman by dog skull. The graft did well but surgeon was forced to remove it on pressure by church

1800- Frog skin was used for repair of burns by British surgeon

1920 – Sergei Voranov , French surgeon injected monkey testicle aspirates to elderly males to rejuvenate sexual vigour

1905- French doctor, Princeteau put rabbit thinly sliced kidney in a case of acute renal failure . Patients had significantly increased urine output, but 16 days later patient died of pulmonary edema.

1909 - German doctor tried to transplant monkey kidney to patient with renal failure in the thigh, 32 hours after the transplant ,renal vein thrombosis noted.

1964 - Reemtsma, Lousiana transplanted gorilla’s kidney into 13 patients with CKD, and gave immunosuppressive therapy at the same time. Only one patients kidney remained normal for nine months.

The surviving recipient was school teacher who even resumed her duty but died of electrolyte imbalance. Graft biopsy was normal with no evidence of rejection.

1965- J. Hardy did first cardiac transplant (baboon), failed due to small heart to tolerate adult circulation

1992- Pittsburg, first liver tranplant, died due to infection due to heavy immunosuppresion 2 months later

1995 – Jeff Getty recieved immune cells from baboon for AIDS, mysteriously improved .

1997- a 20-year-old man suffering from acute liver failure was hooked up to external transgenic pig livers developed by Nextran.

(ELADS)

1998- There were three successful transplantation of pig neural cells into patients suffering from strokes and Parkinson’s disease

Who can be the potential donorsPrimates Closer to humans in terms of evolutionary lineage

Less chance of rejection (Concordant xenografting )

Due to their similarities, there is a higher chance that

primate infections will spread to humans

Raises many ethical concerns

1) Chimpanze are endangered species

2) So close to humans that some might equate it with killing other humans

Baboon organs are too small to support adult function, but may be useful for children

Pigs

Reproduce quickly

Produce many offspring

Inexpensive

Organs are of similar size to those of humans

Domestic animal might pose fewer ethical

concerns

Drawbacks –

Not as closely related to humans Discordant xenografting

Life span Pigs live for 15-20 years, so their

organs might be in danger of breaking down if

they are in humans for too long

Potential uses

A) Can help treat patients with –

a) Serious burns,

b) Visual impairments,

c) Diabetes,

c) Parkinson’s disease, Alzheimer’s

d) and those in organ failure waiting for donor

B) Combat the consistent shortage of organs and

tissues needed for transplantation

(Vaccines, Blood & Biologics)

C) Help people who are in need of a transplant but

who are not eligible to be put on the organ/tissue

donor waiting list.

D) Abolish the black marketing of organs

E) Families would be pardoned from the difficult

decisions about organ donation of deceased

relatives

Concerns

1) Infected animal organs could be transplanted

into humans, transferring infectious diseases

into the human population (Xenoses/zoonoses)

a) Monkeypox virus

b) Herpes B virus

c) Simian Immunodeficiency Virus (SIV)

(similar to HIV)

2) Animals can be infected with organisms that are usually not transferrable to humans that may become transferrable with the assimilation of organs/tissues into human bodies, creating unknown diseases

3) Animal organs may not be able to complete all of the necessary functions in human bodies

4) High levels of immunosuppressant drugs can make patients more susceptible to other diseases

5) Is it acceptable to use animals as organ/tissue

sources? – may not be for some religions

6) Will necessitate the breeding and killing of animals on a large scale. ( Though inc. employment) – PETA, animal right activists

7) Is it acceptable to genetically modify animals so the organs/tissues they produce are compatible with those of humans? - Religious authorities against it .

8) None Clinical trials done - Is it right to subject humans to xenografts if itis unlikely that they will survive?

9) Should we proceed with developing xenotransplantation when other technologies, such as artificial organs, could be invented/developed to tackle the same problems and might prove even better ?

Prospect

Xenotransplantation will open up a new treatment strategya)Gene transfer strategy b)modification of donor organs, c)immune tolerance d)newer immunosuppressants..