Xenotransplantation

"Congratulations! The transplantation surgery has been successful! Your daughter has a brand-new heart now and she has a whole world to explore and begin her new life” Dr. Reddy was jubilant at the success, as this was one of the rare surgeries and this was the tenth one that he performed. The technology was developed by him along with his team and it was now available commercially.

The joy of the parents was beyond words as the tears were uncontrollably flowing out of their eyes. The recipient was Sudha who was 15 years old and had a serious defect in the heart valve due to which pure blood was getting mixed with impure blood. She would need heart transplantation at the earliest or she would die within two years. Her condition could not be rectified by any of the advanced surgeries available at that time. Dr.Reddy patiently explained this to everyone there about this novel technology. Sudha's friend Sunaina was also listening with rapt attention.

The donor of heart for Sudha was Sus scofa. Are you thinking that it is somebody from outside India? No, it is the scientific name of the pig. Yes, you have heard it correctly. it is a pig. The reason for using pigs, though unpleasant for many of us, was because genetically they were closer to human beings. They were specially bred and raised in the pigsty of the heart transplantation unit of Gandharva hospitals, Hyderabad. It was by no means an ordinary pigsty. It is a closed unit, called a controlled unit, with temperature and pressure set according to the requirements of the pigs, separate Air Handling Units (AHUs) where the incoming is filtered to remove germs, to prevent any microbes contaminating the environment and causing disease in the pig. The pigs were brought up with utmost care.

The Sus pig itself was by no means an ordinary pig, it had a very special lineage. Its grandparents were genetically modified to make hearts suitable for humans. Few of the pig genes responsible for tissue rejection if allowed to be expressed in the pig heart and presented to the human immune system, were knocked out or silenced. This means they were destroyed to no longer express themselves. A few other genes to prevent unnecessary growth of heart tissue were also knocked off. Finally, a few human genes to improve the acceptance by the human immune system were added. All these genetic modifications are done in vitro at the early embryo stage. Embryos at a very early stage of development were taken out from the uterus of a pregnant female pig and after all the genetic manipulations by microinjection, these embryos are transferred back into the uterus of a female pig. The pigs born out of this female pig are genetically modified pigs. The first genetically modified pig line was well characterized by DNA fingerprinting and other technics and formed the parent line. It was carefully continued to breed and each progeny was again verified to make sure that the gene knockout was maintained and the background genetic makeup was not changed.

Once all the characterization studies were completed it is marked with a Sus Donor Number and is ready to donate the heart within a certain timeframe if somebody required transplantation. Beyond a certain age, Sus is not acceptable to be a donor and goes waste.

Records of all the Sus bred from this facility are maintained in electronic form. The facility and the records are periodically verified by inspectors from different Government regulatory agencies. This is the procedure followed for the commercialization of the technology.

A lot of work had gone before the technology could be commercialized. This technology was made possible by the dedicated research team in Reddy’s R&D unit. This team was responsible for the identification of pig genes that needed to be knocked off and human genes to be inserted into pigs in order for technology to work. The concept was verified at the laboratory level and before transplantation into humans, it was verified that the genetically modified pigs were no longer making antigens which can cause rejection and also unnecessary growth of the heart. Also, the presence of useful antigens was confirmed. The data was presented to the government agencies and final approval was obtained to commercialize the technology as described above. An international patent was applied for this novel technology, and it was awarded. It was very unusual that the doctor took the time to explain the technology to all of them. Dr.Reddy and his team were likely to get the Nobel prize in medicine for this Xenotransplantation which means transplantation from a different species. Their observations were published in top international journals.

Sunaina fell from the sofa on which she fell asleep and for some time she was confused but slowly she completely woke up from her afternoon nap. She realized that she had a wild dream after reading a Scientific fiction article on a website. She had to submit an essay to the college on the topic of science fiction and as she was browsing the web for an idea. She read about the xenotransplantation technology and slowly she slipped into a deep sleep. In sleep, she dreamt that the technology was tested and ready and under implementation. How very thrilling the dream was and how very useful the technology was! The site information said that the first recipient was alive for 4 months and the second one was under observation the technology really held a lot of promise and is likely to succeed by the year 2030. She proceeded to write the essay enthusiastically.