Stem Cell Organ Transplants?
There is hope that eventually, humans will be able to undergo organ transplants using tissues that have been developed in the laboratory from their own cells. This would therefore completely change the idea of organ donation for treating diseases.
The main problem with this idea is that large organs such as the liver, kidneys, pancreas and heart are difficult to grow due to the large number of different cells involved within each organ.
There is hope however, as within the past few years, windpipes and bladders using patients own stem cells have been successfully grown and transplanted.
With this type of technique, researchers hope that liver buds could be given to patients, not as a full replacement of the original liver, but as an addition to it, which would help restore part of its function.
Patient-Grown Organs vs. Classic Transplants
At the moment, organ donation requires moving the organ from one person to another, but this process can be time-consuming and sometimes fails to work.
This is because of the immune response in the recipient’s body; the cells in the donated organ have specific markers, such as blood groups that are unique to the donor. If an organ is transplanted into someone who doesn’t have the same markers, it will be attacked and rejected by the host immune system, as it is ‘foreign.’
Therefore, a donated organ has to be as close a match as possible to the new owner, otherwise the new owner’s immune system will reject the transplant. Waiting for an appropriate match can be time-consuming and even after this, the patient will have to remain on immunosuppressive drugs for the rest of their lives to minimise the risk of rejection. These drugs then leave the patient more susceptible to infections, as their immune system is suppressed.
In contrast to this, organs that are grown from host cells will have the same tissue markers, therefore minimising the risk of organ rejection. But, just like classic organ donations, the patient would have to wait for the organ to be grown, so stem cell treatments cannot be considered as a ‘quick fix’. Also, this research is still in its infancy, and outcomes of using induced stem cells is still unclear,
Rakesh Jain, Professor of tumor biology at Harvard Medical School, is the co-senior author of a study recently published from a team at the Massachusetts General Hospital, who have produced functional blood vessels that lasted for several months in animal models, using induced pluripotent stem cells, the same type of stem cells that the team in Japan used to create the liver buds. Decoded Science asked Professor Jain, and he explained,
“Incomplete or partially reprogrammed clones that have not fully been differentiated pose a real risk of malignant transformation in vivo. At this point in time, we have no idea of knowing how the iPS- differentiated cells behave in vivo in humans. Our knowledge of the host immune system to iPS derivatives is unclear. iPS studies on larger animals like primates might help bridge in our understanding of long term efficacy in vivo.”
When also asked about the possibility of using grown organs instead of donor organs, Dr Jain told Decoded Science:
“Not in the near-future. But it may replace some of them depending on its urgency and extent of the need. iPS technology was discovered only 6 years ago, by Yamanaka and Takahashi at a time where it was inconceivable that adult somatic cells could undergo a switch to an embryonic phenotype. It is optimistic to presume that iPS- cell based therapy or iPS-generated organs might completely replace organ transplants one day. The challenge remains to provide functional derivatives of each component of organs and to ensure that they remain functional as a complex unit over time in vivo.”
Stem Cells: Medicine of the Future
With an ever-increasing body of research showing the potential of stem cells, it seems likely that medical treatments and organ transplants will look very different in the future.
Rekha Samuela, Laurence Daheronb, Shan Liaoa, Trupti Vardama, Walid S. Kamouna, Ana Batistaa, Christa Bueckerb, Richard Schäferb, Xiaoxing Hana, Patrick Aua, David T. Scaddenc, Dan G. Dudaa, Dai Fukumuraa, and Rakesh K. Jaina. Generation of functionally competent and durable engineered blood vessels from human induced pluripotent stem cells. (2013). Accessed July 21, 2013.
Sample, Ian. Human liver tissue transplants in mice raise stem cell treatment hopes. (2013). The Guardian. Accessed July 21, 2013.
Gallagher, James. Tiny stem-cell livers grown in laboratory. (2013). BBC News. Accessed July 21, 2013.
Bazian. Scientists grow ‘tiny livers’ from human stem cells. (2013). NHS Choices. Accessed July 21, 2013.
National Institute of Health. Stem Cell Basics. Accessed July 21, 2013.
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