Japan is preparing for clinical trials involving the transplantation of genetically modified pig kidneys into humans. This development suggests that xenotransplantation may soon move from experimental medicine toward practical clinical use. For pathologists and transplant physicians, however, the challenge will not end with making transplantation possible; the transplanted organ must also be carefully monitored and maintained.
This morning, I heard the news that preparations are underway in Japan for clinical trials involving the transplantation of genetically modified pig kidneys into humans.
It made me feel that organ transplantation is finally beginning to take a step into its next stage.
If we think of the human body simply as a combination of organs with different functions, all that should be necessary is for a transplanted organ to adapt to the recipient’s body and continue functioning properly.
One of the greatest obstacles to that adaptation, however, is rejection.
If technologies for controlling rejection continue to advance, and if problems such as coagulation abnormalities and infections can also be overcome, transplantation from another species into humans—xenotransplantation—may become part of actual clinical medicine.
Transplantation of major organs, including the heart, kidneys, liver, pancreas, lungs, and intestines, is already performed as part of routine medical care.
In Japan, however, transplantation still depends heavily on living donors, often relatives, while the number of organs donated after death remains insufficient.
The addition of transplantation from pigs as a new option would therefore be groundbreaking.
Of course, this would mean taking the life of a pig, so it cannot be said to raise no ethical concerns.
Nevertheless, because pigs have long been raised by humans as livestock, particularly for food, the ethical barrier may be considered somewhat lower than it would be with other animals.
Pig pericardium is already widely used as a medical material.
One of the areas that pathologists find particularly difficult is the diagnosis of transplanted organs.
I often examine transplanted kidneys, and the diagnosis can be remarkably challenging.
The kidney filters waste products from the blood. It is composed of many different structures, including blood vessels that carry blood, tubules that transport the filtered fluid, and the interstitium that supports them.
Rejection, drug toxicity, and infections can each appear differently within these structures.
Are the blood vessels damaged?
Are the tubules affected?
Is the interstitium inflamed?
Could there be an infection that was not present before transplantation, or one that is unusual in humans?
To what extent is each lesion contributing to dysfunction of the transplanted kidney?
Identifying individual histological findings is possible to a certain degree.
Integrating them into a single diagnosis and communicating that diagnosis clearly to the clinicians, however, is not easy.
Clinicians combine pathological findings with blood tests, urine tests, imaging studies, and other clinical data in order to maintain the transplanted organ and preserve its function for as long as possible.
Advances in artificial intelligence are likely to change this diagnostic process.
AI can already assist in organizing and analyzing clinical data.
When a pathologist provides the individual histological findings, AI may be able to integrate them and suggest the most likely pathological processes.
Through several rounds of discussion between the pathologist and AI, it may become possible to reach a more accurate diagnosis of the transplanted organ.
Combining that assessment with clinical data may also make it possible to predict the risks of rejection and infection and to select more appropriate treatment and maintenance strategies.
In xenotransplantation as well, a time may come when AI integrates numerous factors, including the patient’s immunological background, general condition, and the characteristics of the genetically modified pig.
I hope that within the next several years, the barriers to organ transplantation will fall dramatically.
That does not mean, of course, that we humans will be free to neglect the maintenance of our own bodies.
Even in an age when organs may become replaceable, caring for the body we already have will remain our first responsibility.
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genetically modified
Altered through biotechnology by adding, removing, or changing specific genes.
遺伝子改変された
clinical trial
A research study conducted with human participants to evaluate the safety and effectiveness of a medical treatment.
臨床試験、治験
recipient
A person who receives an organ, tissue, blood, or another medical treatment from a donor.
レシピエント、移植を受ける人
rejection
An immune reaction in which the recipient’s body attacks a transplanted organ or tissue.
拒絶反応
xenotransplantation
The transplantation of living cells, tissues, or organs from one species to another.
異種移植
living donor
A person who donates an organ or part of an organ while still alive.
生体ドナー
coagulation abnormality
A disorder affecting the normal process by which blood forms clots.
凝固異常
interstitium
The supporting tissue and space between the functional structures of an organ.
間質
drug toxicity
Tissue or organ damage caused by the harmful effects of a medication.
薬剤毒性
histological finding
An abnormality or feature identified by examining tissue under a microscope.
組織学的所見
integrate
To combine separate pieces of information into a unified interpretation.
統合する
immunological background
The characteristics of a person’s immune system that may influence reactions to infection or transplantation.
免疫学的背景
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