Will tissue engineering eliminate the need for immunosuppressive drugs?

Factual Questions
1

If we are able to someday grow replacement organs and transplant them into those needing organ replacement, will those patients require immunosuppressive therapy to prevent rejection. In autografts nowadays, what do we do to prevent acute rejection?

Thanks,
Rob

2

That’s certainly the goal, and it seems like a reasonable goal. As with many things, the devil’s in the details, and we’ll have to wait and see once it’s actually done.

3

An autograft, by definition is the patient’s own tissue, so there is no rejection.

4

Unless there is some sort of autoimmune disease at work. That’s the only reason I could think of for an immunosuppressive regimen after an autograft, but it could happen.

5

Autografts never reject except in the case Broomstick mentioned?

Thanks,
Rob

6

Curious to see if anyone has any more information.

Thanks,
Rob

7

Generally speaking, transplants are recognized because they have cells that express foreign proteins. The immune system generates immune cells that target foreign proteins. It’s sort of an evolutionary process. It starts when immature immune cells generate randomly scrambled versions of immune receptors or antibodies. Then there is positive selection for immune cells that can bind to foreign proteins, combined with negative selection against cells that bind to any “self” proteins. This maturation happens in specific organs (IIRC bone marrow and the thymus) so it is the cells in those tissues that define “self”. Meanwhile, “antigen presenting cells” wander the body looking for foreign proteins and bring them back to the maturing immune cells, while other foreign proteins are carried in the blood to the site of maturation.

Along comes a transplant. Through natural genetic variability, the cells of the transplant are probably expressing proteins distinct from the host. When the immune system is working “properly” in this case, it learns to recognize and attack cells with these foreign proteins. Thus the transplant is rejected, unless it is carefully matched to the host and/or the the immune system is suppressed.

An autograft, on the other hand, only expresses proteins that are normally present in the host, and thus is never recognized as “foreign”.

In recent years there have been a handful of transplants where a donor organ is stripped of cells and used as a scaffold for the patient’s own cells. This trachea transplant for example happened five years ago without any immune complications.