Author Topic: question(s) about organ transplants  (Read 162 times)

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Offline God Bomb

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question(s) about organ transplants
« on: January 18, 2017, 04:57:51 AM »
Feel free to nitpick anything and everything I'm saying in the topic.

When someone receives an organ, they have to take drugs so that organ is not rejected.  Over time, many years for example, does the chance of rejection drop?  I would assume it does, because cell tissue in our bodies gets replaced over time.  So an organ that started out as 100% foreign DNA would over time become 'assimilated'.  I'm assuming some tissues are permanent and don't get replaced?  What about something like Skin?  there are face transplants now and skin is definitely a type of tissue that is regenerated constantly.  So can these types of transplants become 'permanent', so that no drugs are needed to stop rejection?

Also, semi-serious question about testicles.  If a testicle was transplanted, I'm assuming it would produce the donor's sperm, because they are made within the testicle and based on DNA inside the testicle? 
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Offline starnado

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Re: question(s) about organ transplants
« Reply #1 on: January 18, 2017, 07:51:09 AM »
Sorry to constantly thread lurk but :munch: again, mmmm chips of knowledge

I feel like I should know this but I actually literally and practically don't
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Re: question(s) about organ transplants
« Reply #2 on: January 18, 2017, 09:24:19 AM »
Do they even do testicle transplants? If they do, I presume your guess would be right.

As for the transplanted organ becoming "permanent" due to cell regeneration, I presume that the regenerated cells would still carry the donor's DNA and so would still be rejected without the drugs. I'm guessing the drugs would need to be taken forever. Unless maybe the donor is an identical twin?

However, I'm just talking through my hat here. I have no knowledge of this. Maybe we have a transplant surgeon on the board who could answer the question.
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Offline brilligtove

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Re: question(s) about organ transplants
« Reply #3 on: January 18, 2017, 09:43:12 AM »
Do they even do testicle transplants? If they do, I presume your guess would be right.

As for the transplanted organ becoming "permanent" due to cell regeneration, I presume that the regenerated cells would still carry the donor's DNA and so would still be rejected without the drugs. I'm guessing the drugs would need to be taken forever. Unless maybe the donor is an identical twin?

However, I'm just talking through my hat here. I have no knowledge of this. Maybe we have a transplant surgeon on the board who could answer the question.

[talk object="hat" direction="through"]
Hm. I would guess you would have to do some stem cell voodoo to make the transplant become self or be recognized as self. If the organ's stem cells are replaced with the recipient's stem cells it might become 'you' over time. Depends on how fast the cells are replaced from new, instead if just dividing. If you killed off the recipient's immune system and restarted it from scratch that might do it?
[/talk]
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Offline starnado

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Re: question(s) about organ transplants
« Reply #4 on: January 18, 2017, 10:08:53 AM »
As far as I am aware, immunosuppressant therapy is needed for the lifetime of the transplant
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Re: question(s) about organ transplants
« Reply #5 on: January 18, 2017, 10:28:47 AM »
The tissues of the organ are replaced by the process of mitosis and division of the organ's cells, they don't migrate into he organ from elsewhere in the body.  The resulting cells have the same DNA as the parent cell, therefore.

My understanding is that the risk of rejection actually increases with time as the body develops antibodies to the foreign cells.
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Offline brilligtove

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Re: question(s) about organ transplants
« Reply #6 on: January 18, 2017, 10:34:14 AM »
I wonder if CRISPR tech could delete the donor's MHC from the organ in the dish, and perhaps copy and paste the recipient's?
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Online daniel1948

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Re: question(s) about organ transplants
« Reply #7 on: January 18, 2017, 10:34:57 AM »
Do they even do testicle transplants? If they do, I presume your guess would be right.

As for the transplanted organ becoming "permanent" due to cell regeneration, I presume that the regenerated cells would still carry the donor's DNA and so would still be rejected without the drugs. I'm guessing the drugs would need to be taken forever. Unless maybe the donor is an identical twin?

However, I'm just talking through my hat here. I have no knowledge of this. Maybe we have a transplant surgeon on the board who could answer the question.

[talk object="hat" direction="through"]
Hm. I would guess you would have to do some stem cell voodoo to make the transplant become self or be recognized as self. If the organ's stem cells are replaced with the recipient's stem cells it might become 'you' over time. Depends on how fast the cells are replaced from new, instead if just dividing. If you killed off the recipient's immune system and restarted it from scratch that might do it?
[/talk]

I don't think that replacing the organ's stem cells with the recipient's stem cells is actually a thing. Nor "restarting" the immune system from scratch.

"Hat" was a euphemism for another noun, which I uncharacteristically chose to avoid for that post. Which also would not have been physiologically possible, but is merely a figure of speech.
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Re: question(s) about organ transplants
« Reply #8 on: January 18, 2017, 10:36:57 AM »
I wonder if CRISPR tech could delete the donor's MHC from the organ in the dish, and perhaps copy and paste the recipient's?

You would have to delete the MHC (whatever that is) from every single cell in the donated organ. Probably not possible.

Before we can do that, we'll probably be able to grow a whole new organ from the recipient's own stem cells.
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Offline brilligtove

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Re: question(s) about organ transplants
« Reply #9 on: January 18, 2017, 11:02:55 AM »
Do they even do testicle transplants? If they do, I presume your guess would be right.

As for the transplanted organ becoming "permanent" due to cell regeneration, I presume that the regenerated cells would still carry the donor's DNA and so would still be rejected without the drugs. I'm guessing the drugs would need to be taken forever. Unless maybe the donor is an identical twin?

However, I'm just talking through my hat here. I have no knowledge of this. Maybe we have a transplant surgeon on the board who could answer the question.

[talk object="hat" direction="through"]
Hm. I would guess you would have to do some stem cell voodoo to make the transplant become self or be recognized as self. If the organ's stem cells are replaced with the recipient's stem cells it might become 'you' over time. Depends on how fast the cells are replaced from new, instead if just dividing. If you killed off the recipient's immune system and restarted it from scratch that might do it?
[/talk]

I don't think that replacing the organ's stem cells with the recipient's stem cells is actually a thing. Nor "restarting" the immune system from scratch.

"Hat" was a euphemism for another noun, which I uncharacteristically chose to avoid for that post. Which also would not have been physiologically possible, but is merely a figure of speech.

Yeah, I'm not saying stem cell replacement in organs is a thing. Just speculating. Immune system transplants / resets are a thing, though dangerous and experimental (at least they were in 2010).

I enjoyed the way you used hat, and decided to geekily build on it.

I wonder if CRISPR tech could delete the donor's MHC from the organ in the dish, and perhaps copy and paste the recipient's?

You would have to delete the MHC (whatever that is) from every single cell in the donated organ. Probably not possible.

Before we can do that, we'll probably be able to grow a whole new organ from the recipient's own stem cells.

MHC = Major Histocompatibility Complex

Short version: The major histocompatibility complex (MHC) is an key way the immune system recognizes foreign substances in the body. The MHC determines compatibility of donors for organ transplant.

Quote
The major histocompatibility complex (MHC) is a set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates, which in turn determines histocompatibility. The main function of MHC molecules is to bind to antigens derived from pathogens and display them on the cell surface for recognition by the appropriate T-cells.[1] MHC molecules mediate interactions of leukocytes, also called white blood cells (WBCs), which are immune cells, with other leukocytes or with body cells. The MHC determines compatibility of donors for organ transplant, as well as one's susceptibility to an autoimmune disease via crossreacting immunization. The human MHC is also called the HLA (human leukocyte antigen) complex (often just the HLA). The mouse MHC is called the H-2 complex or H-2.

As for replacing this in every cell... one delivery mechanism is through viruses. I don't know if it is possible to use CRISPR/CAS tools to do that sort of thing in an organ. A Google Scholar search on "CRISPR MHC transplant" has papers like this that indicate that sort of technology and technique are being developed, however.

To be clear, I don't really understand what that paper says
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Online Friendly Angel

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Re: question(s) about organ transplants
« Reply #10 on: January 18, 2017, 12:16:01 PM »
Do they even do testicle transplants?

Without googling, I'm trying to imagine why.

Orchidectomy patients frequently get prosthetic testicles, I think just for cosmetic reasons. 

If the goal is reproduction, seems like the other methods are more reliable and just as satisfying.
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Offline God Bomb

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Re: question(s) about organ transplants
« Reply #11 on: January 18, 2017, 10:30:56 PM »
The tissues of the organ are replaced by the process of mitosis and division of the organ's cells, they don't migrate into he organ from elsewhere in the body.  The resulting cells have the same DNA as the parent cell, therefore.

My understanding is that the risk of rejection actually increases with time as the body develops antibodies to the foreign cells.

That pretty much answers it, thanks.  And sorry for deliberately misquoting you in another topic.
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Offline God Bomb

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Re: question(s) about organ transplants
« Reply #12 on: January 18, 2017, 10:31:46 PM »
Do they even do testicle transplants?

Without googling, I'm trying to imagine why.

Orchidectomy patients frequently get prosthetic testicles, I think just for cosmetic reasons. 

If the goal is reproduction, seems like the other methods are more reliable and just as satisfying.

to produce testosterone?
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Offline brilligtove

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Re: question(s) about organ transplants
« Reply #13 on: January 18, 2017, 10:50:28 PM »
Do they even do testicle transplants?

Without googling, I'm trying to imagine why.

Orchidectomy patients frequently get prosthetic testicles, I think just for cosmetic reasons. 

If the goal is reproduction, seems like the other methods are more reliable and just as satisfying.

to produce testosterone?

Given the many detrimental effects of organ transplants and the aggressive immunosuppression that is required to maintain those organs, I suspect taking testosterone as a drug would likely have a much lower risk profile.
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