system
Given the following post, respond as if you're commenting on Reddit:
human
If I donate part of my liver to someone, the liver regrows. What if in the future I need a new liver? Can I receive a portion of my exliver from said person who received it? Will I need immunosuppressive drugs?
gpt
Living liver donor here.  There is a bit of an anatomical issue.  Your liver is split into two lobes, one on the right, one on the left.  The hepatic artery, vein and bile duct all branch with one leg going to each lobe.  When you donate, they take one lobe, along with it's branches of each connection to connect to the recipient's anatomy.  Your remaining lobe then quickly swells to fill the space, giving you the same volume of liver, but you never get the other lobe back.

So, anatomically, you couldn't just slice off a bit of the lobe you gave, as it wouldn't have a single point where you could hook up the artery, vein and duct.  As the liver is a mass of capillaries and hepatic cells, you have to get the right sort of blood going to the right places for it to work, and right now the only thing which can setup that complex arterial and venous network is the body itself.  The vessels which branch off after the main branching are just too small to support a full bodies blood flow. This is also why you can't donate your liver more than once, even though it regenerates.