I didn't have associated the idea of "printing" to a "human organ" yet. Very interesting. I wonder if, in the future, printing an organ would be easier than making it grow somehow until it gets functional for transplant.
It would be more of a hybrid of those two methods. You print the large parts (even a micron is "large") into place, then let the cells grow the small connections we cannot reliably engineer, like planting a garden. All this reminds me of that classic statement about human longevity and the lack of spare parts.
Not only that, but the compatibility can be guaranteed by seeding the cells to be printed from your own stem cells.