What are the technical obstacles to growing artificial organs outside the body, perhaps from the patient's own cells so rejection isn't an issue? Are artificia

What are the technical obstacles to growing artificial organs outside the body, perhaps from the patient's own cells so rejection isn't an issue? Are artificial organs effectively impossible due to some law of biology or design of the human body? Is it so far-fetched that nobody's funding it? Or if it's being worked on, what's the time-frame -- will we see this in 100 years, 30 years, 10 years or 3 years?