This type of question is what bothers me with so many people and ONVO. They keep jumping to printing organs which is years away and is not what the company is about right now. This is a play in the big pharma space, not the organ replacement space at least for the forseeable future.
To your point, as premature as it is, there is a huge difference between a trachea and a liver. The liver has hundreds of functions in metabolism, the trachea, not as complex. Same with the bladder which has had similar early replacement surgeries. Not to discount the significance of these efforts with the trachea and bladder, but it is not in the same league of complexity.
The main point though is that the notion of printing a liver is not the issue. ONVO is creating a liver assay, a mini liver model that is several cell layers thick so that Pharma can test drugs for toxicity - long before phase III trials where many drugs fail due to the drug being toxic to the liver when the drug is metabolized. The standard now is not as good where liver cells in a 2D format are tested. The 2D version is not good - the cells do not act like liver cells, do not possess many metabolic qualities that a 3D model possesses. I feel, for the time being, this is what investors in ONVO should focus on and it is coming in 2014. What is that worth to Big Pharma? Well by the time a drug gets to Phase III and fails due to the liver a large Pharma may have shot hundreds of millions to a billion dollars on it. So the answer seems obvious. ONVO has indicated they do not just want to be paid for the liver assay though - they want a piece of the drug sales when the drug is approved. Interesting strategy I think.
The question is really more about scaffolding approach to creating functional liver (models) vs. 3D printing. It would seem as though HBIO could create the same assay and eventually generate entire organs in a more efficient manner than ONVO with their technology platform.
Also, I believe HBIO is up to lungs and have successfully grown and implanted lung tissue in rats in a preclinical models. So, it may be a matter of funding more than lack of technological no how in making the jump from bladders and trachea to lung and liver.