The success of the tissue engineered trachea, prepared using decellularization, shows cell-laden implants are functional. Natural biological and physical cues matured the implant into a stable, functional tissue. To translate this to bottom-up design process, such as 3D cell printing, lets characterize the decellularized scaffold's heterogenous architecture, mechanical properties and chemistry. Then engineer manufacturing processes to build the model to design specifications. Also, allow the built biologial construct to grow, mimicking the in vivo conditions using a bioreactor. A place to start determining which properties, chemical, mechanical, cell type, are most important might be too measure which properties of the decellularized matrix are changed, minutes, days and years after implantation. https://www.ncbi.nlm.nih.gov/pubmed/24161821

Right now this research seems to be at the stage of bioprinting small amounts of tissue only as outlined in this report from the USA about the kidney -

http://harvardmagazine.com/2017/01/building-toward-a-kidney

Cell to cell communication is a significant issue as well. They can obtain structure but not necessarily the requisite function. A fully functional organ seems a fair way off at this stage.

I completely agree with this point of view, about signaling network, but there are many others such as new kind of bioinks, vascularization, bioreactors for microtissues culture, induction of cells and tissues differentiation, scalable spheroids, new types of BioCAD and files, integration among different areas of expertise, systems integration, among others. 

Today we are producing 3 d printed structures for various organic or non- organic use. This feat was like a sci-fi few years back so no doubt things can improve and we may actually be successful in creating better organs as physiologically active entities.