Below find linked an open access paper that looks at what has to be done to reach the goal of engineered patient-matched organs, built as needed for transplantation, and the resulting end to shortages and waiting lists. It is interesting for putting some figures on the table for time and cost for the various lines of development required. From my perspective, over the longer term of the next twenty to fifty years, the interesting race in tissue engineering and regenerative medicine is between as-needed production of patient-matched tissues and organs for transplant on the one hand and in-situ restoration of all damage in existing tissues and organs on the other. If organs can be comprehensively repaired in place through regenerative medicine, a process that would have to incorporate the SENS portfolio of damage repair therapies for the old, and thus be much more than just an evolution of the stem cell approaches in their infancy today, then there would be little need for transplantation. At present the production of tissues for transplant is much more advanced, however, on the verge of producing useful, functioning sections of internal organs for medicine rather than research.

Thus, over the next couple of decades the immediate race is between the varied established approaches to engineering organs to order, between the range of possible ways to improve transplantation procedures, and between the research groups specializing in different organs or methodologies. These methodologies include decellularization of existing donor organs, xenotransplantation of transgenic pig organs, the bioprinting of tissue scaffolds and cells, and force-growing tissues from stem cells, with the latter still having a long way to go yet. Researchers have demonstrated tiny sections of functional tissue for the kidney, liver, intestines, thymus, and various other organs, but at present these are intended to speed up research. They are only a stepping stone. Scaling up beyond a sliver of tissue is a real challenge, as it involves building complex vascular networks to supply the cells, something that has been a roadblock for more than a decade now, and this despite a great deal of funding, ingenuity, and effort. This is why decellularization and xenotransplantation (or both together) have gathered support and funding: they represent a shorter path to expanding the supply of viable organs.

There are other challenges to the near future of organ engineering beyond those involved in building blood vessel networks of tiny capillaries. All will require time and effort to overcome, and while the scientific community devoted to this work has better funding and support than those involved in aging or rejuvenation research, there is never enough funding or support as would be justified given the end results. No society in history has devoted as much to research as would make sense from a purely logical point of view, sad to say. It is human nature to be consumed by what is, and not with what might be. Progress is an afterthought, which is why even in fields with a sizable output of papers and trials, it is still the case that we need the advocacy of groups like the Methuselah Foundation and the New Organ prize series. Research prizes and contests such as the NASA Vascular Tissue Challenge spur progress, and faster progress towards engineered organs is a good thing indeed.

Bioengineering Priorities on a Path to Ending Organ Shortage