[extropy-chat] Printing Organs on Demand

[Brett Paatsch]

Guilio, your referenced article looks to be similar if not the same as the
link Adrian posted recently.

Organs are tissues.

This free article from the Nature group of journals might be of interest

Gene Therapy Progress and Prospects: In tissue engineering
http://www.nature.com/gt/journal/v12/n24/full/3302651a.html#bib19

Here's a cut n paste from the article of some "current limitations".
(Note. TE = tissue engineering.)

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Clinical application of TE strategies needs to meet a variety of
challenges:

Although tissue engineered skin substitutes and cartilage grafts have
been used with some success for several years, most clinical applications
of TE constructs need to be considered as experimental at this time due
to the following limitations:

1 Cell source: At present, the only reliable cell source is autologous cells
   from the patient. This source has serious limitations of numbers of cells
   available and ability of the cells to maintain a phenotype capable of
   generating a viable ECM. Cloned, immortal cell lines are capable of
   proliferating but usually lack the differentiation needed for stable 
tissue
    repair.

2 Stable 3-D constructs: All tissues and organs have a complex
   interdependence of cell types with an interconnected 3-D architecture.
   Most tissue engineered constructs involve only one, or at most two,
   cell phenotypes grown primarily in a two-dimensional configuration.
   This compromise in structure limits the clinical viability of the 
constructs.

3 Vascularization: All tissues/organs have an interpenetrating network of
   blood vessels connected to the circulatory system to provide nutrition
   and eliminate waste products. Tissue engineered constructs at present
    lack this vital network when they are transplanted. The host tissues
    must quickly infiltrate the TE graft with a blood supply or the cells
    will die. A major challenge of TE is to achieve angiogenesis rapidly
    after implantation and maintain a viable nutrient supply as the 
construct
    becomes integrated.

4 Interfacial stability: The limitations of TE constructs listed above often
   result in problems at the host tissue-graft interface. Shrinkage,
   infiltration by new tissue or breakdown of the interface leads to less
   than desirable clinical outcomes.

5. Sterilization: Maintaining sterility of a TE construct containing living
   cells is a serious challenge in manufacturing, handling, storage,
   transport and regulation. Most methods used for sterilization of
   nonliving implants and devices, such as gamma-irradiation and
   autoclaving kill cells. Sterility must be achieved during processing
   and maintained until implantation is complete.

6 Cost: All of the above factors add to the manufacturing costs and
   presently limit many TE applications to exploratory patients.

7 Survivability: Long-term survivability of TE constructs is uncertain.
  Consequently, in many cases use is restricted to applications where
  no other procedure is available, as required by ethical and legal
  considerations. These 'worse-case' surgical scenarios make it
  difficult to assess viability and success of the new procedures.

8 Regulatory considerations: Tissue engineered products are
   subject to the same regulatory procedures as nonliving biomaterials
   and devices. At present, only few products have been produced
   to meet these regulatory requirements. Costs and risk/benefit
   factors are often hard to predict because of the uncertainty of
   regulatory approval.

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Brett Paatsch