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February 26, 2009

Stem Cells for Universal Tissue and Replacement Organs


Stem cells on threads

1. Weaving stem cells into synthetic universal tissue (UK)

Embryonic stem cells can survive being spun into polymer threads – a technique that could be used to weave flexible synthetic tissues able to adapt to any transplant environment, say UK biophysicists. The approach could be a step towards the production of artificial organs. They are able weave stem cells into synthetic tissues.

There are a number of competing techniques for shaping living cells into custom-made tissue, including one based on inkjet printing, and another that uses air pressure to pull a cell solution into long threads.

That technology is able to weave networks of thread containing live brain cells without damaging them. Now, Suwan Jayasinghe's team at University College London has shown that a similar technique can be employed to create threads of embryonic stem cells. The group say this is the first time such cells have been printed using any technique.

The team use a technique called electrospraying, where two stainless steel needles, one inside the other, combine a stream of a viscous biodegradable polymer with a suspension of embryonic stem cells.

Applying a voltage to the needles charges the polymer and cells and they accelerate towards an "earthed" copper ring a short distance beneath, emerging as a single thin thread.


2. Bioscaffolds with blood flow networks have been made and blood, fat, and bone marrow grew. They are now able to make rejection free, three dimensional organ structures.

A novel approach to overcome organ construction obstacles using autologous explanted microcirculatory beds (EMBs) as bioscaffolds for engineering complex three-dimensional constructs. In this study, EMBs consisting of an afferent artery, capillary beds, efferent vein, and surrounding parenchymal tissue are explanted and maintained for 24 h ex vivo in a bioreactor that preserves EMB viability and function. Given the rapidly advancing field of stem cell biology, EMBs were subsequently seeded with three distinct stem cell populations, multipotent adult progenitor cells (MAPCs), and bone marrow and adipose tissue-derived mesenchymal stem cells (MSCs).







scientists from Stanford and New York University Langone Medical Center describe how they were able to use a "scaffolding" material extracted from the groin area of mice on which stem cells from blood, fat, and bone marrow grew. This advance clears two major hurdles to bioengineered replacement organs, namely a matrix on which stem cells can form a 3-dimensional organ and transplant rejection.


Synthetic tissue and better scaffolds for structure are step towards fully functional artificial organs. Another recent study showed how the artificial capillary networks needed to feed such organs could be grown using cotton candy at very low cost.
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