Figure 1. Cells bearing complementary cell surface oligonucleotides react to form stable cell-cell contacts.
Zev J. Gartner and Carolyn R. Bertozzi from the Department of Chemistry and Molecular Cell Biology have assembled the microtissues by using the ‘bottom up’ approach. They have been able to create a 3D tissue of different cell types (Fig. 2 and 3) that can perform functions that the cells wouldn’t be able to perform separately.
Figure 2. 3D reconstruction of one of the multicellular structures that were created.
Figure 3. Multicellular structures of different sizes were synthesised.
Gartner and Bertozzi constructed and maintained survival of a paracrine signalling network with the same functions as a natural cell system that communicates by growth factors. The paracrine signalling network used hematopoietic progenitor cells (a kind of stem cell for blood cells), which needs interleukin-3 (biological signalling mechanism) to operate, by combining the progenitor cells in a microtissue with Chinese hamster ovary cells that were engineered to secrete interleukin-3.
Previously only 2D cellular arrays or 3D cell aggregates of a single cell type have been created from this ‘bottom up’ approach. The ‘top down’ approach is used for skin grafts, bone marrow transplants and blood substitutes, as well as in basic medical and biological research. The ‘top down’ method works by attempting to improve or repair natural tissues by manipulating living cells from donors, sometimes in combination with synthetic materials. This approach causes the cells to assemble themselves randomly which causes the tissue to loose its function.
By using duplex DNA to bond the cells together so that the tissue functions as if it were produced in our body this has achieved a means of analysing cellular behaviour in vitro as a function of overall tissue architecture. This may also be able to provide access to fundamental units of tissue function such as the stem cell niche, building blocks for artificial organs and in vitro models of human disease that include multiple cell types.
If the development of this technology continues then artificially produced organs may be able to be produced which could be eventually implanted into humans.
References
ScienceDaily. Retrieved March 17, 2009, from http://www.sciencedaily.com /releases/2009/03/090305091046.htm
Zev J. Gartner and Carolyn R. Bertozzi. Programmed assembly of 3-dimensional microtissues with defined cellular connectivity. PNAS, March 2, 2009
Berkeley Press Release. Retrieved March 17, 2009 from http://newscenter.lbl.gov/press-releases/2009/03/05/3-d-microtissues/
Author: J.Burgin 41011586
