A new way to assemble cells into 3-D mi...( BERKELEY CA Scientists at the U.S. ...)

BERKELEY, CA Scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory can now control how cells connect with one another in vitro and assemble themselves into three-dimensional, multicellular microtissues. The researchers demonstrated their method by constructing a tailor-made artificial cell-signaling system, analogous to natural cell systems that communicate via growth factors.

Artificial tissues are presently used in medicine for a range of applications such as skin grafts, bone marrow transplants, or blood substitutes, as well as in basic medical and biological research. Tissue engineers try to improve upon or repair natural tissues by manipulating living cells from one or more donors, sometimes in combination with synthetic materials. Unfortunately, in this "top down" approach, the cells assemble themselves randomly, losing the 3-D organization that is key to many tissue functions.

"Our method allows the assembly of multicellular structures from the 'bottom up,'" says Carolyn Bertozzi, principal investigator in the research, who directs DOE's Molecular Foundry nanoscience research facility at Berkeley Lab and is a member of the Lab's Materials Sciences and Physical Biosciences Divisions. "In other words, we can control the neighbors of each individual cell in a mixed population. By this method, it may be possible to assemble tissues with more sophisticated properties."

An example of a state that depends on sophisticated cellular connectivity and communication is the stem-cell niche, "which can maintain stem cells in an undifferentiated state, or in some cases guide their differentiation down a specific pathway," says Bertozzi, who is also a professor in the Departments of Chemistry and Molecular and Cell Biology at the University of California at Berkeley and a Howard Hughes Medical Institute investigator.

Bertozzi and her colleague Zev Gartner, who is now an assistant professor of Pha
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