In nature, the extracellular matrix provides not only support but also a location for molecular signals that are traded back and forth as the cells build a specific structure or organ. Taking advantage of this cell-gel crosstalk, Jeffrey A. Hubbell and his group at the École Polytechnique Fédérale de Lausanne (Switzerland) have shown in animal studies that a synthetic gel can provide a matrix that stimulates the animal's bone marrow to fill the gaps between fragments with strong bone cells. The matrix is laced with encapsulated doses of a growth-promoting protein that are only released, dose by dose, when growing bone-marrow cells send an activating signal to a cache of the protein within the gel.

With further advances, artificial gels may also be tailored to support stem cells—an important requirement for any cell-based treatments of Parkinson's disease or type 1 diabetes, which so far do not provide lasting benefits in the body. A customized gel could guide the process of coaxing precursors to become the desired cell type. The gel would then protect the therapeutic cells with molecular barriers. And it would be embedded with further instructions for cell therapy—signals to be activated once the cells were implanted in the body. Brain cells, for example, could be encouraged to send out axons and perhaps be guided to connect with specific types of neurons.

The technical advances needed to take advantage of these opportunities will require synergistic efforts across disciplines. Scientists and engineers working together will advance gel niches from their infancy to mature, sophisticated environments, illuminating the possibilities for cell-based strategies to repair tissues.

Kristi Anseth does research and teaches at the University of Colorado at Boulder.

Interview by Janet Basu

	PAGE 2 OF 2	Back