The deepening red color (representing bone) demonstrates how synthetic clay progressively induces stem cells to become bone cells.

For centuries, clay has helped us build both beautiful and practical things. French sculptor Auguste Rodin focused on beauty, using clay models to help him shape impressive bronze sculptures of the human form, including “The Thinker.” Brigham and Women’s Hospital (BWH) biomedical engineer Ali Khademhosseini, PhD, Division of Biomedical Engineering and his team, however, specialize in practicality, working with clay and human bone. But they use clay to grow bone, not shape it.

Khademhosseini’s team recently reported in the journal Advanced Materials that synthetic silicate nanoplatelets (also known as layered clay) can activate bone marrow stem cells to become bone cells, without the aid of any other bone-growth agents. This synthetic clay consists of simple or complex salts of silicic acids and has been used extensively for various commercial and industrial applications, including food additives, glass and ceramic filler materials, and anti-caking agents.

To measure the clay’s ability to promote growth, researchers combined a solution of microscopic clay particles with human stem cells in a variety of mediums. One medium included dexamethasone (a steroid known to promote connective tissue growth) and another medium had no dexamethasone (or any other additional growth-promoting agent). Researchers first observed bone growth in both of these samples on day 14, demonstrating that the clay could promote bone growth effectively with or without the aid of another agent. Not only that, researchers also found that clay by itself promoted bone growth quicker than dexamethasone by itself (14 days vs. 21 days).

Based on their findings, Khademhosseini’s team believes that this synthetic clay has great potential for helping repair human bone and other types of damaged tissue. “With an aging population in the US, injuries and degenerative conditions are subsequently on the rise,” says Khademhosseini, senior study author. “As a result, there is an increased demand for therapies that can repair damaged tissues. In particular, there is a great need for new materials that can direct stem cell differentiation and facilitate functional tissue formation. Silicate nanoplatelets have the potential to address this need in medicine and biotechnology.”

– Chris P

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