This paper is behind a paywall but there is a free preview available via ReadCube Access.
This entry was posted in biomimcry, coatings, medicine, nanotechnology and tagged Abhishek Jain, Alexander L Watters, Anna Waterhouse, Anne R Hansen, Arthur Nedder, Benjamin D. Hatton, Caitlin Howell, Christopher P Johnson, Dana E Bolgen, Daniel C Leslie, Donald E. Ingber, Elana H Super, gecko, Harvard University, Harvard University School of Engineering and Applied Sciences, heparin, Joanna Aizenberg, Julia B Berthet, Kathryn Donovan, Michael Aizenberg, Michael Super, Philseok Kim, pitcher plant, Sami Rifai, SEAS, SLIPS (Slippery Liquid-Infused Porous Surfaces), superhydrophobic surfaces, Tethered-Liquid Perfluorocarbon surface (TLP), Thomas M Valentin, Thy L Vu, Wyss Institute, Wyss Institute for Biologically Inspired Engineering on October 14, 2014 by Maryse de la Giroday.
A bit of pressure from a new shrinking, sponge-like gel is all it takes to turn transplanted unspecialized cells into cells that lay down minerals and begin to form teeth.
The bioinspired gel material could one day help repair or replace damaged organs, such as teeth and bone, and possibly other organs as well, scientists from the Wyss Institute for Biologically Inspired Engineering at Harvard University, Harvard School of Engineering and Applied Sciences (SEAS), and Boston Children’s Hospital report recently in Advanced Materials.
Embryonic tissues have the power to drive cells and tissues to specialize and form organs. To do that, they employ biomolecules called growth factors to stimulate growth; gene-activating chemicals that cause the cells to specialize, and mechanical forces that modulate cell responses to these other factors.
But so far tissue engineers who want to build organs in the laboratory have employed only two of the three strategies — growth factors and gene-activating chemicals. Perhaps as a result, they have not yet succeeded in producing complex three-dimensional tissues.
A few years ago, Ingber and Tadanori Mammoto, M.D., Ph.D., Instructor in Surgery at Boston Children’s Hospital and Harvard Medical School, investigated a process called mesenchymal condensation that embryos use to begin forming a variety of organs, including teeth, cartilage, bone, muscle, tendon, and kidney.
In mesenchymal condensation, two adjacent tissue layers — loosely packed connective-tissue cells called mesenchyme and sheet-like tissue called an epithelium that covers it — exchange biochemical signals. This exchange causes the mesenchymal cells to squeeze themselves tightly into a small knot directly below where the new organ will form.
By examining tissues isolated from the jaws of embryonic mice, Mammoto and Ingber showed that when the compressed mesenchymal cells turn on genes that stimulate them to generate whole teeth composed of mineralized tissues, including dentin and enamel.
To develop such a material, Ingber and Hashmi teamed up with researchers led by Joanna Aizenberg, Ph.D., a Wyss Institute Core Faculty member who leads the Institute’s Adaptive Materials Technologies platform. Aizenberg is the Amy Smith Berylson Professor of Materials Science at SEAS and Professor of Chemistry and Chemical Biology at Harvard University.
They chemically modified a special gel-forming polymer called PNIPAAm that scientists have used to deliver drugs to the body’s tissues. PNIPAAm gels have an unusual property: they contract abruptly when they warm.
But they do this at a lukewarm temperature, whereas the researchers wanted them to shrink specifically at 37°C — body temperature — so that they’d squeeze their contents as soon as they were injected into the body. Hashmi worked with Lauren Zarzar, Ph.D., a former SEAS graduate student who’s now a postdoctoral associate at Massachusetts Institute of Technology, for more than a year, modifying PNIPAAm and testing the resulting materials. Ultimately, they developed a polymer that forms a tissue-friendly gel with two key properties: cells stick to it, and it compresses abruptly when warmed to body temperature.
Not only were they alive — they activated three genes that drive tooth formation.
“They were in full-throttle tooth-development mode,” Hashmi said.
In the embryo, mesenchymal cells can’t build teeth alone — they need to be combined with cells that form the epithelium. In the future, the scientists plan to test whether the shrinking gel can stimulate both tissues to generate an entire functional tooth.
This entry was posted in biomimcry and tagged Akiko Mammoto, Amanda Jiang, Basma Hashmi, bioinspired, Boston Children's Hospital, Developmentally-Inspired Shrink-Wrap Polymers for Mechanical Induction of Tissue Differentiation, Donald E. Ingber, embryonic cells, embryonic tissue, Harvard School of Engineering and Applied Sciences, Harvard University, Joanna Aizenberg, Lauren D. Zarzar, mesenchymal condensation, SEAS, Tadanori Mammoto, teeth, tissue engineering, Wyss Institute for Biologically Inspired Engineering on March 6, 2014 by Maryse de la Giroday.
In a recent article in Solar Energy Materials & Solar Cells, Hatton and colleagues at Harvard University describe a novel process to cut down on heat loss during the winter and keep buildings cool during the summer. Their “bio-inspired approach to thermal control for cooling (or heating) building window surfaces” calls for attaching optically clear, flexible elastomer sheets, bonded to regular glass window panes.
The elastomer sheets, made from polydimethylsiloxane (PDMS) have channels running through them through which room temperature water flows. The technique has resulted in 7 to 9 degrees of cooling in laboratory experiments and is effective both at small and large scales, Hatton and his colleagues said.
“Our results show that an artificial vascular network within a transparent layer, composed of channels on the micrometer to millimeter scale, and extending over the surface of a window, offers an additional and novel cooling mechanism for building windows and a new thermal control tool for building design,” he said.
An artificial vasculature for adaptive thermal control of windows by Benjamin D. Hatton, Ian Wheeldon, Matthew J. Hancock, Mathias Kolle, Joanna Aizenberg, and Donald E. Ingber. Solar Energy Materials and Solar Cells, 2013; 117: 429 DOI: 10.1016/j.solmat.2013.06.027; Volume 117, October 2013, Pages 429–436.
I have written about thermal control of windows before as per this Sept. 4, 2012 posting which features an excerpt of an article discussing thermochromic, electrochromic, and gasochromic windows.
This entry was posted in biomimcry and tagged An artificial vasculature for adaptive thermal control of windows, artifical vasculature, Ben Hatton, Benjamin D. Hatton, Donald E. Ingber, Harvard University, Ian Wheeldon, Joanna Aizenberg, Mathias Kolle, Matthew J. Hancock, University of Toronto on August 6, 2013 by Maryse de la Giroday.