School Notes: School of Engineering & Applied Science
September/October 2010

Scientists create 3-D models of whole intact mouse organs

Combining an imaging technique called multiphoton microscopy with “optical clearing,” Yale researchers are the first to create 3-D images of whole intact mouse organs, including the brain. With traditional microscopy, researchers are only able to image tissues up to depths of about three times the thickness of a human hair. In that process, tissue samples are cut into thin slices, stained with dyes to highlight different structures and cell types, individually imaged, then stacked back together to create 3-D models. By contrast, the Yale team was able to avoid slicing or staining the organs by relying on natural fluorescence generated from the tissue itself.

“The intrinsic fluorescence is just as effective as conventional staining techniques,” said Michael Levene, associate professor of biomedical engineering. “It’s like creating a virtual 3-D biopsy that can be manipulated at will. And you have the added benefit that the tissue remains intact even after it’s been imaged.” He added, “The range of applications of this technique is immense, including everything from improved evaluation of patient tissue biopsies to fundamental studies of how the brain is wired.”

Engineering lungs

A team of Yale researchers, led by professor of anesthesiology and biomedical engineering Laura Niklason, has successfully engineered partly functioning rat lungs. As reported in the journal Science, the process involved stripping down the lungs of a dead adult rat to its basic infrastructure—airways, vascular system, and matrix—then repopulating it with lab-grown cells. Within days, cells that had repopulated the matrix formed the highly complex branching structure typical of a lung. More significantly, when transplanted into live rats, the engineered organ successfully exchanged oxygen and carbon dioxide, just as lungs do. While it will be a long time before this work can be translated to human studies, it is another remarkable success for the field of regenerative medicine.

Colors of butterfly wings yield clues to light-altering structures

The multidisciplinary team that showed the brilliant blues of some bird feathers was a result of light scattering off of tiny nanostructures has now reported on three-dimensional curving structures, called gyroids, that give butterflies their vivid colors. The Yale team investigated how a cell could sculpt itself into the extraordinary crystal nanostructure form, which resembles a network of three-bladed boomerangs.

Photonic engineers are using gyroid shapes to try to create more efficient solar cells and, by mimicking nature, may be able to produce more efficient optical devices as well, said biology professor Richard Prum, who led the Yale team, which included engineering professors Chinedum Osuji and Eric Dufresne ’96. (For a photo illustration of a network of gyroids, see “Local Color.”)