Scientists are growing functioning mini-organs of the skull and face that may help treat facial deformities in newborns. Organs of the craniofacial complex \u2013 the skull and face \u2013 often go terribly wrong during fetal development. Deformities of these bones or soft tissues, the most common of birth defects, can cut life short by blocking the airway or circulation. They can disfigure a face so profoundly that a child struggles to see, hear, or talk. Such deformities may also lead to a lifetime of corrective surgeries and social isolation. Researchers at the University of California, San Francisco in the US are growing teeth, muscles and tissues that make up the face, salivary glands and 3D printed bones. Using stem cells from patients with craniofacial deformities, researchers are growing tiny functioning segments of organs, called organoids, to figure out exactly when and how in fetal development such design flaws occur. As the reservoirs of human development, stem cells renew and differentiate into the myriad cell types required to build out a body from an embryo. The organoids model craniofrontonasal syndrome \u2013 a birth defect that is caused by a mutation in a single gene and that dramatically impacts the shape of the face and head. Studies on craniofrontonasal syndrome in mice show that the first place something goes wrong is in a cell type called the neuroectoderm. To create an organoid to study this, researchers obtained skin cells from patients with the syndrome. "We studied this simple system to see how this mutation affected the organisation of these cells," said Bush. His group has filmed cells as they rush about to self- organise when they are mixed together. In those films, "you can see that the mutated cells, which are dyed red, segregate from the normal cells, which are green," said Jeffrey Bush, an assistant professor at the UC San Fransisco. The mutated cells completely disrupt the behaviour of all the cells. By contrast, in the films of cells without the mutation, all the cells circulate easily among one another. This understanding has allowed Bush to begin to think about a drug that blocks this separation. He has several promising candidates that his team will test in pregnant mice. "Right now there isn't a single drug that we can use for any kind of structural birth defects," Bush said. "If we could show that a medication blocks the effects of this mutation, it would serve as proof of principle that something besides surgery can be done. But we would have to know that it was safe for mother and child and that we could catch it early enough," he said.