The lab of Children's surgeon Dario Fauza, MD has come closer than any lab in the country using fetal stem cells, taken from amniotic fluid during pregnancy, to fix congenital defects in babies. These mesenchymal stem cells can form many of the tissues needed by surgeons, including tendon, muscle, skin, cartilage and even bone. The idea is to harvest them during amniocentesis -- which is often done when a congenital defect is seen on ultrasound-then use them to engineer tissues to repair the defects. The first application is likely to be tissue engineered "patches" to repair congenital diaphragmatic hernias -- openings in the membrane separating the lungs and chest cavity from the visceral organs.