We know that mammals cannot regenerate lost limbs but they can repair large sections of their ribs. A team of US researchers has now discovered the healing power of the rib cells in both humans and mice.Using computed tomography (CT) imaging, researchers at the University of California, San Francisco, monitored the healing of a human rib that had been partially removed by a surgeon.The eight cm of missing bone and one cm of missing cartilage did partially repair after six months.To better understand this repair process, they surgically removed sections of rib cartilage - ranging from three to five mm - from a related mammal, mice.When they removed both rib cartilage and its surrounding sheath of tissue called the perichondrium, the missing sections failed to repair even after nine months.
However, when they removed rib cartilage but left its perichondrium, the missing sections repaired themselves entirely within one to two months.They also found that a perichondrium retains the ability to produce cartilage even when disconnected from the rib and displaced into nearby muscle tissue - further suggesting that the perichondrium contains progenitor or stem cells."The mouse provides us with an exceptional ability to make progress and we are excited about the potential for using cells derived from the rib perichondrium or using rib perichondrium-like cells for regenerative therapy," said Francesca Mariani, an assistant professor of cell and neurobiology at University of California, San Francisco.The findings are important for making progress in the field of skeletal repair where an acute clinical need is present for ameliorating skeletal injury, chronic osteoarthritis and the severe problems associated with reconstructive surgery, concluded the study that appeared in the Journal of Bone and Mineral Research.