Cartilage to Bone Transformation During Fracture Healing Is Coordinated by the Invading Vasculature and Induction of the Core Pluripotency Genes

The document from January 15, 2017, presents a study that investigated the role of core pluripotency genes (Sox2, Oct4, Nanog) in the transformation of cartilage to bone during fracture healing, with a focus on the involvement of the vasculature. The study utilized immunohistochemistry on wild-type mice (n>12) and found that these genes, which are typically associated with maintaining pluripotency in stem cells, were expressed in hypertrophic chondrocytes near the vasculature in the transition zone of the fracture callus. The study demonstrated that Sox2 is functionally important for fracture healing, as Sox2 knockout mice showed decreased callus size, bone, and vasculature volume. The findings suggest that the vasculature signals the activation of pluripotency genes in chondrocytes, which may then transdifferentiate into osteoblasts, challenging the traditional view that hypertrophic chondrocytes undergo apoptosis rather than contributing to new bone formation.