Callus Formation in Fractured Femur of Rats Treated with Injection of Human Umbilical Cord Mesenchymal Stem Cell-Conditioned Medium

Mesenchymal stem cells-conditioned medium (MSC-CM) is the extraction from stem cell medium containing biological substances, including growth factors and cytokines. These substances play roles in the various functions of body regulatory, including bone formation. However, the effect of MSC-CM derived from human umbilical cord injection in femur fracture healing of rats has not been reported previously. This study aims to see the effect of MSC-CM derived from human umbilical cord injection on the callus formation of bone fracture healing in Wistar rats (Rattus norvegicus). A femur fracture in 54 Wistar rats was made by surgery according to the procedure under sterile conditions. After the surgery, rats were divided into 2 groups of 27, respectively. Injection in the control (0.1 mL/kg body weight NaCl) and MSC-CM group (0.1 mL/kg body weight MSC-CM) was performed on weeks 0, 1, 2, 3, 4, 5, 6, 7, and 8 after surgery. Radiographic images and the femur bone samples were taken and collected on days 1, 7, 14, 21, 28, 35, and 60 after surgery. Bone samples were then fixed in Bouin solution. Histologic preparations were done by the paraffin method, by cutting the tissue blocks into 5 μm thickness and then staining with Mallory aniline blue staining. The results were analyzed descriptively and quantitatively. The result showed that the soft callus formation occurred rapidly and got wider in the MSC-CM group than that of the control group. The administration of MSC-CM injection postfracture surgery to femur fracture cases in rats was capable to accelerate the callus formation.