Platelet-derived growth factor BB treated osteoprogenitors inhibit bone regeneration

The study evaluates the ability of osteoprogenitors treated with platelet-derived growth factor BB (PDGF-BB) delivered on vinyl styrene microbeads (VSM) to regenerate rat calvarial critical-size defects (CSDs). Fetal rat calvarial cells were cultured and tested for their ability to attach to VSM using scanning electron microscopy. Twenty-five rats were equally divided into 5 groups; a negative control (GPI), vinyl styrene microbeads (GPII), PDGF-BB (GPIII), VSM plus osteoblastic progenitors (GPIV), and VSM plus PDGF-BB treated osteoblastic progenitors (GPV). CSDs were created and reconstructed according to the mentioned study design. After 16 weeks, animals were sacrificed and defect areas evaluated for bone regeneration. Cells attached to the microbeads; however, their morphology and topography were affected by the PDGF-BB. Transplanting the VSM/cells constructs to CSDs revealed significant reduction of bone regeneration upon pretreatment of the cells with PDGF-BB. However, short-term application of PDGF-BB to CSD stimulated bone regeneration. The ability of osteoprogenitor cells to regenerate bone was significantly reduced upon pretreatment with PDGF-BB in vitro. However, adding PDGF-BB at the time of surgery had stimulated bone regeneration.