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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.

Purpose: The aim of the present study was to evaluate the use of the nonresorbable vinyl styrene microbeads (VSM) alloplast as a delivery vehicle for platelet-derived growth factor (PDGF-BB) in rat calvarial critical size defects., Materials and Methods: Seventy-three Long-Evans male rats were divided into 4 groups; a negative control, vinyl styrene microbeads (VSM), PDGF-BB, and VSM plus PDGF-BB. Critical size calvarial defects were carried out and isolated with membranes sandwiching the defects with their fillers. Animals were sacrificed after 2, 4, and 16 weeks classifying each group into 3 subgroups. Calvarial specimens were radiographed for evaluation of regenerated bone volume and densitometry histogram analysis. Specimens were divided mid-sagittally and stained with hematoxylin and eosin (H&E) and trichrome stain for qualitative and histomorphometric analysis using an image analysis software., Results: The VSM groups showed statistically higher defect fills than the VSM-free groups at all sacrifice times except for the VSM/PDGF group that showed this difference after 2 weeks in relation to the PDGF group and the negative control after 4 and 16 weeks. For the radiographic analysis, the VSM/PDGF group showed the lowest bone volume compared with the other groups except when it was compared with the 4 weeks VSM group. In contrast, the PDGF showed the highest bone volumes at all sacrifice times that were only significant when compared with the 4 weeks VSM group and the 4 and 16 weeks VSM/PDGF group., Conclusions: VSM enhances bone defect fill whereas the VSM/PDGF-BB is not able to improve bone regeneration capacity when compared with VSM alone.