Calcification and ossification have been described in artery wall in pathologic conditions and aging. We previously described the use of cryopreserved arterial allografts as membranes for guiding bone regeneration. We hypothesize that artery is as good as synthetic membranes (e-PTFE, gold-standard in guided bone regeneration) due to the osteogenic potential of cells from its medial layer. A comparative study was made creating 10 mm mid-diaphyseal radial defects in 15 New Zeland rabbits (30 forearms): 10 defects were covered with an e-PTFE membrane and 10 defects with no membrane (control group). Studies: X-rays, CT, MR, morpho-densitometric analysis, electronic and optical microscopy. To demonstrate the cellular arterial stock, cryopre-served and fresh rabbit thoracic aorta specimens were studied. Medial layer was isolated and cultured as explants in normal medium. Cells were harvested and added to a 3-D scaffold based on plasmatic albumin in osteogenic medium. Immunocitochemical study was made. Radial defects surrounded by cryopreserved arterial membranes showed total regeneration in nine of 10 defects versus seven of 10 defects in e-PTFE group (no statistically significant differences were detected between them). No tissue layer was found between bone and artery while a connective tissue layer was observed between e-PTFE and bone. Neither radiological nor histological healing were detected in the control group. Cells cultured had smooth muscle features as they showed immunofluorescence with anti-smooth muscle alpha-actin, anti-calponin and anti-vimentin antibodies. When cells were added to a 3-D matrix, they showed chondro and osteogenic differentiation, as they stained positive for types II and X collagen, alkaline phosphatase and von Kossa. Although no statistically significant differences between artery and e-PTFE groups were detected, histological and cellular findings suggest a superiority of cryopreserved arterial allografts when compared with synthetic membranes of e-PTFE, with a contribution of the cellular stock of the medial layer in the healing process.
