Guided tissue fabrication from periosteum using preformed biodegradable polymer scaffolds

A successful tissue engineering method for bone replacement would imitate n atural bone graft by providing the essential elements for new bone formatio n using synthetic scaffolds, osteogenic cell populations, and bone inductio n factors. This is a study of the suitability of various formulations of po ly(DL-lactic-co-glycolic acid) (PLGA) foams to provide a tissue conducting scaffold in an ovine model for bone flap fabrication. Three formulations we re used of different copolymer ratio and molecular weight. Porous wafers of PLGA were stacked into rectangular chambers (volume 4 cm(3)) enclosed on f ive sides. Some chambers also contained autologous morcellized bone graft ( MBG). The chambers were inserted with the open face adjacent to the cambium layer of the periosteum in rib beds of seven sheep and harvested after 8 w eeks in vivo. Gross and histologic examination of the resulting tissue spec imens demonstrated molded units of vascularized tissue generally conforming to the shape of the chambers and firmly attached to the periosteum. Polyme r degradation appeared to occur by varying degrees based on polymer formula tion. New bone formation was observed only in areas containing MEG. There w as no evidence of significant inflammatory reaction or local tissue damage at 8 weeks. We conclude that a PLGA foam scaffold is (1) an efficient condu ctor of new tissue growth but not osteoinductive, (2) contributes to the sh ape of molded tissue, and (3) biocompatible when used in this model. Furthe r studies are warranted to develop practical methods to deliver bone induct ion factors to the system to promote osseous tissue generation throughout t he synthetic scaffold. (C) 1999 Elsevier Science Ltd. All rights reserved.