Rc. Thomson et al., Guided tissue fabrication from periosteum using preformed biodegradable polymer scaffolds, BIOMATERIAL, 20(21), 1999, pp. 2007-2018
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.