title: Engineering new bone tissue in vitro on highly porous poly(alpha-hydroxyl acids)/hydroxyapatite composite scaffolds.
abstract: Engineering new bone tissue with cells and a synthetic extracellular matrix (scaffolding) represents a new approach for the regeneration of mineralized tissues compared with the transplantation of bone (autografts or allografts). In the present work, highly porous poly(L-lactic acid) (PLLA) and PLLA/hydroxyapatite (HAP) composite scaffolds were prepared with a thermally induced phase separation technique. The scaffolds were seeded with osteoblastic cells and cultured in vitro. In the pure PLLA scaffolds, the osteoblasts attached primarily on the outer surface of the polymer. In contrast, the osteoblasts penetrated deep into the PLLA/HAP scaffolds and were uniformly distributed. The osteoblast survival percentage in the PLLA/HAP scaffolds was superior to that in the PLLA scaffolds. The osteoblasts proliferated in both types of the scaffolds, but the cell number was always higher in the PLLA/HAP composite scaffolds during 6 weeks of in vitro cultivation. Bone-specific markers (mRNAs encoding bone sialoprotein and osteocalcin) were expressed more abundantly in the PLLA/HAP composite scaffolds than in the PLLA scaffolds. The new tissue increased continuously in the PLLA/HAP composite scaffolds, whereas new tissue formed only near the surface of pure PLLA scaffolds. These results demonstrate that HAP imparts osteoconductivity and the highly porous PLLA/HAP composite scaffolds are superior to pure PLLA scaffolds for bone tissue engineering.
authors.affiliation: Department of Biologic and Materials Sciences, 1011 North University Ave., Room 2211, University of Michigan, Ann Arbor, Michigan 48109, USA. mapx@umich.edu
authors.forename: P X
authors.initials: PX
authors.lastname: Ma
authors.forename: R
authors.initials: R
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Xiao
authors.forename: R
authors.initials: R
authors.lastname: Franceschi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D018786:Bone Substitutes; D016025:Bone Transplantation; D002448:Cell Adhesion; D002454:Cell Differentiation; D002455:Cell Division; D017690:Cell Transplantation; D002478:Cells, Cultured; D005109:Extracellular Matrix; D007202:Indicators and Reagents; D007700:Kinetics; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology
chemical_list: D018786:Bone Substitutes; D007202:Indicators and Reagents