In vivo response to starch-based scaffolds designed for bone tissue engineering applications.
Our purpose was to evaluate the in vivo endosseous response to three starch-based scaffolds implanted in rats (n = 54). We implanted the three scaffold groups; a 50/50 (wt %) blend of corn starch and ethylene-vinyl alcohol (SEVA-C), the same composition coated with a biomimetic calcium phosphate (Ca-P) layer (SEVA-C/CaP), and a 50/50 (wt %) blend of corn starch and cellulose acetate (SCA), all produced by extrusion with blowing agents, into distal femurs proximal to the epiphyseal plate, for 1, 3, or 6 weeks. Our results showed that at 1 week considerable reparative bone formed around all scaffold groups, although the bone was separated from the scaffold by an intervening soft tissue interfacial zone that comprised two distinct compartments: the surface of the scaffold was occupied by multinucleate giant cells and the compartment between these cells and the surrounding bone was occupied by a streaming fibrous-like tissue. The extracellular matrix of the latter was continuous with the extracellular bone matrix itself, labeled positively for osteocalcin and appeared mineralized by back-scattered electron imaging. All three scaffolds showed a similar tissue response, with the soft tissue interface diminishing with time. No bone contact was observed with SEVA-C at any time point, only transitory bone contact was observed with SEVA-C/CaP at 3 weeks, but SCA exhibited direct bone contact at 6 weeks where 56.23 +/- 6.46% of the scaffold surface was occupied by bone. We conclude that all materials exhibited a favorable bony response and that the rapidly forming initial "connective tissue" seen around all scaffolds was a very early form of bone formation.
Salgado
A J
AJ
3B's Research Group, Biomaterials, Biodegradables and Biomimetics, University of Minho, Campus de Gualtar, Braga, Portugal. asalgado@ecsaude.uminho.pt
Coutinho
O P
OP
Reis
R L
RL
Davies
J E
JE
D000818:Animals; D000943:Antigens, Differentiation / Q000096:biosynthesis; D040761:Biomimetic Materials; D001861:Bone Regeneration; D018786:Bone Substitutes; D002130:Calcium Phosphates; D002454:Cell Differentiation; D005109:Extracellular Matrix / Q000378:metabolism / Q000648:ultrastructure; D005264:Femoral Fractures / Q000473:pathology / Q000628:therapy*; D015726:Giant Cells / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis; D011145:Polyvinyls; D051381:Rats; D017208:Rats, Wistar; D013213:Starch; D013499:Surface Properties; D013997:Time Factors; D023822:Tissue Engineering
D000943:Antigens, Differentiation; D018786:Bone Substitutes; D002130:Calcium Phosphates; D011145:Polyvinyls; C439612:corn starch-co-ethylene vinyl alcohol blend; D013213:Starch; C020243:calcium phosphate