Polycaprolactone scaffold and reduced rhBMP-7 dose for the regeneration of critical-sized defects in sheep tibiae.
The transplantation of autologous bone graft as a treatment for large bone defects has the limitation of harvesting co-morbidity and limited availability. This drives the orthopaedic research community to develop bone graft substitutes. Routinely, supra-physiological doses of bone morphogenetic proteins (BMPs) are applied perpetuating concerns over undesired side effects and cost of BMPs. We therefore aimed to design a composite scaffold that allows maintenance of protein bioactivity and enhances growth factor retention at the implantation site. Critical-sized defects in sheep tibiae were treated with the autograft and with two dosages of rhBMP-7, 3.5 mg and 1.75 mg, embedded in a slowly degradable medical grade poly(ε-caprolactone) (PCL) scaffold with β-tricalcium phosphate microparticles (mPCL-TCP). Specimens were characterised by biomechanical testing, microcomputed tomography and histology. Bridging was observed within 3 months for the autograft and both rhBMP-7 treatments. No significant difference was observed between the low and high rhBMP-7 dosages or between any of the rhBMP-7 groups and autograft implantation. Scaffolds alone did not induce comparable levels of bone formation compared to the autograft and rhBMP-7 groups. In summary, the mPCL-TCP scaffold with the lower rhBMP-7 dose led to equivalent results to autograft transplantation or the high BMP dosage. Our data suggest a promising clinical future for BMP application in scaffold-based bone tissue engineering, lowering and optimising the amount of required BMP.
Julius Wolff Institute & Center for Musculoskeletal Surgery, Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
Amaia
A
Cipitria
Johannes C
JC
Reichert
Devakar R
DR
Epari
Siamak
S
Saifzadeh
Arne
A
Berner
Hanna
H
Schell
Manav
M
Mehta
Michael A
MA
Schuetz
Georg N
GN
Duda
Dietmar W
DW
Hutmacher
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000737:chemistry / Q000494:pharmacology; D010012:Osteogenesis / Q000187:drug effects; D011091:Polyesters / Q000737:chemistry*; D012756:Sheep; D013977:Tibia / Q000166:cytology; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
D019485:Bone Morphogenetic Proteins; D011091:Polyesters; C016240:polycaprolactone
BMP (bone morphogenetic protein); Bone tissue engineering; Ovine animal model; Polycaprolactone