Spatial control of bone formation using a porous polymer scaffold co-delivering anabolic rhBMP-2 and anti-resorptive agents.
Current clinical delivery of recombinant human bone morphogenetic proteins (rhBMPs) utilises freeze-dried collagen. Despite effective new bone generation, rhBMP via collagen can be limited by significant complications due to inflammation and uncontrolled bone formation. This study aimed to produce an alternative rhBMP local delivery system to permit more controllable and superior rhBMP-induced bone formation. Cylindrical porous poly(lactic-co-glycolic acid) (PLGA) scaffolds were manufactured by thermally-induced phase separation. Scaffolds were encapsulated with anabolic rhBMP-2 (20 µg) ± anti-resorptive agents: zoledronic acid (5 µg ZA), ZA pre-adsorbed onto hydroxyapatite microparticles, (5 µg ZA/2% HA) or IkappaB kinase (IKK) inhibitor (10 µg PS-1145). Scaffolds were inserted in a 6-mm critical-sized femoral defect in Wistar rats, and compared against rhBMP-2 via collagen. The regenerate region was examined at 6 weeks by 3D microCT and descriptive histology. MicroCT and histology revealed rhBMP-induced bone was more restricted in the PLGA scaffolds than collagen scaffolds (-92.3% TV, p < 0.01). The regenerate formed by PLGA + rhBMP-2/ZA/HA showed comparable bone volume to rhBMP-2 via collagen, and bone mineral density was +9.1% higher (p < 0.01). Local adjunct ZA/HA or PS-1145 significantly enhanced PLGA + rhBMP-induced bone formation by +78.2% and +52.0%, respectively (p ≤ 0.01). Mechanistically, MG-63 human osteoblast-like cells showed cellular invasion and proliferation within PLGA scaffolds. In conclusion, PLGA scaffolds enabled superior spatial control of rhBMP-induced bone formation over clinically-used collagen. The PLGA scaffold has the potential to avoid uncontrollable bone formation-related safety issues and to customise bone shape by scaffold design. Moreover, local treatment with anti-resorptive agents incorporated within the scaffold further augmented rhBMP-induced bone formation.
Orthopaedic Research & Biotechnology, Research Building, The Children's Hospital at Westmead, Locked Bag 4001, Westmead, NSW 2145, Australia.nicole.yu@sydney.edu.au.
N Y C
NY
Yu
M
M
Gdalevitch
C M
CM
Murphy
K
K
Mikulec
L
L
Peacock
J
J
Fitzpatrick
L C
LC
Cantrill
A J
AJ
Ruys
J J
JJ
Cooper-White
D G
DG
Little
A
A
Schindeler
D000818:Animals; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism*; D001861:Bone Regeneration; D002460:Cell Line; D004164:Diphosphonates / Q000494:pharmacology*; D005269:Femur / Q000187:drug effects / Q000601:surgery; D048091:Guided Tissue Regeneration; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D007093:Imidazoles / Q000494:pharmacology*; D019344:Lactic Acid / Q000494:pharmacology; D008297:Male; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D011100:Polyglycolic Acid / Q000494:pharmacology; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051381:Rats; D017208:Rats, Wistar; D054457:Tissue Scaffolds / Q000737:chemistry*; D000077211:Zoledronic Acid
C525718:BMP2 protein, human; D050071:Bone Density Conservation Agents; D055396:Bone Morphogenetic Protein 2; D004164:Diphosphonates; D007093:Imidazoles; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D000077211:Zoledronic Acid; D051550:I-kappa B Kinase