Silk fibroin microparticles as carriers for delivery of human recombinant bone morphogenetic protein-2: in vitro and in vivo bioactivity.
The in vitro and in vivo efficiency of fibroin microparticles as a delivery carrier for bone morphogenetic protein-2 (BMP-2) was evaluated. BMP-2 was encapsulated in silk fibroin particles that were produced by a simple and very mild processing method. The dose-response of BMP-2-loaded fibroin particles was examined in C2C12 cells, after 5 days of culture. The BMP-2 retained most of its activity as observed by the increase in alkaline phosphatase activity, which was much higher when BMP-2 was encapsulated into the particles rather than just surface-adsorbed. After 2 weeks of culture, increased mineralization was observed with BMP-2-loaded particles in comparison to soluble added growth factor. No significant cytotoxicity was detected. When implanted in a rat ectopic model, bone formation was observed by in vivo micro-computed tomography after 2 and 4 weeks postimplantation, with particles loaded with 5 or 12.5 microg BMP-2. An increase in bone density was observed over time. Histology revealed further evidence of ectopic bone formation, observed by strong alizarin red staining and osteocalcin immunostaining. Our findings show that fibroin microparticles may present an interesting option for future clinical applications in the bone tissue engineering field, and therefore, further studies have been planned.
Bessa
Paulo César
PC
3B's Research Group-Biomaterials, Biodegradables, and Biomimetics, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, University of Minho, Guimarães, Portugal. paulo.bessa@dep.uminho.pt
Balmayor
Elizabeth R
ER
Hartinger
Joachim
J
Zanoni
Gerald
G
Dopler
Daniela
D
Meinl
Alexandra
A
Banerjee
Asmita
A
Casal
Margarida
M
Redl
Heinz
H
Reis
Rui L
RL
van Griensven
Martijn
M
D000818:Animals; D001846:Bone Development; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage*; D002460:Cell Line; D004337:Drug Carriers; D005349:Fibroins / Q000008:administration & dosage*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage; D047011:Silk / Q000737:chemistry*; D014057:Tomography, X-Ray Computed
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D004337:Drug Carriers; D011994:Recombinant Proteins; D047011:Silk; D005349:Fibroins