Critical assessment of rhBMP-2 mediated bone induction: an in vitro and in vivo evaluation.
Understanding the influence of formulation and storage conditions on rhBMP-2 bioactivity is extremely important for its clinical application. Reports in the literature show that different research groups employ different parameters such as formulation conditions, storage, doses for in vivo applications etc. that makes it difficult to correlate results from different experiments. We therefore decided to rationalize these anomalies by performing a basic study on such parameters using two commercially available BMPs. Our in vitro experiments suggest that BMPs from different sources have significant differences in their bioactivity. The clinically approved rhBMP-2 (InductOs®; BMP-P) showed superior stability, compared to rhBMP-2 from R&D Systems (BMP-R) at physiological pH (determined by ALP assay). This BMP-P also showed lower binding to polypropylene Eppendorf tube. The BMP-R almost lost its bioactivity within 30 min at physiological pH and also shows more adhesion to plastic surfaces. This aggregation behavior was unequivocally ascertained by performing light scattering studies of the two BMPs, which revealed linear aggregation with time for BMP-R unlike BMP-P. The in vitro results were also reflected in the in vivo experiments, in a rat ectopic model with injectable hyaluronic acid (HA) hydrogel as BMP carrier. After 7 weeks post-implantation we observed larger bone volume with oriented collagen in the BMP-P group but a smaller bone with disoriented collagen in the BMP-R case. Our results highlight the large difference in activity between seemingly identical substances and also the importance of proper handling of such sensitive proteins.
Scilifelab Uppsala, Division of Polymer Chemistry, Department of Chemistry, Ångström Laboratory, Uppsala University, SE-75121 Uppsala, Sweden.
Marta
M
Kisiel
Manuela
M
Ventura
Oommen P
OP
Oommen
Anu
A
George
X Frank
XF
Walboomers
Jöns
J
Hilborn
Oommen P
OP
Varghese
D000447:Aldehydes / Q000737:chemistry; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage* / Q000737:chemistry; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003094:Collagen / Q000378:metabolism; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry; D004355:Drug Stability; D006820:Hyaluronic Acid / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry; D020100:Hydrogels / Q000008:administration & dosage / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008297:Male; D051379:Mice; D041681:NIH 3T3 Cells; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000737:chemistry; D012212:Rheology; D016212:Transforming Growth Factor beta / Q000008:administration & dosage* / Q000737:chemistry
D000447:Aldehydes; D055396:Bone Morphogenetic Protein 2; D004337:Drug Carriers; D006834:Hydrazines; D020100:Hydrogels; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D006820:Hyaluronic Acid; D003094:Collagen; D000469:Alkaline Phosphatase; C019289:carbohydrazide