Porous bone morphogenetic protein-2 microspheres: polymer binding and in vitro release

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Tissue Engineering

Background:

• Recombinant human bone morphogenetic protein 2 (rhBMP-2) is crucial for bone regeneration.
• Poly-lactic-co-glycolic acid (PLGA) microspheres are widely used for controlled protein delivery.
• Optimizing rhBMP-2 binding and release from PLGA carriers is essential for therapeutic efficacy.

Purpose of the Study:

• To compare the binding and release characteristics of rhBMP-2 with hydrophobic and hydrophilic PLGA copolymers.
• To investigate the influence of PLGA properties and adsorption techniques on rhBMP-2 delivery.
• To establish control over rhBMP-2 release profiles through PLGA microsphere carrier selection.

Main Methods:

• Porous PLGA microspheres were fabricated using a double emulsion method.
• rhBMP-2 binding was quantified by measuring protein concentration after soaking microspheres.
• Protein release kinetics were analyzed over time using reversed-phase high-performance liquid chromatography.

Main Results:

• Hydrophilic PLGA microspheres exhibited significantly higher rhBMP-2 binding capacity compared to hydrophobic counterparts.
• Increased binding correlated with higher polymer acid values; adsorption was influenced by protein concentration and technique.
• rhBMP-2 release occurred in two phases: rapid release of unbound protein within 3 days, followed by sustained release tied to PLGA mass loss.

Conclusions:

• PLGA microsphere properties, particularly hydrophilicity and acid value, critically influence rhBMP-2 binding.
• Adsorption techniques and protein concentration can be optimized to enhance rhBMP-2 loading.
• Selection of appropriate PLGA microsphere carriers allows for controlled delivery of rhBMP-2.