Protein-loaded PLGA-PEG-PLGA microspheres: a tool for cell therapy

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Drug Delivery Systems

Background:

• Poly-(d,l lactide-co-glycolide) (PLGA) microspheres are used for growth factor delivery in organ repair.
• PLGA exhibits poor protein release, limiting its effectiveness.
• Hydrophilic PLGA-PEG-PLGA (A-B-A) copolymers show potential for improved protein release.

Purpose of the Study:

• To investigate the impact of varying PLGA-PEG-PLGA copolymer compositions on protein release profiles.
• To optimize microsphere formulations for sustained and controlled growth factor delivery.
• To assess the suitability of these polymers for tissue engineering applications.

Main Methods:

• Synthesis and characterization of PLGA-PEG-PLGA triblock copolymers with varied segment molecular weights.
• Fabrication of microspheres for growth factor encapsulation and release studies.
• Analysis of protein release kinetics, including burst release, sustained release, and incomplete release factors.
• Evaluation of cell viability and adhesion on fibronectin-coated microspheres.

Main Results:

• Continuous protein release profiles without lag phases were observed.
• A specific triblock ABA copolymer (low PEG, high PLGA molecular weight) demonstrated a minimal burst release (<10% in 48h) followed by sustained release over 36 days.
• Factors contributing to incomplete protein release were identified as protein adsorption, aggregation, and denaturation under acidic conditions.
• Microspheres coated with fibronectin supported significant cell viability and adhesion.

Conclusions:

• PLGA-PEG-PLGA copolymers offer tunable protein release profiles superior to traditional PLGA.
• Optimized copolymer formulations can achieve sustained growth factor delivery crucial for organ repair.
• The observed cell adhesion and viability highlight the potential of these advanced biomaterials in tissue engineering.