Modulation of protein delivery from modular polymer scaffolds

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Drug Delivery

Background:

• In vitro studies of growth factor release from tissue engineering scaffolds often use aqueous environments, which differ from in vivo conditions.
• Understanding protein release kinetics is crucial for optimizing tissue regeneration therapies.

Purpose of the Study:

• To investigate the release of model proteins (histone and bovine serum albumin) from various scaffold surfaces and microspheres.
• To evaluate the influence of ions, serum proteins, and cells on protein release kinetics.
• To explore strategies for achieving sustained growth factor release in complex biological environments.

Main Methods:

• Studied release of positively charged histone and negatively charged bovine serum albumin (BSA) from different scaffold surfaces (PCL, plasma-etched PCL, collagen-coated PCL).
• Investigated protein release in media with varying ion concentrations, serum proteins, and cells.
• Encapsulated proteins into poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres embedded in scaffolds to control release.

Main Results:

• Electrostatic interactions affected protein release, with stronger binding of positively charged histone to negatively charged substrates.
• Plasma etching increased BSA release but not histone release from PCL scaffolds.
• Serum proteins and cells abolished electrostatic effects, leading to rapid release from collagen-coated scaffolds.
• PLGA microsphere composition modulated protein release, with BSA adsorbed to collagen releasing faster than encapsulated histone in complex media.

Conclusions:

• Growth factor release is significantly influenced by scaffold surface properties, ions, serum proteins, and cells.
• Sustained release strategies require consideration of these complex in vivo environmental factors.
• Future studies and multi-growth factor delivery systems must account for these variables for effective tissue regeneration.