Controlled release of bioactive PDGF-AA from a hydrogel/nanoparticle composite

Area of Science:

• Biomaterials Science
• Neuroscience
• Drug Delivery Systems

Background:

• Polymeric nanoparticles are utilized for protein encapsulation, but excipients like poly(ethylene glycol) (PEG) can yield contradictory outcomes on protein stability.
• Platelet-derived growth factor-AA (PDGF-AA) is crucial for neural stem/progenitor cell (NSPC) survival and oligodendrocyte differentiation, key processes in central nervous system regeneration.

Purpose of the Study:

• To investigate the impact of low molecular weight PEG on the stability and bioactivity of encapsulated PDGF-AA within poly(lactide-co-glycolide) nanoparticles.
• To develop and validate an injectable nanoparticle/hydrogel drug delivery system for controlled release of bioactive PDGF-AA.

Main Methods:

• Encapsulation of PDGF-AA in poly(lactide-co-glycolide) nanoparticles, with and without co-encapsulated low molecular weight PEG.
• Assessment of PDGF-AA loading efficiency, release kinetics over 21 days, aggregation state via ELISA, and bioactivity through NSPC oligodendrocyte differentiation assays.

Main Results:

• Co-encapsulation of PEG increased PDGF-AA loading but significantly accelerated protein aggregation, leading to reduced bioactivity.
• PDGF-AA released from nanoparticles without PEG maintained its bioactivity, effectively inducing NSPC oligodendrocyte differentiation, comparable to fresh PDGF-AA controls.
• The study demonstrated controlled, sustained release of bioactive PDGF-AA from an injectable nanoparticle/hydrogel system.

Conclusions:

• Low molecular weight PEG has a detrimental effect on PDGF-AA stability and bioactivity during encapsulation in polymeric nanoparticles.
• The developed nanoparticle/hydrogel system enables controlled release of bioactive PDGF-AA, offering a promising strategy for central nervous system regeneration.
• This research provides critical insights into the role of excipients in protein encapsulation and highlights a novel approach for delivering differentiation factors.