Maintaining bioactivity of NGF for controlled release from PLGA using PEG

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Tissue Engineering

Background:

• Nerve growth factor (NGF) is crucial for neuronal survival and growth.
• Encapsulating sensitive biomolecules like NGF in biodegradable polymers (e.g., PLGA) is challenging due to potential loss of bioactivity.
• Controlled release systems are needed for sustained therapeutic effects of growth factors.

Purpose of the Study:

• To investigate methods for retaining nerve growth factor (NGF) bioactivity during encapsulation in poly(lactic-co-glycolic acid) (PLGA) discs.
• To explore the role of poly(ethylene glycol) (PEG) as a porogen and bioactivity stabilizer.
• To optimize controlled release of NGF using PLGA-PEG formulations.

Main Methods:

• NGF and PEG were encapsulated in PLGA using dissolution-evaporation with methylene chloride.
• Colyophilization of PEG and NGF was performed prior to PLGA encapsulation at various PEG:NGF mass ratios.
• NGF bioactivity was assessed after encapsulation and during controlled release studies.
• The influence of PEG content on NGF release rate was evaluated.

Main Results:

• Encapsulation without prior colyophilization resulted in complete loss of NGF activity.
• Colyophilization of PEG and NGF successfully retained NGF bioactivity throughout the fabrication process.
• The amount of encapsulated PEG was the primary determinant of NGF release rate.
• PEG effectively acted as a porogen to modulate release and preserve NGF activity.

Conclusions:

• Colyophilization of PEG with NGF is a critical step to maintain bioactivity during PLGA encapsulation.
• PEG serves a dual role: controlling release kinetics and protecting NGF from degradation.
• This technique offers a viable strategy for the controlled delivery of bioactive growth factors, with potential applications beyond NGF.