Comparison of Two Nanoparticle Formulations for Localized Delivery of Platelet-Derived Growth Factor (PDGF) from Aligned Collagen Fibers

We have synthesized two types of nanoparticles (NPs) for controlled, localized delivery of platelet-derived growth factor (PDGF). One type is based on a liposome formulation; another type is based on a biodegradable polymer formulation. Liposome NPs have high PDGF loading and loading efficiency. With similar small particle size and size distribution, PLGA-m-PEG-PDGF NPs have lower PDGF loading and loading efficiency. It allows for controlled release of PDGF over a long period (e.g., up to 42 days). Based on an electrochemical process which uses electrolysis of water and isoelectric focusing of collagen, we also fabricated aligned collagen fibers which can incorporate the above formulated NPs as well as non-encapsulated (free) PDGF. The loading of NPs inside collagen fibers was confirmed by using fluorescence microscope, scanning electron microscope, and optical microscope. Cell proliferation study confirmed that both types of collagen-NP fibers are biocompatible and can enhance the proliferation of adipose derived stem cells in the short term. Our research demonstrated that two different NP formulations, as well as free PDGF can be loaded inside collagen to form aligned collagen-NP fibers, which can be used to enhance the proliferation of stem cells for connective tissue repair and regeneration (e.g., tendon).