Charge-engineered microparticles for targeted delivery of RhoA activator to nucleus pulposus

Area of Science:

• Biomaterials Science
• Cell Biology
• Regenerative Medicine

Background:

• Intervertebral disc degeneration (IVDD) involves nucleus pulposus (NP) cell mechanobiology disruption, F-actin disorganization, and inflammation-driven extracellular matrix (ECM) breakdown.
• Restoring actomyosin contractility is key to mitigating ECM degradation.
• Current treatments require sustained and spatially targeted delivery of therapeutic agents like CN03, a Rho activator.

Purpose of the Study:

• To engineer a poly-(lactic-co-glycolic) acid microparticle system (ePLGA) for sustained, spatially targeted delivery of CN03 to NP cells.
• To functionalize ePLGA with avidin (Av-ePLGA-CN03) to enhance NP matrix binding and retention.
• To evaluate the bioactivity, release profile, and biocompatibility of Av-ePLGA-CN03 for IVDD treatment.

Main Methods:

• Encapsulation of hydrophilic CN03 within an engineered PLGA microparticle with a viscous core (ePLGA-CN03) for sustained release.
• Functionalization of ePLGA-CN03 with cationic avidin (Av-ePLGA-CN03) for enhanced electrostatic binding to the NP matrix.
• In vitro assessment of CN03 release, NP cell F-actin organization, RhoA/ROCK pathway activation, and cell viability.
• Ex vivo evaluation of Av-ePLGA-CN03 tissue binding, spatial localization, and NP swelling properties.

Main Results:

• Sustained release of bioactive CN03 from ePLGA-CN03 restored F-actin organization and reduced cell spreading in NP cells under TNFα stimulation.
• Av-ePLGA-CN03 demonstrated strong electrostatic binding to the NP matrix, achieving month-long intra-NP localization and outperforming unmodified particles.
• Avidin functionalization did not adversely affect NP swelling or cell viability, indicating biocompatibility.
• The Av-ePLGA system maintained sustained CN03 release and bioactivity over time.

Conclusions:

• Charge-guided, avidin-modified PLGA microparticles (Av-ePLGA) provide a modular platform for sustained, spatially targeted intra-NP delivery of hydrophilic biologics.
• This system effectively delivers CN03 to NP cells, restoring cytoskeletal integrity and offering a promising therapeutic strategy for IVDD.
• Av-ePLGA facilitates long-term retention within the NP, minimizing off-target diffusion and enhancing treatment efficacy for intervertebral disc degeneration.