# Development of a Biodegradable PLGA Carrier to Provide Wnt Agonists and Antibiotics to Meet the Requirements for Patients with Bone Infections

## TL;DR

A biodegradable PLGA bead system was developed to deliver antibiotics and a bone growth enhancer for treating bone infections, showing effective drug release and improved bone healing in rabbits.

## Contribution

A novel PLGA bead system combining vancomycin and lithium chloride was developed for sustained drug delivery and enhanced bone regeneration in bone infections.

## Key findings

- Vancomycin and lithium were released for over 42 and 28 days respectively, maintaining concentrations above bacterial sensitivity thresholds.
- Lithium cotreatment enhanced vancomycin's bactericidal effect and promoted osteogenic marker expression in mesenchymal stem cells.
- In rabbits, the system supported sustained drug release for over 6 weeks and led to increased mature bone tissue formation.

## Abstract

Antibiotic beads can be used to treat surgical infections. In this study, polylactide–polyglycolide (PLGA) was mixed with vancomycin, the osteogenic enhancer lithium chloride (LiCl), and hot compression to form PLGA-vancomycin-LiCl delivery beads to treat bone infection. An elution method was used to characterize in vitro release characteristics of vancomycin and Li over a 42-day period. The release profiles lasted for more than 42 days for vancomycin and 28 days for Li. The concentration of vancomycin in each sample was well above the breakpoint sensitivity. Lithium cotreatment enhanced the bactericidal effect of vancomycin. Released Li and vancomycin increased the mRNA or protein expressions of osteogenic markers of mesenchymal stem cells (MSCs). In vivo, the PLGA delivery systems were implanted into the distal femoral cavities of rabbits, and the cavity fluid content was aspirated and analyzed at each time point. The released Li and vancomycin lasted more than 6 weeks, and the vancomycin concentrations were much greater than the breakpoint sensitivity. Four rabbits in each group were sacrificed at 8 weeks for histological observation. More mature bone tissue was observed in the Li treatment group. This study provides a PLGA drug delivery system to meet the requirements of patients with bone infections.