Long-term sustained release of salicylic acid from cross-linked biodegradable polyester induces a reduced foreign body response in mice

Biomacromolecules. 2015 Feb 9;16(2):636-49. doi: 10.1021/bm5017282. Epub 2015 Jan 21.

Abstract

There has been a continuous surge toward developing new biopolymers that exhibit better in vivo biocompatibility properties in terms of demonstrating a reduced foreign body response (FBR). One approach to mitigate the undesired FBR is to develop an implant capable of releasing anti-inflammatory molecules in a sustained manner over a long time period. Implants causing inflammation are also more susceptible to infection. In this article, the in vivo biocompatibility of a novel, biodegradable salicylic acid releasing polyester (SAP) has been investigated by subcutaneous implantation in a mouse model. The tissue response to SAP was compared with that of a widely used biodegradable polymer, poly(lactic acid-co-glycolic acid) (PLGA), as a control over three time points: 2, 4, and 16 weeks postimplantation. A long-term in vitro study illustrates a continuous, linear (zero order) release of salicylic acid with a cumulative mass percent release rate of 7.34 × 10(-4) h(-1) over ∼1.5-17 months. On the basis of physicochemical analysis, surface erosion for SAP and bulk erosion for PLGA have been confirmed as their dominant degradation modes in vivo. On the basis of the histomorphometrical analysis of inflammatory cell densities and collagen distribution as well as quantification of proinflammatory cytokine levels (TNF-α and IL-1β), a reduced foreign body response toward SAP with respect to that generated by PLGA has been unambiguously established. The favorable in vivo tissue response to SAP, as manifest from the uniform and well-vascularized encapsulation around the implant, is consistent with the decrease in inflammatory cell density and increase in angiogenesis with time. The above observations, together with the demonstration of long-term and sustained release of salicylic acid, establish the potential use of SAP for applications in improved matrices for tissue engineering and chronic wound healing.

MeSH terms

  • Animals
  • Biocompatible Materials / administration & dosage*
  • Biocompatible Materials / chemistry
  • Biocompatible Materials / metabolism
  • Cross-Linking Reagents / administration & dosage*
  • Cross-Linking Reagents / chemistry
  • Cross-Linking Reagents / metabolism
  • Delayed-Action Preparations / administration & dosage
  • Delayed-Action Preparations / chemistry
  • Delayed-Action Preparations / metabolism
  • Foreign-Body Reaction / metabolism
  • Foreign-Body Reaction / pathology
  • Foreign-Body Reaction / prevention & control*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Polyesters / administration & dosage*
  • Polyesters / chemistry
  • Polyesters / metabolism
  • Salicylic Acid / administration & dosage*
  • Salicylic Acid / chemistry
  • Salicylic Acid / metabolism
  • Time Factors

Substances

  • Biocompatible Materials
  • Cross-Linking Reagents
  • Delayed-Action Preparations
  • Polyesters
  • Salicylic Acid