114: The incorporation of human recombinant tropoelastin improves the biocompatibility of high or low porosity polyurethane

Abstract

Polyurethanes (PU) are synthetic polymer and have been widely used in medical devices and artificial organs for tissue repair. High and low porous polymer scaffolds containing recombinant human tropoelastin (TE) and PU were generated by electrospinning technique; these scaffolds have favourable mechanical and biological properties used as implantable applications. This study was to evaluate the acute and chronic inflammatory response to implantation of low and high porosity PU scaffolds with/without TE in mouse model. The back of each C57B/L6 mouse (n = 32) was subcutaneously implanted with control PU, low porosity PU/tropoelastin (PU/TE) and high porosity PU/tropoelastin (HP PU/TE) implants. Mice (n = 8) were euthanized and harvested the tissue samples at 1 day, 1 week, 2 weeks and 4 weeks. Histopathology and immunohistochemistry were performed to assess inflammatory cell infiltration, collagen deposition and granulation formation of each sample. Compared to control PU, fewer neutrophils were found on PU/TE and HP PU/TE implant surface, associated with lower expression of GM-CSF at 1 day following implantation. After 1 weeks, compared the surrounding granulation tissue formation from PU, both HP PU/TE and PU/TE have been found that thinner capsule thickness with less total infiltrating cells and proliferating cells PCNA, fewer macrophage/FBGCs F4/80, less neovascularization VWF, down-regulation level of MMP-2, MMP-9 and cytokines, including GM-CSF, IL-6, IL-10. Compared the tissue ingrowth of low porosity PU/TE implant, high porous HP PU/TE scaffolds demonstrated a larger number of total infiltrating cells inside the implant, associated with larger collagen deposition, greater proliferation rate PCNA, higher level of cytokines GM-CSF, IL-10 and MMP-2 after 2 weeks. Overall results suggested that firstly, the incorporation of TE into either high or low porosity PU scaffold could improves in the biocompatibility of PU alone, uniquely measured here as a reduced foreign body inflammatory response and better wound healing response at whole implant sites. Secondary, high porosity PU/TE enhanced and accelerated the active cells proliferation and infiltration into the scaffolds compared to low porosity scaffold.