Perioperative steroid administration inhibits angiogenic host tissue response to porous polyethylene (Medpor) implants.

Porous polyethylene (Medpor) is an alloplastic biomaterial, which is commonly used in plastic and reconstructive surgery. In the present study, we analyzed the effect of perioperative steroid administration on the inflammatory and angiogenic host tissue response to implanted Medpor. For this purpose, Medpor was implanted into the dorsal skinfold chamber of prednisolone-treated and vehicle-treated (control) balb/c mice and analyzed by means of intravital fluorescence microscopy over a 14-day period. Incorporation of the implants was evaluated by histology. An aortic ring assay and Western blot analyses were performed to determine in vitro the effect of prednisolone on angiogenesis. Implantation of Medpor did not induce a leukocytic inflammatory host tissue response. However, in prednisolone-treated and control animals giant cells could be detected at the interface between the implants and the surrounding granulation tissue as a typical indicator for a chronic foreign body reaction. Interestingly, perioperative prednisolone administration inhibited vascularisation of the implants, as indicated by a significantly decreased functional density of newly developing capillary blood vessels. Accordingly, prednisolone suppressed in vitro endothelial sprouting and tube formation in the aortic ring assay and reduced proliferating cell nuclear antigen (PCNA), Tie2, vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 expression of murine endothelioma cells. In conclusion, prednisolone treatment inhibits the early vascularisation of Medpor implants due to direct inhibition of distinct angiogenic mechanisms. Therefore, perioperative steroid therapy should be avoided in case of Medpor implantation to achieve a rapid incorporation of the biomaterial at the implantation site.