Vol. 42 (3): 585-593, May – June, 2016
Host inflammatory response to polypropylene implants: insights from a quantitative immunohistochemical and birefringence analysis in a rat subcutaneous model
Alessandro Prudente 1, Wágner José Fávaro 2, Paulo Latuf Filho 3, Cássio Luis Zanettini Riccetto 1
1 Faculdade de Ciências Médicas da Universidade de Campinas, Campinas, SP, Brasil; 2 Instituto de Biologia, Universidade de Campinas, Campinas, SP, Brasil; 3 Laboratório de Investigação Patologica, Centro de Investigação em Pediatria,Universidade de Campinas, Campinas, SP, Brasil
Objectives: To describe acute and sub acute aspects of histological and immunohistoche¬mical response to PP implant in a rat subcutaneous model based on objective methods.
Materials and Methods: Thirty rats had a PP mesh subcutaneously implanted and the same dissection on the other side of abdomen but without mesh (sham). The animals were euthanized after 4 and 30 days. Six slides were prepared using the tissue remo¬ved: one stained with hematoxylin-eosin (inflammation assessment); one unstained (birefringence evaluation) and four slides for immunohistochemical processing: IL-1 and TNF-α (pro-inflammatory cytokines), MMP-2 (collagen metabolism) and CD-31 (angiogenesis). The area of inflammation, the birefringence index, the area of immu¬noreactivity and the number of vessels were objectively measured.
Results: A larger area of inflammatory reaction was observed in PP compared to sham on the 4th and on the 30th day (p=0.0002). After 4 days, PP presented higher TNF (p=0.0001) immunoreactivity than sham and no differences were observed in MMP-2 (p=0.06) and IL-1 (p=0.08). After 30 days, a reduction of IL-1 (p=0.010) and TNF (p=0.016) for PP and of IL-1 (p=0.010) for sham were observed. Moreover, area of MMP-2 immunoreactivity decreased over time for PP group (p=0.018). Birefringence index and vessel counting showed no differences between PP and sham (p=0.27 and p=0.58, respectively).
Conclusions: The implantation of monofilament and macroporous polypropylene in the subcutaneous of rats resulted in increased inflammatory activity and higher TNF production in the early post implant phase. After 30 days, PP has similar cytokines immunoreactivity, vessel density and extracellular matrix organization.
Keywords: urinary incontinence, pelvic organ prolapse, polypropylenes, graft versus host reaction, foreign body reaction, immunohistochemistry