Host inflammatory response to polypropylene implants: insights from a quantitative immunohistochemical and birefringence analysis in a rat subcutaneous model.
OBJECTIVE
To describe acute and sub acute aspects of histological and immunohistochemical response to PP implant in a rat subcutaneous model based on objective methods.


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 removed: 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 immunoreactivity 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.
Faculdade de Ciências Médicas da Universidade de Campinas, Campinas, SP, Brasil.
Alessandro
A
Prudente
Instituto de Biologia, Universidade de Campinas, Campinas, SP, Brasil.
Wagner Jose
WJ
Favaro
Laboratório de Investigação Patologica, Centro de Investigação em Pediatria,Universidade de Campinas, Campinas, SP, Brasil.
Paulo
P
Latuf
Faculdade de Ciências Médicas da Universidade de Campinas, Campinas, SP, Brasil.
Cassio Luis Zanettini
CL
Riccetto
D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects; D001718:Birefringence; D002481:Cellulitis / Q000209:etiology / Q000473:pathology; D003094:Collagen / Q000032:analysis / Q000378:metabolism; D005260:Female; D005549:Foreign-Body Reaction / Q000139:chemically induced* / Q000209:etiology* / Q000473:pathology*; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000032:analysis / Q000378:metabolism; D008422:Materials Testing; D020778:Matrix Metalloproteinase 2 / Q000032:analysis / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis / Q000378:metabolism; D011126:Polypropylenes / Q000009:adverse effects*; D017208:Rats, Wistar; D015203:Reproducibility of Results; D040521:Subcutaneous Tissue / Q000473:pathology*; D013526:Surgical Mesh / Q000009:adverse effects*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000378:metabolism
D001672:Biocompatible Materials; D007375:Interleukin-1; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011126:Polypropylenes; D014409:Tumor Necrosis Factor-alpha; D003094:Collagen; D020778:Matrix Metalloproteinase 2