Reactive capsule formation around soft-tissue implants is related to cell necrosis

Abstract

Low-density polethylene disks with smooth or course surfaces were implanted in the abdominal wall of rats, and the tissue response was evaluated after 1, 6, or 12 weeks. Cell damage was detected by two different methods. Cells with increased membrane permeability could be identified using fluorescence microscopy by injection of propidium iodide prior to the killing of the rats. Second, cell death was verified by detection of DNA fragmentation. At 1 week a considerable number of the interfacial cells was stained with propidium iodide. Propidium-iodide-positive cells also were enriched at the edges of the disks irrespective of surface texture. The numbers of positive interfacial cells decreased markedly over time. Cells with DNA fragmentation initially displayed a scattered distribution; at later time points they appeared mainly in the outer portion of the enveloping capsule. The reactive capsule was thicker for the smooth surface, and there was a positive correlation between capsule thickness and propidium-iodide-positive cells at earlier implantation periods. The results suggest that the thickness of the reactive capsule is related to the extent of cell necrosis. It is suggested that the major initiator for this cell necrosis is mechanical shear since cell necrosis was found mainly in areas where mechanical shear could be expected.

Tissue reactions evoked by porous and plane surfaces made out of silicon and titanium

“…This is in accordance with previous studies showing that when both material and surface texture are varied, the surface texture appear to be the predominant factor relative to the induced tissue response [30], [31]. There are several reports indicating that structured and/or porous implant surfaces are favorable as compared with planar ones [29], [34], [40], [44]- [49]. It is conceivable that the different surface structures of the implants elicit different macrophage responses, which in turn may induce different tissue reactions by producing different secretion products such as: chemotactic agents for other cells, growth factors which stimulate the collagen production by the fibroblasts and neutral proteases which may affect the implant surface [50], [51] leading to different foreign-body formation including the thickness of the reactive capsule.…”

“…Both materials will be oxidized naturally in air or in a biological environment. In addition, cell damage including increased membrane permeability was identified using flourescence microscopy after propidium iodide injection [40]. …”

A new model for in vitro testing of vitreous substitute candidates

“…This is in accordance with previous studies that demonstrated pathological changes in the retina in vivo, primarily in parts more likely to have been in direct contact with the gel [37], suggesting at least in part a toxic or immunological response. Recently, clinical use of Bio-Alcamid® in reconstructive surgery has become increasingly controversial due to late complications such as inflammation, infection and excessive capsule formation [45][46][47][48].…”

Biocompatibility of Injectable Microspheres

“…A simple experiment [11] with rods of 1 mm in diameter, but different shapes implanted into rats showed that triangular polymer implants with sharp edges caused significantly higher cellular responses and acid phosphatase enzyme activity than square or round implants. Around implanted polyethylene disks with coarse surface in rats, a significant larger number of PI (propidium iodine stained) -positive cells with increased permeability were found in the tissue adjacent to the edges of the implant, when compared to implants with smooth surface [12]. A microsphere with an absolute smooth surface absorbs proteins and becomes slowly covered with collagen fibers.…”