Vol. 282, Issue 6, E1316-E1323, June 2002
Analyte flux through chronically implanted subcutaneous
polyamide membranes differs in humans and rats
N.
Wisniewski1,
N.
Rajamand2,
U.
Adamsson3,
P. E.
Lins3,
W. M.
Reichert1,
B.
Klitzman1,4, and
U.
Ungerstedt2
Departments of 1 Biomedical Engineering and
4 Plastic Surgery, Duke University Medical Center, Duke
University, Durham, North Carolina 27710; 2 Department
of Physiology and Pharmacology, Karolinska Institute, Stockholm
S-17177; and 3 Department of Medicine, Karolinska
Institute, Danderyd Hospital, Stockholm S-18288, Sweden
The rat is commonly used to
evaluate physiological responses of subcutaneous tissue to implanted
devices. In vivo longevity of various devices and the biocompatibility
of biomaterials depend on how adjacent tissue interacts. How closely
the rat model predicts the human response has not been well
characterized. The objective of this study was to compare rat and human
subcutaneous foreign body responses by monitoring the biochemical
environment at a polymer-tissue interface over 8 days using
microdialysis. Polyamide microdialysis probes were implanted
subcutaneously in humans and rats (n = 12). Daily
microdialysis samples were analyzed for glucose, lactate, pyruvate,
glycerol, and urea. Blood glucose was also monitored. Analyte
concentrations differed significantly between rats and humans at the
implant-tissue interface. There were also qualitative differences in
the 8-day trends. For example, over 8 days, microdialysate glucose
increased two- to fourfold in humans but decreased in rats
(P < 0.001). This study reveals profound physiological
differences at material-tissue interfaces in rats and humans and
highlights the need for caution when extrapolating subcutaneous rat
biocompatibility data to humans.
wound healing and foreign body responses; microdialysis; diffusion; glucose monitoring; biosensor biocompatibility
