Quantitative in vivo studies of hyperemia in the course of the tissue response to biomaterial implantation

Abstract

Hyperemia associated with an inflammatory response has been investigated in rats, by using four different experimental models, i.e., "positive" and "negative" polymer implants from the pharmacopea, operative control, and abscess induced by turpentine oil. 133Xenon clearance, infrared thermography and Laser Doppler Flowmetry (LDF) were used to monitor the subcutaneous local hemodynamic changes from 1 to 40 postoperative days. LDF proved to be a sensitive, reproducible method, able to discriminate positive from negative implants already at the 3rd postoperative day and up to 40 days. This increased local blood flow was also visualized at the site of positive implants at the 14th and 21st postoperative days by means of 133Xe Clearance. Additional information obtained by infrared thermography allowed discrimination between positive implants and control sites but only at the very early stage (1 to 3 days). The significance of the different data collected by the three techniques was correlated with histological events occurring at the different implant sites. LDF may therefore represent a useful technique for noninvasive semiquantitative assessment of tissue response to biomaterials.

Blood Flow in the Foreign-Body Capsules Surrounding Surgically Implanted Subcutaneous Devices

“…In the past, investigators have studied implantable biomaterials and evaluated histological features of the foreign-body response [1, 5, 7, 9–11, 13–16], as well as semi-quantitatively measured blood flow in the FBC with 133 Xenon clearance, infrared thermography, and laser doppler flowometry [16]. However, these studies have been performed in relationship to implants of millimeter dimensions or smaller and not devices of clinically-relevant size.…”

“…In relationship to biomaterials and implants of millimeter dimension or smaller, investigators have quantified histological characteristics of the FBC such as thickness [1,7,9–11], collagen content and density [1,5,7,11] fibrinogen content [12], cell composition [7,11,13–15], size and extent of vessel formation [7, 10], general inflammatory response [11], and have made semi-quantitative measurements of blood flow [16]. However, no study of which we are aware has directly quantified blood flow in the FBC surrounding implanted devices of clinically relevant size.…”