A new vascularized skin transplant model in rats

Assessment of Skin Flaps Using Optically Based Methods for Measuring Blood Flow and Oxygenation

The objective of this study was to compare two noninvasive techniques, laser Doppler and optical spectroscopy, for monitoring hemodynamic changes in skin flaps. Animal models for assessing these changes in microvascular free flaps and pedicle flaps were investigated. A 2 x 3-cm free flap model based on the epigastric vein-artery pair and a reversed MacFarlane 3 x 10-cm pedicle flap model were used in this study. Animals were divided into four groups, with groups 1 (n = 6) and 2 (n = 4) undergoing epigastric free flap surgery and groups 3 (n = 3) and 4 (n = 10) undergoing pedicle flap surgery. Groups 1 and 4 served as controls for each of the flap models. Groups 2 and 3 served as ischemia-reperfusion models. Optical spectroscopy provides a measure of hemoglobin oxygen saturation and blood volume, and the laser Doppler method measures blood flow. Optical spectroscopy proved to be consistently more reliable in detecting problems with arterial in flow compared with laser Doppler assessments. When spectroscopy was used in an imaging configuration, oxygen saturation images of the entire flap were generated, thus creating a visual picture of global flap health. In both single-point and imaging modes the technique was sensitive to vessel manipulation, with the immediate post operative images providing an accurate prediction of eventual outcome. This series of skin flap studies suggests a potential role for optical spectroscopy and spectroscopic imaging in the clinical assessment of skin flaps.

Outcome of different models of multiorgan transplantation in rats

In the PVG (RT1(c)) to DA(RT1(a)) rat combination, liver allografts are spontaneously accepted across a complete MHC barrier while cardiac and renal allografts are rejected. We postulated that this spontaneous liver acceptance was associated with the large quantity of antigen in the transplanted liver. In order to test this hypothesis, we have developed three different models of multiorgan transplantation: model I, triple heart transplantation; model II, triple kidney transplantation; and model III, double heart and double kidney transplantation. The results showed that prolongation of heart and kidney allografts was achieved with the increasing number of organs transplanted. The models proved reliable and useful in transplant immunological studies.