Since ischemia-reperfusion injury continues to be a major problem in reconstructive microsurgery, improvement of experimental models is still desirable. We developed a model that allows direct visualization of flap microcirculation in mice by intravital microscopic techniques. A newly designed skinfold chamber was installed on the dorsum of mice, and microcirculation was inspected with an intravital microscope. An island flap, nourished by the deep circumflex iliac arteries, was elevated after implantation of the chamber, allowing visualization of the microcirculation in the island flap. The island flap was exposed to global ischemia by clamping the pedicles, and the clamps were then released to allow reperfusion. Various microcirculatory responses induced by ischemia-reperfusion were visualized. This model accurately simulated the clinical situation in reconstructive surgery and successfully realized chronic visualization of the flap microcirculation in vivo.

Mice are popular animals for biomedical studies, but few skin flap models have been reported in them. To investigate the ischaemia/reperfusion phenomenon in skin flaps, we first investigated the vascular anatomy of murine dorsal skin and then designed a suitable murine dorsal skin flap model. In 120 mice, six distinct vascular patterns were identified, one being seen in 111 mice (93%). Based on this finding, in Part 2 of the study, 15 mice had flaps (4 x 4 cm) raised based on the two caudal vascular pedicles of the left and right deep circumflex iliac vessels as a bipedicled flap in which the mean (SD) survival was 96 (5)%. In a further 10 mice, flaps were raised based on a single pedicle, the left deep circumflex iliac vessel, as a monopedicled flap, in which the mean (SD) survival was 71 (12)%. The bipedicled flap model was then used to study ischaemia/reperfusion injury. Twenty flaps were subjected to eight hours of ischaemia and subsequent reperfusion, and their mean (SD) survival was 43 (26)%. Histological assessments were also carried out using neutrophil and leucocyte counts, and significant differences between groups were observed.

To investigate whether hyperthermic preconditioning can actually protect skin flaps against ischemia/reperfusion injury, the authors first developed a new skin-flap model in 15 mice, a dorsal bipedicle island skin-flap model. Then, another 75 mice were separated into five groups. Mice in Groups 1 to 4 received the same hyperthermic preconditioning, but had different recovery times of 6 hr, 24 hr, 48 hr, and 72 hr, respectively. Mice in Group 5 served as control. Island skin flaps were elevated in all groups, and then were subjected to 8 hr of ischemia and subsequent reperfusion. Flap survival was statistically significantly higher than in controls in animals in Groups 1 and 3, with recovery times of 6 hr and 48 hr, respectively. Mice in Groups 2 and 4 had recovery times of 24 hr and 72 hr, respectively. Hyperthermic preconditioning could thus protect skin flaps against ischemia/reperfusion injury, and there were two optimal periods for such a protective effect.

For the purpose of reconstructive surgery training and research, we have developed a new skin flap model: canine lateral thoracic fasciocutaneous flap. Anatomical study found that the lateral thoracic arteries in dogs have similar anatomical characteristics to human's ones. Based on these vessels, if a skin flap was designed within the vessels territory (size 5 x 8 cm) it could survive completely, whereas, if designed beyond the vessels territory (size 5 x 14 cm) would result in partial necrosis of the flap. This fasciocutaneous flap model closely simulates the human surgery and could be valuable for training and research. Furthermore, this flap could be applied in the veterinary practice for reconstruction of canine forelimbs and cervical area.

Intense pulsed light (IPL) has been used extensively in aesthetic and cosmetic dermatology. To test whether IPL could change the tissue vascularity and improve wound healing, mice were separated into 4 groups. Mice in Group I were not treated with IPL, whereas, dorsal skins of mice in Groups II, III, and IV were treated with 35 J/cm2, 25 J/cm2, and 15 J/cm2 IPL, respectively. After 2 weeks, dorsal island skin flaps were raised, based on the left deep circumflex iliac vessels as pedicles; then, survival rate was assessed. Flaps in Group IV (treated with lowest dose of IPL) have a survival rate significantly higher than other groups. Counting blood vessels did not demonstrate any significant differences; however, vessel dilation was found in this group. The results show that IPL at the therapeutic doses which are usually applied to humans is harmful to mouse dorsal skin and did not enhance wound healing, whereas, IPL at much lower dose could improve wound healing. The possible mechanism is the dilation of tissue vasculature thanks to the electromagnetic character of IPL. Another mechanism could be the heat-shock protein production.