Aprotinin in Ischemia-Reperfusion injury: Flap survival and neutrophil response in a rat skin flap model

Abstract

Multiple drugs have been used in experimental skin flap models to reduce the effects of reperfusion ischemia. The effects of antiproteases, however, have not been studied. A skin flap ischemia reperfusion model was developed in the rat to study the effects that aprotinin, a broad-spectrum antiserine protease, would have on skin flap viability. Thirty-two male rats underwent elevation of a ventral pedicled skin flap based on the superficial inferior epigastric artery. The flaps were subjected to 10 hr of warm ischemia by clamping the neurovascular pedicle followed by reperfusion. Aprotinin or saline (control) was administered systemically via the contralateral femoral vein either before or after the ischemic insult. Full-thickness skin biopsies were obtained at 1, 8, and 24 hr into reperfusion. Biopsies were evaluated for neutrophil concentration (using a myeloperoxidase [MPO] assay) and thromboxane B2 [TxB2] content. Flap survival was calculated at 1 week using standardized photography and computer-assisted digital imaging. Aprotinin given before an ischemic insult significantly improved flap survival compared to saline controls (52.3% alive vs. 29.6%, P = 0.0132, unpaired t-test). Aprotinin given after ischemia did not significantly influence flap survival (28.8% vs. 34.4% in saline controls, P = 0.708). MPO levels in the aprotinin preischemia treatment group were significantly less at 1 and 8 hr into reperfusion, indicating decreased neutrophil numbers. No statistical difference in TxB2 levels was noted in either group at any time after reperfusion. Aprotinin significantly improves skin flap survival when given prior to but not after an ischemic insult. Aprotinin appears to lower the concentration of neutrophils in skin flaps pretreated with the drug. Reperfused skin flap levels of thromboxane B2 are unaffected by the pre- or postischemic administration of aprotinin.

Protective effect of aprotinin on ischemia–reperfusion injury in rat ovary

“…found both edema and increased permeability occurred in vivo after ischemia–reperfusion, due to disruption of endothelial cell junctional integrity 28 . A growing body of literature supports the theory that the neutrophil is the primary cell responsible for reperfusion damage 29 . Hallett et al .…”

“…Aprotinin has a prolonged effect on PMN chemotaxis and inhibits the production of reactive oxygen metabolites. After a period of ischemia, aprotinin has been shown to inhibit reperfusion‐induced oxygen radical production 29 . Lord et al.…”

“…Kallikrein, an enzyme inhibited by aprotinin, is known to promote the release of neutrophil elastase (believed to be a major contributor to proteolysis) and can also prime neutrophils to produce superoxide anions on stimulation. Many proteolytic enzymes released by neutrophils are inhibited by aprotinin and this inhibition may occur within the lysosomal body prior to degranulation 29 . Whether or not aprotinin affects neutrophils directly or indirectly in the setting of ovarian ischemia is not known.…”

Comparison of the effects of systemic sildenafil, tadalafil, and vardenafil treatments on skin flap survival in rats

“…Occurrence of necrosis may be attributed to the metabolic, anatomic, and haemodynamic changes in the flap [1][2][3]. Numerous experimental and clinical studies have been performed to improve flap viability by alternating the pathological changes in flap metabolism occurring after elevation [4][5][6][7][8][9][10][11]. Phosphodiesterase type 5 (PDE5) is an enzyme that is responsible for the degradation of cyclic 3',5'-guanosine monophosphate (cGMP).…”

Ischemia-Reperfusion Injury

“…Aprotinin additionally limits myocardial reperfusion injury by reducing neutrophil infiltration and myocyte apoptosis as well as expression of proinflammatory genes like P-/E-selectin, ICAM-1, TNF-a, IL-6, MCP-1 and Fas (CD95) in a rat model of cardiac ischemia [114,115], it significantly attenuates expression of P-selectin and reduces leukocyte rolling, adherence and transendothelial migration in a rat model of mesenteric ischemia-reperfusion [116] and it enhances hepatic microcirculation and reduces hepatic reperfusion injury in a rat model of warm liver ischemia [117]. Aprotinin was also successfully employed to improve skin flap survival in a rat model of warm skin-flap ischemia [118]. In summary, preclinical data strongly suggest that aprotinin may reduce aspects of ischemiareperfusion injury, but prospective clinical trials are needed to evaluate the impact of aprotinin on patient outcomes [112].…”