Aprotinin exerts differential and dose-dependent effects on myocardial contractility, oxidative stress, and cytokine release after ischemia-reperfusion

Aprotinin reduces oxidative stress induced by pneumoperitoneum in rats

BACKGROUND

Ischemia-reperfusion injury induced by pneumoperitoneum is a well-studied entity, which increases oxidative stress during laparoscopic operations. The reported anti-inflammatory action of aprotinin was measured in a pneumoperitoneum model in rats for the first time in this study.

MATERIALS AND METHODS

A total of 60 male Albino Wistar rats were used in our protocol. Prolonged pneumoperitoneum (4 h) was applied, causing splanchnic ischemia and a period of reperfusion with a duration of 60 or 180 min followed. Several cytokines and markers of oxidative stress were measured in liver, small intestine, and lungs to compare the aprotinin group with the control group. Tissue inflammation was also evaluated and compared between groups using a five-scaled histopathologic score.

RESULTS

In aprotinin group values of biochemical markers (tumor necrosis factor α, interleukin 6, endothelin 1, C reactive protein, pro-oxidant-antioxidant balance, and carbonyl proteins) were lower in all tissues studied. Statistical significance was greater in liver and lungs (P < 0.05). Histopathologic examination revealed significant difference between control and aprotinin groups in all tissues examined. Aprotinin groups showed mild to moderate lesions, while in control groups severe to very severe inflammation was present. Aprotinin subgroup with prolonged reperfusion period (180 min) showed milder lesions in all tissues than the rest of the groups.

CONCLUSIONS

Aprotinin reduced inflammatory response and oxidative stress induced by pneumoperitoneum in liver, small intestine, and lungs.

Proangiogenic microtemplated fibrin scaffolds containing aprotinin promote improved wound healing responses

Survival of tissue engineered constructs after implantation depends heavily on induction of a vascular response in host tissue, promoting a quick anastomosis of the cellular graft. Additionally, implanted constructs typically induce fibrous capsule formation, effectively preventing graft integration with host tissue. Previously we described the development of a high density microtemplated fibrin scaffold for cardiac tissue engineering applications with tunable degradation and mechanical properties which promoted seeded cell survival and organization in vitro (Thomson et al., Tissue Eng Part A, 2013). Scaffold degradation in vitro was controllable by addition of the serine protease inhibitor aprotinin and/or the fibrin cross-linker Factor XIII (FXIII). The goal of this study was to assess host tissue responses to these fibrin scaffold formulations by determining effects on scaffold degradation, angiogenic responses, and fibrous capsule formation in a subcutaneous implant model. Aprotinin significantly decreased scaffold degradation over 2 weeks of implantation. A significant increase in capillary infiltration of aprotinin implants was found after 1 and 2 weeks, with a significantly greater amount of capillaries reaching the interior of aprotinin scaffolds. Interestingly, after 2 weeks the aprotinin scaffolds had a significantly thinner, yet apparently more cellular fibrous capsule than unmodified scaffolds. These results indicate aprotinin not only inhibits fibrin scaffold degradation, but also induces significant responses in the host tissue. These included an angiogenic response resulting in increased vascularization of the scaffold material over a relatively short period of time. In addition, aprotinin release from scaffolds may reduce fibrous capsule formation, which could help promote improved integration of cell-seeded scaffolds with host tissue.

A comparative study of the immune modulating properties of antifibrinolytics in cardiac surgery

PURPOSE

Antifibrinolytics, used in cardiac surgery to abate postoperative blood loss, share anti-inflammatory properties by suppression of pro-inflammatory D-dimer and plasmin levels. Additional drug specific immune modulating qualities are often mentioned in the discussion on which antifibrinolytic can best be used. To determine the extent and relevance of these effects, we investigated cytokine and growth factor plasma levels in cardiac surgery patients randomized to receive either tranexamic acid, aprotinin, or placebo. Corticosteroid-treated patients served to put the effects in perspective.

METHODS

Using a biochip immunoassay, plasma of 36 cardiac surgery patients was quantified for 12 cytokines and growth factors, assessed preoperatively and 6, 12, 24, and 48 h after the start of cardiopulmonary bypass. Eight patients were treated with tranexamic acid, nine with aprotinin, and nine received placebo. Ten placebo-treated patients received corticosteroids.

RESULTS

IL-1ß, IL-6, IL-8, IL-10, IFN-γ, TNF-α, VEGF, MCP-1, and EGF plasma concentrations significantly changed over time across all patients. Aprotinin-treated patients showed decreased pro-inflammatory TNF-α and peak MCP-1 plasma levels when compared with placebo. However, corticosteroids attenuated the inflammatory response to a much larger extent, lowering postoperative IL-6, IL-10, IFN-γ, and VEGF concentrations also.

CONCLUSIONS

Aprotinin attenuates postoperative pro-inflammatory levels TNF-α and MCP-1 whereas tranexamic acid does not. The majority of plasma proteins studied, however, were not affected by the use of antifibrinolytics when compared with placebo. A clinically relevant common anti-inflammatory effect through inhibition of fibrinolysis seems therefore unlikely.

Heme oxygenase-1 induced by aprotinin inhibits vascular smooth muscle cell proliferation through cell cycle arrest in hypertensive rats

Spontaneous hypertensive rats (SHR) are an established model of genetic hypertension. Vascular smooth muscle cells (VSMC) from SHR proliferate faster than those of control rats (Wistar-Kyoto rats; WKY). We tested the hypothesis that induction of heme oxygenase (HO)-1 induced by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats. Aprotinin treatment inhibited VSMC proliferation in SHR more than in normotensive rats. These inhibitory effects were associated with cell cycle arrest in the G1 phase. Tin protoporphyrin IX (SnPPIX) reversed the anti-proliferative effect of aprotinin in VSMC from SHR. The level of cyclin D was higher in VSMC of SHR than those of WKY. Aprotinin treatment downregulated the cell cycle regulator, cyclin D, but upregulated the cyclin-dependent kinase inhibitor, p21, in VSMC of SHR. Aprotinin induced HO-1 in VSMC of SHR, but not in those of control rats. Furthermore, aprotinin-induced HO-1 inhibited VSMC proliferation of SHR. Consistently, VSMC proliferation in SHR was significantly inhibited by transfection with the HO-1 gene. These results indicate that induction of HO-1 by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats.