Effect of antifibrinolytic therapy on subarachnoid fibrosis in dogs after experimental subarachnoid haemorrhage

LSKL peptide alleviates subarachnoid fibrosis and hydrocephalus by inhibiting TSP1-mediated TGF-β1 signaling activity following subarachnoid hemorrhage in rats

Hydrocephalus has been demonstrated to be an independent risk factor for poor outcomes in patients with subarachnoid hemorrhage (SAH). Blockage of cerebrospinal fluid (CSF) flow and drainage is widely considered to play a vital role in communicating hydrocephalus, possibly due to subarachnoid fibrosis. A previous study indicated that transforming growth factor-β1 (TGF-β1), a key fibrogenic factor, is significantly increased in the CSF following SAH, implying a pivotal role in the development of chronic hydrocephalus. To investigate whether LSKL peptide, a small molecular peptide and competitive antagonist for TGF-β1, protects against subarachnoid fibrosis and hydrocephalus after SAH, a two-hemorrhage injection model of SAH was created in Sprague-Dawley rats. LSKL (1 mg/kg) was administered intraperitoneally immediately following the first intravenous injection of blood in the SAH model, with repeated injections of LSKL every 12 h until sacrifice. Thrombospondin-1 (TSP1), TGF-β1, p-Smad2/3, collagen I and pro-collagen I c-terminal propeptide levels were assessed via western blotting and ELISA. Lateral ventricular index, Masson staining and Morris water maze tests were employed to evaluate subarachnoid fibrosis, hydrocephalus and long-term neurological function following SAH. It was found that the LKSL peptide readily crossed the blood brain barrier, was protective against subarachnoid fibrosis, attenuated ventriculomegaly and effectively suppressed hydrocephalus. In addition, the results indicated that the protective effects of the LSKL peptide were achieved via the inhibition of TGF-β1 activity and subsequent Smad2/3 signaling. Importantly, the LSKL peptide may improve long-term neurocognitive deficits after SAH. In conclusion, the LSKL peptide suppresses subarachnoid fibrosis via inhibition of TSP1-mediated TGF-β1 activity, prevents the development of chronic hydrocephalus and improves long-term neurocognitive defects following SAH.

Rebleeding, ischaemia and hydrocephalus following anti-fibrinolytic treatment for ruptured cerebral aneurysms: a retrospective clinical study

350 patients with subarachnoid haemorrhage from aneurysmal rupture--admitted in the years 1966-1983--were selected for a retrospective controlled study on the efficacy of antifibrinolytic therapy (AFT). Patients treated with antifibrinolytics were divided into two groups, according to the day of hospital admission and onset of therapy, respectively between 0 and 3 days (SG 1) and between 4 and 7 days from SAH (SG 2); treated patients (260 cases) received i.v. tranexamic acid (6 gr/day) for at least two weeks. Patients admitted before 1974, not receiving antifibrinolytics (90 cases), were selected as controls and divided into two groups (CG 1 and CG 2), according to the day of admission. In the first study group (admission 0-3 days) the rebleeding rate within 2 weeks was 9% versus 23% in controls (p less than 0.01). The incidence of rebleeding within 3 and 4 weeks was also significantly lower (p less than 0.05) than in controls. No significant difference was observed in the rebleeding rate in treated and untreated patients with late admission (4-7 days). Mortality from rebleeding was 16% in the first study group versus 17% in controls; in the second study group the figure was 6% versus 8% in controls. Seventy-five cases of ischaemic disorders (29%) were registered in treated patients versus 13 cases in controls (14%; p less than 0.01). Thirty-seven patients receiving AFT (14%) developed significant ventricular dilatation requiring shunt insertion, versus one patient in the control groups (1%; p less than 0.001). Final outcome was similar in the 4 groups. In conclusion--according to our data--AFT modifies the behaviour of rebleeding and the patients' course, although it does not modify the outcome after SAH. Clinical use of antifibrinolytic therapy appears still justified in those patients who cannot be operated on in the acute stage after SAH, provided that an associated anti-ischaemic therapy is undertaken.

Antifibrinolytic agents in subarachnoid haemorrhage

For many years clinicians have used antifibrinolytic agents to try to reduce rebleeding after subarachnoid haemorrhage. Early studies of their effectiveness produced conflicting results. This paper re-evaluates the available trials and considers benefits in the light of potential complications. Present evidence conclusively demonstrates that epsilon-aminocaproic acid and tranexamic acid administered in standard dosage, reduce the risk of rebleeding but, as a result of an increased incidence of ischaemic complications, do not benefit patients' outcome.