Platelet RNA as Biomarker for Delayed Cerebral Ischemia in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a relatively rare subtype of hemorrhagic
stroke with a devastating outcome. The mortaity of 32-39% and a permanent
disability rate of 50% among the survivors is mostly due to delayed cerebral
ischemia (DCI), a common complication of the disease. DCI has a complex
multifactorial pathophysiology, existing of cerebral vasospasm and several key
pathophysiological pathways, such as cortical spreading depolarisation,
endothelial dysfunction, microthrombosis, neuroinflammation and oxidative
stress. As a result of this not fully understood complex pathofysiology no
sufficiently effective diagnostic test nor treatment strategy has been
developed yet.

Besides the abovementioned components of the multifactorial pathofysiology of
DCI the pathogenesis also includes cell damage, inflammation, altered
metabolism and vascular tone and microparticles. Blood platelets are key
mediators in the generation of microthrombi, a hallmark of DCI pathogenesis,
and are regarded as the immediate responders to local nd systemic inflammation
in the human body, including in neuro-inflammatory diseases such as multiple
sclerosis. Previous studies have shown that blood platelets are possibly
associated with the development of DCI in SAH patients.

At the Neuro-Oncology Research Group (NRG) of Cancer Center Amsterdam, blood
platelets have been identified as a rich and stable biosource of (m)RNA,
providing pan-cancer diagnostics in blood. SMARTer mRNA amplification and
sequencing and SVM analysis of 100-500 pg of platelet RNA (equivalent to 1 drop
of blood) resulted in the development of a pan-cancer diagnostic test that
reached a 96% accuracy for detecting cancer in blood. Additionaly, the platelet
RNA profiles contained repertoires associated to the primary tumor type. This
research has been extended to encompass other forms of cancer, Alzheimer's
disease, epilepsy and multiple sclerosis.

Subsequently, the question appeared whether this fast growing diagnostic and
prognostic tool could contribute to improving DCI-identification and management
in SAH patients. The development of a DCI-specifik blood platelet RNA-profile
will lead to improved diagnostics and management of these patients and thereby
improve functional outcome.

The primary objective of this study is to evaluate whether SAH patients at risk
of developing DCI show a distinguished platelet RNA profile compared to
patients without DCI. Secundary objective; to evaluate whether platelet RNA
analyses can predict clinical outcome in patients who develop DCI after SAH.
Other objectives are: investigating the effect of tranexamic acid on platelet
RNA profiles, to study whether SAH patients with DCI development show chronic
changes in platelet RNA-profiles six months after SAH, to evaluate whether
specific subtypes of SAH (aneurysmal/perimesencephalic/angio-negative) show a
distinguished platelet RNA-profile, to evaluate whether other common
complications of SAH (hydrocephalus, meningitis, delirium, rebleed and
seizures) show a significantly different platelet RNA-profile and to provide
biological observational insight into the role of platelets in the
pathophysiology of DCI. Additionally, we will investigate by visco elastic
testing ROTEM analyses whether alterations in coagulation are associated with
DCI-development.

a monocenter, prospective observational study

In order to obtain a DCI-specific platelet RNA-profile of SAH-patients multiple
blood sample collections are required. Blood samples will be collected at day
0, 4 and 10 post-SAH. The first blood collection will take place during routine
blood collection at the Emergency Department of the AMC. The second blood
collection, at day 4, will be part of routine blood collection at the Intensive
Care or the Neurosurgery Department. Hence, for these blood samples no
additional procedures are required. Blood collection at day 10 will only take
place when the patient is still admitted at the AMC. If the patient has already
been discharged prior to the blood collection timepoint, blood samples will not
be obtained. No extra visitations are required.

Blood collection on day 0 and day 4 post-SAH exists of: 2x2,7mL citrate tubes +
1x6mL EDTA tube
Blood collection on day 10 after the SAH exists of: 1x6mL EDTA tube