Peptide5 Attenuates rtPA Related Brain Microvascular Endothelial Cells Reperfusion Injury via the Wnt/β-Catenin Signalling Pathway
Authors: Ren Weimin , Huang Chuyi , Chu Heling , Tang Yuping , Yang Xiaobo 
Published: August 2021

Aims:
Brain vascular endothelial cell dysfunction after rtPA treatment is a significant
factor associated with poor prognosis, suggesting that alleviation of rtPA-related endothelial cell injury
may represent a potential beneficial strategy along with rtPA thrombolysis.

Background:
Thrombolysis with recombinant tissue plasminogen activator (rtPA) is beneficial for
acute ischemic stroke but may increase the risk of Hemorrhagic Transformation (HT), which is considered
ischemia-reperfusion injury. The underlying reason may contribute to brain endothelial injury
and dysfunction related to rtPA against ischemic stroke. As previous studies have demonstrated
that transiently blocked Cx43 using peptide5 (Cx43 mimetic peptide) during retinal ischemia reduced
vascular leakage, it is necessary to know whether this might help decrease side effect of
rtPA within the therapeutic time window.

Objective:
In this study, we established a cell hypoxia/reoxygenation H/R model in cultured primary
Rat Brain Microvascular Endothelial Cells (RBMECs) and evaluated endothelial cell death
and permeability after rtPA treatment with or without transient peptide5. In addition, we also investigated
the potential signaling pathway to explore the underlying mechanisms preliminarily.
Results: The results showed that peptide5 inhibited rtPA-related endothelial cell death and permeability.
It also slightly increased tight junction (ZO-1, occluding, claudin-5) and β-catenin mRNA expression,
demonstrating that peptide5 might attenuate endothelial cell injury by regulating the Wnt/
β-catenin pathway. The following bioinformatic exploration from the GEO dataset GSE37239
was also consistent with our findings.

Methods:
In this study, we established a cell hypoxia/reoxygenation H/R model in cultured primary
Rat Brain Microvascular Endothelial Cells (RBMECs) and evaluated endothelial cell death
and permeability after rtPA treatment with or without transient peptide5. In addition, we also investigated
the potential signaling pathway to explore the underlying mechanisms preliminarily.

Results:
The results showed that peptide5 inhibited rtPA-related endothelial cell death and permeability.
It also slightly increased tight junction (ZO-1, occluding, claudin-5) and β-catenin mRNA expression,
demonstrating that peptide5 might attenuate endothelial cell injury by regulating the Wnt/
β-catenin pathway. The following bioinformatic exploration from the GEO dataset GSE37239
was also consistent with our findings.

Conclusion:
This study showed that the application of peptide5 maintained cell viability and
permeability associated with rtPA treatment, revealing a possible pathway that could be exploited
to limit rtPA-related endothelial cell injury during ischemic stroke. Furthermore, the altered Wnt/β-
catenin signaling pathway demonstrated that signaling pathways associated with Cx43 might have
potential applications in the future. This study may provide a new way to attenuate HT and assist
the application of rtPA in ischemic stroke.