Induced neural stem cell grafts exert neuroprotection through an interaction between Crry and Akt in a mouse model of closed head injury

Mou Gao,Lihua Chen,Jianning Zhang,Yingzhou Lu,Ruxiang Xu,Qin Dong,Boyun Ding,Zhijun Yang,Lili Guo,Wenjia Wang

doi:10.1186/s13287-021-02186-z

Abstract

BackgroundRecently, growing evidence has indicated an important role of the complement system, a crucial component of immunity, in mediating neuroinflammation and promoting neuronal apoptosis following closed head injury (CHI). We previously reported that transplanted induced neural stem cells (iNSCs) pre-treated with CHI mouse serum could enhance complement receptor type 1-related protein y (Crry) expression and ameliorate complement-mediated damage in mouse CHI models. However, the mechanism underlying the elevated levels of Crry expression remains elusive.MethodsCHI models were established using a standardized weight-drop device. We collected CHI mouse serum at 12 h post-trauma. RT-QPCR assay, western blot analysis, complement deposition assay, Akt inhibition assay, flow cytometry, cell transplantation, and functional assay were utilized to clarify the mechanism of Crry expression in iNSCs receiving CHI mouse serum treatment.ResultsWe observed dramatic increases in the levels of Crry expression and Akt activation in iNSCs receiving CHI mouse serum treatment. Remarkably, Akt inhibition led to the reduction of Crry expression in iNSCs. Intriguingly, the treatment of iNSC-derived neurons with recombinant complement receptor 2-conjugated Crry (CR2-Crry), which inhibits all complement pathways, substantially enhanced Crry expression and Akt activation in neurons after CHI mouse serum treatment. In subsequent in vitro experiments of pre-treatment of iNSCs with CR2-Crry, we observed significant increases in the levels of Crry expression and Akt activation in iNSCs and iNSC-derived astrocytes and neurons post-treatment with CHI mouse serum. Additionally, an in vivo study showed that intracerebral-transplanted iNSCs pre-treated with CR2-Crry markedly enhanced Crry expression in neurons and protected neurons from complement-dependent damage in the brains of CHI mice.ConclusionINSCs receiving CR2-Crry pre-treatment increased the levels of Crry expression in iNSCs and iNSC-derived astrocytes and neurons and attenuated complement-mediated injury following CHI.

Highlights

Closed head injury (CHI) is regarded as a major cause of neurological disorders and impairs quality of life and creates an enormous financial burden throughout the world [1]
Akt inhibition led to the reduction of complement receptor type 1-related protein y (Crry) expression in induced neural stem cells (iNSCs)
In subsequent in vitro experiments of pre-treatment of iNSCs with Complement receptor 2 (CR2)-Crry, we observed significant increases in the levels of Crry expression and Akt activation in iNSCs and iNSC-derived astrocytes and neurons post-treatment with closed head injury (CHI) mouse serum

Summary

Introduction

Closed head injury (CHI) is regarded as a major cause of neurological disorders and impairs quality of life and creates an enormous financial burden throughout the world [1]. Previous studies have shown that the modulation of complement activation post-CHI by various complement regulators such as CD59, factor H, and complement receptor type 1-related protein y (Crry), which block different complement pathways, prevents ongoing neuroinflammation and neuronal damage [6,7,8,9]. The recombinant complement receptor 2-conjugated factor H (CR2-fH) protein, which inhibits the alternative complement pathway, can suppress neuroinflammation and improve neurological function in the treatment of CHI [8, 9]. Growing evidence has indicated an important role of the complement system, a crucial component of immunity, in mediating neuroinflammation and promoting neuronal apoptosis following closed head injury (CHI). We previously reported that transplanted induced neural stem cells (iNSCs) pre-treated with CHI mouse serum could enhance complement receptor type 1-related protein y (Crry) expression and ameliorate complement-mediated damage in mouse CHI models. The mechanism underlying the elevated levels of Crry expression remains elusive

Methods

Results

Conclusion