Notch pathway participates in regulation of c-kit+ retinal precursor cell division and differentiation in adult mice for repair of NMDA-induced retinal injury

Abstract

Objective To analyze the characteristics of c-kit+ endogenous retinal precursor cells (RPCs) in the retina of adult mice and their roles in the repair of N-methyl-D-aspartic acid (NMDA)-induced retinal damage. Methods Mouse models of NMDA-induced retinal injury were established in 4-week-old adult C57BL/6J mice. Immunofluorescence assay was used to analyze the relationship between c-kit+ RPCs and c-kit stem cell factor (SCF)-positive cells and determine the number of c-kit+ RPCs and their division activity at 1, 2 and 4 weeks after NMDA injury. The mRNA expression levels of Hes1, Hes5, S100b and Pou4f1 in the injured retinal tissues were analyzed using real-time PCR. Results SCF+ Müller cells surrounding the c-kit+ RPCs were observed in the inner nuclear layer (INL) of the retina of adult mice. C-kit+ RPCs still maintained a low level of cell division activity. Two weeks after NMDA-induced retinal injury, the number of c-kit+ RPCs significantly increased in the retina (P < 0.001) with markedly increased proportions of dividing cells (P=0.016) and c-kit+GAD65/67+cells/c-kit+ cells (P < 0.001). Two weeks after retinal injury, the Notch pathway components Hes1 and Hes5 were up-regulated (P < 0.001) and the expression levels of S100b and Pou4f1 were augmented significantly in the retina (P < 0.001). Conclusion Two weeks after NMDA-induced retinal injury, c-kit+ RPCs in the retina undergo both symmetrical and asymmetrical cell division and then differentiate into GAD65/67+ neurons possibly under regulation by the Notch pathway.

Keywords

• retina
• c-kit+ retinal progenitor cells
• n-methyl-d-aspartic acid
• cell division
• notch pathway