Identification of neural stem-like cells in adult rodent intrinsic cardiac nervous ganglia

Abstract

Introduction

At the cardiac level, the intrinsic cardiac nervous system (ICNS) functions as a local integration center for autonomic afferent signals. As such, it plays a critical role in the regulation of cardiac function, and its pathophysiological remodeling is subject to growing research interest. Recent evidence suggests that progenitor cells lead to neurogenesis in the adult peripheral nervous system. This interrogates the potential presence and role of such progenitor cells within the ICNS and their involvement in pathological remodeling.

Objective

Given that ICNS can be influenced by cardiac pathologies and clinical interventions such as atrial fibrillation ablation, we investigated the presence of progenitor cells in the adult ICNS and their capacity to exhibit key stem cell properties in vitro.

Method

Cardiac ganglia from adult mice were dissociated and cultured in neural stem cell medium. Progenitor cells were identified through the expression of stem cell markers SOX2 and nestin. Self-renewal and proliferative capacities were assessed by replating experiments and by the expression of the Ki-67 marker. In vitro differentiation was evaluated through BrdU incorporation and beta III tubulin expression in differentiation medium. Besides, the impact of a monocrotaline-induced rat model of right heart disease on progenitor cell proliferation was assessed in situ via immunohistochemistry.

Results

Our study demonstrated the presence of the stem cell marker SOX2 in the cardiac ganglia of adult mice. In vitro, these cells form primary spheres that express the proliferation marker Ki-67, along with the progenitor markers SOX2 and Nestin. These spheres can be replated to obtain secondary sphere expressing the same markers indicating the self-renewing properties of SOX2 positive cells. Besides, these cells undergo differentiation in culture toward a neuronal fate, as demonstrated by the expression of tubulin beta 3, the neuron specific protease PGP9.5 and PSA-NCAM. Finally, numerous proliferative cells expressing Ki-67 can be observed in ganglia of the monocrotaline rat model compared to control, including SOX2 positive cells.

Conclusion

Our study unveils for the first time the existence of neurogenesis in adult rodent ICNS through the identification of SOX2 positive cells that display properties of neuronal progenitor in vitro.