Introduction to the special section: Spinal Cord a model to understand CNS development and regeneration

Abstract

The spinal cord contains the nerves that allow us to sense our environment and respond to it by moving muscles. This region of the CNS is generated over an extended period in a head to tail sequence, therefore it has been an ideal model for studying the temporal sequence of events that control organ growth. Decades of research using a multitude of vertebrate animal models has provided a detailed and in depth understanding of many aspects of the molecular, cellular and morphogenetic aspects underlying CNS induction, development, function and repair. This special section of Developmental Biology will highlight and contextualise the most recent advances in many of these key areas of research. The prevailing view of vertebrate CNS formation proposes two different embryonic origins for making anterior and posterior central nervous system progenitors; while the anterior neural plate is generated by initial neural induction, the posterior neural plate arises from progenitor cells with a neuromesodermal (NMps) potential. These cells arise within the caudal lateral epiblast adjacent to the primitive streak and the node, via a mechanism that is separable from that which establishes neural fate in the anterior epiblast. NMps are molecularly defined as cells that co-express Sox2 and T/Bra and thus harbour the dual possibility of becoming neural or mesodermal. The study of NMps is important not only because of their central role in elongating the embryonic body axis, but also because of the potential to recapitulate this cell type in vitro and thereby generate spinal cord neurons in culture. Because NMps can be derived in vitro from human pluripotent cells, research in this area is providing important new insight into embryo development and holds the promise of contributing to our understanding of the fundamental biology of human spinal cord development. The contribution of Steventon and Martinez Arias, reviews lineage studies across four key vertebrate models: mouse, chicken, Xenopus and zebrafish and relates them to the underlying gene regulatory networks that are known to be required for NMps specification and caudal spinal cord formation. Steventon and Martinez Arias propose that by applying a dynamical systems approach to understanding how distinct neural and mesodermal fates arise from NMps, it is possible to understand how differences in the dynamical cell behaviours such as proliferation rates and cell movements can map onto conserved regulatory networks to generate diversity in the timing of tissue generation and cell fate determination during spinal cord development.