The known, unknown, and unknown unknowns of cell-cell communication in planarian regeneration
Jiajia Chen, 浙江大学生命科学学院, 浙江 杭州 310058, 中国, Kai Lei, 西湖大学生命科学学院浙江省生长调控及转化研究重点实验室和生命科学与生物医学西湖实验室, 浙江 杭州 310030, 中国, 浙江西湖高等研究院, 浙江 杭州 310024, 中国
Abstract
Planarians represent the most primitive bilateral triploblastic animals. Most planarian species exhibit mechanisms for whole-body regeneration, exemplified by the regeneration of their cephalic ganglion after complete excision. Given their robust whole-body regeneration capacity, planarians have been model organisms in regenerative research for more than 240 years. Advancements in research tools and techniques have progressively elucidated the mechanisms underlying planarian regeneration. Accurate cell-cell communication is recognized as a fundamental requirement for regeneration. In recent decades, mechanisms associated with such communication have been revealed at the cellular level. Notably, stem cells (neoblasts) have been identified as the source of all new cells during planarian homeostasis and regeneration. The interplay between neoblasts and somatic cells affects the identities and proportions of various tissues during homeostasis and regeneration. Here, this review outlines key discoveries regarding communication between stem cell compartments and other cell types in planarians, as well as the impact of communication on planarian regeneration. Additionally, this review discusses the challenges and potential directions of future planarian research, emphasizing the sustained impact of this field on our understanding of animal regeneration.