Advances in hemocytes regeneration of aquatic invertebrates: Mechanisms and implications

Hematopoiesis is the process responsible for the generation of blood cells in both the circulation and tissues. It plays a crucial role in maintaining homeostasis and defending against infections in animals. Although hematopoiesis is a common feature among animals with a circulatory system, the specific mechanisms involved in hematopoietic events vary significantly among invertebrates. Our understanding of this process in invertebrates is largely based on studies conducted on species used as developmental models, with limited research having been conducted on aquatic invertebrates. In this review, we summarize current knowledge regarding the hematopoietic lineage in aquatic invertebrates, particularly within the groups of Crustacea, Mollusca, and Echinodermata, which hold potential economic and medical significance. Hemocytes are primarily produced in hematopoietic tissues and subsequently released into the circulation, where they undergo final maturation. We discuss the application of various markers used for hemocyte classification, with a particular emphasis on the molecular mechanisms underlying hematopoiesis, including transcriptional regulation and humoral factors such as cytokines, growth factors, and signaling pathways. These insights contribute to a more comprehensive understanding of hematopoiesis in aquatic invertebrates.