Cilia abundance in regenerating zebrafish cardiac tissue and their potential relation to cell signaling pathways.

Abstract

Heart disease is one of the leading causes of death worldwide. After injury caused by trauma such as a myocardial infarction, human cardiac tissue is unable to heal without scaring. Damage to adult human heart tissue results in replacement of necrotic tissue with stiff scar tissue. In contrast, zebra fish (Danio rerio) have the remarkable ability to regenerate injured heart tissue within the period of a month through complex signaling and response mechanisms involving the dedifferentiation and proliferation of heart cells. It has been observed that regenerating cardiac tissue reacts similarly to that of embryonic tissue where primary cilia are prevalent as control mechanisms for the Hedgehog and Wnt signaling pathways that assist in tissue differentiation, cell organization and mass migration. Recent findings demonstrate that cilia are present on developing heart cells during carcinogenesis. We hypothesize that cilia form in response to injury and that they may play a sensory role, as either mechanical or chemical sensors that resemble cellular antennae, to assist injured tissue through the process of regeneration. This hypothesis was tested through immunofluorescent staining and confocal microscopy to highlight cilia in regenerating tissue. A staining combination of Hoechst, Gamma tubulin and acetylated tubulin antibody were used to define the structure of cilia on 15um sections of cardiac tissue. These stains reinforced our current data to create a time line of cilia proliferation in heart regeneration to provide information of the spatial and temporal location of cilia in regenerating zebrafish cardiac tissue.