Zebrafish Models of Induced Lymphangiogenesis: Current Advancements and Therapeutic Discovery

Abstract

Lymphangiogenesis, the formation of new lymphatic vessels, is essential for embryonic development and the maintenance of tissue fluid balance, as well as for responding to physiological challenges such as injury, inflammation, and oedema. This process is also aberrantly activated in pathological conditions including lymphatic anomalies and cancer. Understanding the molecular and cellular mechanisms regulating induced lymphangiogenesis in various conditions is critical for the development of novel anti- or pro-lymphangiogenic therapeutic strategies. In recent years, the zebrafish has emerged as an important model organism for studying both physiological and pathological lymphangiogenesis. Its optical transparency, conserved lymphatic architecture and signalling pathways, and amenability to genetic manipulation and drug screening make it an especially well-suited model. In this review, we highlight zebrafish models used to investigate induced lymphangiogenesis in the context of regeneration, inflammation, fluid imbalance, and congenital lymphatic anomalies. We will also demonstrate how zebrafish are used to discover new drugs targeting lymphatic vessels under various conditions. Finally, we will discuss the current limitations of using zebrafish to model induced lymphangiogenesis and highlight potential future directions. The findings presented in this review underscore the undeniable value the zebrafish model brings to lymphatic research and therapeutic discovery.

Keywords: drug discovery; lymphatic; lymphatic disease; regeneration; zebrafish.

Figure 1

(A) Confocal lateral image of a 7 days post-fertilisation (dpf) Tg(-5.2lyve1b:DsRed2)^nz101;Tg(kdrl:EGFP)^s843 zebrafish larvae, showing blood vessels in green and lymphatic vessels and veins in magenta. Regions where induced lymphangiogenesis can be observed in reviewed models are outlined. The asterisk (*) labels the position of inset showing magnified and labelled trunk lymphatic vessels, including the thoracic duct (TD), intersegmental lymphatic vessels (ISLV), lateral lymphatics (LL), and the dorsal longitudinal lymphatic vessel (DLLV). Note that for some models that use adult zebrafish, the outlines point to relative positions in the larvae. (B–G) Schematic representation showing developmental stages of trunk lymphatic vessels. At approximately 32 h post-fertilisation (hpf), a subset of venous endothelial cells in the posterior cardinal vein (PCV) begin to express Prox1a (B). These Prox1a-positive endothelial cells sprout from the PCV at approximately 36 hpf (C) and give rise to parachordal LECs (PLs) at the horizontal myoseptum by 2 dpf (D). Venous sprouting also happens at the same time (C), and these venous sprouts anastomose with intersegmental vessels (ISVs, (D)) to form venous ISVs (vISVs, (E,F)). PLs continue to proliferate and migrate along arteries such as the arterial ISVs (aISVs), dorsal aorta (DA), and the dorsal longitudinal anastomotic vessel (DLAV) (E) to eventually form the trunk lymphatic vessels (such as the TD, ISLV, and DLLV, (F)) by 5 dpf. By approximately 10 dpf, spinal lymphatics (SL), collateral cardinal lymphatics (CCL, also known as supraintestinal lymphatics (SIL)), and superficial lymphatic vessels (SLV) start to form (G). Scale bar indicates 100 μm.