Blood and lymphatic vascular remodeling in intervertebral disc degeneration.

A defining histological feature of the intervertebral disc (IVD) in healthy adults is its avascular and alymphatic status, which is closely related to its mode of nutrient supply and local immune homeostasis. Following the onset of intervertebral disc degeneration (IDD), blood vessels invade the interior of the degenerated IVD under the combined effects of anatomical barrier disruption, inflammatory responses, and aberrant activation of growth factor regulatory networks, thereby accelerating the degenerative process and being closely associated with discogenic pain. However, as another major component of the vascular system, there is still no consensus regarding the presence of lymphatic vessels in the adult IVD, their spatial distribution, and whether they serve functional drainage and immunoregulatory roles. In addition, differences among studies in species background, tissue sampling range, degeneration stage, and detection strategies have further increased the complexity of mechanistic interpretation. Against this background, this review first outlines the vascular anatomical and physiological basis of the normal IVD, summarizes vascular-related pathological changes and key regulatory networks during IDD, and synthesizes the principal findings, major controversies, and methodological limitations of lymphatic research. On this basis, it further discusses the potential links between remodeling of the vascular system, including both blood vessels and lymphatic vessels, and pain generation as well as degenerative outcomes, and outlines potential intervention strategies targeting vasculature-related pathways, with the aim of informing subsequent mechanistic studies and translational therapeutic development.