Fig. 1.

Schematic illustration of the vascularized tissues in hydrogels for tissue regeneration, organ-on-chips, and drug screening. Angiogenesis and vasculogenesis mechanisms of vascular formation are introduced both in the embryo stage and postnatal life, respectively. The enrichment of the effective vascular networks enables the delivery of nutrients and waste products for the recovery of organs upon severe damage. In addition, the emerging organ-on-chips approach provides excellent opportunities for incorporating vasculatures within chips for the stimulation of physiological 3D organoids. These target 3D organoids bridge the gap between clinical trials and in vitro drug screening.