Stochastic\nto Deterministic: A Straightforward Approach\nto Create Serially Perfusable Multiscale Capillary Beds

Generation of <i>in vitro</i> tissue models\nwith serially\nperfused hierarchical vasculature would allow greater control of fluid\nperfusion throughout the network and enable direct mechanistic investigation\nof vasculogenesis, angiogenesis, and vascular remodeling. In this\nwork, we have developed a method to produce a closed, serially perfused,\nmultiscale vessel network fully embedded within an acellular hydrogel,\nwhere flow through the capillary bed is required prior to fluid exit.\nWe confirmed that the acellular and cellular gel-gel interface was\nfunctionally annealed without preventing or biasing cell migration\nand endothelial self-assembly. Multiscale connectivity of the vessel\nnetwork was validated via high-resolution microscopy techniques to\nconfirm anastomosis between self-assembled and patterned vessels.\nLastly, using a simple acrylic cassette and fluorescently labeled\nmicrospheres, the multiscale network was demonstrated to be perfusable.\nDirected flow from inlet to outlet mandated flow through the capillary\nbed. This method for producing closed, multiscale vascular networks\nwas developed with the intention of straightforward fabrication and\nengineering techniques so as to be a low barrier to entry for researchers\nwho wish to investigate mechanistic questions in vascular biology.\nThis ease of use offers a facile extension of these methods for incorporation\ninto organoid culture, organ-on-a-chip (OOC) models, and bioprinted\ntissues.