02587nas a2200313   4500000000100000008004100001260001500042653002300057653002200080653002000102653001700122653003100139653002100170100001600191700001900207700002500226700001600251700002300267700002600290700002500316700002100341700003000362700002300392245025700415856006300672300001100735490000700746520152000753       2023                            d  c2023-08-1610aanimal replacement10aEndothelial Cells10aneo-vasculature10anitric oxide10athree-dimensional printing10atissue-mimicking1 aLisa Asciak1 aLauren Gilmour1 aJonathan A. Williams1 aEuan Foster1 aLara Díaz-García1 aChristopher McCormick1 aJames F. C. Windmill1 aHelen E. Mulvana1 aJoseph C. Jackson-Camargo1 aRoger Domingo-Roca00aInvestigating multi-material hydrogel three-dimensional printing for in vitro representation of the neo-vasculature of solid tumours: a comprehensive mechanical analysis and assessment of nitric oxide release from human umbilical vein endothelial cells  uhttps://royalsocietypublishing.org/doi/10.1098/rsos.230929  a2309290 v103 aMany solid tumours (e.g. sarcoma, carcinoma and lymphoma) form a disorganized neo-vasculature that initiates uncontrolled vessel formation to support tumour growth. The complexity of these environments poses a significant challenge for tumour medicine research. While animal models are commonly used to address some of these challenges, they are time-consuming and raise ethical concerns. In vitro microphysiological systems have been explored as an alternative, but their production typically requires multi-step lithographic processes that limit their production. In this work, a novel approach to rapidly develop multi-material tissue-mimicking, cell-compatible platforms able to represent the complexity of a solid tumour's neo-vasculature is investigated via stereolithography three-dimensional printing. To do so, a series of acrylate resins that yield covalently photo-cross-linked hydrogels with healthy and diseased mechano-acoustic tissue-mimicking properties are designed and characterized. The potential viability of these materials to displace animal testing in preclinical research is assessed by studying the morphology, actin expression, focal adhesions and nitric oxide release of human umbilical vein endothelial cells. These materials are exploited to produce a simplified multi-material three-dimensional printed model of the neo-vasculature of a solid tumour, demonstrating the potential of our approach to replicate the complexity of solid tumours in vitro without the need for animal testing.