Vascularization Strategies in 3D Cell Culture Models: From Scaffold-Free Models to 3D Bioprinting

Abstract

The discrepancies between the findings in preclinical studies, and in vivo testing and clinical trials have resulted in the gradual decline in drug approval rates over the past decades. Conventional in vitro drug screening platforms employ two-dimensional (2D) cell culture models, which demonstrate inaccurate drug responses by failing to capture the three-dimensional (3D) tissue microenvironment in vivo. Recent advancements in the field of tissue engineering have made possible the creation of 3D cell culture systems that can accurately recapitulate the cell-cell and cell-extracellular matrix interactions, as well as replicate the intricate microarchitectures observed in native tissues. However, the lack of a perfusion system in 3D cell cultures hinders the establishment of the models as potential drug screening platforms. Over the years, multiple techniques have successfully demonstrated vascularization in 3D cell cultures, simulating in vivo-like drug interactions, proposing the use of 3D systems as drug screening platforms to eliminate the deviations between preclinical and in vivo testing. In this review, the basic principles of 3D cell culture systems are briefly introduced, and current research demonstrating the development of vascularization in 3D cell cultures is discussed, with a particular focus on the potential of these models as the future of drug screening platforms.

Keywords: 3D cell culture; bioprinting; drug screening; microfluidics; scaffold-based; scaffold-free; spheroids; tumor modelling; vascularization.

Figure 3

(I) Spatial distribution of β cells inside EC spheroid, reported by Urbanczyk et al. [83] (licensed under CC BY 4.0). (II) Actin cytoskeletal organization and pre-vascular patterns in MSC/HUVEC spheroids encapsulated in collagen/fibrin hydrogels, reported by Heo et al. [79]. (III) Basal membrane highlighted using anti-collagen IV staining in vascularized spheroids, reported by Muller et al. [81] (licensed under CC BY 4.0). (IV) Scanning electron microscopy showcasing formation of endothelial cell tubes (indicated by arrows), reported by Chaddad et al. [85]. (V) Sprouting branches of co-cultured spheroids, reported by Kim et al. [84].

Figure 4

(I) Bioink ratio to bioprint hepatic liver lobule model, illustrated by Janani et al. [88]. (II) Tumor angiogenesis observed using fluorescent imaging, reported by Dey et al. [90]. (III) Preset extrusion bioprinting technique to model hepatic lobule structure, illustrated by Kang et al. [89]. (IV) Self-organization of hMSCs via extrusion bioprinting using the BATE concept, reported by Brassard et al., scale bar 500 μm [87]. (V) Illustration of angiogenesis of MCTSs seeded on bioprinted vascularized tissue, reported by Han et al. [86] (licensed under CC BY 4.0).

Figure 5

(I) Heart-on-a-chip device, illustration of the multilayer model by Vivas et al. [94]. (II) Retina-on-a-chip device (top) and imaging showcasing ROC seeding into device, reported by Achberger et al., scale bar 500 μm [93] (licensed under CC BY 4.0). (III) Kidney-on-a-chip device, illustration of the dynamic culture system by Lee et al. [92] (licensed under CC BY 4.0). (IV) Microfluidic system for generating liver organoids (left) and multiorgan model (right), reported by Jin et al. [95].

Figure 1

Illustration showing different approaches towards scaffold-free 3D cell culture models. Created with BioRender.com, accessed on 25 September 2022.

Figure 2

Illustration showing different approaches towards scaffold-based 3D cell culture models. Created with BioRender.com, accessed on 25 September 2022.