Advanced Multi-Dimensional Cellular Models as Emerging Reality to Reproduce In Vitro the Human Body Complexity

Abstract

A hot topic in biomedical science is the implementation of more predictive in vitro models of human tissues to significantly improve the knowledge of physiological or pathological process, drugs discovery and screening. Bidimensional (2D) culture systems still represent good high-throughput options for basic research. Unfortunately, these systems are not able to recapitulate the in vivo three-dimensional (3D) environment of native tissues, resulting in a poor in vitro-in vivo translation. In addition, intra-species differences limited the use of animal data for predicting human responses, increasing in vivo preclinical failures and ethical concerns. Dealing with these challenges, in vitro 3D technological approaches were recently bioengineered as promising platforms able to closely capture the complexity of in vivo normal/pathological tissues. Potentially, such systems could resemble tissue-specific extracellular matrix (ECM), cell-cell and cell-ECM interactions and specific cell biological responses to mechanical and physical/chemical properties of the matrix. In this context, this review presents the state of the art of the most advanced progresses of the last years. A special attention to the emerging technologies for the development of human 3D disease-relevant and physiological models, varying from cell self-assembly (i.e., multicellular spheroids and organoids) to the use of biomaterials and microfluidic devices has been given.

Keywords: 3D in vitro models; multicellular spheroids; nanostructured biomaterials; organ-on-a-chip; organoids; tissue engineering.

Figure 1

Schematic representation of the most promising technologies and tools for the engineering of 3D in vitro models.

Figure 2

Thrombosis 3D bioprinted model designed by Zhang and coworkers from [108] with permission. Sacrificial bioprinting of vascularized hydrogels. (A) Schematic representation of the bioprinting process steps (i–vi) and (B) corresponding photographs of: (i) and (ii) bioprinting of a Pluronic template; (iii) template drying placed on a PDMS support; (iv) GelMA filling and ultraviolet crosslinking; (v) dissolution of the sacrificial channels; (vi) final construct with hollow channels. (C) Visualization of hollow microchannels endothelialization inside the GelMA construct: (i) linear and (ii) bifurcating microchannels; (iii) CD31 (green) and nuclei (blue) staining of the confluent layer of HUVECs.

Figure 3

Example of a 3D convoluted renal proximal tubule on chip [114]. Schemes of a nephron highlighting the convoluted proximal tubule (a) and different steps in the fabrication of the 3D model (b,c); a 3D rendering of the printed convoluted proximal tubule acquired by confocal microscopy (d–f). PECTs: proximal endothelial tubule cells

Figure 4

3D perfused humanized liver from [131]. Schematic experimental plan to generate 3D humanized liver by using acellularization and human patient-derived cells repopulation strategy.

Figure 5

3D PN model from [155]. Formation of bands of Büngner (BoB) by SCs (A); overview of the model components (B); representation of neural cell population (PC12 or DRG)-SCs co-culture procedure (C,D).

Figure 6

3D vSM from [196] with permission. (1) Self-organization of cells in GelMA spring (a), 13.33 length-to-diameter ratio of a MSC spring (b), live/dead images of MSCs spring in GelMA spring (c), F-actin (green) and nuclei (blue) staining of MSCs spring. Unlabeled scale bars 400 µm. (2) Semi-automated coiling assembly (a,b), images of helical microtubes (c) with various diameters (c1), GelMA spring (red) in the helical microtube of Ca-alginate shell (green) (c2), perfusion of the helical microtube (c3). Scale bars 800 µm.