Table 1. Resume table with comparison of the bioprinted renal models developed so far.

Renal compartment	Cells	Biomaterial	Bioprinting technique	Model description	Advantages	Disadvantages	Ref.
Proximal tubule model	HUVECs, PTECs, HK-2 cells	dECM, sodium alginate, pluronic	Extrusion-based	Bioprinted monolayer and bilayer cell tubules	Cells bioprinted in different concentric configurations; Function demonstrated	Resolution above 500 µm; dECM requires source organ	[20]
Proximal tubule model	HUVECs, renal fibroblast, PTECs	Thermo-responsive proprietary biomaterial ink	Extrusion-based (piston-driven)	Bioprinted cell-laden bioink onto a transwell membrane	Barrier function demonstrated; Suitable for nephrotoxicity studies	Layered model not compatible with perfusion	[24]
Proximal tubule model with and without vasculature	PTECs, GMECs, HUVECs	Gelatin, fibrin, pluronic	Extrusion-based	Printing of fugitive ink filaments Encapsulation with hydrogel Seeding hollow channels after removal of filaments	Demonstrated function between tubules; Models allow perfusion/long term culture	Cells not included in the process; Tubule resolution as low as 20 µm but below 200 µm cell seeding is limited	[22,23,25]
Proximal tubule, glomerulus	Human primary kidney cells	dECM, gelatin, Hyaluronic acid, glycerol	Extrusion-based	Bioprinting of dECM-based bioinks	Developed bioinks suitable for primary cells; Reabsorption function observed on cells	dECM requires source organ; Limited functional readout demonstrated	[29]
Kidney tubulointerstitium	Primary murine epithelial cells, HUVECs	Alginate, pectin and gelatin	Extrusion-based (microfluidics core-shell)	Core-shell constructs with epithelial and endothelial concentrically bioprinted into shell and with a sacrificial gel core	Multiple configurations in core–shell format	Limited formation of cellular lumen	[14]
Kidney organoid model for drug testing	Induced pluripotent stem cell (iPSC)-derived kidney organoids	Biomaterial ink free	Extrusion bioprinting (piston-based)	High-throughput (96-well plate format) platform for organoid maturation and drug screening studies	Patterning with clear impact on differentiation and maturation of organoids	Bioprinting conformation limited in thickness; Absence of supporting biomaterials	[50]
Kidney organoid model for disease modelling, toxicity and improved differentiation	Embryonic or iPSC-derived kidney organoids	Biomaterial ink free	Liquid handling dispensing system	High-throughput organoid platform (96-well plate format)	Allows high throughput screenings for differentiation, toxicity and disease modeling	Dispensing approach without patterning control described	[75]