The ability to create engineered microfluidic human renal tissues such as vascularized renal tubule and glomerular microvessel that recapitulate native function would enable scientific and technological advances in renal drug screening, disease modeling, and regenerative medicine. Numerous approaches such as soft lithography and micromolding ingberg , hollow fibers , liquid mold have been raised for the fabrication of microfluidic renal tubule tissues channel. More recently, kidney organoids have been also created that contain various nephronal features 17–21. However, there are some concerns over the outcomes from these studies, such as the use of animal cells, 2D tissue culture model, and small size of the kidney organoids that limited the in vivo like physiological functions. Unfortunately, the inability of these approaches to create a truly complex in vivo like engineered 3D renal tissues has hindered progress in the field of renal drug screening, disease modeling for decades.
In such a context, 3D cell printing has regarded as a versatile technology with the potential to fabricate 3D tissue constructs endowed with in-vivo-like functional behavior compared to conventional microfabrication approaches i.e. micro molding, and soft-lithography, hollow fibers. 3 An important advantage offered by this technology is precise placement of biomaterials or cell-loaded biomaterials with predesigned patterns and geometries, producing desired 3D tissue-like structures.3 In the past, researchers have tried Recently, Jenifer A. Lewis group has been explored the integration of channels within hydrogel to create a renal proximal tubule on chip. However, this approach generates embedded microchannels and seeded cells inside channel that require the delicate, slow, and multistep processes. In-addition, this approach lack ability to generate the dual layered glomerular microvessel and only demonstrated the proximal tubule channel without nearby micro-vessel.
More recently, 3D coaxial printing has been shown the ability to direct fabricating perfusable hollow fibers,5, 7 which is the basic requirement for generating functional tubular tissues. Gao et als produced perfusable vascular blood vessel using coaxial nozzle printing and decellularized ecm hybrid bioink. Zhang et al. employed a coaxial-nozzle extrusion method that enabled direct bioprinting of cellular microfluidic channels in the form of hollow tubes. Ali , koesy et explored coaxial nozzle printing to generate the complex vascularized tissue 3D tubular tissues.
Despite the significant progress in 3D bioprinting, up to now, direct bioprinting of microfluidic complex 3D kidney models such as dual layered glomerular capillary, both renal proximal tubule and vascular networks patterned alongside is remains challenging and has not yet been created.
Hence, there is a critical need to bioprinting of microfluidic vascularized renal tissues that can recapitulate in vivo like biological function to overcome the current demand for drug screening, disease modeling, and, ultimately, serve as a modular building block for engineering human renal tissues.