title: Principles of the Kenzan Method for Robotic Cell Spheroid-Based Three-Dimensional Bioprinting<sup/>.
abstract: Bioprinting is a technology with the prospect to change the way many diseases are treated, by replacing the damaged tissues with live de novo created biosimilar constructs. However, after more than a decade of incubation and many proofs of concept, the field is still in its infancy. The current stagnation is the consequence of its early success: the first bioprinters, and most of those that followed, were modified versions of the three-dimensional printers used in additive manufacturing, redesigned for layer-by-layer dispersion of biomaterials. In all variants (inkjet, microextrusion, or laser assisted), this approach is material ("scaffold") dependent and energy intensive, making it hardly compatible with some of the intended biological applications. Instead, the future of bioprinting may benefit from the use of gentler scaffold-free bioassembling methods. A substantial body of evidence has accumulated, indicating this is possible by use of preformed cell spheroids, which have been assembled in cartilage, bone, and cardiac muscle-like constructs. However, a commercial instrument capable to directly and precisely "print" spheroids has not been available until the invention of the microneedles-based ("Kenzan") spheroid assembling and the launching in Japan of a bioprinter based on this method. This robotic platform laces spheroids into predesigned contiguous structures with micron-level precision, using stainless steel microneedles ("kenzans") as temporary support. These constructs are further cultivated until the spheroids fuse into cellular aggregates and synthesize their own extracellular matrix, thus attaining the needed structural organization and robustness. This novel technology opens wide opportunities for bioengineering of tissues and organs.
authors.affiliation: 1 Department of Biomedical Engineering, Schools of Engineering and Medicine, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana.|2 Department of Ophthalmology, Schools of Engineering and Medicine, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana.
authors.forename: Nicanor I
authors.initials: NI
authors.lastname: Moldovan
authors.affiliation: 3 Department of Surgery, Division of Cardiac Surgery, Johns Hopkins University , Baltimore, Maryland.
authors.forename: Narutoshi
authors.initials: N
authors.lastname: Hibino
authors.affiliation: 4 Department of Regenerative Medicine and Biomedical Engineering, Faculty of Medicine, Saga University , Japan .
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakayama
mesh_terms: D001672:Biocompatible Materials; D062028:Bioprinting; D065287:Robotic Surgical Procedures; D018874:Spheroids, Cellular; D023822:Tissue Engineering
chemical_list: D001672:Biocompatible Materials
keywords: biofabrication; bioprinting; cell spheroids; microneedles; scaffold-free