3D bioprinting for lungs and hollow organs

Abstract

Three-dimensional bioprinting has been gaining attention as a potential method for creating biological tissues, supplementing the current arsenal of tissue engineering techniques. 3D bioprinting raises the possibility of reproducibly creating complex macro- and microscale architectures using multiple different cell types. This is promising for creation of multilayered hollow organs, which has been challenging using more traditional tissue engineering techniques. In this review, the state of the field in bioprinting of epithelialized hollow and tubular organs is discussed. Most of the progress for the pulmonary system has been restricted to the trachea. Due to the gross structural similarities and common engineering challenges when creating any epithelialized hollow organ, this review also covers current progress in printing within the gastrointestinal and genitourinary systems, as well as applications of traditional plastic printing in engineering these tissues.

Figure 1:

Illustration showing the pulmonary epithelial cells and their locations along the airways; MGC: mucous gland cells; SGC: serous gland cells; SMGs: submucosal glands; GC: goblet cells; PNE: pulmonary neuroendocrine; AI: alveolar type I cells; AII: alveolar type II cells. Reprinted from “Pulmonary Epithelium: Cell Types and Functions,” by M. M.-J. Chang, L. Shih, and R. Wu, 2008, In The Pulmonary Epithelium in Health and Disease, page 2. Copyright 2008 by “John Wiley and Sons”. Reprinted with permission.

Figure 2:

Dual extruded PCL/alginate tracheal graft, A) longitudinal view, B) cross sectional view, C) SEM image with labeled layers (a) outer layer to (e) luminal layer. Reprinted from “3D Bioprinted Artificial Trachea with Epithelial Cells and Chondrogenic-Differentiated Bone Marrow-Derived Mesenchymal Stem Cells,” by S. Bae, K.-W. Lee, J. Park, et. al, 2018, Int. J. Mol. Sci., 19(6), pg. 5. Copyright 2018 by “MDPI”. Reprinted with permission.

Figure 3:

Experimental overview starting with isolation of cell types from F344 rat, expansion, spheroid culture, spheroid assembly, maturation, and implantation in another F344 rat. Reprinted from “Scaffold-free trachea regeneration by tissue engineering with bio-3D printing,” by D. Taniguchi, K. Matsumoto, T. Tsuchiya, et. al, 2018 Interact. Cardiovasc. Thorac. Surg., 26(5), pg. 747. Copyright 2018 by “Elsevier Science and Technology Journals”. Reprinted with permission.

Figure 4:

An overview of the bellows graft development. A) 3D printed sacrificial mold, injected with PCL/gelatin, crosslinking and dissolving the outer mold. B) Treating and loading gelatin sponge with TFG-b3 and seeding with chondrocytes. Reprinted from “A novel tissue-engineered trachea with a mechanical behavior similar to native trachea,” by J.H. Park, J.M. Hong, Y.M. Ju, et. al, 2015, Biomaterials, 62, pg. 107. Copyright 2015 by “Elsevier Science and Technology Journals”. Reprinted with permission.

Figure 5:

Distal lung model with red blood cell perfusion and air sac ventilation, scale bar 1mm. Reprinted from “Multivascular networks and functional intravascular topologies within biocompatible hydrogels,” by B. Grigoryan., S.J. Paulsen, D.C. Corbett, et. al, 2019, Science, 364, pg 461. Copyright 2019 by “The American Association for the Advancement of Science”. Adapted with permission.

Figure 6:

Schematic of the structure of the esophageal wall. The innermost layers of the mucosa and submucosa are bordered by the neurons of the submucosal plexus. The next layer is the circular smooth muscle, which is separated from the outer longitudinal smooth muscle by the neurons of the myenteric plexus. Adventitia/serosa and vasculature not shown. Reprinted from “Development, Anatomy, and Physiology of the Esophagus,” by K. Staller, B. Kuo, 2013, In Principles of Deglutition, pg. 283. Copyright 2013 by “ Springer ”. Reprinted with permission

Figure 7:

3D bioprinting of a urethra. A-D) printing process, crosslinking, and immersion in culture medium. E-F) views of bioprinter before and during printing. Reprinted from “3D bioprinting of urethra with PCL/PLCL blend and dual autologous cells in fibrin hydrogel: An in vitro evaluation of biomimetic mechanical property and cell growth environment,” by K. Zhang, Q. Fu, J. Yoo, et. al, 2017, Acta Biomater., 50, pg. 158. Copyright 2017 by “Elsevier BV “. Reprinted with permission.

Figure 8:

Schematic summary of hollow tissue fabrication methods. (A) Dual Head Extrusion Printing; multiple printing heads are used to print a construct of multiple materials with distinct regions. (B) Organoid Printing; spherical organoids are grown in a well plate, then assembled in a needle array and fused into a solid construct. (C) Sacrificial molding; a sacrificial mold is made using stereolithography, then the hydrogel mixture is injected and solidifies in the mold. (D) Scaffold prefabrication; a PCL scaffold is printed, then flooded with a cell laden hydrogel. (E) Decelled ECM supported with 3D printed PCL rings; rings are printed out of PCL and sheets of decellularized tissue are wrapped around them. (F) Electrospun PCL supported by 3D printed PCL rings; rings are printed out of PCL and then PCL is electrospun around them. (G) Tissue engineered esophagus made by printing PCL in a cross-hatched pattern, then coated with rabbit MSCs in a fibrin hydrogel. (H) Acellular esophagus graft with 3D printed PCL rings on a rotating mandrel, subsequently covered with PCL electrospinning. (I). 3D bioprinting used to create a two-layered intestinal epithelium model in a transwell plate. The first layer contained fibroblasts, which was covered by a second layer of epithelial cells. The tissue matured and organized in culture. (J) 3D bioprinting of a urethra graft by simultaneously printing PCL/PLCL blend, a SMC bioink outside, and a UC bioink inside.