A challenge for tissue engineering is producing three-dimensional (3D), vascularized cellular constructs of clinically relevant size, shape and structural integrity. We present an integrated tissue–organ printer (ITOP) that can fabricate stable, human-scale tissue constructs of any shape. Mechanical stability is achieved by printing cell-laden hydrogels together with biodegradable polymers in integrated patterns and anchored on sacrificial hydrogels. The correct shape of the tissue construct is achieved by representing clinical imaging data as a computer model of the anatomical defect and translating the model into a program that controls the motions of the printer nozzles, which dispense cells to discrete locations. The incorporation of microchannels into the tissue constructs facilitates diffusion of nutrients to printed cells, thereby overcoming the diffusion limit of 100–200 μm for cell survival in engineered tissues. We demonstrate capabilities of the ITOP by fabricating mandible and calvarial bone, cartilage and skeletal muscle. Future development of the ITOP is being directed to the production of tissues for human applications and to the building of more complex tissues and solid organs.
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- Supplementary Figure 1: Integrated tissue and organ printing (ITOP) system (237 KB)
The ITOP system consists of three major units; 1) 3-axis stage/controller, 2) dispensing module including multi-cartridge and pneumatic pressure controller, and 3) a closed acrylic chamber with temperature controller and humidifier.
- Supplementary Figure 2: Optimization of composite hydrogel system for 3D bioprinting (56 KB)
Dispensing rates (dispensed volume per unit time) with different concentrations of (a) gelatin (n=30) and (b) HA (n=30). The dispensing rate could by increased or decreased by decreasing or increasing the concentration of gelatin, respectively. Irregularities in dispensing rates to varying gelatin concentrations were directly related to the coefficient of variation (COV); where a COV of greater than 30% was associated with uneven dispensing of the hydrogel. However, introduction of HA to gelatin significantly improved uniformity of dispensing rate with low COV values. *Coefficient of variation (COV) was calculated by dividing average with standard deviation.
- Supplementary Figure 3: Optimization of PCL and TCP ratio (54 KB)
(a) Compression modulus and (b) water uptake ability of the printed PCL/TCP constructs with different ratios (*P<0.05, n = 3). (c) Quantification of calcium content showing the osteogenic differentiation of hAFSCs seeded on the PCL/TCP constructs with different ratios (no significance, n = 3).
- Supplementary Figure 4: Vascularization of 3D printed ear (350 KB)
The engineered cartilage tissues showed vascularization of the implanted constructs in the periphery region at 1 and 2 months after implantation, as confirmed by vWF immunostaining, but similar to normal cartilage tissue, no vascularization was noted in the central region.
- Supplementary Figure 5: Immunofluorescent images of 3D printed muscle organization (482 KB)
3D printed muscle structures were cultured in the growth medium up to 3 days, and then induced myotube formation in the differentiation medium for 7 days. Live/dead staining of the printed muscle organization at (a) 1 day and (b) 3 days. (c) Immunofluorescent staining for MHC of the printed muscle organization at 7 days after cell differentiation. The myotubes formed in the printed constructs showed unidirectionally organized myotubes that are consistently aligned along the longitudinal axis of the printed organization.