Layer by Layer Three-dimensional Tissue Epitaxy by Cell-Laden Hydrogel Droplets

Center for Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School , Cambridge, MA, USA.
Tissue Engineering Part C Methods (Impact Factor: 4.64). 08/2009; 16(1):157-66. DOI: 10.1089/ten.TEC.2009.0179
Source: PubMed


The ability to bioengineer three-dimensional (3D) tissues is a potentially powerful approach to treat diverse diseases such as cancer, loss of tissue function, or organ failure. Traditional tissue engineering methods, however, face challenges in fabricating 3D tissue constructs that resemble the native tissue microvasculature and microarchitectures. We have developed a bioprinter that can be used to print 3D patches of smooth muscle cells (5 mm x 5 mm x 81 microm) encapsulated within collagen. Current inkjet printing systems suffer from loss of cell viability and clogging. To overcome these limitations, we developed a system that uses mechanical valves to print high viscosity hydrogel precursors containing cells. The bioprinting platform that we developed enables (i) printing of multilayered 3D cell-laden hydrogel structures (16.2 microm thick per layer) with controlled spatial resolution (proximal axis: 18.0 +/- 7.0 microm and distal axis: 0.5 +/- 4.9 microm), (ii) high-throughput droplet generation (1 s per layer, 160 droplets/s), (iii) cell seeding uniformity (26 +/- 2 cells/mm(2) at 1 million cells/mL, 122 +/- 20 cells/mm(2) at 5 million cells/mL, and 216 +/- 38 cells/mm(2) at 10 million cells/mL), and (iv) long-term viability in culture (>90%, 14 days). This platform to print 3D tissue constructs may be beneficial for regenerative medicine applications by enabling the fabrication of printed replacement tissues.

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    • "Several enabling DOD microdroplet deposition systems developed in recent years include inkjet printing [15,25,29,32–35], laser-induced forward transfer (LIFT) [36] [37], electrohydrodynamic jetting (EHDJ) [38] [39] [40], microvalve-based jetting [41], and acoustic beam jetting [42]. Specifically, inkjet printing is widely used owing to being highly efficient and inexpensive; however, it is limited to low viscosity of dispensable materials (<20 mPa s), and instantaneous high temperature (about 300 C) exists in thermal inkjet printing [43]. "
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    • "While a variety of strategies have been established to bioprint hydrogels as a seeding substrate upon which cells can proliferate [7, 12–17], methods for bioprinting naturally derived cell-laden hydrogels are still limited [7]. Interesting tissue engineering alternatives have been reported for inkjet printing of natural proteins and polysaccharides, such as agar [18], fibrin [16], Ficoll [19], hyaluronic acid [15], gelatin [15], collagen [11] and blends of these materials [20] [21]. However, direct-write bioprinting of cell-laden ECM-derived hydrogels has remained a challenge. "
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