Cell Printing
Over the past twenty years, the commercial inkjet printers have been used in innovative ways to perform biological experiments. Researchers have applied DOD technologies to creation of biologically-compatible surfaces, precise distribution of protein for various assays and arrays, and formation of standardized tissues. More recently, coupling the printing of 3D-hydrogels with cellular printing has led promising advancements in the creation of patient-specific tissue formation for eventual use in organ printing technologies.
However, despite these advances, cell printing has not gained widespread use in the biological engineering field. Current inkjet technologies inherently limit the number of cell types or substrates that can be distributed onto a surface due to restrictions in cartridge number on existing platforms, meaning only four cartridges can typically be loaded onto an existing inkjet print head. Printing technologies may be limited by cell adhesion time, since mammalian cell culture typically takes about an hour to adhere to a plate.
One of the biggest issues with cell printing technologies is cell viability since DOD inkjet methods expose the cell to harsh conditions throughout the entire printing process. Since thermal inkjet technologies function by running current through the tip of the printing cartridge, cells are subjected to both electric and thermal effects that can potentially kill the cell. Many inkjet printers can print up to 10,000 or more drops per minute, and the high throughput leads to high velocity and sheer stresses on the cell, which can be harmful. Furthermore, cell size in some printer-heads that print drops of 50 microns or less can cause nozzle clogging. Therefore, cells are exposed to hyperosmolarity solution to shrink the cell size in as it passes through the ink cartridge. Each of these factors greatly jeopardizes cell viability and decreases the success of the cell printing system.
Despite these setbacks, these technologies still hold the promise of revolutionary tissue engineering techniques and advancement. The prospect of creation of tissues with defined spatial organization is motivated by the hypothesis of biomimetic patterns can help to achieve improved therapeutic outcomes. Cell printing based on inkjet printing technologies can be used to fabricate biomimetic patterns that can be used to tissue function and generation and ultimately transferred to clinical applications.
