3D bioprinting is transforming tissue engineering in medicine by providing novel methods that are precise and highly customizable to create biological tissues. The selection of a “cell ink”, a printable formulation, is an integral part of adapting 3D bioprinting processes to allow for process optimization and customization related to the target tissue. Bioprinting hydrogels allows for tailorable material, physical, chemical, and biological properties of the cell ink and is suited for biomedical applications. Hydrogel-based cell ink formulations are a promising option for the variety of techniques with which bioprinting can be achieved. In this review, we will examine some of the current hydrogel-based cell inks used in bioprinting, as well as their use in current and proposed future bioprinting methods. We will highlight some of the biological applications and discuss the development of new hydrogels and methods that can incorporate the completed print into the tissue or organ of interest.

The skeletal system is a key support structure within the body. Bones have unique abilities to grow and regenerate after injury. Some injuries or degeneration of the tissues cannot rebound and must be repaired by the implantation of foreign objects following injury or disease. This process is invasive and does not always improve the quality of life of the patient. New techniques have arisen that can improve bone replacement or repair. 3D bioprinting employs a printer capable of printing biological materials in multiple directions. 3D bioprinting potentially requires multiple steps and additional support structures, which may include the use of hydrogels for scaffolding. In this review, we discuss normal bone physiology and pathophysiology and how bioprinting can be adapted to further the field of bone tissue engineering.

Additive manufacturing (3D printing) has been deployed across multiple platforms to fabricate bioengineered tissues. We demonstrate the use of a Thermal Inkjet Pipette System (TIPS) for targeted de... Method summary Thermal jet bioprinting can provide targeted cellular delivery with high viability onto a flexible matrix for repair of biological anomalies and future clinical applications. Plain language summary 3D bioprinting is a rapidly developing field of research that allows for the creation of synthetic biological solutions to disease or injury. In this study, we used an inkjet...

This study proposes a patient-specific three-dimensional (3D)-printed surgical guide designed for scaphoid fracture fixation through a limited dorsal approach. Computed tomography scans of five cadaveric wrists were modeled in 3D segmentation software and cannulated screw guidewire trajectory was planned. Custom 3D-printed surgical guides for guidewire insertion were designed for each scaphoid. Guidewire placement was performed with and without the surgical guide through a dorsal approach. Postoperative scans were overlaid with the planned trajectory and compared. Five variables were measured: angular deviation, distance between entry points, distance between exit points, embedded guidewire length, and number of attempts. Mean angular deviation from the planned trajectory was 10.80 ± 6.72° for the guided and 14.08 ± 4.65° for the freehand group. The offset between entry and exit for the guided group was 2.22 ± 1.04 and 3.52 ± 2.80 mm and for the freehand group 2.95 ± 1.31 and 4.91 ± 2.37 mm, respectively. The mean length for the guided group was 23.25 ± 3.33 mm and 23.31 ± 3.07 mm for the freehand group. All guided cases took one attempt and the freehanded cases 2.0 ± 1.0 attempts. A significant positive correlation was found between trajectory and exit. No significance between groups was found between any of the measured variables. A minimum sample size of 28 was determined for follow-up studies. The use of a custom surgical guide improved guidewire placement in four of five specimens when compared with a freehand approach. Specifically, the trajectory was closer to the planned trajectory. All guidewire placements were clinically acceptable. Therefore, we consider the use of this surgical guide for the dorsal approach feasible to be used in clinical practice. This device could be used to treat nondisplaced scaphoid fractures. The use of a custom surgical guide could allow for accurate and efficient screw placement as well as reduced operating time and fluoroscopy exposure.