(1) Background: In the present study, we evaluated the efficacy of a 3D-printed, patient-specific polycaprolactone/beta tricalcium phosphate (PCL/β-TCP) scaffold in the treatment of complex zygomatico-maxillary defects. (2) Methods: We evaluated eight patients who underwent immediate or delayed maxillary reconstruction with patient-specific PCL implants between December 2019 and June 2021. The efficacy of these techniques was assessed using the volume and density analysis of computed tomography data obtained before surgery and six months after surgery. (3) Results: Patients underwent maxillary reconstruction with the 3D-printed PCL/β-TCP scaffold based on various reconstructive techniques, including bone graft, fasciocutaneous free flaps, and fat graft. In the volume analysis, satisfactory volume conformity was achieved between the preoperative simulation and actual implant volume with a mean volume conformity of 79.71%, ranging from 70.89% to 86.31%. The ratio of de novo bone formation to total implant volume (bone volume fraction) was satisfactory with a mean bone fraction volume of 23.34%, ranging from 7.81% to 66.21%. Mean tissue density in the region of interest was 188.84 HU, ranging from 151.48 HU to 291.74 HU. (4) Conclusions: The combined use of the PCL/β-TCP scaffold with virtual surgical simulation and 3D printing techniques may replace traditional non-absorbable implants in the future owing to its accuracy and biocompatible properties.

Joo OY, et al. Yonsei Med J. 2023 Apr;64(4):291-296. https://doi.org/10.3349/ymj.2022.0547

Kim M, et al. Yonsei Med J. 2024 Jun;65:e31. https://doi.org/10.3349/ymj.2023.0444

Tissue engineering holds a significant promise for the development of bioartificial organs applicable to transplantation. However, the size of engineered tissues remains limited, primarily due to the challenge of establishing microvascular networks within tissue constructs. In this study, engineered tissues are fabricated and embedded with functional microvascular networks by assembling endothelial cell‐covered spheroidal microtissues. Utilizing a preset extrusion bioprinting and microfluidic emulsification approach, spheroidal microtissues covered with endothelial cells are successfully fabricated, demonstrating high structural integrity compared with non‐structured spheroidal microtissues. Upon assembling endothelial cell‐covered microtissues, vascularized tissue structures are generated. Additionally, perfusion of the culture medium through the tissue structure created by microtissue assembly preserves the intermicrotissue spaces, which can be considered vascular channels, facilitating the development of highly vascularized tissues. By controlling the medium perfusion rate, volumetric functional tissues are produced that can be cultured for 7 days in vitro. This innovative technique for fabricating highly vascularized volumetric tissues holds potential as a foundational technology for producing artificial organs.

The rete ridges, undulating structures located between the epidermis and dermis, play a crucial role in maintaining the skin’s barrier function, which protects the body from pollutants and ultraviolet (UV) radiation. This formation of rete ridges within in vitro skin models is essential for evaluating the efficacy and safety of pharmaceuticals or cosmetics, replacing the need for animal models. Micro-molding is a prominent technique for recreating the rete ridge structure in in vitro skin models, however, this method is characterized by high technical difficulty. Although three-dimensional (3D) bioprinting technology shows potential for fabricating skin models incorporating the rete ridge structure, it is also limited by the extended time required for structural implementation. In this study, we introduce a methodology for fabricating full-thickness skin equivalents with rete ridges using preset extrusion bioprinting. A polycaprolactone frame was 3D-printed, and the dermal layer was bioprinted in the frame. Subsequently, furrowing steps were undertaken to create a substrate for the stable anchoring of strands produced by the preset extrusion bioprinting, fabricating a dermis layer with a rete ridge structure. Keratinocytes were then seeded and differentiated, resulting in the formation of the stratum corneum. We observed that protein expression was preserved in the valleys of the rete ridge after UV irradiation of the rete ridge full-thickness skin equivalent, demonstrating a similarity to human ex vivo skin models. Therefore, the rete ridge full-thickness skin equivalent generated using our method shows potential as a promising model to replace animal experiments and human ex vivo skin models.