Intraoperative bioprinting of human adipose-derived stem cells and extra-cellular matrix induces hair follicle-like downgrowths and adipose tissue formation during full-thickness craniomaxillofacial skin reconstruction.

Craniomaxillofacial (CMF) reconstruction is a challenging clinical dilemma. It often necessitates skin replacement in the form of autologous graft or flap surgery, which differ from one another based on hypodermal/dermal content. Unfortunately, both approaches are plagued by scarring, poor cosmesis, inadequate restoration of native anatomy and hair, alopecia, donor site morbidity, and potential for failure. Therefore, new reconstructive approaches are warranted, and tissue engineered skin represents an exciting alternative. In this study, we demonstrated the reconstruction of CMF full-thickness skin defects using intraoperative bioprinting (IOB), which enabled the repair of defects via direct bioprinting of multiple layers of skin on immunodeficient rats in a surgical setting. Using a newly formulated patient-sourced allogenic bioink consisting of both human adipose-derived extracellular matrix (adECM) and stem cells (ADSCs), skin loss was reconstructed by precise deposition of the hypodermal and dermal components under three different sets of animal studies. adECM, even at a very low concentration such as 2 % or less, has shown to be bioprintable via droplet-based bioprinting and exhibited de novo adipogenic capabilities both in vitro and in vivo. Our findings demonstrate that the combinatorial delivery of adECM and ADSCs facilitated the reconstruction of three full-thickness skin defects, accomplishing near-complete wound closure within two weeks. More importantly, both hypodermal adipogenesis and downgrowth of hair follicle-like structures were achieved in this two-week time frame. Our approach illustrates the translational potential of using human-derived materials and IOB technologies for full-thickness skin loss.

Nested Biofabrication: Matryoshka-Inspired Intra-Embedded Bioprinting.

Engineering functional tissues and organs remains a fundamental pursuit in bio-fabrication. However, the accurate constitution of complex shapes and internal anatomical features of specific organs, including their intricate blood vessels and nerves, remains a significant challenge. Inspired by the Matryoshka doll, here a new method called "Intra-Embedded Bioprinting (IEB)" is introduced building upon existing embedded bioprinting methods. a xanthan gum-based material is used which served a dual role as both a bioprintable ink and a support bath, due to its unique shear-thinning and self-healing properties. IEB's capabilities in organ modeling, creating a miniaturized replica of a pancreas using a photocrosslinkable silicone composite is demonstrated. Further, a head phantom and a Matryoshka doll are 3D printed, exemplifying IEB's capability to manufacture intricate, nested structures. Toward the use case of IEB and employing an innovative coupling strategy between extrusion-based and aspiration-assisted bioprinting, a breast tumor model that included a central channel mimicking a blood vessel, with tumor spheroids bioprinted in proximity is developed. Validation using a clinically-available chemotherapeutic drug illustrated its efficacy in reducing the tumor volume via perfusion over time. This method opens a new way of bioprinting enabling the creation of complex-shaped organs with internal anatomical features.

Intraoperative Bioprinting of Human Adipose-derived Stem cells and Extra-cellular Matrix Induces Hair Follicle-Like Downgrowths and Adipose Tissue Formation during Full-thickness Craniomaxillofacial Skin Reconstruction.

Craniomaxillofacial (CMF) reconstruction is a challenging clinical dilemma. It often necessitates skin replacement in the form of autologous graft or flap surgery, which differ from one another based on hypodermal/dermal content. Unfortunately, both approaches are plagued by scarring, poor cosmesis, inadequate restoration of native anatomy and hair, alopecia, donor site morbidity, and potential for failure. Therefore, new reconstructive approaches are warranted, and tissue engineered skin represents an exciting alternative. In this study, we demonstrated the reconstruction of CMF full-thickness skin defects using intraoperative bioprinting (IOB), which enabled the repair of defects via direct bioprinting of multiple layers of skin on immunodeficient rats in a surgical setting. Using a newly formulated patient-sourced allogenic bioink consisting of both human adipose-derived extracellular matrix (adECM) and stem cells (ADSCs), skin loss was reconstructed by precise deposition of the hypodermal and dermal components under three different sets of animal studies. adECM, even at a very low concentration such as 2% or less, has shown to be bioprintable via droplet-based bioprinting and exhibited de novo adipogenic capabilities both in vitro and in vivo . Our findings demonstrate that the combinatorial delivery of adECM and ADSCs facilitated the reconstruction of three full-thickness skin defects, accomplishing near-complete wound closure within two weeks. More importantly, both hypodermal adipogenesis and downgrowth of hair follicle-like structures were achieved in this two-week time frame. Our approach illustrates the translational potential of using human-derived materials and IOB technologies for full-thickness skin loss.

Nested biofabrication: Matryoshka-inspired Intra-embedded Bioprinting.

Engineering functional tissues and organs remains a fundamental pursuit in biofabrication. However, the accurate constitution of complex shapes and internal anatomical features of specific organs, including their intricate blood vessels and nerves, remains a significant challenge. Inspired by the Matryoshka doll, we here introduce a new method called 'Intra-Embedded Bioprinting (IEB),' building upon existing embedded bioprinting methods. We used a xanthan gum-based material, which served a dual role as both a bioprintable ink and a support bath, due to its unique shear-thinning and self-healing properties. We demonstrated IEB's capabilities in organ modelling, creating a miniaturized replica of a pancreas using a photocrosslinkable silicone composite. Further, a head phantom and a Matryoshka doll were 3D printed, exemplifying IEB's capability to manufacture intricate, nested structures. Towards the use case of IEB and employing innovative coupling strategy between extrusion-based and aspiration-assisted bioprinting, we developed a breast tumor model that included a central channel mimicking a blood vessel, with tumor spheroids bioprinted in proximity. Validation using a clinically-available chemotherapeutic drug illustrated its efficacy in reducing the tumor volume via perfusion over time. This method opens a new way of bioprinting enabling the creation of complex-shaped organs with internal anatomical features.