Intravital three-dimensional bioprinting

Abstract

Despite the tremendous technical advancements in 3D bioprinting, the concept of fabricating 3D structures and functional tissues directly in live animals remains a visionary challenge. We show that 3D cell-laden hydrogels can be efficiently bioprinted across tissues and within tissues of living animals.We developed photo-sensitive polymers that allow in vitro and in vivo fabrication of hydrogels into pre-existing structures, by bio-orthogonal two-photon cycloaddition and crosslinking at wavelengths longer than 850 nm, without byproducts. By this technique, that we name intravital 3D bioprinting, after injection of these polymers in vivo it is possible to fabricate complex 3D structures inside tissues of living mice, including the dermis across epidermis, the skeletal muscle across epimysium or the brain across meninges. The use of commonly available multi-photon microscopes allows accurate (XYZ) positioning and orientation of bioprinted structures into specific anatomical sites. Finally, we show that intravital 3D bioprinting of donor muscle-derived stem cells allows de novo formation of myofibers in host animals. We envision that this strategy will offer an alternative in vivo approach to conventional bioprinting technology, holding great promises to substantially change the paradigm of 3D bioprinting for pre-clinical and clinical use.

An open-source handheld extruder loaded with pore-forming bioink for in situ wound dressing

“…In realizing such a goal, three-axis movable bioprinting units have been accordingly designed, where the in situ bioprinting processes are controlled by dedicated software to achieve precise spatial deposition of the dressing biomaterials [ [9] , [10] , [11] ]. This approach is referred to by us as the robotic arm approach, which has interestingly been more recently extended to a few other variations enabled by light-based bioprinting, requiring only single-axis movements [ 12 , 13 ].…”

3D printing of tissue engineering scaffolds: a focus on vascular regeneration

“…Minimally invasive treatment is a trend in clinical surgery. In recent years, increased intraoperative printing and intravital printing have been reported [ 43 , 44 ]. Using these technologies, a scaffold in vivo can be directly formed by injection of bioinks or biomaterial inks followed by 3D printing.…”

“…Recently, the conversion of near-infrared light to UV light has been reported using up-conversion nanoparticles [ 106 ]. In particular, the feasibility of intravital 3D printing was provided by this method [ 44 ]. Up to now, patients are inevitably traumatized when implanting scaffolds by traditional methods.…”

Controlling Structure with Injectable Biomaterials to Better Mimic Tissue Heterogeneity and Anisotropy

“…Proof of concept studies have bioprinted cartilage and muscle using NIR light with longer wavelength (>800 nm), which allows for deeper tissue penetration compared to UV. [122,123] Another potential avenue for the translation of bioprinting is the combination of embedded 3D printing, currently capable of producing accurate but nonfunctional structures, with controlled cellular deposition via the aforementioned bioprinting technologies. [124] Depending on future developments in material research, the topology of organs could be recreated using a cell-supporting biomaterial, thus facilitating cell printing while achieving high-fidelity structure replication Through the development of novel technologies with the aforementioned benefits, a path toward tissue engineering capable of resolution at the single-cell level and of depositing structures indistinguishable from the native counterparts, is being laid but a long road is still ahead of us.…”