In vivo evaluation of bioprinted prevascularized bone tissue

Abstract

Bioprinting can be considered as a progression of the classical tissue engineering approach, in which cells are randomly seeded into scaffolds. Bioprinting offers the advantage that cells can be placed with high spatial fidelity within three-dimensional tissue constructs. A decisive factor to be addressed for bioprinting approaches of artificial tissues is that almost all tissues of the human body depend on a functioning vascular system for the supply of oxygen and nutrients. In this study, we have generated cuboid prevascularized bone tissue constructs by bioprinting human adipose-derived mesenchymal stem cells (ASCs) and human umbilical vein endothelial cells (HUVECs) by extrusion-based bioprinting and drop-on-demand (DoD) bioprinting, respectively. The computer-generated print design could be verified in vitro after printing. After subcutaneous implantation of bioprinted constructs in immunodeficient mice, blood vessel formation with human microvessels of different calibers could be detected arising from bioprinted HUVECs and stabilization of human blood vessels by mouse pericytes was observed. In addition, bioprinted ASCs were able to synthesize a calcified bone matrix as an indicator of ectopic bone formation. These results indicate that the combined bioprinting of ASCs and HUVECs represents a promising strategy to produce prevascularized artificial bone tissue for prospective applications in the treatment of critical-sized bone defects.

Vascularization Strategies in Bone Tissue Engineering

“…These human blood vessels were stabilized by mouse mural cells invading the artificial tissue. Moreover, in these experiments, bioprinted MSCs were able to synthesize a calcified bone matrix as an indicator of ectopic bone formation [101]. Similarly, Leucht and colleagues printed human dermal microvascular endothelial cells (HDMECs) and adipose tissue-derived MSCs in gelatin-based hydrogels by extrusion printing [111].…”

“…As discussed in other parts of this review, bone tissue engineering is making remarkable strides and we are now able to produce constructs which, upon implantation, form perfused blood vessels and produce mineralized matrix [ 101 ]. However, knowledge of common osteogenic and angiogenic processes, types of partners and conditions of co-cultivation as well as modes of interaction between them, are prerequisites for such developments, and these can be gained only by systematic and standardized research under defined conditions.…”

“…These human blood vessels were stabilized by mouse mural cells invading the artificial tissue. Moreover, in these experiments, bioprinted MSCs were able to synthesize a calcified bone matrix as an indicator of ectopic bone formation [ 101 ].…”

3D Bioprinting of Vascularized Tissues for in vitro and in vivo Applications

“…The endothelial cells gave rise to organized microvascular networks of significance at 2 months suggesting that in vivo bioprinting with LAB is an invaluable tool for bone tissue pre-vascularization not only in vitro , but in situ ( Figure 7 ; Kérourédan et al, 2019b ). Rukavina et al (2020) constructed pre-vascularized bone tissue with adipose-derived mesenchymal stem cells (ASCs) and HUVECs. The construct was then implanted subcutaneously in immunodeficient mice ( Rukavina et al, 2020 ).…”

“… Rukavina et al (2020) constructed pre-vascularized bone tissue with adipose-derived mesenchymal stem cells (ASCs) and HUVECs. The construct was then implanted subcutaneously in immunodeficient mice ( Rukavina et al, 2020 ). Not only did new micro-vessels start to develop, the newly formed vessels were stabilized by mouse pericytes, indicating that the pre-vascularized artificial bone tissue can lead to normal bone and vascular development after implantation ( Rukavina et al, 2020 ).…”