3D bioassembly of cell-instructive chondrogenic and osteogenic hydrogel microspheres containing allogeneic stem cells for hybrid biofabrication of osteochondral constructs

Abstract

Recently developed modular bioassembly techniques hold tremendous potential in tissue engineering and regenerative medicine, due to their ability to recreate the complex microarchitecture of native tissue. Here, we developed a novel approach to fabricate hybrid tissue-engineered constructs adopting high-throughput microfluidic and 3D bioassembly strategies. Osteochondral tissue fabrication was adopted as an example in this study, because of the challenges in fabricating load bearing osteochondral tissue constructs with phenotypically distinct zonal architecture. By developing cell-instructive chondrogenic and osteogenic bioink microsphere modules in high-throughput, together with precise manipulation of the 3D bioassembly process, we successfully fabricated hybrid engineered osteochondral tissue in vitro with integrated but distinct cartilage and bone layers. Furthermore, by encapsulating allogeneic umbilical cord blood-derived mesenchymal stromal cells (UCB-MSCs), and demonstrating chondrogenic and osteogenic differentiation, the hybrid biofabrication of hydrogel microspheres in this 3D bioassembly model offers potential for an off-the-shelf, single-surgery strategy for osteochondral tissue repair.

3D‐Bioassembly of VH‐Spheroids for Cartilage Regeneration: in Vitro Evaluation of Chondrogenesis, Fusion and Lateral Integration

“…[70][71][72] Furthermore, successful 3D-bioassembly of osteogenic and chondrogenic hydrogel microspheres in 3D-printed thermoplastic scaffolds to biofabricate osteochondral constructs confirms the applicability of modular building blocks in bottom-up TE strategies. [73] Subsequently, populating these mechanically strong thermoplastic scaffolds with living VH tissue units holds the potential to biofabricate complex and large lesion size tissues on a clinical scale, [6] providing a unique platform for healthy cartilage ECM production both within the building block and at the tissue-tissue interface.…”

Review on Bioinspired Design of ECM-Mimicking Scaffolds by Computer-Aided Assembly of Cell-Free and Cell Laden Micro-Modules

“…Bone tissue scaffolds were obtained by heat or the chemical sintering of thermoplastic polymeric microspheres, such as PCL and PLGA [ 13 , 97 ]. Biological sintering, such as that modulated by cells/cells and cells/ECM interlocking, may allow for the better preservation of cellular viability and, therefore, was used to obtain hybrid cell/material constructs from cell laden modules [ 79 , 88 , 98 , 99 ]. Nevertheless, bio-constructs prepared by the random assembly of these modules rarely replicate the hierarchical architecture of native tissues, and therefore new advanced CAD approaches were recently proposed to fabricate bioconstructs based on in silico pre-defined patterns.…”

“…The second group of modular strategies described in this review uses hybrid bioprinting approaches involving the integration of cell-laden microspheres and/or tissue spheroids within the pores of a CAD scaffold made of a thermoplastic synthetic polymer ( Figure 5 ) [ 24 , 99 , 117 , 118 , 119 , 120 ].…”

“…The skeleton structure of the thermoplastic polymer, typically PCL, is used to minimize the forces that the upper layers of the bioink impart on the underlying layers, thereby stabilizing the size and structure of the sample. Woodfield and co-workers used this strategy to fabricate hybrid tissue-engineered constructs for cartilage and osteochondral tissue [ 99 , 118 , 120 ]. A similar approach using tissue spheroids made of two different cell populations was used to replicate the zonal organization of chondrocytes in native cartilage tissue [ 117 ].…”

“…Aspects of the printing process that could cause the structure of the spheroid to be compromised during processing have been addressed in the literature. In order to bioassemble the cell-laden modules into a pre-printed and mechanically stable thermoplastic scaffold lattice, the shape fidelity of the modules should be carefully designed to match lattice pores size, while automated module handling must ensure the maintenance of the cell viability and specific differentiation capacity [ 24 , 99 ]. The automated bioassembly of tissue spheroids using fluidic handling and bioprinters is extremely advantageous if compared with manual placement, as it may allow to develop completely automated 3D in vitro tissue models for medium- or high-throughput screening [ 121 ].…”