Biofabrication of human articular cartilage: a path towards the development of a clinical treatment

Abstract

Cartilage injuries cause pain and loss of function, and if severe may result in osteoarthritis (OA). 3D bioprinting is now a tangible option for the delivery of bioscaffolds capable of regenerating the deficient cartilage tissue. Our team has developed a handheld device, the Biopen, to allow in situ additive manufacturing during surgery. Given its ability to extrude in a core/shell manner, the Biopen can preserve cell viability during the biofabrication process, and it is currently the only biofabrication tool tested as a surgical instrument in a sheep model using homologous stem cells. As a necessary step toward the development of a clinically relevant protocol, we aimed to demonstrate that our handheld extrusion device can successfully be used for the biofabrication of human cartilage. Therefore, this study is a required step for the development of a surgical treatment in human patients. In this work we specifically used human adipose derived mesenchymal stem cells (hADSCs), harvested from the infra-patellar fat pad of donor patients affected by OA, to also prove that they can be utilized as the source of cells for the future clinical application. With the Biopen, we generated bioscaffolds made of hADSCs laden in gelatin methacrylate, hyaluronic acid methacrylate and cultured in the presence of chondrogenic stimuli for eight weeks in vitro. A comprehensive characterisation including gene and protein expression analyses, immunohistology, confocal microscopy, second harmonic generation, light sheet imaging, atomic force mycroscopy and mechanical unconfined compression demonstrated that our strategy resulted in human hyaline-like cartilage formation. Our in situ biofabrication approach represents an innovation with important implications for customizing cartilage repair in patients with cartilage injuries and OA.

3D Bioprinting: from Benches to Translational Applications

“…In 2007, Campbell and Weiss introduced the concept of in situ bioprinting; however, back then it was considered challenging due to the fact that clinicians prefer simple off‐the‐shelf solutions instead of complex bioprinting devices . To overcome this hurdle, several improved and simplified bioprinting systems have been since developed to make in situ bioprinting available to the broader audience and to facilitate its translation into the clinics …”

“…A different strategy for in situ bioprinting, which has already shown promising translation to the clinics, is the use of handheld bioprinting devices . Di Bella et al developed a handheld 3D bioprinting pen (biopen) for the treatment of articular cartilage damage ( Figure A) .…”

Combining Innovative Bioink and Low Cell Density for the Production of 3D-Bioprinted Cartilage Substitutes: A Pilot Study

“…MSC three-dimensional (3D) bioprinting is an emerging technology that is expected to revolutionize the field of regenerative medicine [6,20,[38][39][40], including hyaline articular cartilage engineering [41][42][43][44][45][46][47][48][49][50][51][52]. Previous tissue engineering approaches for cartilage repair usually failed to generate functional tissues recapitulating the zonal organization, extracellular matrix (ECM) content, and biomechanical properties of native cartilage.…”

Human articular cartilage repair: Sources and detection of cytotoxicity and genotoxicity in photo-crosslinkable hydrogel bioscaffolds

“…Nevertheless, the increased efficiency of LAP suggests that shorter light exposure times can yield sufficiently crosslinked hydrogels hence, the reduced viability observed at longer exposure times does not necessarily have a practical implication. Indeed, a short 10 second exposure time of LAP to UV light (365 nm, 700 mW/cm 2 ) produces hardened GelMa‐HAMa scaffolds suitable for cartilage tissue regeneration whereas identical concentrations of other PIs such as Irgacure 2959 and VA‐086 did not achieve the same stiffness even after 2 minutes …”

“…It has higher water solubility compared with Irgacure 2959, thus permits cell encapsulation in PEGDA at lower PI concentrations and shorter light exposure times while maintaining >95% viability of human neonatal fibroblasts. HAMa scaffolds suitable for cartilage tissue regeneration whereas identical concentrations of other PIs such as Irgacure 2959 and VA-086 did not achieve the same stiffness even after 2 minutes 5,62. The use of visible light (>380 nm) with appropriate PIs can increase the safety of the photo-crosslinking process by removing exposure to harmful mutagenic light wavelengths, thus maximizing cell viability and reducing the risk of malignant transformation.…”