Engineering Human TMJ Discs with Protein-Releasing 3D-Printed Scaffolds

Abstract

The temporomandibular joint (TMJ) disc is a heterogeneous fibrocartilaginous tissue positioned between the mandibular condyle and glenoid fossa of the temporal bone, with important roles in TMJ functions. Tissue engineering TMJ discs has emerged as an alternative approach to overcoming limitations of current treatments for TMJ disorders. However, the anisotropic collagen orientation and inhomogeneous fibrocartilaginous matrix distribution present challenges in the tissue engineering of functional TMJ discs. Here, we developed 3-dimensional (3D)-printed anatomically correct scaffolds with region-variant microstrand alignment, mimicking anisotropic collagen alignment in the TMJ disc and corresponding mechanical properties. Connective tissue growth factor (CTGF) and transforming growth factor beta 3 (TGFβ3) were then delivered in the scaffolds by spatially embedding CTGF- or TGFβ3-encapsulated microspheres (µS) to reconstruct the regionally variant fibrocartilaginous matrix in the native TMJ disc. When cultured with human mesenchymal stem/progenitor cells (MSCs) for 6 wk, 3D-printed scaffolds with CTGF/TGFβ3-µS resulted in a heterogeneous fibrocartilaginous matrix with overall distribution of collagen-rich fibrous structure in the anterior/posterior (AP) bands and fibrocartilaginous matrix in the intermediate zone, reminiscent of the native TMJ disc. High dose of CTGF/TGFβ3-µS (100 mg µS/g of scaffold) showed significantly more collagen II and aggrecan in the intermediate zone than a low dose (50 mg µS/g of scaffold). Similarly, a high dose of CTGF/TGFβ3-µS yielded significantly higher collagen I expression in the AP bands compared with the low-dose and empty µS. From stress relaxation tests, the ratio of relaxation modulus to instantaneous modulus was significantly smaller with CTGF/TGFβ3-µS than empty µS. Similarly, a significantly higher coefficient of viscosity was achieved with the high dose of CTGF/TGFβ3-µS compared with the low-dose and empty µS, suggesting the dose effect of CTGF and TGFβ3 on fibrocartilage formation. Together, our findings may represent an efficient approach to engineering the TMJ disc graft with anisotropic scaffold microstructure, heterogeneous fibrocartilaginous matrix, and region-dependent viscoelastic properties.

Tendon stem/progenitor cells regulate inflammation in tendon healing via JNK and STAT3 signaling

“…Nonspecific reactive sites were masked by incubating tissue slides for 90 min with 5% bovine serum albumin with 1% normal serum, followed by incubating the slides overnight at 4°C with primary antibodies at 1:100 dilution. Slides were then washed 5 times (5 min each time) with 0.1% Tween solution, incubated with secondary antibody or antibodies in the dark at room tempera- (21,39). Randomly selected tissue sections (n = 10 each group) were used for all the quantitative analyses.…”

Nanoscale and Macroscale Scaffolds with Controlled-Release Polymeric Systems for Dental Craniomaxillofacial Tissue Engineering

“…3D printing allows for even more custom fabrication of these biomaterial systems with complex topologies. Legemate K et al describe generation of TMJ fibrocartilage using CTGF and TGF-β3 within PLGA microspheres, during PCL electrospinning, to promote MSC differentiation [162]. These strategies indicate engineering components or the complete TMJ may be clinically feasible in the near future.…”

Recent Tissue Engineering Advances for the Treatment of Temporomandibular Joint Disorders

“…Scaffolds used in TMJ disc tissue engineering include alginate hydrogels [71], polylactic acid (PLA) [72], polyglycolic acid (PGA) [71, 73, 74, 20], poly–L–lacticacid (PLLA) [75], decellularized native ECM materials [76], polytetrafluoroethylene (ePTFE) monofilaments [77], poly (glycerol sebacate) (PGS) [78], and, recently, polycaprolactone (PCL) polyester [79••]. As noted above, scaffold characteristics must be tailored to the cell types used to engineer the tissue.…”

“…Toward this end, additive manufacturing was used to 3D print PCL scaffolds with an anisotropic internal structure [79••]. Seeded with mesenchymal stem cells (MSCs), anisotropic properties were observed.…”