FLRT2 mediates chondrogenesis of nasal septal cartilage and mandibular condyle cartilage.

Nasal septal cartilages (NSCs) and mandibular condyle cartilages (MCCs) are two important cartilages for craniomaxillofacial development. However, the role of FLRT2 in the formation of NSCs and MCCs remains undiscovered. NSCs and MCCs were used for immunocytochemistry staining of collagen II, toluidine blue staining, and alcian blue staining. Quantitative reverse transcription­PCR and western blot were used to detect mRNA and protein expressions of FLRT2, N-cadherin, collagen II, aggrecan, and SOX9. Cell proliferation of MCCs and NSCs was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell counting kit­8 assay. Cell migration of MCCs and NSCs was examined by wound healing assay and Transwell. Chondrogenesis of MCCs and NSCs were similar in morphological characteristics, while different in cell proliferation, migration, and extracellular matrix. FLRT2 promotes the proliferation and migration of NSCs. There were up-regulation of N-cadherin and down-regulation of collagen II, aggrecan, and SOX9 in NSC with knock down FLRT2. The current study, as demonstrated by Xie et al., reveals that FLRT2 overexpression in Sprague-Dawley neonatal rats promotes the proliferation and migration of NSCs and MCCs, decreases N-cadherin while increases collagen II, aggrecan, and SOX9 in NSC and MCCs. Altogether, FLRT2 mediates chondrogenesis of NSCs and MCCs.

Regenerative Potential of Mandibular Condyle Cartilage and Bone Cells Compared to Costal Cartilage Cells When Seeded in Novel Gelatin Based Hydrogels.

The field of temporomandibular joint (TMJ) condyle regeneration is hampered by a limited understanding of the phenotype and regeneration potential of cells in mandibular condyle cartilage. It has been shown that chondrocytes derived from hyaline and costal cartilage exhibit a greater chondro-regenerative potential in vitro than those from mandibular condylar cartilage. However, our recent in vivo studies suggest that mandibular condyle cartilage cells do have the potential for cartilage regeneration in osteochondral defects, but that bone regeneration is inadequate. The objective of this study was to determine the regeneration potential of cartilage and bone cells from goat mandibular condyles in two different photocrosslinkable hydrogel systems, PGH and methacrylated gelatin, compared to the well-studied costal chondrocytes. PGH is composed of methacrylated poly(ethylene glycol), gelatin, and heparin. Histology, biochemistry and unconfined compression testing was performed after 4 weeks of culture. For bone derived cells, histology showed that PGH inhibited mineralization, while gelatin supported it. For chondrocytes, costal chondrocytes had robust glycosaminoglycan (GAG) deposition in both PGH and gelatin, and compression properties on par with native condylar cartilage in gelatin. However, they showed signs of hypertrophy in gelatin but not PGH. Conversely, mandibular condyle cartilage chondrocytes only had high GAG deposition in gelatin but not in PGH. These appeared to remain dormant in PGH. These results show that mandibular condyle cartilage cells do have innate regeneration potential but that they are more sensitive to hydrogel material than costal cartilage cells.

[Advances in research of microRNA in the growth and development of mandibular condyle cartilage].

MicroRNA (miRNA) are a class of small non-coding single-stranded RNA that exert their biological effects by binding to target messenger RNA (mRNA). There is new evidence that miRNA may play an important role in regulating the growth and development of mandibular condylar cartilage. In this paper, the production and mechanism of miRNA are reviewed, and the progress of studies on the growth and development of mandibular condylar cartilage, which is helpful to further study the growth and development of mandibular condylar cartilage.