Differential Effects of TGF-beta 1 and TGF-beta 3 on Chondrogenesis in Posterofrontal Cranial Suture-Derived Mesenchymal Cells In Vitro

Background: Transforming growth factor (TGF)-beta 1 has been associated with cranial suture fusion, whereas TGF-beta 3 has been associated with suture patency. The mouse posterofrontal suture, analogous to the human metopic suture, fuses through endochondral ossification. Methods: TGF-beta 1 and TGF-beta 3 expression in the posterofrontal suture was examined by immunohistochemistry. Next, the authors established cultures of suture-derived mesenchymal cells from the posterofrontal suture and examined the cellular responses to TGF-beta 1 and TGF-beta 3. Proliferation in response to TGF-beta isoforms was examined by bromodeoxyuridine incorporation. High-density micromass culture of posterofrontal mesenchymal cells was used to study the effect of TGF-beta 1 and TGF-beta 3 on chondrogenic differentiation. Results: TGF-beta 1 but not TGF-beta 3 protein was highly expressed in chondrocytes within the posterofrontal suture. Significant increases in posterofrontal cell proliferation were observed with TGF-beta 3 but not TGF-beta 1. TGF-beta 1 led to significant increases in chondrogenic-specific gene expression (including Sox9, Col II, Aggrecan, and Col X) as compared with moderate effects of TGF-beta 3. TGF-beta 1 increased cellular adhesion molecule expression (N-cadherin and fibronectin) and promoted cellular condensation, whereas TGF-beta 3 increased cellular proliferation (PCNA expression). Finally, TGF-beta 1 and, to a lesser extent, TGF-beta 3 induced the expression of fibroblast growth factors (FGF-2 and FGF-18). Conclusions: TGF-beta 1 and TGF-beta 3 exhibit marked differences in their effects on chondrogenesis in posterfrontal suture-derived mesenchymal cells, influencing different stages of chondrogenic differentiation. TGF-beta 3 significantly increased cellular proliferation, whereas TGF-beta 1 induced precartilage condensation, promoting chondrocyte differentiation. (Plast. Reconstr. Surg. 123: 31, 2009.)