The spatiotemporal expression of TGF‐β1 and its receptors during periosteal chondrogenesis in vitro

Abstract

Transforming growth factor-pl (TGF-PI) has been shown to stimulate chondrogenesis in periosteal explants cultured in agarose suspension. TGF-Ps exert their cellular effects through a heteromeric cell membrane receptor complex consisting of TGF-P type I and type I1 receptors. In this study, the spatial and temporal expressions of the type I receptor (TPR-I), type I1 receptor (TPR-11) and endogenous TGF-P1 in periosteal explants cultured in vitro were examined using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The temporal changes in the expression of the TPR-I and TPR-I1 mRNAs correlated with that of TGF-PI. Exogenous administration of TGF-PI upregulated the expression of both receptors and of the TGF-PI ligand in a biphasic pattern. The earlier peak of upregulation was observed at 7 days in culture. A later peak of upregulation was seen at 42 days, at which time cartilage formation reached a maximum. Imniunohistocheniical studies demonstrated co-localization of TPR-I and TPR-I1 simultaneously among the same cells expressing TGF-PI. TGF-P1 treatment increased the expression of TGF-PI, TPR-I and TPR-I1 in mesenchymal cells in the cambium layer at 7 days in culture. Small round chondrocytes showed widely distributed immunoreactivity of TGF-PI, TPR-I and TPR-I1 in the 42-day explants treated with TGF-PI . These observations support the hypothesis that TGF-P1 regulates the initiation and formation of cartilage during periosteal chondrogenesis.

Effects of Cyclic Compressive Loading on Chondrogenesis of Rabbit Bone‐Marrow Derived Mesenchymal Stem Cells

“…This finding is further supported by the observation that TGF-β1 treatment and cyclic compressive loading promoted TGF-β1 gene expression in rabbit BM-MSCs. The effects of TGF-β1 treatment on the endogenous TGF-β1 gene expression found in this study were consistent with a recent finding, which showed that the TGF-β1 gene expression of rabbit periosteal explants increased after the TGF-β1 treatments of 7 and 42 days [26]. Previous studies have also demonstrated that mechanical loading can promote TGF-β1 production in cell cultures [32] and tissues [33,34].…”

“…The TGF-β1 gene expression was also evaluated, since TGF-β1 treatment was shown to promote its gene expression in MSCs that resided in rabbit periosteal grafts [26]. Since compressive loading can transiently modulate the chondrocyte biosynthesis of cartilage-specific macromolecules, a set of specimens (n = 36: four groups per rabbit per time period × 3 rabbits × 3 time periods) were cultured in serum-free medium for 5 extra days after experimentation to account for the transient effects.…”

Temporal evolution of mechanical properties of skeletal tissue regeneration in rabbits: an experimental study

“…The periosteum was left in situ in order to contribute quantitatively and qualitatively to the regeneration process. Indeed, its release from the bone surface triggers the proliferation of the mesenchymal progenitors from its cambium layer [24,28] as well as the emission of growth factors which recruit precursor cells from the neighbour tissue and orientate their differentiation [13,22,29]. Thus, the regenerative process lead to the production of different skeletal elements: bone cartilage or fibrous tissue, according to the environmental variables [3].…”

Identification of chondrocyte proliferation following laser irradiation, thermal injury, and mechanical trauma

“…Positive controls were cultured in growth media containing transforming growth factor beta (TGF-b) (Sigma, St. Louis, MO) (10 mM). TGF-b has been determined to influence chondrocyte differentiation and proliferation, is abundant in articular cartilage, and has been shown to stimulate chondrogenesis in vitro [10,11].…”