Transforming Growth Factor Beta Signaling Is Essential for the Autonomous Formation of Cartilage-Like Tissue by Expanded Chondrocytes

Abstract

Cartilage is a tissue with limited self-healing potential. Hence, cartilage defects require surgical attention to prevent or postpone the development of osteoarthritis. For cell-based cartilage repair strategies, in particular autologous chondrocyte implantation, articular chondrocytes are isolated from cartilage and expanded in vitro to increase the number of cells required for therapy. During expansion, the cells lose the competence to autonomously form a cartilage-like tissue, that is in the absence of exogenously added chondrogenic growth factors, such as TGF-βs. We hypothesized that signaling elicited by autocrine and/or paracrine TGF-β is essential for the formation of cartilage-like tissue and that alterations within the TGF-β signaling pathway during expansion interfere with this process. Primary bovine articular chondrocytes were harvested and expanded in monolayer culture up to passage six and the formation of cartilage tissue was investigated in high density pellet cultures grown for three weeks. Chondrocytes expanded for up to three passages maintained the potential for autonomous cartilage-like tissue formation. After three passages, however, exogenous TGF-β1 was required to induce the formation of cartilage-like tissue. When TGF-β signaling was blocked by inhibiting the TGF-β receptor 1 kinase, the autonomous formation of cartilage-like tissue was abrogated. At the initiation of pellet culture, chondrocytes from passage three and later showed levels of transcripts coding for TGF-β receptors 1 and 2 and TGF-β2 to be three-, five- and five-fold decreased, respectively, as compared to primary chondrocytes. In conclusion, the autonomous formation of cartilage-like tissue by expanded chondrocytes is dependent on signaling induced by autocrine and/or paracrine TGF-β. We propose that a decrease in the expression of the chondrogenic growth factor TGF-β2 and of the TGF-β receptors in expanded chondrocytes accounts for a decrease in the activity of the TGF-β signaling pathway and hence for the loss of the potential for autonomous cartilage-like tissue formation.

Combined effects of oscillating hydrostatic pressure, perfusion and encapsulation in a novel bioreactor for enhancing extracellular matrix synthesis by bovine chondrocytes

“…However, as expected, higher levels of Col I were detected in micromass samples, with M+ significantly higher than all other groups but S+. Consistent with previous studies (Hering et al 1994; Tekari et al 2015), we also note that addition of CM caused significant 4.4- and 23- fold increases in Col I expression in micromass (M+) and static scaffold (S+) samples in comparison to the non-CM-stimulated M− and S− counterparts. No such upregulation was observed in samples maintained in more chondrogenic conditions including Pel, S−, the bioreactor with perfusion, and combined perfusion and OHP.…”

Platelet lysate induces chondrogenic differentiation of umbilical cord-derived mesenchymal stem cells

“…In this study, we used PL in the chondrogenic differentiation medium without adding recombinant TGF-β, which is considered a basic and essential factor in chondrogenic differentiation medium [6]. Our results also showed that culturing MSCs in a 3D system as pellets in chondrogenic differentiation medium supplement with 5% PL, without the addition of purified recombinant TGF-β, generated a tissue structure similar to cartilage.…”

“…We showed that 5% PL-supplemented medium with other differentiation components, could direct the differentiation of MSCs to chondrocytes, which might be due to a high concentration of TGF-β in PL, since TGF-β is known to play a key role in the triggering of chondrocyte differentiation [6, 9]. …”

“…All detailed differentiation protocols use transforming growth factor-β (TGF-β) among other components in culture media to direct differentiation of MSCs to chondrocytes, because TGF-β signaling is crucial in chondrogenic differentiation [6, 7]. Recent protocols have focused on developing efficient chondrogenic differentiation conditions: environment, growth factors and types of culture system, including 3D-cultures [8, 9].…”

Effect of Pharmacological Blocking of TLR-4 on Osteoarthritis in Mice

“…Because Tgf-B1 can exhibit a chondroprotective effect, especially immediately following an injury, the dose-increased levels of Tgf-B1 could have ameliorated the destructive effects of increased Mmp-13 as TAK-242 concentration was increased [9,23]. Wild-type mice exhibited lower Tgf-B1 levels at all treatment levels, another possible explanation of more advanced OA in this genotype: Mmp-13 increases were not countered by a chondroprotective increase in Tgf-B1.…”