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Inhibition of TGF-β signaling in mesenchymal stem cells of subchondral bone attenuates osteoarthritis.

Zhen G, Wen C, Jia X, Li Y, Crane JL, Mears SC, Askin FB, Frassica FJ, Chang W, Yao J, Carrino JA, Cosgarea A, Artemov D, Chen Q, Zhao Z, Zhou X, Riley L, Sponseller P, Wan M, Lu WW, Cao X - Nat. Med. (2013)

Bottom Line: There is no effective medical therapy for the condition because of limited understanding of its pathogenesis.High concentrations of TGF-β1 induced formation of nestin-positive mesenchymal stem cell (MSC) clusters, leading to formation of marrow osteoid islets accompanied by high levels of angiogenesis.We found that transgenic expression of active TGF-β1 in osteoblastic cells induced osteoarthritis, whereas inhibition of TGF-β activity in subchondral bone attenuated the degeneration of articular cartilage.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.

ABSTRACT
Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for the condition because of limited understanding of its pathogenesis. We show that transforming growth factor β1 (TGF-β1) is activated in subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) mouse model of osteoarthritis. TGF-β1 concentrations are also high in subchondral bone from humans with osteoarthritis. High concentrations of TGF-β1 induced formation of nestin-positive mesenchymal stem cell (MSC) clusters, leading to formation of marrow osteoid islets accompanied by high levels of angiogenesis. We found that transgenic expression of active TGF-β1 in osteoblastic cells induced osteoarthritis, whereas inhibition of TGF-β activity in subchondral bone attenuated the degeneration of articular cartilage. In particular, knockout of the TGF-β type II receptor (TβRII) in nestin-positive MSCs led to less development of osteoarthritis relative to wild-type mice after ACLT. Thus, high concentrations of active TGF-β1 in subchondral bone seem to initiate the pathological changes of osteoarthritis, and inhibition of this process could be a potential therapeutic approach to treating this disease.

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Local subchondral administration of TGF–β antibody reduced abberant subchondral bone formation and articular cartilage degeneration in ACLT rats(a) Three dimensional μCT images of tibia subchondral bone medial compartment (sagittal view) in rats that underwent sham (Sham) or ACLT surgery with implantation of an alginate bead containing either vehicle (Vehicle) or TGF–β antibody (Antibody) 3 months post surgery. Scale bar, 1 mm. (b–d) Quantitative analysis of structural parameters of subchondral bone by μCT analysis: thickness of subchondral bone plate (SBP), trabecular pattern factor (Tb. Pf) and connectivity density (Conn. Dn). (e) Immunohistochemical and quantitative analysis of osterix (brown). Scale bars, 100 μm. (f) Sanfranin O–fast green staining of sagittal sections of subchondral tibia medial compartment, scale bar, 400 μm. (g) OARSI scores. (h) Immunofluorescent or immunohistochemical and quantitative analysis of type X collagen (green,) and MMP13 (brown) in articular cartilage. DAPI stains nuclei (blue) (center). Scale bars, 200 μm. n = 8; *P < 0.05, **P < 0.01 vs. sham, #P < 0.05 vs. vehicle ACLT rats.
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Figure 5: Local subchondral administration of TGF–β antibody reduced abberant subchondral bone formation and articular cartilage degeneration in ACLT rats(a) Three dimensional μCT images of tibia subchondral bone medial compartment (sagittal view) in rats that underwent sham (Sham) or ACLT surgery with implantation of an alginate bead containing either vehicle (Vehicle) or TGF–β antibody (Antibody) 3 months post surgery. Scale bar, 1 mm. (b–d) Quantitative analysis of structural parameters of subchondral bone by μCT analysis: thickness of subchondral bone plate (SBP), trabecular pattern factor (Tb. Pf) and connectivity density (Conn. Dn). (e) Immunohistochemical and quantitative analysis of osterix (brown). Scale bars, 100 μm. (f) Sanfranin O–fast green staining of sagittal sections of subchondral tibia medial compartment, scale bar, 400 μm. (g) OARSI scores. (h) Immunofluorescent or immunohistochemical and quantitative analysis of type X collagen (green,) and MMP13 (brown) in articular cartilage. DAPI stains nuclei (blue) (center). Scale bars, 200 μm. n = 8; *P < 0.05, **P < 0.01 vs. sham, #P < 0.05 vs. vehicle ACLT rats.

Mentions: To validate the role of TGF–β in the subchondral bone at the onset of osteoarthritis, we implanted TGF–β antibody (1D11)38,39 in alginate beads40,41 directly in the tibial subchondral bone of rat ACLT joints. The knee joints were harvested 3 months post surgery. Similar to systemic use of TβRI inhibitor, the micro–architecture of the bone was improved with local application of the antibody as compared to that of vehicle–treated ACLT rats (Fig. 5a–d). The number of osterix+ progenitor clusters in bone marrow cavity of rat ACLT joints was significantly less in antibody treated rats compared to that of the vehicle–treated rats (Fig. 5e). Notably, degeneration of articular cartilage was attenuated as reflected in OARSI scores by administration of the antibody in the subchondral bone (Fig. 5f(top), g). Moreover, the percentages of MMP13+ and type X collagen+ chondrocytes were significantly reduced, indicating protection from degeneration of articular cartilage (Fig. 5f). In contrast, MMP13 and ColX expression were not reduced significantly with systemic injection of TβRI inhibitor (Fig. 3g, h) since TGF–β is essential for homeostasis of articular cartilage. Therefore, specific administration of TGF–β antibody in the subchonbdral bone reduced aberrant bone formation, but did not inhibit TGF–β signaling in articular cartilage. The protective effect on articular cartilage in our rat osteoarthritis model was primarily through improvement of subchondral bone by site–specific administration of TGF–β antibody. The results further validate that the role of TGF–β in the subchondral bone is distinct from its role in articular cartilage; high concentrations of active TGF–β1 in the subchondral bone induced abnormal bone formation leading to development of osteoarthritis.


Inhibition of TGF-β signaling in mesenchymal stem cells of subchondral bone attenuates osteoarthritis.

Zhen G, Wen C, Jia X, Li Y, Crane JL, Mears SC, Askin FB, Frassica FJ, Chang W, Yao J, Carrino JA, Cosgarea A, Artemov D, Chen Q, Zhao Z, Zhou X, Riley L, Sponseller P, Wan M, Lu WW, Cao X - Nat. Med. (2013)

Local subchondral administration of TGF–β antibody reduced abberant subchondral bone formation and articular cartilage degeneration in ACLT rats(a) Three dimensional μCT images of tibia subchondral bone medial compartment (sagittal view) in rats that underwent sham (Sham) or ACLT surgery with implantation of an alginate bead containing either vehicle (Vehicle) or TGF–β antibody (Antibody) 3 months post surgery. Scale bar, 1 mm. (b–d) Quantitative analysis of structural parameters of subchondral bone by μCT analysis: thickness of subchondral bone plate (SBP), trabecular pattern factor (Tb. Pf) and connectivity density (Conn. Dn). (e) Immunohistochemical and quantitative analysis of osterix (brown). Scale bars, 100 μm. (f) Sanfranin O–fast green staining of sagittal sections of subchondral tibia medial compartment, scale bar, 400 μm. (g) OARSI scores. (h) Immunofluorescent or immunohistochemical and quantitative analysis of type X collagen (green,) and MMP13 (brown) in articular cartilage. DAPI stains nuclei (blue) (center). Scale bars, 200 μm. n = 8; *P < 0.05, **P < 0.01 vs. sham, #P < 0.05 vs. vehicle ACLT rats.
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Figure 5: Local subchondral administration of TGF–β antibody reduced abberant subchondral bone formation and articular cartilage degeneration in ACLT rats(a) Three dimensional μCT images of tibia subchondral bone medial compartment (sagittal view) in rats that underwent sham (Sham) or ACLT surgery with implantation of an alginate bead containing either vehicle (Vehicle) or TGF–β antibody (Antibody) 3 months post surgery. Scale bar, 1 mm. (b–d) Quantitative analysis of structural parameters of subchondral bone by μCT analysis: thickness of subchondral bone plate (SBP), trabecular pattern factor (Tb. Pf) and connectivity density (Conn. Dn). (e) Immunohistochemical and quantitative analysis of osterix (brown). Scale bars, 100 μm. (f) Sanfranin O–fast green staining of sagittal sections of subchondral tibia medial compartment, scale bar, 400 μm. (g) OARSI scores. (h) Immunofluorescent or immunohistochemical and quantitative analysis of type X collagen (green,) and MMP13 (brown) in articular cartilage. DAPI stains nuclei (blue) (center). Scale bars, 200 μm. n = 8; *P < 0.05, **P < 0.01 vs. sham, #P < 0.05 vs. vehicle ACLT rats.
Mentions: To validate the role of TGF–β in the subchondral bone at the onset of osteoarthritis, we implanted TGF–β antibody (1D11)38,39 in alginate beads40,41 directly in the tibial subchondral bone of rat ACLT joints. The knee joints were harvested 3 months post surgery. Similar to systemic use of TβRI inhibitor, the micro–architecture of the bone was improved with local application of the antibody as compared to that of vehicle–treated ACLT rats (Fig. 5a–d). The number of osterix+ progenitor clusters in bone marrow cavity of rat ACLT joints was significantly less in antibody treated rats compared to that of the vehicle–treated rats (Fig. 5e). Notably, degeneration of articular cartilage was attenuated as reflected in OARSI scores by administration of the antibody in the subchondral bone (Fig. 5f(top), g). Moreover, the percentages of MMP13+ and type X collagen+ chondrocytes were significantly reduced, indicating protection from degeneration of articular cartilage (Fig. 5f). In contrast, MMP13 and ColX expression were not reduced significantly with systemic injection of TβRI inhibitor (Fig. 3g, h) since TGF–β is essential for homeostasis of articular cartilage. Therefore, specific administration of TGF–β antibody in the subchonbdral bone reduced aberrant bone formation, but did not inhibit TGF–β signaling in articular cartilage. The protective effect on articular cartilage in our rat osteoarthritis model was primarily through improvement of subchondral bone by site–specific administration of TGF–β antibody. The results further validate that the role of TGF–β in the subchondral bone is distinct from its role in articular cartilage; high concentrations of active TGF–β1 in the subchondral bone induced abnormal bone formation leading to development of osteoarthritis.

Bottom Line: There is no effective medical therapy for the condition because of limited understanding of its pathogenesis.High concentrations of TGF-β1 induced formation of nestin-positive mesenchymal stem cell (MSC) clusters, leading to formation of marrow osteoid islets accompanied by high levels of angiogenesis.We found that transgenic expression of active TGF-β1 in osteoblastic cells induced osteoarthritis, whereas inhibition of TGF-β activity in subchondral bone attenuated the degeneration of articular cartilage.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.

ABSTRACT
Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for the condition because of limited understanding of its pathogenesis. We show that transforming growth factor β1 (TGF-β1) is activated in subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) mouse model of osteoarthritis. TGF-β1 concentrations are also high in subchondral bone from humans with osteoarthritis. High concentrations of TGF-β1 induced formation of nestin-positive mesenchymal stem cell (MSC) clusters, leading to formation of marrow osteoid islets accompanied by high levels of angiogenesis. We found that transgenic expression of active TGF-β1 in osteoblastic cells induced osteoarthritis, whereas inhibition of TGF-β activity in subchondral bone attenuated the degeneration of articular cartilage. In particular, knockout of the TGF-β type II receptor (TβRII) in nestin-positive MSCs led to less development of osteoarthritis relative to wild-type mice after ACLT. Thus, high concentrations of active TGF-β1 in subchondral bone seem to initiate the pathological changes of osteoarthritis, and inhibition of this process could be a potential therapeutic approach to treating this disease.

Show MeSH
Related in: MedlinePlus