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Matrix metalloproteinase 9 and vascular endothelial growth factor are essential for osteoclast recruitment into developing long bones.

Engsig MT, Chen QJ, Vu TH, Pedersen AC, Therkidsen B, Lund LR, Henriksen K, Lenhard T, Foged NT, Werb Z, DelaissΓ© JM - J. Cell Biol. (2000)

Bottom Line: Hanahan. 2000.Cell Biol. 2:737-744).These observations identify specific actions of MMP-9 and VEGF that are critical for early bone development.

View Article: PubMed Central - PubMed

Affiliation: OSTEOPRO A/S and Center for Clinical and Basic Research, DK-2750 Herlev/Ballerup, Denmark. me@osteopro.dk

ABSTRACT
Bone development requires the recruitment of osteoclast precursors from surrounding mesenchyme, thereby allowing the key events of bone growth such as marrow cavity formation, capillary invasion, and matrix remodeling. We demonstrate that mice deficient in gelatinase B/matrix metalloproteinase (MMP)-9 exhibit a delay in osteoclast recruitment. Histological analysis and specialized invasion and bone resorption models show that MMP-9 is specifically required for the invasion of osteoclasts and endothelial cells into the discontinuously mineralized hypertrophic cartilage that fills the core of the diaphysis. However, MMPs other than MMP-9 are required for the passage of the cells through unmineralized type I collagen of the nascent bone collar, and play a role in resorption of mineralized matrix. MMP-9 stimulates the solubilization of unmineralized cartilage by MMP-13, a collagenase highly expressed in hypertrophic cartilage before osteoclast invasion. Hypertrophic cartilage also expresses vascular endothelial growth factor (VEGF), which binds to extracellular matrix and is made bioavailable by MMP-9 (Bergers, G., R. Brekken, G. McMahon, T.H. Vu, T. Itoh, K. Tamaki, K. Tanzawa, P. Thorpe, S. Itohara, Z. Werb, and D. Hanahan. 2000. Nat. Cell Biol. 2:737-744). We show that VEGF is a chemoattractant for osteoclasts. Moreover, invasion of osteoclasts into the hypertrophic cartilage requires VEGF because it is inhibited by blocking VEGF function. These observations identify specific actions of MMP-9 and VEGF that are critical for early bone development.

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Effect of MMP-9 deficiency on number and distribution of TRAP+ cells in developing metatarsals. Litters of E17, E18, and E19 embryos were obtained from MMP-9+/βˆ’ and MMP-9βˆ’/βˆ’ parents. The embryos were genotyped as MMP-9+/βˆ’ or MMP-9βˆ’/βˆ’. Metatarsal triads were analyzed with respect to number of nuclei of TRAP+ cells localized outside or inside the calcified cartilage. Means Β± SD were calculated for each age group and genotype. Total numbers of embryos were as follows: at E17, 12 MMP-9+/βˆ’ and 11 MMP-9βˆ’/βˆ’ (pool of 3 litters); at E18, 31 MMP-9+/βˆ’ and 20 MMP-9βˆ’/βˆ’ (pool of 7 litters); and at E19, 9 MMP-9+/βˆ’ and 8 MMP-9βˆ’/βˆ’ (pool of 3 litters). Mean counts outside the calcified cartilage are shown by a block to the left of the zero axis, and mean counts inside the calcified cartilage by a block to the right. Each horizontal bar resulting from the alignment of these two blocks represents the mean number of total nuclei in one section of a metatarsal triad. At E18 and E19, MMP-9βˆ’/βˆ’ and MMP-9+/βˆ’ metatarsals differed significantly with respect to both total number of nuclei of TRAP+ cells and their proportion in the calcified cartilage (P < 0.05). In contrast, at E17 no significant differences were found.
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Figure 5: Effect of MMP-9 deficiency on number and distribution of TRAP+ cells in developing metatarsals. Litters of E17, E18, and E19 embryos were obtained from MMP-9+/βˆ’ and MMP-9βˆ’/βˆ’ parents. The embryos were genotyped as MMP-9+/βˆ’ or MMP-9βˆ’/βˆ’. Metatarsal triads were analyzed with respect to number of nuclei of TRAP+ cells localized outside or inside the calcified cartilage. Means Β± SD were calculated for each age group and genotype. Total numbers of embryos were as follows: at E17, 12 MMP-9+/βˆ’ and 11 MMP-9βˆ’/βˆ’ (pool of 3 litters); at E18, 31 MMP-9+/βˆ’ and 20 MMP-9βˆ’/βˆ’ (pool of 7 litters); and at E19, 9 MMP-9+/βˆ’ and 8 MMP-9βˆ’/βˆ’ (pool of 3 litters). Mean counts outside the calcified cartilage are shown by a block to the left of the zero axis, and mean counts inside the calcified cartilage by a block to the right. Each horizontal bar resulting from the alignment of these two blocks represents the mean number of total nuclei in one section of a metatarsal triad. At E18 and E19, MMP-9βˆ’/βˆ’ and MMP-9+/βˆ’ metatarsals differed significantly with respect to both total number of nuclei of TRAP+ cells and their proportion in the calcified cartilage (P < 0.05). In contrast, at E17 no significant differences were found.

Mentions: To investigate whether MMP-9 is actually required in this invasion process, and to characterize its role in osteoclast recruitment by direct observations, we analyzed the effect of MMP-9 deficiency on the numbers and distribution of TRAP+ cells and their nuclei in the metatarsals of E17, E18, and E19 embryos (Fig. 5). At E17, there were only a few TRAP+ cells in the mesenchyme surrounding the bone, and none of them had invaded the calcified cartilage in agreement with earlier reports on the wild-type mice (Blavier and DelaissΓ© 1995). We did not detect differences between MMP-9–positive and MMP-9–negative bones with respect to number, size, and distribution of TRAP+ cells. Thus, there is no indication that MMP-9 has an obligatory role in the differentiation of preosteoclasts into TRAP+ cells before bone invasion.


Matrix metalloproteinase 9 and vascular endothelial growth factor are essential for osteoclast recruitment into developing long bones.

Engsig MT, Chen QJ, Vu TH, Pedersen AC, Therkidsen B, Lund LR, Henriksen K, Lenhard T, Foged NT, Werb Z, DelaissΓ© JM - J. Cell Biol. (2000)

Effect of MMP-9 deficiency on number and distribution of TRAP+ cells in developing metatarsals. Litters of E17, E18, and E19 embryos were obtained from MMP-9+/βˆ’ and MMP-9βˆ’/βˆ’ parents. The embryos were genotyped as MMP-9+/βˆ’ or MMP-9βˆ’/βˆ’. Metatarsal triads were analyzed with respect to number of nuclei of TRAP+ cells localized outside or inside the calcified cartilage. Means Β± SD were calculated for each age group and genotype. Total numbers of embryos were as follows: at E17, 12 MMP-9+/βˆ’ and 11 MMP-9βˆ’/βˆ’ (pool of 3 litters); at E18, 31 MMP-9+/βˆ’ and 20 MMP-9βˆ’/βˆ’ (pool of 7 litters); and at E19, 9 MMP-9+/βˆ’ and 8 MMP-9βˆ’/βˆ’ (pool of 3 litters). Mean counts outside the calcified cartilage are shown by a block to the left of the zero axis, and mean counts inside the calcified cartilage by a block to the right. Each horizontal bar resulting from the alignment of these two blocks represents the mean number of total nuclei in one section of a metatarsal triad. At E18 and E19, MMP-9βˆ’/βˆ’ and MMP-9+/βˆ’ metatarsals differed significantly with respect to both total number of nuclei of TRAP+ cells and their proportion in the calcified cartilage (P < 0.05). In contrast, at E17 no significant differences were found.
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Related In: Results  -  Collection

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Figure 5: Effect of MMP-9 deficiency on number and distribution of TRAP+ cells in developing metatarsals. Litters of E17, E18, and E19 embryos were obtained from MMP-9+/βˆ’ and MMP-9βˆ’/βˆ’ parents. The embryos were genotyped as MMP-9+/βˆ’ or MMP-9βˆ’/βˆ’. Metatarsal triads were analyzed with respect to number of nuclei of TRAP+ cells localized outside or inside the calcified cartilage. Means Β± SD were calculated for each age group and genotype. Total numbers of embryos were as follows: at E17, 12 MMP-9+/βˆ’ and 11 MMP-9βˆ’/βˆ’ (pool of 3 litters); at E18, 31 MMP-9+/βˆ’ and 20 MMP-9βˆ’/βˆ’ (pool of 7 litters); and at E19, 9 MMP-9+/βˆ’ and 8 MMP-9βˆ’/βˆ’ (pool of 3 litters). Mean counts outside the calcified cartilage are shown by a block to the left of the zero axis, and mean counts inside the calcified cartilage by a block to the right. Each horizontal bar resulting from the alignment of these two blocks represents the mean number of total nuclei in one section of a metatarsal triad. At E18 and E19, MMP-9βˆ’/βˆ’ and MMP-9+/βˆ’ metatarsals differed significantly with respect to both total number of nuclei of TRAP+ cells and their proportion in the calcified cartilage (P < 0.05). In contrast, at E17 no significant differences were found.
Mentions: To investigate whether MMP-9 is actually required in this invasion process, and to characterize its role in osteoclast recruitment by direct observations, we analyzed the effect of MMP-9 deficiency on the numbers and distribution of TRAP+ cells and their nuclei in the metatarsals of E17, E18, and E19 embryos (Fig. 5). At E17, there were only a few TRAP+ cells in the mesenchyme surrounding the bone, and none of them had invaded the calcified cartilage in agreement with earlier reports on the wild-type mice (Blavier and DelaissΓ© 1995). We did not detect differences between MMP-9–positive and MMP-9–negative bones with respect to number, size, and distribution of TRAP+ cells. Thus, there is no indication that MMP-9 has an obligatory role in the differentiation of preosteoclasts into TRAP+ cells before bone invasion.

Bottom Line: Hanahan. 2000.Cell Biol. 2:737-744).These observations identify specific actions of MMP-9 and VEGF that are critical for early bone development.

View Article: PubMed Central - PubMed

Affiliation: OSTEOPRO A/S and Center for Clinical and Basic Research, DK-2750 Herlev/Ballerup, Denmark. me@osteopro.dk

ABSTRACT
Bone development requires the recruitment of osteoclast precursors from surrounding mesenchyme, thereby allowing the key events of bone growth such as marrow cavity formation, capillary invasion, and matrix remodeling. We demonstrate that mice deficient in gelatinase B/matrix metalloproteinase (MMP)-9 exhibit a delay in osteoclast recruitment. Histological analysis and specialized invasion and bone resorption models show that MMP-9 is specifically required for the invasion of osteoclasts and endothelial cells into the discontinuously mineralized hypertrophic cartilage that fills the core of the diaphysis. However, MMPs other than MMP-9 are required for the passage of the cells through unmineralized type I collagen of the nascent bone collar, and play a role in resorption of mineralized matrix. MMP-9 stimulates the solubilization of unmineralized cartilage by MMP-13, a collagenase highly expressed in hypertrophic cartilage before osteoclast invasion. Hypertrophic cartilage also expresses vascular endothelial growth factor (VEGF), which binds to extracellular matrix and is made bioavailable by MMP-9 (Bergers, G., R. Brekken, G. McMahon, T.H. Vu, T. Itoh, K. Tamaki, K. Tanzawa, P. Thorpe, S. Itohara, Z. Werb, and D. Hanahan. 2000. Nat. Cell Biol. 2:737-744). We show that VEGF is a chemoattractant for osteoclasts. Moreover, invasion of osteoclasts into the hypertrophic cartilage requires VEGF because it is inhibited by blocking VEGF function. These observations identify specific actions of MMP-9 and VEGF that are critical for early bone development.

Show MeSH
Related in: MedlinePlus