Histochemical aspects of the vascular invasion at the erosion zone of the epiphyseal cartilage in MMP-9-deficient mice

Abstract

We have histologically examined vascular invasion and calcification of the hypertrophic zone during endochondral ossification in matrix metalloproteinase (MMP)-9 deficient (MMP-9 −/− ) mice and in their littermates at 3 days, 3 weeks and 6 weeks after birth. Capillaries and osteoclasts at the chondro-osseous junction showed an intense MMP-9 immunopositivity, suggesting that they recognize chemical properties of cartilaginous matrices, and then release MMP-9 for cartilage degradation. CD31-positive capillaries and tartrate-resistant acid phosphatase-reactive osteoclasts could be found in the close proximity in the region of chondro-osseous junction in MMP-9 −/− mice, while in wild-type mice, vascular invasion preceded osteoclastic migration into the epiphyseal cartilage. Although MMP-9 −/− mice revealed larger hypertrophic zones, the index of calcified area was significantly smaller in MMP-9 −/− mice. Interestingly, the lower layer of the MMP-9 −/− hypertrophic zone showed intense MMP-13 staining, which could not be observed in wild-type mice. This indicates that MMP-13 may compensate for MMP-9 deficiency at that specific region, but not to a point at which the deficiency could be completely rescued. In conclusion, it seems that MMP-9 is the optimal enzyme for cartilage degradation during endochondral ossification by controlling vascular invasion and subsequent osteoclastic migration.Endochondral ossification enables the longitudinal growth of long bones, keeping the balance between chondrocyte proliferation and differentiation (i.e., appositional and interstitial growth) and vascular invasion into cartilage prior to bone deposition (12,27). The length of the hypertrophic zone appears to be maintained by two mechanisms: 1) the rate at which chondrocytes enter the hypertrophic phenotype and 2) the pace at which vascular endothelial cells invade the hypertrophic zone of the cartilage. After the formation of calcified cartilage matrices, the process of endochondral ossification involves a well-defined series of events in which osteogenic and osteoclastic cells replace calcified cartilage for bone (2). At an erosion zone, vascular endothelial cells invade and collapse incompletely-calcified transverse partitions of cartilage matrix, making a way for osteoclastic and osteoblastic migration. On the other hand, the longitudinal intercolumnar septae are

Destroy to Rebuild: The Connection Between Bone Tissue Remodeling and Matrix Metalloproteinases

“…This phenotype eventually resolve, resulting in correction of bone growth defects after approximately 4 weeks of age. Vu et al, 1998;Ortega et al, 2003;Nyman et al, 2011;Kojima et al, 2013 Mmp13 −/− Mmp13 −/− (vs. Mmp13 ± ) mice embryos show: (i) progressive changes in the embryonic growth plates (e.g., increased length which persisted in adults), (ii) delayed endochondral ossification, (iii) augmented metaphyseal trabecular bone mass as the mice aged (e.g., 3 months old), (iv) diminished resistance to fracture in long bones, (v) delay in fracture repair, (vi) defective vascular penetration and chondroclast attraction to the fracture callus, (vii) noticeable expression of collagen type X, osteopontin, and VEGF by hypertrophic chondrocytes. Inada et al, 2001;Inada et al, 2002;Inada et al, 2004;Stickens et al, 2004;Kosaki et al, 2007;Tang et al, 2012;Singh et al, 2013 Mmp14 −/− MMP-14 knockout (vs. wild-type) mice show: (i) progressive disturbances (e.g., smaller body size and weight, very high postnatal mortality), possibly caused by deprived feeding and therefore malnutrition, (ii) craniofacial dysmorphism in surviving mice (e.g., short snout, hypertelorism, dome-shaped skull, orbital protrusions, unclosed cranial sutures), (iii) incomplete cartilage remodeling, (iv) impaired formation of secondary ossification centers in the epiphyses, (v) ankylosis resulting from joints with arthritis and other factors (e.g., greater vascularity of the ligaments and tendons, overgrowth of hypercellular and wrongly vascularized synovial tissue), (vi) augmented bone resorption, (vii) osteopenia, (viii) osteoporosis, (ix) dwarfism, (x) mesenchymal stem cells commitment to chondrogenesis and adipogenesis instead of osteogenesis.…”

Histochemical examination on principal collagen fibers in periodontal ligaments of ascorbic acid-deficient ODS-od/od rats

“…To detect acid phosphatase activity, as previously reported [22], histological sections were incubated with a mixture of 2.5 mg of naphthol AS-BI phosphate (Aldrich-Sigma, St. Louis, MO) and 18 mg of red violet LB salt (Sigma) diluted in 30 mL of 0.1 M sodium acetate buffer (pH 5.0) for 15 min at 37°C.…”

Matrix metalloproteinases in bone development and pathology: current knowledge and potential clinical utility

“…33 These knockout mice also demonstrate an accumulation of lengthened hypertrophic chondrocytes at the growth plate, despite normal proliferation of these cells. 33,36 It has been postulated that MMP-9 is required for the cleavage of galectin-3 to prevent accumulation of late hypertrophic chondrocytes. 37 These findings suggest that MMP-9 plays a role in influencing the structural properties of whole bones through its activity at the growth plate during endochondral bone formation.…”