Weight‐bearing alters the expression of collagen types I and II, BMP 2/4 and osteocalcin in the early stages ofdistraction osteogenesis

Distraction osteogenesis has proven to be of great value for the treatment of a variety of musculoskeletal problems. Little is still known, however, about the phenotypic changes in the cells participating in the bone formation process, induced by the procedure. Recent findings of the expression of a contractile muscle actin isoform, a-smooth muscle actin (SMA), in musculoskeletal connective tissue cells prompted this immunohistochemical study of the expression of SMA in cells participating in distraction osteogenesis in a rat model. The tissues within and adjacent to the distraction site could be distinguished histologically on the basis of cell morphology, density, and extracellular matrix make-up. The percentage of SMA-containing cells within each tissue zone was graded from 0 to 4. The majority of the cells in each of the zones stained positive for SMA within five days of the distraction period. The SMA-containing cells included those with elongated morphology in the center of the distraction site and the active osteoblasts on the surfaces of the newly forming bone.These finding warrant further investigation of the role of this contractile actin isoform in distraction osteogenesis and investigation of the effects of modulation of this actin isoform on the procedure.

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“…Table 1 shows the grading for the percentage of SMA-containing cells within each of the zones. 21 (2003) [20][21][22][23][24][25][26][27] …”

Section: Resultsmentioning

confidence: 99%

Expression of smooth muscle actin in cells involved in distraction osteogenesis in a rat model

Kinner

Pacicca

Gerstenfeld

et al. 2003

Journal Orthopaedic Research

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“…Mechanical tension-stress modulates cell shape and phenotype, and stimulates the expression of the mRNA for bone matrix proteins, as well as the assembly of collagen and mineralization during distraction osteogenesis (45)(46)(47). Many experimental data indicate that during active distraction, collagen type-I is expressed in the periosteum and the PMF, whereas collagen type-II transcripts are localized to discrete regions on the periosteal surfaces, immediately adjacent to the osteotomy ends.…”

Section: Collagen and Osteogenic Markersmentioning

confidence: 99%

Angiogenesis and Mineralization During Distraction Osteogenesis

et al. 2002

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Distraction osteogenesis is currently a standard method of bone lengthening. It is a viable method for the treatment of short extremities as well as extensive bone defects, because large amounts of bone can be regenerated in the distraction gap. Mechanical stimulation by distraction induces biological responses of skeletal regeneration that is accomplished by a cascade of biologic processes that may include differentiation of pluripotential tissue, angiogenesis, mineralization, and remodeling. There are complex interactions between bone-forming osteoblasts and other cells present within the bone microenvironment, particularly vascular endothelial cells that may be pivotal members of a complex interactive communication network in bone. Regenerate bone forms by three modes of ossification, which include intramembranous, enchondral, and transchondroid ossifications, although intramembraneous bone formation is the predominant mechanism of ossification. In this review we discussed the coupling between angiogenesis and mineralization, the biological and mechanical factors affecting them, the cellular and molecular events occurring during distraction osteogenesis, and the emerging modalities to accelerate regenerate bone healing and remodeling.

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“…The novel fi xator is based upon external fi xation, which is widely used for distraction osteogenesis (Pacicca et al, 2002;Radomisli et al, 2001;Richards et al, 1999;Sato et al, 1999;Sato et al, 1998;Seebach et al, 2004;Sojo et al, 2005;Yasui et al, 1997), fracture fi xation (Harrison et al, 2003;Kaspar et al, 2007;Mark et al, 2003;Mark et al, 2004;Mark and Rydevik, 2005;McCann et al, 2008;Smith-Adaline et al, 2004) and large defect models in experimental animals (Betz et al, 2006;Cullinane et al, 2002;Cullinane et al, 2003;Dickson et al, 2008;Jager et al, 2005). As well as imposing a controlled and reproducible local mechanical environment, its accessibility allows the modulation of this environment at different stages of healing.…”

Section: Introductionmentioning

confidence: 99%

Design, characterisation and in vivo testing of a new, adjustable stiffness, external fixator for the rat femur

Glatt¹,

Evans²,

Matthys³

2012

eCM

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Very little is known about the infl uence of the mechanical environment on the healing of large segmental defects. This partly refl ects the lack of standardised, well characterised technologies to enable such studies. Here we report the design, construction and characterisation of a novel external fi xator for use in conjunction with rat femoral defects. This device not only imposes a predetermined axial stiffness on the lesion, but also enables the stiffness to be changed during the healing process. The main frame of the fi xator consists of polyethylethylketone with titanium alloy mounting pins. The stiffness of the fi xator is determined by interchangeable connection elements of different thicknesses. Fixators were shown to stabilise 5 mm femoral defects in rats in vivo for at least 8 weeks during unrestricted cage activity. No distortion or infections, including pin infections, were noted. The healing process was simulated in vitro by inserting into a 5 mm femoral defect, materials whose Young's moduli approximated those of the different tissues present in regenerating bone. These studies confi rmed that, although the external fixator is the major determinant of axial stiffness during the early phase of healing, the regenerate within the lesion subsequently dominates this property. There is much clinical interest in altering the mechanics of the defect to enhance bone healing. Our data suggest that, if alteration of the mechanical environment is to be used to modulate the healing of large segmental defects, this needs to be performed before the tissue properties become dominant.

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Weight‐bearing alters the expression of collagen types I and II, BMP 2/4 and osteocalcin in the early stages ofdistraction osteogenesis

Cited by 42 publications

References 33 publications

Expression of smooth muscle actin in cells involved in distraction osteogenesis in a rat model

Expression of smooth muscle actin in cells involved in distraction osteogenesis in a rat model

Angiogenesis and Mineralization During Distraction Osteogenesis

Design, characterisation and in vivo testing of a new, adjustable stiffness, external fixator for the rat femur

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