Typ-I-Kollagen im xenogenen Knochenmaterial reguliert Anbindung und Verbreitung von Osteoblasten über die

Abstract

Xenogenic bone biomaterials have been proposed as an alternative to autografts or allografts in human bone restoring or in complement of prosthetic surgery. When appropriate treatments were applied, immunological, inflammatory, bacteriological or virological adverse responses can be prevented. However, these treatments may interact with type I collagen, the major component of the organic bone matrix. Type I collagen can bind osteoblasts via specific cell surface receptors, the integrins. In this work, two different xenogenic biomaterials were studied. Both biomaterials have a bovine bone origin. They displayed similar architectural organization with connected plates and rods and similar surface topography and roughness. They differed by the presence or not of collagen type I. The first one was characterized by preservation of the type I collagen matrix associated with spindle-shaped hydroxypatite crystals and the second was solely composed by heat-modified apatite crystals. Osteoblast-like cells (Saos-2) were cultured on both biomaterials and examined in scanning and transmission electron microscopy after 7 and 14 days. Both biomaterials were cytocompatible as demonstrated by good ultrastructural cell preservation. (1) At the surface of the collagen containing biomaterial, cells were elongated in shape and oriented according to the trabecular architecture and to the superficial collagen network. After 14 days of culture, cells were confluent and the biomaterial surface was hidden by the cell sheet. The beta 1 integrin subunit was detected by immunogold in transmission electron microscopy in close relationship with the superficial collagen fibres of the biomaterial and with the outer cell surface. When cultures were carried out in presence of anti beta 1 integrin subunit, cells were packed and piled up with lack of specific orientation. (2) At the surface of the deproteinized biomaterial, cells were globular without specific disposition and often partially attached to the surface. After 14 days of culture, large areas of the biomaterial surface remained uncovered. Anti beta 1 subunits conjugated with gold particles were detected around the cells but with no specific association with the deproteinized biomaterial. These results strongly suggest that presence of type I collagen fibres in the matrix of a bone biomaterial is of major interest to determine cell attachment, spreading and orientation via interaction between type I collagen and beta 1 integrin subunit of osteoblasts.

Release kinetics of VEGF165 from a collagen matrix and structural matrix changes in a circulation model

“…Fitted in bony defaults it is not degraded by but incorporated into the regenerating tissue. It accelerates the healing process and reduces the side effects of decomposition products [ 18 , 19 ].…”

Clinical, Radiographic, and Histologic Evaluation of Maxillary Sinus Lift Procedure Using a Highly Purified Xenogenic Graft (Laddec®)

“…Specifically, the b1-subunit is involved in adhesion of osteoblasts to collagen type I and is supposed to play a role in osteoblast morphology. Previous in vitro studies highlighted the importance of preserving the collagen matrix in the xenograft material [ 19 , 20 ]. Comparing two different types of bovine derived bone graft materials, with similar architectural organization, morphological surface topography and roughness index, but with different chemical composition of their matrices, (Laddec ® characterized by preservation of the mineralized collagen matrix, and Bio-Oss ® , characterized by complete deproteinization which only preserves the mineral phase), Balsè et al [ 19 ] reported that osteoblast-like cells cultured at the surface of the two bone xenogenic biomaterials have their orientation mainly influenced by the chemical nature of the underlying surface.…”

“…Unlike other commercially available bovine derived biomaterials in which all the organic phase is chemically removed using ethylene diamine treatment and heating, followed by extensive washing and heating below 600 °C (U.S. patent 5,167,961), Laddec ® is obtained from bovine bone after extensive washing with distilled water and a phosphate buffer (0.4 M, pH 7.4), followed by defatting at a temperature <50 °C with ethanol/dichloromethane and proteoglycan removal by urea and mercaptoethanol (International patent: PCT/WO/91/07194). This process has previously been shown to preserve the collagen type I fibres in the matrix of the xenograft [ 7 ], which seem to play a crucial role in cell attachment, as well as the spreading and orientation of osteoblasts, as collagen type I can bind osteoblasts via specific cell surface receptors, the integrins [ 19 , 20 ]. In addition to the maintenance of the collagen fibres, Laddec ® presents physical characteristics very similar to human cancellous bone, with an average thickness of trabecules of 164.8 (35.1) µm, an intertrabecular separation (porosity) of 342.9 (105.6) µm, and 2 (0.4) trabecules per mm [ 21 ].…”

“…Preclinical studies have already shown the capacity of Laddec ® to stimulate osteoblastic activity, facilitating the formation of multiple cell layers, and to increase the expression of alkaline phosphatase in mesenchymal cell cultures [ 20-22 ].…”