The Mineralization of Bone and Its Analogies with Other Hard Tissues

Abstract

Bone is one of the many biological tissues characterized by the still poorly defined process of mineralization, that is, by the deposition of inorganic substance in their organic matrix, and is one that, chiefly due to its important biological functions, but also because of its widespread presence in primates and its easy availability, has been investigated for hundred of years by thousand of investigators (see reviews by [1-3]). Its study, however, is a demanding task, because of the complexity and variability of the tissue-factors that derive mainly from differences in its histological types, biochemical composition, phases of maturation, and degree of mineralization (the terms 'mineralization', 'biomineralization', and 'calcification' are treated as equivalents in this paper; see Bonucci [2]). These differences, although recently emphasized [4-5], have not always received due recognition. In this connection, revealing indicative examples include, for instance, the differences between the compact, lamellar bone and spongy, woven bone [4], or between the dense rostrum bone of toothed whales [6] and the medullary bone of birds [7]. These differences may lead to incorrect interpretations of apparently contrasting results, but may also lead to new insights if they are recognized to derive from distinctive traits of tissues belonging to the same broad type, which is what they are. The concepts that follow, which chiefly focus on the local mechanism of matrix calcification, mainly refer to woven bone, which raises fewer technical issues than compact bone, but they are valid for, and can be extended to, all other types of bone and hard tissue. 2. Historical notes So much research has been carried out on bone mineralization that it is hard to provide an inclusive summary; moreover, research of this kind is often interlaced with that on other cal

Surface-Activated Fibre-Like SBA-15 as Drug Carriers for Bone Diseases

“…The elongated fibrelike domains of SBA-15-R have been covered with (Fig. 7b) showed that in comparison to the samples immersed for 14 days in SBF, the corresponding atomic ratio of Ca/P increased to 1.62, which is close to the Ca/P~1.75 value observed in human bone (32). Figure 8 presents a low-angle XRD pattern of the SBA-15-R both non-immersed and immersed in SBF for 7 and 14 days.…”

“…Finally, after 21 days in SBF, the wide-angle XRD analysis confirmed that the observed spherulites with platelike domains (Fig. 7) are composed of hydroxyapatite featuring crystallinity similar to that of hydroxyapatite present in bone tissue (32). Table I lists the N 2 adsorption/desorption data of SBA-15-R immersed in SBF for various time periods.…”

Historical Review of Biological Apatite Crystallography

“…Thus, sintering enamel or dentin above 800 ℃ gives HA and small amounts of b-TCP varying the b-TCP/HA ratio depending on the portions or individuals 49,95,96) . For the more information of biomineralization concerning to biological apatites, refer the references 60,61,83,[113][114][115][116] .…”

Model of Pathological Collagen Mineralization Based on Spine Ligament Calcification

“…Collagen fibrils occurring in bones demonstrate specific interfibrillar spaces (structural gaps) endowed with an electric charge where the nucleation of bone apatite can be started. Collagen is not a crystallization promoter but the process is assisted by matrix vesicles released from the osteoblast cell membrane [8,9]. The matrix vesicles are rich in proteins, phospholipids, calcium, and inorganic phosphates and provide the right concentration of Ca and P for crystal precipitation.…”

“…The matrix vesicles are rich in proteins, phospholipids, calcium, and inorganic phosphates and provide the right concentration of Ca and P for crystal precipitation. During bone mineralization, collagen fibrils aggregate side by side in a lateral register, their gap zones also come to be in the register, and give rise to transverse, 'electron-dense bands' that cross the collagen bundles [9]. The effect of such fibril aggregation is the creation of electrically charged areas in which the hydroxyapatite crystals are formed.…”