In Vitro Mineralization of Collagen

Abstract

certain sponges. [4] In this respect the most important minerals are probably those related to calcium ions (HAp) and silicon ions (amorphous silica). Although many other biominerals are known, such as calcium carbonate and magnetite (iron), these are not encountered with collagen in biological systems. Moreover, even though there is no record of collagen-based calcium carbonate skeletons, the first successful experiments for intrafibrillar mineralization of collagen were achieved for this mineral. [5] The mechanism of formation of calcium carbonate inside collagen, however, may have illuminated that of HAp and silica. The formation of minerals, whether crystalline or amorphous, in or around a collagen template is generally termed collagen mineralization (a misnomer as another compound crystallizes within collagen).The reasoning behind collagen mineralization in vitro is two-fold: 1) understanding the processes behind bone mineralization and 2) mimicking bone tissue via synthetic procedures. Although these are two very different aspects, these often go hand-in-hand. Hence, numerous studies, both in living and synthetic systems, were performed to investigate the processes involved in collagen mineralization. [6] In this paper, we deal with the mineralization of collagen with minerals of calcium and silicon and, to a much lesser extent, other minerals, like yttria-stabilized zirconia and combinations of silica and HAp. In Section 2, we first provide a detailed summary of the molecular structure of collagen type I, the collagen type of interest for mineralization purposes. We provide an overview of collagen-based hybrid materials in nature in Section 3. In Section 4, we first cover the in vitro efforts toward mineralization with calcium carbonate and calcium phosphate (Section 4.1), followed by in vitro silicification (Section 4.2). This section is concluded with mineralization with multiphase minerals and other minerals (Section 4.3). In Section 5, the work reviewed here is placed into perspective. We provide some comments on the mechanisms involved in collagen mineralization and end this section with some concluding remarks and prospects for further research. Collagen Type I General Introduction about CollagenCollagen is a ubiquitous protein in animals. Only among the vertebrates, already 28 different types of collagen can be found. [7] All collagen-containing supramolecular structures in an organism are formed by different types of collagen and Collagen mineralization is a biological process in many skeletal elements in the animal kingdom. Examples of these collagen-based skeletons are the siliceous spicules of glass sponges or the intrafibrillar hydroxyapatite platelets in vertebrates. The mineralization of collagen in vitro has gained interest for two reasons: understanding the processes behind bone formation and the synthesis of scaffolds for tissue engineering. In this paper, the efforts toward collagen mineralization in vitro are reviewed. First, general introduction toward collagen type I, the main compone...

Self-Organization Provides Cell Fate Commitment in MSC Sheet Condensed Areas via ROCK-Dependent Mechanism

“…MSC committed to osteoblasts increase deposition of collagen I [ 90 ] and the latter promotes osteogenic differentiation inducing ALP expression via ERK1/2 pathway [ 54 , 91 ]. Observed formation of bulky mineralized aggregates at differentiation endpoint ( Figure 3 B) is also in line with these findings as far as collagen I is the main mineralization substrate at terminal stages of bone formation [ 92 ]. Specificity of collagen I deposition pattern was supported by contrastingly homogenous distribution of ED A-fibronectin—another ECM protein produced by MSC ( Figure 5 , lower part).…”

Time-Resolved Cryo-TEM Study on the Formation of Iron Hydroxides in a Collagen Matrix

“… 34 For the reaction with only collagen and the reaction with only pAsp ( Supporting Information Section 1, Figures S1.5 and S1.6) as additives, this plateau is significantly shortened, indicating that both collagen and pAsp are binding Fe 3+ . From the length of this plateau, the amount of Fe 3+ binding to collagen or pAsp can be estimated: 30 and 36% of Fe 3+ are bound to the amino acid residues on the outside of the collagen fibril 5 , 38 , 39 or to pAsp, respectively ( Supporting Information Section 1). Working in synergy, during the reaction with both collagen and pAsp as additives, the plateau at pH 3 is almost absent, indicating that almost all of Fe 3+ is bound to collagen and/or pAsp.…”

Advances in biomineralization-inspired materials for hard tissue repair

“…In a landmark review, Tay et al 49 critically commented several well-known mechanisms, including capillary forces, electrostatic interaction, size exclusion, and self-assembly of collagen and apatite; later in 2016, they discovered a novel mechanism on intrafibrillar mineralization from the perspective of Gibbs–Donnan equilibrium. 50 Very recently, With et al 51 thoroughly summarized various approaches of in vitro mineralization of collagen in their detailed review; besides, many experimental parameters and effects of these approaches were kindly listed in tables. These two reviews are highly recommended to readers who expect a comprehensive overview of intrafibrillar mineralization.…”