The Formation of Fibrils From Collagen Solutions

Abstract

The kinetics of collagen reprecipitation from solutions of salt-extracted calf dermis in the presence of small amounts of mucopolysaccharidc and nucleic acids (0.005 per cent in the final reaction mixture) has been reported by . The present paper is a parallel study using the same materials, and describes the electron microscopic (EM) morphology of the collagen precipitates replicated after 24 hours at room temperature. Satisfactory, uncontaminated EM preparations were obtained which showed that all the deposits were fibrous and bore the 640 A cross-banding characteristic of collagen except some narrow, background fibrils 200 to 1000 A wide precipitated in the presence of heparin. These exhibited fine striations about 220 A apart. Chondroitin sulfate greatly increased the rate of precipitation to give a deposit of low optical density consisting of narrow, rigid, discrete fibrils resembling fresh dermis. In contrast, heparin prevented macroscopic gelation, delayed precipitation, and only produced a scanty deposit of abnormal, short, wide, striated tactoids and compound fibers of varying length. The control preparations and the deposits formed in the presence of hyaluronic acid were intermediate between these two extremes. Delayed precipitation was associated with a coarser deposit and aggregation of the fibrils. A duplicate series of deposits precipitated in the presence of RNA and DNA, together with their controls, were examined after 1~, 1, 1}~, 3, 9, and 24 hours. One set employed an acetic extract of whole calf dermis and the other salt-extracted dermis. The presence of 0.005 per cent DNA in the reaction mixture markedly delayed collagen precipitation with the slow formation of abnormal, short, wide tactoids and compound fibers. RNA also interfered with the quantity and quality of the deposits which contained far less collagen resembling unfixed, normal, adult human dermis, than the controls at the corresponding time intervals. Comparison of the experiments employing whole calf dermis with those employing the salt-extracted material demonstrated that at every time interval in all the experiments the deposits were retarded when salt-extracted dermis was used. This suggests that the saltsoluble components of the dermis play a part in fiber formation.Previous work in this series of experiments (1-3) described the kinetics of collagen precipitation from salt-extracted calf dermis based on a systematic study of the effect of experimental conditions on both the rate of fibril formation and the morphology as seen under the electron microscope. Samples of the identical solutions used for the rate studies revealed that factors which speeded up the precipitation of neutral salt collagen (increased temperature; decreased ionic strength)

Collagen I hydrogel microstructure and composition conjointly regulate vascular network formation

“…Consistent with previous findings, CRM micrographs suggested that cold cast collagen hydrogels contained larger fibers relative to warm cast hydrogels (Fig. 2a) [27], [28], and [29]. Interestingly, the addition of Matrigel appeared to increase fiber size in cold cast collagen hydrogels, while appearing to have no effect under warm cast conditions.…”

Engineering Functional Collagen Scaffolds: Cyclical Loading Increases Material Strength and Fibril Aggregation

“…Although the biochemistry of fibril assembly was largely established 50 years ago, [16,17] many details of how 3D collagen fibril networks assemble, grow and adapt remain elusive. Fibrillogenesis is driven by the formation of short-range non-covalent, ionic, hydrogen and hydrophobic bonds between molecules lying in quarter-stagger register.…”

“…assembly [17] but are limited in explaining the dynamic (remodelling) of matrices. [18] It is assumed here that at least some degree of this cyclical load-dependent fusion process will occur in any new tissue in vivo under load, just as in vitro fibrillogenesis is a simple model of the in vivo process, however the extent of this and its local importance is yet to be tested.…”

Increased glycosaminoglycan accumulation as a genetic characteristic in cell cultures of one variety of dominant dystrophic epidermolysis bullosa.

“…As suggested by McKusick (18), however, in dominant diseases (such as DDEB), an alteration in the synthesis of a critical structural macromolecule might well be expected to be expressed as an abnormal phenotype. In this regard, there is considerable evidence to indicate that glycosaminoglycans interact with collagen to influence both the rate and quality of collagen fibril formation (19). Indeed, whereas some mucopolysaccharides promote fibril formation (20,21), others hinder it (22).…”