Growth, collagenous tissue

Y. Hiraoka, et al.. In situ regeneration of adipose tissue in rat fat pad by combining a collagen scaffold with gelatin microspheres containing basic fibroblast growth factor. Tissue Eng. 12 (2006) 1475-1487. 

Phase Transition s Control of Collagenous Tissue Growth and Resorption Including Bone... 

Very fundamental involvements of ascorbic acid have been presented, such as its role in the regulation of gene expression or in cell growth and tissue culture. For example, the effects of ascorbic acid on the expression of type I and X collagen genes have been considered. Interactions between ascorbic acid and other redox active micronutrients (vitamin E and selenium) have been discussed. An understanding of the fundamental roles of ascorbic acid will provide a rationale for the biomedical implications of this essential nutrient. 

The properties described above have important consequences for the way in which these skeletal tissues are subsequently preserved, and hence their usefulness or otherwise as recorders of dietary signals. Several points from the discussion above are relevant here. It is useful to ask what are the most important mechanisms or routes for change in buried bones and teeth One could divide these processes into those with simple addition of new non-apatitic material (various minerals such as pyrites, silicates and simple carbonates) in pores and spaces (Hassan and Ortner 1977), and those related to change within the apatite crystals, usually in the form of recrystallization and crystal growth. The first kind of process has severe implications for alteration of bone and dentine, partly because they are porous materials with high surface area initially and because the approximately 20-30% by volume occupied by collagen is subsequently lost by hydrolysis and/or consumption by bacteria and the void filled by new minerals. Enamel is much denser and contains no pores or Haversian canals and there is very, little organic material to lose and replace with extraneous material. Cracks are the only interstices available for deposition of material. 

The ability of these peptidomimetic collagen-structures to adopt triple helices portends the development of highly stable biocompatible materials with collagenlike properties. For instance, it has been found that surface-immobilized (Gly-Pro-Meu)io-Gly-Pro-NH2 in its triple-helix conformation stimulated attachment and growth of epithelial cells and fibroblasts in vitro [77]. As a result, one can easily foresee future implementations of biostable collagen mimics such as these, in tissue engineering and for the fabrication of biomedical devices. 

Abstract Synthetic polymers and biopolymers are extensively used within the field of tissue engineering. Some common examples of these materials include polylactic acid, polyglycolic acid, collagen, elastin, and various forms of polysaccharides. In terms of application, these materials are primarily used in the construction of scaffolds that aid in the local delivery of cells and growth factors, and in many cases fulfill a mechanical role in supporting physiologic loads that would otherwise be supported by a healthy tissue. In this review we will examine the development of scaffolds derived from biopolymers and their use with various cell types in the context of tissue engineering the nucleus pulposus of the intervertebral disc. 

In other studies, mast cells have been shown to be abundant in the marrow of osteoporotic patients, and heparin, which is contained within the secretory granules of connective tissue (peritoneal)-type mast cells, has been shown to enhance bone resorption and to inhibit bone-cell replication and collagen synthesis in vitro [130]. Moreover, heparin is known to bind growth factors such as fibroblast growth factor and may therefore be important in limiting their availability [134], Taken together, these various studies suggest a possible involvement of mast cells in the homeostasis of bone, but much more work is needed before any definitive conclusions can be drawn. 

---