GAG matrix

Fig. 8. Variation of the skin wound half-life with degradation rate R (in collagenase) of collagen-GAG matrix. The half-life is the time required for a wound to contract to 50% of the original area. The degradation is in empirical units, which are defined in terms of an in vitro assay. A somewhat arbitrary broken vertical line is drawn near R = 140 enzyme units. This line shows the level of degradation rate above which the half-life of matrices rapidly drops to the level of the ungrafted wound. The horizontal scale is logarithmic [79]...

The sclera is composed of collagen fibrils embedded in a glycosaminoglycan (GAG) matrix. Scleral collagen is predominantly type I (7). Collagen types III, V, and VI, VIII, and XII are also found in human sclera (8-12), while the lamina cribrosa... 

Fig. 12. The kinetics of contraction of full-thickness guinea pig skin wounds separate collagen-GAG matrices into three classes. The wound half-life t,/2 is the number of days necessary to reduce the original wound area to 50%. An inactive matrix does not delay wound contraction significantly relative to the ungrafted control and eventually allows formation of a linear scar. An active, cell-free matrix delays wound contraction by about 20 days but eventually allows lull contraction to occur. An active matrix, which has been seeded with a minimal number of skin cells, delays contraction significantly, later arrests it, and eventually induces synthesis of a new dermis and epidermis within an expanding wound perimeter...

It is fairly obvious that the unusual biological activity of certain collagen-GAG matrices is due to specific cell-matrix interactions which take place when these matrices are in contact with the skin wound bed or with the cut end of the nerve. The molecular character of these interactions is currently under study. 

Figure 8. The relationship between force ratio and average fiber spacing. Note the force ratio at nm is 19.6. nm is typical of the average spacing of GAG side chains along a core protein and the effective diameter of the albumin molecule which is known to be sieved by an equivalent matrix in capillary endothelium. This varies between 5 and 12 nm. The force ratio is defined as the ratio of the drag force on the fibers to the shear force on the cell process membrane per unit length of cell process. Previously published in You et al. (2001).

There are several pro-angiogenic factors that promote angiogenesis (Table 2). Those include growth factors, hormone receptor agonists, pro-coagulants, extracellular matrix proteins, or glycosaminoglycans (GAGs). 

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