Extracellular matrix organisation

On the side adjacent to the endothelium the cytoplasm contains a dense meshwork of fine filaments, whereas on the outer surface numerous pi-nocytotic vesicles are observed (Weibel 1974). Pulmonary pericytes influenced the actin distribution of pulmonary microvascular endothelial cells (Shepro and Morel 1993). Pericytes enhanced the formation of a distinct dense peripheral band at microvascular endothelial cell periphery and promoted close apposition of adjacent endothelial cells. Transforming growth factor-P appears to mediate this pericyte-endothehal interaction. The role played by TGF-P is supported by the finding that this agonist modulates extracellular matrix organisation and the formation of tubelike structures with apparent tight junctions in three-dimensional cultures of rat epididymal fat pad microvascular en-dothehal cells (Merwin et al. 1990). 

Vreeland, V. and Laetsch, W.M., A gelling carbohydrate in algal cell wall formation, in Organisation and Assembly of Plant and Animal Extracellular Matrix, Adair, W.S. and Mecham, R.P., Eds., Academic Press, San Diego, CA, 1990, 137. 

Hohenester, E., and J. Engel. 2002. Domain structure and organisation in extracellular matrix proteins. Matrix Biol. 21(2) 115-128. 

Figure 21.9. Primary hBMSC response to GRGD modified alginate-coated capsules at 14 days. Alkaline phosphatase expression is significantly increased in GRGD modified capsules compared to un-modified capsules and a proprietary peptide modified alginate. Histological examination of these same capsules reveal concentrated areas of organised collagen extracellular matrix (n=4).

A further major field of investigation for bioerodihle polymers is their use as scaffolds for tissue engineering. Tissue engineering is the use of a bioerodible polymer as an artificial extracellular matrix, supporting cell growth and organisation and will he discussed in Chapter 4, as it represents a major focus of polyphosphazene research. 

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