Possible formation of cutaneous amyloid from degenerative collagen fibers. Ultrastructural collagen changes and the immunoreactivity of cutaneous amyloidosis employing anti-type I, III, IV, V collagen antibodies

The origins of primary cutaneous amyloid have been investigated and several possibilities are proposed. We investigated here several cases by electron microscopy and found in all cases characteristic filamentous changes which were identical with amyloid structures in the collagen bundles. These observations suggested a possible pathway of cutaneous amyloid formation from degenerative collagen fibers. Further studies were performed using immunoelectron microscopical and immunohistochemical methods employing a panel of anti-collagen antibodies to examine the reactivity of amyloid to them. Our results were much more suggestive of the collagen origin of this kind of amyloid.

Correlation between ageing and collagen gel contractility of human fibroblasts

To investigate the influence of ageing on wound healing, we cultured fibroblasts derived from human dermis in type I collagen gel, and evaluated the relationship between gel contractility and ageing. Cells were obtained from children (0-15 years old, Group A), early adulthood (16-40 years old, Group B), mid-adulthood (41-60 years old, Group C), and the elderly (61 or older, Group D). Gel contractility was determined by measuring the diameter on the second day after gel preparation. Within the tenth passage, gel contraction was the most marked in Group A, but did not differ among the other groups. Gel contraction at passages 30-40 did not differ from those within the tenth passage in Groups B, C and D, but it decreased markedly in Group A to a value similar to that in the other groups. These results show that fibroblasts in childhood are more contractile than those in adulthood and are more readily affected by passages (in vitro ageing).

Contraction phenomenon of type I collagen gel by melanoma cells

In order to study the interaction between melanoma cells and collagen, B16 murine melanoma cells were embedded and cultured in type I collagen gel. Melanoma cells cultured in the collagen gel became elongated, as compared with those cultured on plastic, and some of them assumed a dendritic form. The gel contracted very slowly but steadily during culturing of melanoma cells, as in the experiment using fibroblasts. On the 20th day of culture the area of the gel accounted for only 32% of that when culture started. This contraction was enhanced by retinoic acid, which is known to induce cell differentiation. The contractility of the gel differed between various lines of melanoma cells. The present observations raise the possibility of interaction between melanoma cells and type I collagen.