Characterisation of collagen VI within the islet-exocrine interface of the human pancreas: implications for clinical islet isolation?

BACKGROUND: To optimize the methods used for human islet isolation for transplantation, it is important to improve our understanding of the structure of the islet-exocrine interface. In this study, the composition of collagen subtypes in the interface have been characterized and quantified in human pancreas. METHODS: Human adult pancreases were retrieved from older (mean age 55.7+/-3.0 yrs) and young donors (mean age 21.8+/-3.2 yrs). Tissue from the body of each pancreas was examined by quantitative immunohistochemistry. Collagen within the islet-exocrine interface was identified by immunolabeling for collagen I, IV, V or VI and islets identified either morphologically or by immunolabeling for insulin. Collagen subtypes were quantified and data expressed as collagen area at the interface relative to the islet area. Statistical analysis was by ANOVA or Mann Whitney U test. RESULTS: In older pancreases, collagen IV, V and VI were present throughout the islet-exocrine interface, whereas collagen I was more variable. The mean peri-islet collagen VI proportion was significantly greater than that of collagen I or IV. Mean islet area and the proportional collagen VI content in specimens from younger subjects were not significantly different to those in older subjects. CONCLUSIONS: Collagen VI is a major component of the islet-exocrine interface of the adult pancreas, the content being more than double that of collagen I or IV. However, the proportional collagen VI content was not dependent on the age of the donor. These data may facilitate the design of new collagenases, targeting major substrates such as collagen VI in order to improve clinical islet isolation.