Abstract
Stereo-tilt immunoelectron microscopy offers a method for analyzing the inter-relationships among components of the subendothelium at the 3 dimensional level. It has been demonstrated that von Willebrand factor (vWF) is important in the process of platelet adhesion following endothelial injury by serving as a bridge between constituents of the vascular subendothelium and platelet membrane receptors. We had previously shown that type VI collagen microfibrils serve as a binding site for vWF in human vascular subendothelium, and immunolabeling studies of vascular tissues by routine transmission electron microscopy showed apparent co-localization of the 2 proteins. We investigated the relationships among vWF, fibrillin and type VI collagen in human vascular subendothelium with double labeling immunogold localization techniques in conjunction with stereo-tilt electron microscopy to examine the 3 dimensional ultrastructure of vWF-microfibril complexes. Our studies confirmed that vWF co-localizes with the type VI collagen microfibrils in subendothelium and not with fibrillin as suggested by others. The vWF is present in subendothelium in the form of electron-dense aggregates having diameters varying between 65-80 nm that decorate the type VI collagen microfibrils and having structural similarities to intracellular Weibel- Palade bodies. The 3 dimensional representations show that the labeling of the 2 molecular species are not necessarily directly adjacent to one another and can be some distance from each other. These results confirm our previous observations on the association between type VI collagen and vWF. Importantly, they also show that colocalization studies where immunolabeling is performed in situ and observed by electron microscopy must be evaluated 3 dimensionally before one can determine conclusively that the 2 components are associated with one another.
Original language | English |
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Pages (from-to) | 205-212 |
Number of pages | 8 |
Journal | Journal of Histotechnology |
Volume | 21 |
Issue number | 3 |
DOIs | |
State | Published - 1998 |
Keywords
- Fibrillin
- Immunoelectron microscopy
- Three dimensional
- Type VI collagen
- Vascular subendothelium
- Von Willebrand factor