1. Inhibition of Type I Procollagen Production in Photodamage: Correlation Between Presence of High Molecular Weight Collagen Fragments and Reduced Procollagen Synthesis 
James Varani, Patricia Perone, Suzanne E.G. Fligiel 
Journal of Investigative Dermatology 
Volume 119, Issue 1, Pages (July 2002)
DOI: /j x
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

2. Figure 1
Cleavage of type I collagen by human skin organ culture fluid. Intact α1 and α2 chains of type I collagen are observed in control collagen, and are decreased after exposure to either MMP-1 or human skin organ culture fluid. The loss of intact α1 and α2 chains is accompanied by the appearance of 3/4 and 1/4 size fragments. Additional fragments are present in the collagen preparation exposed to the organ culture fluid, but these are minor. (The prominent band in the center of the organ culture fluid lane is a product of the organ culture fluid.)
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

3. Figure 2
Scanning electron microscopic appearance of an intact collagen lattice and a lattice that has been partially degraded by exposure to human skin organ culture fluid.(A) The intact collagen lattice consists of a fine network of interconnected fibers with no apparent broken ends. (B) After partial digestion, the collagen lattice appears to have collapsed, and there is less open space within the lattice. Numerous blunt-ends, indicative of breaks in the collagen chains, are apparent. (C) Breaks are more easily seen at higher magnification (arrows). Original magnification: (A,B) Scale bars: 30 µm, (C) Scale bar: 50 µm.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

4. Figure 3
Collagen contraction and type I procollagen synthesis on partially degraded collagen lattices.Upper panel: contraction of intact and partially degraded collagen by human dermal fibroblasts. Collagen contraction was assessed at day 2 as described in Materials and Methods. Values shown represent the average percent reduction in the diameter of the collagen lattice ± SEM based on five separate experiments. Lower panel: type I procollagen synthesis by human dermal fibroblasts on intact and partially degraded collagen lattices. Values represent average nanograms of type I procollagen per ml ± SEM based on five separate experiments. Prior to assay, culture media volumes from the control and treated groups were adjusted to a common cell number. Statistical significance was determined by ANOVA, followed by paired-group comparisons. *p <0.05; **p <0.01.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

5. Figure 4
Fragmentation of intact type I collagen by MMP-1, MMP-8, or MMP-13. This figure demonstrates the α1 and α2 chains of intact type I collagen after exposure of the substrate to buffer alone for 18 h (collagen). It also demonstrates the loss of intact α1 and α2 chains and the appearance of 3/4 and 1/4 size fragments after exposure of the substrate to either MMP-1 or MMP-8 and the loss of intact α1 and α2 chains and the presence of multiple fragments after exposure of the substrate to MMP-13.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

6. Figure 5
Collagen contraction and inhibition of type I procollagen synthesis on collagen lattices exposed to MMP-1, MMP-8, or MMP-13.Upper panel: collagen contraction was assessed at day 2 as described in Materials and Methods. Values shown represent the average percent reduction in the diameter of the collagen lattice ± SEM based on five separate experiments. Lower panel: type I procollagen synthesis. Values represent average nanograms of type I procollagen per ml ± SEM based on five separate experiments. Prior to assay, culture media volumes from the control and treated groups were adjusted to a common cell number. Statistical significance was determined by ANOVA, followed by paired-group comparisons. *p <0.05; **p <0.01.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

7. Figure 6
Cleavage of type I collagen by various MMP alone or in combination. (A) Cleavage of intact collagen. This figure demonstrates the α1 and α2 chains of intact type I collagen after exposure of the substrate to buffer alone for 18 h. It also demonstrates the loss of intact α1 and α2 chains and the appearance of 3/4 and 1/4 size fragments after exposure of the substrate to MMP-1 but not MMP-2 or MMP-9. (B) Cleavage of heat-denatured collagen (i.e., gelatin). This figure demonstrates the α1 and α2 chains of intact heat-denatured type I collagen after exposure of the substrate to buffer alone for 18 h. Loss of intact α1 and α2 chains and the appearance of multiple smaller fragments are seen after exposure of the substrate to MMP-2 or MMP-9 for 18 h. (C) Cleavage of intact collagen. This figure demonstrates the α1 and α2 chains of intact type I collagen after exposure of the substrate to buffer alone for 18 h. The figure also demonstrates the loss of intact α1 and α2 chains and the appearance of 3/4 and 1/4 size fragments after exposure of the substrate to MMP-1 for 18 h. Finally, the figure demonstrates the ability of MMP-9 (and, to a lesser extent, MMP-2) to induce further degradation of the 3/4 and 1/4 size fragments generated by MMP-1.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

8. Figure 7
Collagen contraction and inhibition of type I procollagen synthesis on collagen lattices exposed to MMP-1 and/or MMP-2 or MMP-9. (A) Collagen contraction was assessed at day 2 as described in Materials and Methods. Values shown represent the average percent reduction in the diameter of the collagen lattice ± SEM based on five separate experiments. (B) Type I procollagen synthesis. Values represent average nanograms of type I procollagen per ml ± SEM based on five separate experiments. Prior to assay, culture media volumes from the control and treated groups were adjusted to a common cell number. Statistical significance was determined by ANOVA, followed by paired-group comparisons. *p <0.05; **p <0.01, ***p <0.001.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

9. Figure 8
Fibroblast attachment and spreading on intact and collagenase-damaged collagen lattices. Collagen lattices were prepared with 0.5 or 0.25 mg of collagen per 0.5 ml volume. Collagen fragmentation was accomplished by exposing lattices to MMP-1 (400 ng of enzyme per 0.5 mg of collagen for a 5 h period). Following this, fibroblasts were added to the collagen lattices. Attachment and spreading were assessed at various times later as indicated in Materials and Methods. Values shown represent the percentage of cells that were attached and the percentage spread ± differences between individual values and averages at each time-point in two separate experiments.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions