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Fibroblasts were derived from dermis and scar of a 47-year-old white man with a recurrent incisional hernia as a result of fractured ribs. The scar was thin and stretched, suggesting a defect in the maturation of granulation tissue. After surgical repair, biopsy specimens of discarded scar and skin were used to generate fibroblast cell lines. Fibroblasts maintained in medium containing 10% fetal bovine serum and antibiotic were studied between their third and eighth passage. By phase contrast microscopy, no structural differences were obvious, but it was noted that to pass scar fibroblasts, a more aggressive trypsin regimen was required. Immunohistologic and Western blot analysis of patient scar fibroblasts showed (1) more a smooth muscle actin within stress fibers, (2) increased expression of the vitronectin integrin receptor alpha(v) (CD 51), and (3) reduced expression of the collagen integrin receptor alpha2 (CD 49b). The expression of vinculin from focal adhesions or a tubulin from microtubules was the same among cell lines. Contractions of scar and dermal fibroblast-populated collagen lattice were compared. At 24 hours, contractions were 69 percent with newborn fibroblasts (normal); 68 percent for patient dermal fibroblasts; and only 48 percent for patient scar fibroblasts. The retarded contraction of scar fibroblast-populated collagen lattice was significant (p > or = 0.002). Myosin ATPase activity, critical for lattice contraction, and cell migration were equivalent among all cell lines. A plausible mechanism for the retardation of scar lattice contraction is disruption of fibroblasts and collagen interactions, for which the attachment of cells to collagen is altered. It is proposed that either the decrease in the expression of collagen integrin receptor alpha2 (CD 49b), an increase in the expression of the vitronectin receptor alpha(v) (CD 51), or a combination of both is responsible for disruption of collagen fibroblast interactions.

The experimental model reported here was developed initially to examine the possibility of in utero coverage of congenital soft tissue defects using several types of reconstructive techniques. To pursue this, full-thickness skin grafts, pedicle flaps, and skin "islands" were fashioned on the backs of fetal rabbits; equivalent adult control wounds were also created. While all pedicle flaps and skin islands remained viable, none of the full-thickness grafts survived in the fetus. All adult control flaps, skin islands, and skin grafts were viable. Angiogenesis is crucial to full-thickness skin graft survival. These observations suggest that the death of full-thickness fetal skin grafts may be related to a failure of neovascularization in the graft bed. Further analysis using this model may help elucidate the factors involved in fetal angiogenesis. Additionally, this model may permit testing of putative angiogenic factors applied under a full-thickness skin graft; graft survival offers an easy, objective, and quantifiable means of data analysis.

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Introduction: Fetal mouse skin wounds heal without scar before gestational day E17. Because scarless repair is inherent to fetal skin and occurs superimposed on skin differentiation, genome‐wide gene expression during skin development was tested. Methods: Dorsal skin from BALB/C mice fetuses at E14, E15, E18 and E20 was collected. RNAs from individual fetuses were hybridized to mouse microarrays with 42,000 gene elements. The E14/E18 hybridizations were repeated three times, and the E15/E20 repeated twice with different samples. (“x” = fold change). Results: Increased genes on E18 and E20 were clustered into several groups: 1) ECMs: type I (2.8x), III (2.3x), VI, and XIV procollagens; 2) Cell surface: integrin beta1 binding protein2 (5.2x), integral membrane protein2A and 2B (avg 3.8x); 3) Proteases: mast cell protease4 (15x) and 5 (24x), MMP23 (3x); 4) Growth factor‐related: acidic FGF (3.7x), FGF receptor3 (2.9x), TGF‐alpha (2.3x). Decreased genes on E18 and E20 included: 1) Growth factors: TGF‐beta2 (0.42x), PDGF‐alpha (0.41x), PDGF receptor‐beta (0.37x), NGF receptor associated protein (0.18x); 2) Proteases: MMP 11 (0.27x), 14 (0.39x); 3) ECM: fibromodulin (0.5x), Vcam1 (0.22x), keratin18 (0.2x) and 19 (0.46x), collagen XVIII (0.36x). Conclusions: Genes with increased expression at E14, E15 and decreased expression at E18, E20 have possible antifibrotic function. These data identify hundreds of possible anti‐fibrotic and pro‐fibrotic genes as candidates for further functional analysis as regulators of repair. Supported by NIH DE00463–03