Combination of stromal cell-derived factor-1 and collagen-glycosaminoglycan scaffold delays contraction and accelerates reepithelialization of dermal wounds in wild-type mice

Abstract

While dermal substitutes can mitigate scarring and wound contraction, a significant drawback of current dermal replacement technologies is the apparent delay in vascular ingrowth compared with conventional skin grafts. Herein, we examined the effect of the chemokine stromal cell-derived factor-1 (SDF-1) on the performance of a porous collagen-glycosaminoglycan dermal analog in excisional wounds in mice. C57BL/6 mice with 1 cm × 1 cm dorsal full-thickness wounds were covered with a collagen-glycosaminoglycan scaffold, followed by four daily topical applications of 1 μg SDF-1 or phosphate-buffered saline vehicle. Some animals were also pretreated with five daily doses of 300 mg/kg granulocyte colony-stimulating factor. Animals treated with SDF-1 and no granulocyte colony-stimulating factor reepithelialized 36% faster than vehicle controls (16 vs. 25 days), and exhibited less wound contraction on postwounding day 18 (∼ 35% greater wound area) plus three-fold longer neoepidermis formed than controls. Conversely, granulocyte colony-stimulating factor promoted contraction and no epidermal regeneration. Early (postwounding Day 3) inflammatory cell infiltration in the SDF-1-treated group was 86% less, while the fraction of proliferating cells (positive Ki67 staining) was 32% more, when compared with controls. These results suggest that SDF-1 simultaneously delays contraction and promotes reepithelialization and may improve the wound-healing performance of skin substitutes.

Figure 1

Gross morphology of skin wounds grafted with a collagen–GAG scaffold on Day 18 postwounding. Two representative animals are shown for each group.

Figure 2

Wound cross-section harvested on Day 18 postwounding and stained with H&E. (A) SDF-1-treated wound showing intact epidermis over the wound. (B) Control (PBS-treated) wound showing break in the epithelium.

Figure 3

Quantified wound areas on Day 18 postwounding. Data shown are average ± SD of the hair-free areas in the groups shown in Figure 1 above. N=4–5 mice per group. **p < 0.001; ***p < 0.001 compared with the control, respectively.

Figure 4

Contraction distance (A) and neoepidermal length (B) measured on Day 18 postwounding. *p < 0.05; ***p < 0.001 compared with the control. In (A), GCSF and SDF-1 groups are also different from each other at a level of p < 0.001. N=4–5 mice per group. NS: not significantly different from the control.

Figure 5

α-Smooth muscle cell actin (α-SMA) distribution in wound cross-sections on Day 18. (A) Control; (B) GCSF only; (C) SDF-1 only; and (D) GCSF+SDF-1. Note that positive staining of α-SMA (not visible in the GCSF-only group) appears as a reddish brown stain on the tissue section and is pointed out by arrowheads. Bar=100 μm.

Figure 6

Cellular infiltrate seen in H&E-stained wound cross-sections on Day 3 postwounding. (A) Control; (B) GCSF only; (C) GCSF+SDF-1; and (D) SDF-1 only. Bar=10 μm.

Figure 7

Quantification of number of recruited cells in scaffold on Day 3 postwounding. (A) Cell number per high-power field. Data shown are average ± SD. N=5–6 mice per group. ***p < 0.001 compared with the control. (B) Fraction of Ki67-positive cells normalized to the total cell number in the center of the scaffold. Data shown are average±SD. N=5–6 mice per group. *p < 0.05 compared with the control.

Figure 8

Appearance of Masson’s trichrome-stained cross-sections showing collagen fiber organization. (A) Control; (B) GCSF only; (C) GCSF+SDF-1; (D) SDF-1 only; and (E) normal skin. Wound cross-sections are from Day 18 postwounding. Bar=100 μm.