Adipose-derived stromal vascular fraction aids epithelialisation and angiogenesis in an animal model

OBJECTIVE

Limited data exist regarding the correlation between adipose-derived stromal vascular fraction (SVF) and wound healing. The aim of this study was to investigate the direct effect of intradermally injected SVF on full-thickness cutaneous wounds in a murine model.

METHOD

Wistar rats were divided into three groups (A, B and C) according to their day of euthanasia (day 7, 16 and 21). Inguinal fat pad was excised and SVF enzymatically extracted. Full-thickness cutaneous wounds were created on each side of the dorsum; SVF injected intradermally at one side while the contralateral wound served as control receiving normal saline. Postoperatively, evaluation of wound healing was performed by planimetry (percentages of wound contraction, epithelialisation and total wound healing) on days 0, 3, 5, 7, 10, 13, 16 and 21, and histology and immunochemistry (cellular infiltration score, collagen production score, neoangiogenesis and epithelial thickness) on days 7, 16 and 21.

RESULTS

Despite the high rate of wound contraction, it was significantly lower in the SVF-treated wounds on day 21 (p=0.037). On days 13, 16 and 21, the percentages of epithelialisation were higher in the SVF-treated wounds compared with control wounds (p=0.026, p=0.048 and p=0.05, respectively). Histologically, the number of new vessels was significantly higher in the SVF-treated wounds compared with controls on days seven (p=0.028) and 16 (p=0.027). This was also confirmed by immunohistochemistry. No significant differences were found between treated and control wounds regarding cellular infiltration score, collagen production score and epithelial thickness.

CONCLUSION

Data indicate that intradermally injected SVF increases angiogenesis and enhances epithelialisation in full-thickness cutaneous wounds in rats.

Effects of two occlusive, hydrocolloid dressings on healing of full-thickness skin wounds in cats

OBJECTIVES

To determine the effects of two occlusive, hydrocolloid dressings on second intention wound healing in cats.

METHODS

Three 2×2 cm full-thickness skin wounds were created on each side of the trunk of 10 cats. Two bilateral wounds were bandaged using different hydrocolloid dressings, namely Hydrocoll and DuoDerm while a semi-occlusive pad (Melolin) was applied to the third bilateral wound (control group). Wound planimetry, subjective evaluation of wound healing, and qualitative bacterial cultures were performed on the right-sided wounds, whereas left-sided wounds were subjected to histological examination.

RESULTS

Subjective evaluation revealed accelerated (p <0.01) granulation tissue formation in hydrocolloid-treated wounds. The amount of wound exudate was initially greater (p <0.01) in these wounds. Seventeen out of 120 evaluated wounds (14.2%) produced purulent exudate, 11 of which showed Staphylococcus aureus growth. Fewer control wounds (3/17) emitted purulent exudate, but all of them yielded moderate bacterial growth as compared to hydrocolloid-treated wounds (8/17) which had a low incidence of bacterial growth. The only significant difference in histological variables was increased cellular infiltration noted on day 7 in Hydrocoll-treated wounds compared to controls. No significant differences in planimetry variables were found between groups.

CLINICAL SIGNIFICANCE

Despite the initially increased amount of wound exudate and the low growth of Staphylococcus aureus, hydrocolloid dressings accelerate granulation tissue formation and can hence be suggested for second intention wound healing in cats.

Effect of locally injected autologous platelet-rich plasma on second intention wound healing of acute full-thickness skin defects in dogs

OBJECTIVES

Second intention wound healing may be impaired by wound and host factors and thus more advanced therapies are required for a fast and satisfactory outcome. Platelet-rich plasma (PRP), rich in growth factors and cytokines essential for tissue repair, could improve wound healing. The purpose of this experimental study was to evaluate the effect of locally injected autologous PRP on second intention healing of acute full-thickness skin defects in dogs.

METHODS

Three 2 x 2 cm full-thickness skin defects were created bilaterally on the dorsolateral area of the trunk of six Beagle dogs. The wounds of one randomly selected side received PRP treatment, whereas the contralateral wounds were left untreated (controls). Wound healing was evaluated by planimetry, laser-Doppler flowmetry measurements of tissue perfusion, and histologically.

RESULTS

The rate of wound healing did not differ significantly between the two groups. Tissue perfusion was significantly higher in the PRP-treated group (p = 0.008) compared to controls on day 10. Histological evaluation revealed a trend towards greater collagen production and a significantly better collagen orientation (p = 0.019) in PRP-treated wounds on day 20.

CLINICAL SIGNIFICANCE

Locally injected autologous PRP does not accelerate the healing process, but increases tissue perfusion and may promote the formation of organized collagen bundles in acute full-thickness skin defects in dogs.