Background and Objective

Perform a characterization and classification of necrosis in random skin flaps (predisposed to necrosis) according to the macroscopic and histopathological findings, with or without treatment to increase the survival of the flap, it could be useful to analyze in a global way the flap and evaluate different modalities for decrease necrosis.

Our aim is to evaluate if there is more than one skin cutaneous necrosis pattern of the random cutaneous flap on the seventh postoperative day, performing a necrosis classification and to compare the effectiveness of the flap delay and adipose tissue derived stem cells (ASCs) with and without preconditioning methods to increase the survival of the flap.

Methods

Forty adult male rats subjected to random skin flap in the dorsal area of 2 x 8 cm grouped into control group, RTC (flap delay), ASCs (adipose-derived stem cells) and ASCs-H (hypoxic preconditioning of adipose-derived stem cells), were used. Area calculation, necrosis score and histological study of flaps on the seventh day with hematoxylin-eosin, immunohistochemistry with VEGF (vascular endothelial growth factor) and quantification of type I and III collagen were performed.

Results

According to the classification of necrosis, type 0 was considered normal skin; type 0+ with reversible adaptive change; type 1 minor necrosis with superficial inflammation; type 2 minor necrosis with deep inflammation; and finally type 3 necrosis in its maximum degree. Healthy skin maintains coloring, elastic and soft texture. As necrosis progresses shifts towards a darker tone, texture and consistency increases until it becomes stiff and thin. In types 0+ and 1, foci of early re-epithelialization was observed on the seventh day, while more advanced in the classification stages, necrosis is complete. The group of RTC presents a lower score and therefore lesser degree of necrosis with respect to the rest of the treated groups. Moreover the overall percentage of necrosis was lower in the groups treated with ASCs and ASCs-H in the control group (p ≤ 0.05)

Conclusions

The classification and the score of necrosis seems to be a suitable method for understanding the evolution of skin flap necrosis and as a tool for research. Low-grade necrosis allows conservative and expectant confrontation with respect to higher grades. The RTC group presented a lower necrosis score on the seventh day with greater reepithelialization capacity, whereas treatment with ASCs and ASCs-H achieved a lower area of necrosis overall on the seventh day.

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