Nile tilapia skin xenograft versus silver-based hydrofiber dressing in the treatment of second-degree burns in adults
Xenoenxerto (pele da Tilápia-do-Nilo) e hidrofibra com prata no tratamento das queimaduras de II grau em adultos

INTRODUCTION

Approximately 1 million people in Brazil suffer burns every year, particularly second-degree superficial and/or deep burns^1,2. The ideal dressing for such burns is easy to obtain, has good flexibility and adhesion to the wound bed, resists stretching, is easily handled, can suppress pain, if of low cost, is simple to store and, above all, prevents hydroelectrolytic losses and bacterial contamination, promotes epithelization, and encourages the adequate formation of granulation tissue in cases of grafting³.

Temporary skin substitutes and synthetic/biosynthetic dressing have been considered useful in the treatment of superficial burns because they reduce the frequency of dressing changes⁴. However, these materials are expensive and ineffective for deep burns⁵. Thus, alternative biological materials have been sought for this purpose. Tissues of animal origin, such as porcine skin and porcine intestinal submucosa, are among the materials used⁶. Recent studies have suggested the use of Nile tilapia skin (Oreochromis niloticus) as a biomaterial in regenerative medicine since it presented good adhesion to the wound bed in rats³ and satisfactory results of histological, histochemical, and tissue traction tests with human skin⁶.

Tilapia skin displays good tensile and compression resistance⁷, indicating that it may be usable as a biological dressing for burns. The presence of peptides with possible antimicrobial functions within this tissue reinforces this possibility ^8-10.

OBJECTIVE

This study aimed to evaluate the efficacy of the use of Nile tilapia skin as an occlusive biological dressing compared to silver-based hydrofiber dressing (Aquacel AG^®) in the management and treatment of superficial and deep second-degree burns in adults.

METHODS

This analytical interventional open clinical study with a convenience sample was performed at Hospital São Marcos, Recife/PE. The study was approved by the Research Ethics Committee of the Federal University of Pernambuco (no. 2.735.537). A clinical evaluation verified the general health conditions and the inclusion criteriA: Presence of superficial and/or deep second-degree burns affecting up to 10% of the burned body surface; maximum 72 hours since the burn occurred; age 20–60 years; and the absence of previous treatment for the current burns or significant comorbidities.

A total of 30 patients were selected. After receiving the initial explanation and providing written informed consent, they were randomly distributed into two groups: occlusive biological dressing with Nile tilapia skin (n = 15) or conventional treatment with the Aquacel AG^® silver-based hydrofiber dressing (n = 15). The therapeutic process is described in Chart 1.

Chart 1 - Therapeutic process applied to patients.

Nile tilapia skins are decontaminated (2% chlorhexidine and glycerol at high concentrations) and sterilized with gamma irradiation (Cobalt 60) to ensure the safety of their use in humans in addition to sampling microbiological testing for Gram-positive and -negative bacteria and fungi (Figure 1).

Figure 1 - Nile tilapia skin sterilized and packaged for human use.

Figure 1 - Nile tilapia skin sterilized and packaged for human use.

The procedures for both groups are described in Chart 2.

Chart 2 - Treatment procedures in the test and control groups.

The outcomes for this study were:

The results were analyzed using descriptive statistics of absolute and relative frequencies and mean and standard deviation. The treatments were evaluated using Fisher’s exact test with a significance of p < 0.05 using SPSS version 20.0 software.

RESULTS

Of our cohort, 53.3% were treated with Nile tilapia skin, while 46.6% were treated with Aquacel AG^®.

Table 1 shows that the mean treatment times in days were similar between the Nile tilapia skin and the Aquacel AG^® (9.6 ± 2.4 and 10.7 ± 4.5 days, respectively).

Table 1 - Descriptive statistics of the number of days (complete epithelization of the wound) according treatment type applied to second-degree burns in adults, Hospital São Marcos, Recife/PE - 2018.

Table 2 shows that the patients in both groups reported a VAS score greater than 5 during the exchange of dressings (p > 0.05; Fisher’s exact test).

Table 2 - Statistical value of the pain VAS score during dressing exchange according to treatment type applied to seconddegree burns in adults, Hospital São Marcos, Recife/PE - 2018.

After the dressing was changed, a new VAS pain score was collected. Table 3 shows that 86.7% of patients treated with Nile tilapia skin showed a reduced VAS score, and an analysis using Fisher’s exact test showed that it was not inferior to the Aquacel AG^®.

Table 3 - Statistical value of the pain VAS score after the application of dressings according to treatment type for seconddegree burns in adults, Hospital São Marcos, Recife/PE - 2018.

Table 4 presents values regarding the number of skin substitutions or dressings required for complete re-epithelialization represented by patient discharge. Note that 60% of the patients who were treated with the Nile tilapia skin did not require skin replacement at any time during treatment, whereas 53.3% of patients treated with Aquacel AG^® required more than one dressing replacement (p = 0.71), which indicates that the Nile tilapia skin was not inferior to the Aquacel AG^®.

Table 4 - Comparison of treatments according to number of dressing exchanges in the treatment of second-degree burns in adults, Hospital São Marcos, Recife/PE - 2018.

Figures 2 and 3 show the clinical results of two patients in the study from the first visit until medical discharge (complete re-epithelization).

Figure 2 - Clinical case of a patient treated with occlusive biological dressing (Nile tilapia skin). A: Wound assessment and cleaning and visual analog scale (VAS) pain assessment; B: Dressing with the Nile tilapia skin at the first clinical appointment and VAS pain assessment; C: Evaluation of the bandage after 7 days; D: Complete epithelization of the wound after 16 days.

Figure 2 - Clinical case of a patient treated with occlusive biological dressing (Nile tilapia skin). A: Wound assessment and cleaning and visual analog scale (VAS) pain assessment; B: Dressing with the Nile tilapia skin at the first clinical appointment and VAS pain assessment; C: Evaluation of the bandage after 7 days; D: Complete epithelization of the wound after 16 days.

Figure 3 - Clinical case of a patient treated with a silver-based hydrofiber dressing (Aquacel AG®). A: Wound assessment and cleaning and visual analog scale (VAS) pain assessment; B: Dressing with Aquacel AG® at the first clinical appointment and VAS pain assessment; C: Evaluation of the dressing after 7 days; D: Complete epithelization of the wound after 18 days.

Figure 3 - Clinical case of a patient treated with a silver-based hydrofiber dressing (Aquacel AG®). A: Wound assessment and cleaning and visual analog scale (VAS) pain assessment; B: Dressing with Aquacel AG® at the first clinical appointment and VAS pain assessment; C: Evaluation of the dressing after 7 days; D: Complete epithelization of the wound after 18 days.

DISCUSSION

Studies have shown that hot liquids are the most common thermal agents that cause burn injuries^1,2,11,12. In this study, 45% of the cases were due to overheated liquids.

The treatment and care of burns aim to provide a suitable environment for re-epithelialization and control the proliferation of microorganisms, which may delay the healing process¹³. Thus, biological dressings must display properties that prevent microbial growth, promote epithelization, and encourage the formation of granulation tissue^6,14.

Records of the use of silver-based dressings date back to the 18^th century¹⁵. Various properties of this material have been studied, including accelerating healing time, antimicrobial activity, and rapid re-epithelization. Despite its large-scale use, some disadvantages, including cytotoxicity, have inspired the study of other materials^12,15,16.

Although we are far from an ideal temporary skin substitute, biological dressings have shown better functional and aesthetic results^6,14. In this context, Nile tilapia skin is a promising product. Tilapia represents 45.4% of the total fish production in Brazil, but its skin is a waste byproduct of which only 1% is used in handicrafts. Tilapia skin must still be subjected to scientific analyses of its activity in humans. Several studies have compared human skin with Tilapia skin^6,7,14,17-20, and favorable results were described regarding their histological and histochemical aspects and tensiometric properties^18,20.

In this study, Nile tilapia skin was used in the treatment of 15 patients, 53.3% affected by second-degree superficial burns and 46.7% by second-degree deep burns.

To use animal skin as an occlusive dressing, a rigorous disinfection and sterilization protocol must be followed. Recent research indicates that chemical sterilization and radiosterilization are effective for the preparation of Nile tilapia skin¹⁸. The skins were provided by the Center for Research and Development of Medicines of the Federal University of Ceará, which is responsible for the sterilization processing.

Tilapia skin molds and adheres to the wound, creating a kind of tampon that prevents contamination and fluid loss.

The results of this study showed that the mean treatment time with Nile tilapia skin (9.6 ± 2.3 days) was similar to that with Aquacel AG^® (10.7 ± 4.5 days).

Pain during and after the dressing change was assessed using a VAS. Patients in both groups reported a VAS score > 5 at the time of the initial cleaning and dressing application process. At the end of the dressing application, 86.7% of the patients in the Nile tilapia skin group reported feeling less pain, proven by VAS scores ≤ 5, compared to 46.7% of patients in the Aquacel AG^® group (p = 0.05).

Skins and dressings are changed according to the amount of exudate. However, the higher the number of exchanges, the higher the risk of infection, the higher the cost of treatment, and the greater the possibility that the patient will feel pain. Given these aspects, it should be emphasized that fewer patients treated with Nile tilapia skin required dressing exchanges. In nine patients (60%) treated with Nile tilapia skin, there was no need for replacement of any dressing, while 53.3% of patients treated with Aquacel AG^® required at least one exchange. Thus, considering the p value = 0.71 (p ≥ 0.05), skin healing with Nile tilapia skin was not inferior to that with Aquacel AG^®.

The findings of this study suggest that Nile tilapia skin is as effective as Aquacel AG^® in the management and treatment of second-degree burns in adults.

CONCLUSIONS

Based on the results of this study, Nile tilapia skin is an effective occlusive biological dressing in the management and treatment of second-degree burns in adults. The average treatment time of the patients treated with Nile tilapia skin (9.6 ± 2.4 days) was similar to that of patients treated with Aquacel AG^® (10.7 ± 4.5 days). Furthermore, no significant intergroup difference was noted in pain level after dressing or the need for replacement during treatment.