|Year : 2019 | Volume
| Issue : 2 | Page : 717-722
Deantigenicity of skin homografts in management of major burn cases
Mohamed Ahmed Megahed1, Sherief M ElKashty1, Ahmed TT Nassar1, Ezzat AM Allam2
1 Department of Plastic and Reconstructive Surgery, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Plastic and Reconstructive Surgery, El-Materia Teaching Hospital, Cairo, Egypt
|Date of Submission||12-Nov-2017|
|Date of Acceptance||30-Jan-2018|
|Date of Web Publication||25-Jun-2019|
Ezzat AM Allam
Zagazig City, Skarkia Governate
Source of Support: None, Conflict of Interest: None
The aim was to assess the ability of deantigenicity of skin homograft to decrease its rejection and improve its survival in management of patients with major burns.
Skin homograft is considered as a good skin substitute in major burn cases. The major problem of the skin homograft is rejection. So, many methods are used to decrease antigenicity of the skin homograft and prolong its survival.
Patients and methods
This clinical trial included 32 patients with burn who were managed in Plastic Surgery Department, Menoufia University Hospital, from October 2015 to October 2017. Four groups were formed: control group had nine patients without deantigenicity of the homograft; group A had seven patients with freezing of the skin homograft at 4°C; group B had eight patients with skin homograft applied for irradiation; and group C had eight patients, with the recipient patient receiving dexamethasone injection. After escharotomy and coverage with skin homograft, follow-up was done for rejection of the homograft clinically.
In the control group, the mean percentage of rejection of homograft was 62.22 ± 12.01%. In group A, the mean percentage of rejection was 61.4 ± 10.6%, with P value of 0.9. In group B, the mean percentage of rejection was 21.8 ± 10.69%, with P value of less than 0.001. In group C, the mean percentage of rejection was 48.7 ± 15.07%, with P value of 0.036.
Local irradiation dose to the skin homograft can minimize its rejection. Systemic corticosteroids produce less effect regarding the rejection of skin homograft when used with the usual dose, but with increasing dose, the rejection decreased. Freezing of the skin homograft in 4°C has no significant effect on the rejection of the skin homograft.
Keywords: deantigenicity, major burn, skin homograft
|How to cite this article:|
Megahed MA, ElKashty SM, Nassar AT, Allam EA. Deantigenicity of skin homografts in management of major burn cases. Menoufia Med J 2019;32:717-22
|How to cite this URL:|
Megahed MA, ElKashty SM, Nassar AT, Allam EA. Deantigenicity of skin homografts in management of major burn cases. Menoufia Med J [serial online] 2019 [cited 2020 May 27];32:717-22. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/717/260932
| Introduction|| |
Burn injury may lead to extensive skin loss and even death. Finding an ideal skin substitute for patients with burn is an important issue for burn-treatment surgeons. The ideal skin substitute should have similar properties, should be able to do the same functions of the natural skin, should not induce much immune reaction, and should be safe, biocompatible, easily handled, and nontoxic, with no risk of disease transmission. The best burn wound dressing in deep and full-thickness burn is the split-thickness skin autograft. However, in major burns, there is limited donor site for the skin autograft. With limitation of donor site for skin autograft, mortality rate and hospital stay increase; in these cases, an important solution is the skin homograft as a temporary biological dressing. The skin allograft can be used in partial thickness burns, where it can promote healing and decrease pain. Moreover, it can be used after excision of deep or full-thickness burns for preparation of the wound bed with healthy granulation tissue before autograft. Skin homograft is often rejected owing to its antigenicity. Although recent immunosuppressive drugs are effective in delaying or preventing rejection of other organ transplants such as kidney or liver, they have little or no effect on skin transplantation. The aim of this work was to assess the ability of deantigenicity of skin homograft to decrease its rejection and improve its survival in management of patients with major burns.
| Patients and Methods|| |
This clinical trial was conducted at the Department of Plastic Surgery, Menoufia University hospitals, from October 2015 to October 2017. It was approved by the ethical committee on July 2015. All the patients signed an informed consent before undergoing skin homograft for management of deep major burns. All of these patients underwent early escharotomy and coverage with skin homograft. All of these patients were admitted to our burn unit in this period and fulfilled our inclusion criteria for this study. They were divided into nearly equal groups to help in comparison between results. Inclusion criteria included patients with major burns with limited donor site for autograft, burn involved major joints that may lead to contractures, and deep dermal burn that was suspected of leading to long time for healing. Exclusion criteria were superficial burn that was suspected of healing conservatively, critically ill patient who cannot tolerate anesthesia and operation, and patients who refused operation. All of the patients were admitted to burn ICU or burn unit according to the percentage of burn wound, presence of inhalation injury, or presence of other comorbidities. All of them received primary resuscitation treatment, and after stabilization, they were prepared for operation and underwent escharotomy and coverage with skin homograft. Sources of skin homograft varied from one of the parents or excised skin from other patients who underwent operations with excision of excess skin such as abdominoplasty or breast reduction. All of the donors underwent routine preoperative investigation including complete blood count, coagulation profile, and virology investigations including hepatitis B, C, and HIV viral infection. In this study, the patients were divided into four groups. For control group, no methods for homograft deantigenicity were applied. In group A, after harvesting of the homograft, it was applied for cooling in 4°C for 48 h. In group B, after harvesting of the skin homograft, it was applied for irradiation dose of 200 cGy. In group C, the recipient patients received dexamethasone injection at a dose of 0.25 mg/kg body weight/day in children and 8 mg/day for adults. This started from the day of application of homograft and continued for 7–10 days. In one case, we had to increase the dose of dexamethasone to improve the homograft take. For all donors and recipient patients, the following hospital data were obtained: operative details, operative time, preoperative and postoperative photographs, benefits of the operative procedure, and possible operative complications. Antibiotic was given to the patient 1 h preoperatively. Under general anesthesia or spinal anesthesia, split-thickness skin homograft harvesting was done using humpy knife. After fixation of the graft, bulky dressing and splinting in the needed patients were done. The patient was transferred to the ward, and normal diet was allowed after complete recovery. First dressing was done after 3–5 days. After the first dressing, with good graft take dressing was done every other day till improving of the general condition and local condition of the patient. The patient can be discharged with outpatient clinic follow-up on regular basis. Assessment of the homograft take and survival was done by clinical examination on regular follow-up dressing and outpatient clinic visits. Any signs of local allergic reaction such as erythema, edema, local infection, or partial or total homograft loss were detected and documented. If there were any signs of graft rejection, infection, or loss, the patient was kept in the hospital and prepared for another session of skin homograft or autograft if needed. General examination was done for detection of any systemic complications.
Data collected throughout history, basic clinical examination, laboratory investigations, and outcome measures were coded, entered, and analyzed using Microsoft Excel software (Microsoft company, Redmond, Washington, USA). Data were then imported into statistical package for social sciences (SPSS version 20.0; SPSS Inc., Chicago, Illinois, USA) software for analysis. According to the type of data, with qualitative represented as number and percentage and quantitative continuous group represent by mean ± SD, with mean and range as suitable, the following tests were used to test differences for significance: difference and association of qualitative variable by χ2-test and the differences between parametric data multiple by ANOVA test and the non parametric data by Kruskal-Wallis test. P value was set at less than 0.05 for significant results and less than 0.001 for high significant result.
| Results|| |
This study was conducted on 32 patients experiencing acute burn wound injury in which skin homograft was used in their management. In total, 21 male and 11 female cases were included. These patients were divided to four groups: control group included nine patients, group A included seven patients, group B included eight patients, and group C included eight patients. There was no significant difference between different groups regarding age, sex, cause of burn, and total body surface area burn [Table 1].
|Table 1: Comparison between age, sex, cause of burn, and total body surface area burn of different groups|
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Regarding the time period before starting rejection of the skin homograft, there was significant difference among the groups (P < 0.001), with significant increase of this time period in groups B and C than control group and group A [Figure 1]. Maximum increase in the time period before starting rejection was seen in group B, which indicates that irradiation was more effective than other methods in delaying the rejection of the skin homograft [Figure 2]. Regarding the percentage of homograft rejection, there was significant difference between the groups (P < 0.001), with significant decrease of graft rejection in groups B and C in comparison with control group and group A [Figure 3]. Minimum homograft rejection occurred in group B, which indicates that irradiation was the most effective method in decreasing the homograft rejection than other methods of deantigenicity in this study. Owing to the previous results, there was a significant difference between the groups regarding the need for another session of grafting (P > 0.001), as there are six cases that healed conservatively in group B with only two cases that needed another session of grafting. This was different than other groups in which more cases needed another session of grafting, and this indicates that radiation as a method of deantigenicity of skin homograft can decrease the need for further grafting. In this study, no significant difference between different groups regarding the period of hospital stay was detected (P = 0.400; [Table 2]).
|Figure 1: The mean period before starting rejection in different groups.|
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|Figure 2: Very good skin homograft take and survival after 11 days of application in one of the patients of group B.|
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|Figure 3: The mean percentage of rejection of the skin homograft in different groups.|
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There was exception in group C, where when we increased dose of dexamethasone, although the values regarding take and survival of homograft improved than those on usual dose, the complications of increased corticosteroids appeared. These complications included thinning and weakening of normal skin, with occurrence of injury with minimal trauma, and increased weight gain, especially truncal obesity. So, when dexamethasone was withdrawn, these complications started to improve gradually [Figure 4].
|Figure 4: The truncal obesity and weight gain which occur as complications of increase corticosteroids dose.|
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Even the patients who lost parts of the skin homograft got many benefits: they had decreased risk of septicemia and septic shock; most of them showed improvement in systemic inflammatory response syndrome symptoms (less tachycardia, less tachypnea, less fever, and improvement in leukocyte count) and decreased need for intravenous fluids. Moreover, gradual epithelialization started to occur in the remaining raw area, so either the wound healed conservatively or decreased the raw area needed for skin grafting, and the remaining raw area had healthy granulation tissue that facilitated subsequent graft take.
| Discussion|| |
Burn is a common trauma, and cases of major burn usually have high mortality rate. Burn causes systemic physiological derangements, including leakage of intravascular fluids and proteins into the interstitial tissue, hypovolemic shock, and suppression of the immune system. Therefore, re-establishment of the skin barrier is crucial to normalize the victim's physiological state. The use of cadaveric skin allografts as skin substitute in burn management has turned back time to the World War II era and is currently being practiced in many burn centers. Skin banks are also established to address the need for skin allografts. Skin homograft decreased loss of water, electrolytes, and proteins. It also reduces pain and thus allows early exercise, and ambulation, so decreases incidence of contractures. As the cadaveric skin banks are not available in Egypt and because the synthetic skin substitutes are very expensive, live sibling skin homograft is considered a good skin substitute, which is priceless and depends on parent's donation or from the excised skin from operations like abdominoplasty or breast reduction, in which the skin is usually discarded. Skin from a live donor does not require complex preparation, and it can be used immediately after harvesting and provides a ready skin substitute. The closer the donor is related to the patient, the lesser the immunological rejection process. Once adhered to the burn wound bed, skin allograft may exhibit features of revascularization as part of 'take'. Clinically, the peeling off or nonadherence of skin homograft to the wound bed is judged clinically as a rejection apart from its dry, sloughy, or necrotic appearance. The skin allograft is known to be more susceptible to rejection than other organ allografts owing to its unique intrinsic immunological features and antigenicity, including high concentrations of Langerhans's and other dendritic cells as antigen-presenting cells and extracellular matrix glycoproteins that position the T cells for activation and effector functions. In attempts to use the skin allograft as a long-term skin substitute, various methods have been used to prevent or delay its rejection, by either modifying the recipient immune response or decreasing the allograft antigenicity. Parents of the patient are considered an important source of skin homograft donation, because this method has many advantages, as what Phipps and Clarke found in their study: the allograft skin is freshly donated, avoiding the need for storage facilities or complex treatment and packaging, presenting the skin at maximum viability. There is a considerable psychological benefit to the donor parent, who feels that they making a significant contribution to his/her child's recovery, and the transmission of diseases are unlikely. In this study, the first method (group A) for deantigenicity was freezing of the skin homograft for 48 h in 4°C, in which the signs of rejection started after an average of 8.29 ± 0.76 days, which is nearly equal to control group. These findings were different from the findings of Abbott and Hembree who found that freeze-dried skin allografts sustained a prolonged time before rejection (12.8 days). Moreover, they found that there is a great difference between fresh and freeze-dried skin, as freeze-dried skin is not viable and does not seem to behave as usual allogenic transplant but rather it more closely resembles isogenic transplant or autograft. This behavior is owing to the fact that freeze-dried allogenic skin fails to stimulate any measurable immunological reaction in the recipient. The difference between the two studies is that in their study the temperature of freezing is different at −30°C for a longer time of 3 days. This finding was also different from what was found by Parkes; they found that the immunological reaction evoked by the homograft is decreased by freezing it. The same is true for frozen skin homograft. The second method (group B) that was used in this study for deantigenicity was to apply irradiation to the skin homograft before application. This application depends on the finding of Kearney, who concluded that γ-irradiated freeze-dried split-thickness human skin was comparable to the normal human skin because of its human source; he believed that lyophilization followed by γ-irradiation would remove the major antigenic parts of the harvested skin and the product can then be considered nonviable. In another study by Mahdavi-Mazdeh et al., patients did not show any complications or immunological reactions with this method. Although they used a higher dose (25 kGy) in their study, good results were obtained in our study with smaller dose (200 cGy), as long period of graft survival with less rejection was obtained, with no signs of systemic complications. The third method (group C) in our study was to treat the recipient patient with dexamethasone injection to decrease the immunological reaction toward the skin homograft. The idea of immunosuppression to decrease the rejection of homograft started long time ago with immunosuppressive drugs, like cyclosporine, which prevent the rejection even permanently. However, this method was abandoned permanently because of adverse effects. The trials with cortisone started earlier when authors found that cortisone prolongs the life of the skin homograft and facilitates the insidious creeping replacement of the homograft epidermis by epithelium of native origin. It was the general rule in their experiments that the fibrous elements of skin homograft in rabbits under cortisone treatment were progressively resurfaced by native epidermis. Moreover, they concluded that the administration of cortisone lengthens the life of skin homograft in rabbits by a factor of three or four. This prolongation is thought to be because of a nonspecific reduction of the graft's own ability to elicit an immune response and the reduction of the response itself. In another study, the authors used dexamethasone and conclude that the mean survival period in dexamethasone-treated group was significantly prolonged as compared with the control group. This prolongation could be owing to the inhibitory effect of corticosteroids on local inflammatory cellular activity. The other possibility could be owing to lymphocytolytic activity of the drug as observed by minimal or no lymphocytic infiltration of the graft as compared with control group. In our study, the survival of the homograft increased with delayed rejection, and this survival increased with increase in the dose of dexamethasone, but this led to complications of corticosteroid overdose. So, while using corticosteroids for deantigenicity, strict precautions should be taken regarding the dose and period of administration and strict follow-up should be done.
| Conclusion|| |
Irradiation to the skin homograft before its application can prolong survival and minimize the rejection of it. Systemic corticosteroids produce less effect when used with usual safe dose. However, it can lead to less rejection when used in a larger dose but with risk of complications. Freezing of the skin homograft at 4°C for 48 h has no significant effect on the rejection of the skin homograft. Deantigenicity of skin homograft can prolong its survival and decrease its rejection to get much benefits of its use in management of patients with major burns.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]