Lyophilized xenoderm grafts (the size - 100-200-250-300 cm², the thickness - 0,3-0,4 mm) are sterile, processed, packed and can be used as skin substitutes in the treatment of the burns (І, ІІAB, ІІІ degree), donor and scalping lesions, trophic ulcers. These implants can be preserved in the fridge at +2 up to +4 degrees C for 3 years. They are light; one package weighs 70-120 gr. The products are transported within 1- 2 days in any season without any alterations of their therapeutic properties.
After microscopic investigations of the lyophilized skin, the signs of autolytic and necrobiotic alterations and their deep structural abnormalities have not been found in the epidermis and in the papillary layer of the dermis. Well-preserved nuclei and epidermocyte and fibroblast cytoplasm are present in the majority of the cells; pycnosis and vacuolization are only detected episodically. The cell membranes are not distorted; the exfoliation of the epidermis from the dermis is absent. The collagen dermal fibers of the grafts are contoured, forming the network and being placed loosely in the papillary layer. The edema and homogenization of some parts of the collagen fibers and, in some cases, - their fragmentation is present in the deep layers of the dermis.
At picrofuxin staining by Weigert Van Gieson, the collagen fibers are mostly stained intensively red with fuchsin. The part of the elastic network is interwoven with clear contoured fine elastic fibers.
The vitality of the of xenoderm grafts is determined microscopically. All the investigations clearly reveal plasma membranes, intercellular junctions of the growing layer of the epidermis. Euchromatin dominates in the nuclei signifying the activity preservation of the epitheliocyte nuclear apparatus. The fibroblasts, which are characterized by the developed protein synthesis apparatus and insignificant mitochondria distortions, predominate in the cells of the papillary dermis. The nuclear contours are regular and a lot of granules of the ribosomal origin can be seen in the nuclei. But destabilization and destruction of the plasma, nuclear and organic membranes are present episodically in some cells; heterochromatin is predominant in the nuclei signifying the reduced function.
The morphologic investigations have proved that lyophilized xenoderm grafts developed and manufactured by our enterprise are not significantly different from the xenoderm grafts before the conservation (figure 1, 1а).
Stratified epidermocyte placement is preserved concerning regular basal membrane. Basophilic nuclei, vacuolization of separate cells
He microscopic organization of the basal layer epidermocytes. Desmosomal junctions are preserved; Intercellular spaces are significantly widened. Moderate karyolemma invaginations and homogeneous nuclear karyoplasm, the destruction of the separate organelles
Lyophilized porcine xenoderm grafts are used as temporary skin substitutes in the treatment of the burns (І, ІІAB, ІІІ degree), donor and scalping lesions, trophic ulcers.
At the application of xenoderm grafts in the complex therapy of the patients with burns the general state of the patients, their sleep and appetite improve; the body temperature is normalized; the deficiency of the homeostasis indices is reduced; the indices of the blood serum toxicity are decreased; the epithelization of the superficial burns, boundary and insular epithelization of the deep burns is accelerated leading to the decrease of the granular lesions by 23%. The hospitalization of the patients is reduced to 16-18 days; the mortality of the major burn patients is reduced by 30%.
The number of the lyophilized xenoderm grafts necessary for the skin coverage depends on the surface area, depth of the burns and the age of the patient.
Superficial burns (І-ІІA degree)
After the patient hospitalization and hemodynamic stabilization, the wounds are antisepticised at narcosis in the clean dressing or operating room. The skin around the burn is debrided and cleaned with antiseptic solutions – iodine, povidone-iodine, chlorhexidine, dexane. In case of significant contamination (home or industrial dust, soot, smut), the burn area should be sprinkled with antiseptic sterile solutions. After the wound antiseptics, most IIAB degree burn areas are likely to be covered with the perforated lyophilized xenoderm grafts. It relieves the graft modulation at joint areas. The wound epithelization under the lyophilized xenoderm grafts terminates on the 10-12 days (figure 2)
figure 2 The wound epithelization (46%) under the lyophilized xenoderm grafts.
In case of IIAB degree burns the skin dermal layer undergoes partial necrosis (the vital sebaceous and sudoriferous glands and their excretory ducts are preserved), creating preconditions for wound suppuration caused by the development of the pathogenic microflora in the necrotically changed superficial skin tissues.
To create the conditions for the active insular and marginal epithelization with the application of the preserved skin derivatives it is necessary to debride the wound and to conquer wound infections. Thus, sequential (superficial) necrotomy and the wound coverage with lyophilized xenoderm grafts have to be performed to the patients with IIА degree burns during the early stage after the trauma (2-3 days) (figure 3). It prevents the burn disease development, accompanied complications, the scar formation and frequent painful dressings and also promotes wound healing.
figure 3 IIA degree burns. The performance of the early necrotomy (the 2nd day after the trauma).
The xenoderm grafts are closely applied to the skin, resulting in the improvement of the patient’s general state, significant reduction or liquidation of the pain syndrome, the body temperature normalization.
The first dressing is applied the next day after the tangential and sequential necrotomy with xenoplasty. The following dressing are applied daily or once in two days respectively depending on the character of engraftment. When hematomas or accumulated purulent discharge occur under the xenoderm grafts, the grafts are removed, the wound is cleansed and the new xenoderm grafts or wet to dry drying dressings are applied. On the 8-9 day after the trauma the xenoderm grafts dry up at the ends of the wound; the graft rejection and the epithelization of the wound surface are observed. In the other areas of the wound the xenoderm grafts are closely fixed to the adjacent tissues.
On the 11-12 days the xenoderm grafts thicken and fall off. The wound surface is covered with well-developed epithelial regenerator. (figure 4)
figure 4 The wound epithelization under xenoderm grafts (12 day after the trauma).
Taking into account that the number of patients with І-ІІA degree burns makes up 70% of all the burnt, the application of the lyophilized xenoderm grafts allows to avoid painful daily dressings, promotes wound healing, prevents wound purulence, facilitates the course of the disease without the loss of proteins, water and electrolytes. The expenditures on the purchase of the lyophilized xenoderm grafts are less than those on the purchase of ointments, bandages, solutions, narcotic drugs etc. Thus, the described treatment method is said to be not only clinically but also economically efficient.
Deep burns (ІІB-III degree)
The deep burns can be treated with the application of the early necrotomy or without it.
The application of the early necrotomy
The final aim of the local treatment of the deep burns lies in operative restoration of the burnt cutaneous covering. The early surgical interventions fully correspond with the principles of the preventive surgery. During surgical interventions, necrotic tissues are removed tangentially or perifascially on the area up to 10-15 % of the body surface; the formed wounds are temporarily covered with the lyophilized xenoderm grafts that are removed in 2-3 days and after additional necrotomy the wounds are covered with the autodermal grafts The repeated interventions are performed in 2-3 days. Afterwards daily dressings are applied at narcosis and xenoderm and autodermal grafts are cleansed on the wounds.
The application of the lyophilized xenoderm grafts allows to increase the area of the one-phase removal of the necrotic tissues, to reduce the traumatism of the interventions, to detect the areas of the incomplete debridement and it also creates conditions for quick compensation of the postoperative homeostasis violations.
Additional debridement of the unvital tissues promotes better autodermal engraftment. The application of the early necrotomy with xenodermoplasty prevents progressive intoxication of the lesion focus and the development of the wound infection, reduces the possibility of the burn disease development and promotes skin restoration within a short time.
figure 5 The IIAB-ІІІ degree burn of the left side of the trunk, upper extremity, 26 (18)% of the body surface. Early necrotomy. Xenoplasty. Autodermoplasty.
The treatment of the deep burns without the application of the early necrotomy
The main task of the burn treatment is the preparation of the burn lesions to autodermoplasty. Spontaneous necrotic tissue rejection lasts 4-5 weeks. The presence of the specially wet eschar on the burn and the wound microflora vegetation (frequently as gram-positive or gram-negative flora) often lead to the burn complications.
The deep burns are treated without the application of the early necrotomy in the late evacuated patients with purulent wounds and also in the patients with the complicated disease course and accompanied diseases that limit the application of the early necrotomy.
After the chemical and phased necrotomy and deep wound debridement the autodermoplasty is performed. During the autodermoplasty the wounds that remain uncovered with the autodermal grafts, donor wounds and perforated autoskin grafts are covered with the lyophilized xenoderm grafts.
figure 6. IIB-ІІІ degree burns, 70% of the body surface. Auto- and xenoplasty.
The xenoderm grafts can remain fixed up to 2,5-3,5 weeks. The application of the lyophilized xenoderm grafts reduces pain syndrome, plasma loss and the frequency of the wound purulence.
At the same time the granular tissue with the cells of the histogenic and haematogenic origin (fibroblasts and histiocytes) ripens under the xenotransplants.
The hypertrophy of the protein synthesis structures and energy exchange are detected microscopically in the fibroblast cells (Figure 7).
figure 7. The ultrastructure of the active fibroblast and the formation of the intercellular substance components of the connective.
After the xenoderm grafts removal autodermoplasty can be performed (figure 8).
figure 8. IIB-ІІІ degree burn wounds after the xenoderm grafts removal. The 14th day after xenoplasty. The granular tissue is well manifested.
Simultaneously with the granular tissue formation the wound surface is epithelized more actively; the local epithelization in the form of wide cell growth from the preserved skin derivatives occurs together with the marginal epithelization (figure 9).
It promotes reducing the wound surface due to the absence of the secondary wound deepening and necrosis and intensifies the marginal and insular epithelization of the deep burn lesions under the xenoderm grafts
figure 9. ІІAB degree burns covered with the xenoderm grafts. The 12th day after xenoplasty. Active proliferation of the epitheliocytes in the preserved hair follicles and sebaceous glands. The formation of the epidermal layer on the wound surface.
The coverage of the donor lesions
The xenoderm grafts are efficiently used in the treatment of the donor lesions. Thus, there is no necessity in dressings. The epithelization of the donor lesions under the xenoderm grafts occurs on the 6-8 day.
So the application of the xenoderm grafts in the coverage of the donor lesions promotes faster epithelization ((4±1) day) and if necessary earlier autotransplant removal for the recurrent plasty.
The coverage of the perforated autodermal grafts
The perforated autodermal grafts on the wounds can be covered with the xenoderm grafts. There is no need to remove xenoderm grafts during dressings; the epithelization of the wounds in the autografts occurs under the xenoderm grafts.
After the complete wound epithelization between the membranes of the perforated autodermal grafts, the xenoderm grafts dry out and fall off.
The treatment of the scalping lesions and trophic ulcers
Clean scalping lesions and trophic ulcers are covered with the xenoderm grafts. The reduction of the inflammatory process, the activation of the marginal and insular epithelization promoting wound self-healing can be observed under the engrafted xenoderm grafts.
When the lesion area is big, the xenografts have to be substituted with the autodermal grafts on the 7-8 day (the local blood circulation in the wound is the best during this period).
The treatment of the lesions after the scar cryodestruction
On the 2 day after the cryodestruction, the area (the serous cyst and the skin around it) is cleaned with antiseptic solutions – iodine, povidone-iodine, chlorhexidine, dexane; the serous cyst is removed; the wound is dried up with the sterile pads and the lyophilized xenoderm grafts are applied.
On the 6-7-8 day after the procedure, the drying of the xenoderm graft at the wound edges, its rejection and complete epithelization can be observed. The period of the epithelization depends on the size of the lesion formed after cryodestruction.
figure 10. Posttraumatic keloid scars. The cryodestruction with the further xenoplasty.