Current indications for glycerol-preserved allografts in the treatment of burn injuries

Simple and efficient method for consecutive inactivation-cryopreservation of porcine skin grafts

We previously reported that inactivation treatment by high hydrostatic pressurization (HHP) has potential utility as a novel skin regeneration therapy for various skin tumors. In this study, we evaluated whether glycerol-cryopreservation could be applied in order to preserve inactivated skin by HHP using a porcine model. Twenty full-thickness skin grafts (1.5 × 1.5 cm) were prepared from a minipig. The skin samples were inactivated by the HHP in normal saline or glycerol/fructose solution, followed by cryopreservation for 5 weeks at - 80 °C in each same solution. Another 10 grafts immediately after inactivation were prepared as non-cryopreserved controls. Nine grafts in each group were randomly implanted on the fascia of a host pig and removed at 1, 4 and 11 weeks after grafting. All grafts showed engraftment macroscopically. Hematoxylin eosin staining showed the cellular components in all areas of the dermis at 4 and 11 weeks after grafting, and immunohistochemical staining for CD31 showed the presence of capillaries in the grafts in all groups. The surface and cross-sectional areas of grafts in the normal saline solution cryopreserved group decreased between 1 and 11 weeks, whereas these areas in the glycerol cryopreserved group did not decrease significantly. Glycerol cryopreservation may therefore be a simple and efficient method for preserving porcine skin inactivated by HHP.

Treatment of necrotising fasciitis using glycerol-preserved skin allografts for temporary wound coverage

Allografts of human skin have been used for both temporary and permanent wound coverage. They are useful as temporary bridges for the critically ill patient who is not allowed to receive definite wound coverage, or for wound bed preparation before permanent grafting. Glycerol-preserved skin allografts have several benefits including good adherence to the wound bed, water vapour transport, antimicrobial characteristics, low toxicity and antigenicity, ease of application and removal, a long shelf-life, and minimal storage requirements. We achieved lower limb salvage using a glycerol-preserved skin allograft for temporary wound coverage in the treatment of necrotising fasciitis.

Human skin allografts as a useful adjunct in the treatment of purpura fulminans

OBJECTIVE

The aim of this report is to discuss the role of human skin allografts in surgical coverage procedures for patients with purpura fulminans.

METHOD

We describe cases of purpura fulminans in three adults and one infant treated at our burns unit between October 2006 and January 2008.

RESULTS

The application of cryopreserved human skin allografts allowed us to obtain immediate wound closure after necrosis excision and enabled our team to subsequently perform autografts on favourable graft recipient sites.

CONCLUSION

Recourse to human skin allografts must be considered a pertinent therapeutic option in patients with purpura fulminans.

Viability and Efficacy of Coverage of Cryopreserved Human Skin Allografts in Mice

Human skin allografts are considered one of the best temporary biological coverages for severe burn patients. Human skin allografts can be either viable or nonviable depending on their preservation modalities. However, there is a debate about the use of viable versus nonviable skin for severe burn patients because there is no established correlation between viability and efficacy of coverage. The authors tried to correlate the viability of cryopreserved human skin allografts as assessed by the MTT assay, with efficacy of coverage, intensity of rejection at day 8, and delay of wound healing in a xenograft model using human fresh skin (FS) and cryopreserved skin (CPS) on murine recipients (n = 49). Cryopreserved grafts were less rejectable than fresh grafts, with statistically significant different delays ( P = .0008). Mice that had received grafts healed with delays; the delays, whether associated with fresh grafts or cryopreserved grafts, were not statistically significant. On day 8 after the graft, the overall damage score for the tissue’s histological architectural integrity was higher for FS. Furthermore, flow cytometry analysis showed a significant increase in the number of CD4 and CD8 T-cells ( P = .001) in the spleens of FS-grafted mice. These results confirm that the use of viable CPS does not change the potential for healing.

[Skin graft procedures in burn surgery]

Patients with extensive deep partial or full thickness burns require early excision of necrotic tissue, however, in many of these cases simultaneous autografting is not possible due to the general condition of the patient. In this instance temporary dressings like allogeneic or xenogeneic skin or foam dressings can be applied to minimize fluid and protein loss. In Europe glycerolized preserved allogeneic skin remains the treatment standard. Dermal replacements are considered to optimize the long-term outcome of split thickness skin grafting. Reduced contracture rates and increased pliability have been reported after additional dermal enhancement with either collagen-glycosaminoglycan matrix, acellular allogeneic dermis or collagen/elastin matrix. True regeneration of the dermis has not yet been observed. However, these materials are suitable for improvement of the wound bed and also the final result after split thickness skin transplantation.

The versatility of a glycerol-preserved skin allograft as an adjunctive treatment to free flap reconstruction

Skin allografts have been used in medical practice for over a century owing to their unique composition as a biological dressing. Skin allografts can be obtained in several preparations such as cryopreserved, glycerol-preserved, and fresh allograft. A glycerol-preserved allograft (GPA) was introduced in the early 1980s. It has several advantages compared with other dressings such as ease of processing, storage and transport, lower cost, less antigenicity, antimicrobial properties, and neo-vascularisation promoting properties. Skin allografts are mainly used in the management of severe burn injuries, chronic ulcers, and complex, traumatic wounds. Published reports of the use of skin allografts in association with free flap surgery are few or non existent. We would like to share our experience of several cases of free tissue transfer that utilised GPA as a temporary wound dressing in multiple scenarios. On the basis of this case series, we would like to recommend that a GPA be used as a temporary dressing in conjunction with free flap surgery when required to protect the flap pedicle, allowing time for the edema to subside and the wound can then be closed for a better aesthetic outcome.

[Innovative wound therapy and skin substitutes for burns]

The success of modern burn therapy is based mainly on special burn intensive care, topical treatment, early eschar excision, and wound closure by immediate skin grafting or skin substitutes. This paper describes the current state of wound care and skin substitutes in burn therapy.

[Early surgical management of severe burns]

The success of modern burn therapy is based on an understanding of the pathophysiology and application of burn intensive care implying fluid resuscitation and management of pulmonary or other organ failure. With the development of early eschar excision and wound closure by immediate grafting, survival and cosmetic outcome were further improved. Especially in post-acute therapy, early physical rehabilitation, early reintegration, and early plastic surgical correction of the sequelae are indispensable for the outcome.

Suprathel®—An innovative, resorbable skin substitute for the treatment of burn victims

Autologous split skin grafts are the most reliable method for closing third degree burns. Under this scheme, donor sites as well as second degree burns under conservative treatment, however, would benefit from rapid wound closure. For this treatment, biological as well as synthetic materials are available. For the improvement of these materials, primary goals are pain reduction and easy handling in the absence of biological risk. From a synthetic copolymer mainly based on DL-lactic acid a new skin substitute was developed, marketed as Suprathel. Within the scope of a bicentric study Suprathel was compared versus paraffin gauze intraindividually applied on split skin donor sites. Wound pain was measured on the Visual Pain Analog Scale over a period of 10 days as the critical criterion. Accordingly Suprathel versus Omiderm were compared on second degree burns (degree 2a, partial thickness burns). In both study parts, Suprathel significantly reduced pain. Its easy handling was superior compared to other materials. The Suprathel membrane adhered rapidly to the wound thus protecting against infections and promoting wound healing. No allergic reactions were observed. The ability of the material to resorb ensured pain-free removal after complete healing of the wound.

Performance and safety of skin allografts

Skin preservation for transplantation began almost 200 years ago with the pioneering work of Baronio (cited by in Ref. ). Since that time, hundreds of papers have been published on the preservation of skin for later application in wound treatment. This interest stems from the excellent clinical results obtained with skin as a permanent autograft or temporary allograft for wound cover, coupled with the relative ease of preservation and storage methods. The general recognition of the need for human skin allografts has stimulated the establishment of banking facilities and research to improve the methods for harvesting, processing, storage, and subsequent evaluation of transplantation performance.

Use of dressings and bandages in equine wound management

The use and aims of various wound dressings are discussed. Application and indications in the horse vary according to the type and location of the wound as well as the nature and availability of the dressing material. Coaptation and immobilization are essential to promote healing in certain locations. Techniques used for bandage application in horses are described, with special emphasis on problem areas.