Conventional Skin Grafts Research Articles

Favorable donor site for epidermal cultivation for the treatment of burn scars with autologous cultured epithelium.

It is very important to determine from where we select the donor skin for epidermal cultivation in the treatment of burn scar disfigurement. To prove this point, we compared the appearance and histology of grafted sites according to the different donor sites. Thirty-eight patients with skin color difference and irregular contours of matured burn scars were superficially abraded and underwent autologous cultured epithelial grafting. These patients were followed more than 2 years. The donor skin for epidermal cultivations was taken from the buttock (group 1, 8 patients), sole (group 2, 6 patients), and adjacent to the site of the scar (group 3, 24 patients). In group 3, skin elasticity was also measured after 2 years. Hypo- and hyperpigmentation were well treated with autologous cultured epithelial grafting. The most favorable results in terms of color match were obtained in group 3, where the skin color resembled surrounding normal skin. The skin tension returned to almost normal. In group 2, the histology of the grafted site resembled the sole epidermis. It was concluded that the general principle of conventional skin grafting (i.e., "closer is best") was also correct in cultured epithelial grafting. Furthermore, it was revealed that cultured epithelium has a site specificity even after grafting.

Composite Graft Survival

Composite grafts from the ear, consisting of cartilage sandwiched between layers of epidermis, dermis, and fat, are often used for reconstruction of full-thickness nasal ala defects. Survival of these grafts is much lower than that of conventional full-thickness skin grafts. Therefore, various manipulations of the composite graft have been attempted to improve survival. In this …

Transgenic mice expressing MHC class II molecules with truncated A beta cytoplasmic domains reveal signaling-independent defects in antigen presentation.

The thymic development and peripheral activation of CD4+ T cells are critically dependent upon interactions with MHC class II molecules on the surface of antigen presenting cells (APC). In vitro studies involving transfection of cell lines with mutant MHC molecules have demonstrated that the cytoplasmic domains of class II molecules can be required for efficient antigen presentation. To address the role of class II cytoplasmic domains in physiological, non-transformed APC and in vivo immune responses, we have generated transgenic mice which express only truncated class II A beta molecules lacking the 13 membrane distal residues. In vivo, CD4+ T cell development and immune responses to conventional protein antigens, parasitic infections and skin grafts were indistinguishable between control and transgenic mice. Nevertheless, in vitro, APC from transgenic mice poorly stimulate T cell hybridomas and wild-type in vivo-primed T cells. Neither class II-mediated induction of B7-1 expression nor homotypic aggregation were diminished in transgenic B cells, suggesting that both cAMP and tyrosine kinase signaling pathways remain intact despite truncation of the A beta cytoplasmic domain. Furthermore, chemically-fixed cells from transgenic animals are impaired in their antigen presenting capacity. Thus, in contrast to previous studies with cell lines transfected with truncated class II molecules, these results suggest that signaling-independent mechanisms account for the defective in vitro antigen presenting capacity of physiological APC expressing truncated A beta proteins.

Cultured epidermal autografts: A life-saving and skin-saving technique in children

The recent more widespread availability of cultured keratinocytes has increased their clinical applicability in pediatric surgical problems. In life threatening burns (3 patients) and in elective procedures (3 patients) we have used sheets of cultured epithelial autografts. Body surface area affected ranged from fifteen to 85%. Five patients were successfully treated in one grafting session and one required four sessions. Take of the cultured keratinocytes ranged from 75% to 95%. Follow-up as long as 30 months has shown the skin to be comparable to if not superior to conventional split thickness grafts. The use of cultured keratinocytes allows wound coverage without expansion of the affected body surface area seen with conventional split-thickness skin grafting. Although there is an initial delay in the preparation of the grafts, the overall results have been excellent and suggest the more frequent use of this method.

Use of buried skin implants after recurrent failure of conventional skin grafting in a massive burn: the renewal of an old technique

The technique of burying small pieces of skin under old granulation tissue after recurrent failure of conventional skin grafting is described in a patient with 95 per cent full skin thickness burns. This method of treatment, which was described in the past and neglected, is of value for massive burns or grafting in difficult areas. The technique is described again and the relevant literature reviewed.

Scalp Necrosis in a Neonate Treated with Cultured Autologous Keratinocytes

A neonate compromised by a stressful labor, low birth weight, anemia, seizures, and enterocolitis developed necrosis of a caput succedaneum of the calvaria. Coverage with cultured autologous keratinocytes was successful and represents a treatment modality with minimal morbidity compared with conventional split-thickness skin grafts.

Skin Substitutes in Upper Extremity Burns

Four techniques for permanent skin replacement with skin substitutes are described. A claim of superiority to conventional skin grafting on upper extremity and hand burns is not made, but some clinical observations and histologic evidence of different healing characteristics are shown. The composite grafts described appear to effectively replace the bilayered structure of skin and seem to have good subjective resistance to shear forces. If the skin replacement is durable and heals with less scarring than conventional skin grafts, the inexorable course to stiffness and contracture may be altered. Further basic science and clinical investigation may provide us with a better way of managing these difficult problems.

REJECTION OF CULTURED KERATINOCYTE ALLOGRAFTS IN THE RAT

We have made a detailed analysis of the fate of Langerhans cell-free cultured keratinocyte allografts in two rat strain combinations, DA-to-PVG and DA-to-LEW, and compared the results with the rejection of conventional skin allografts in these strain combinations. The cultured keratinocyte layers were grafted both to the body surface using a technique to prevent wound contraction, and to the renal subcapsular site. Histological examination of grafts was made on days 2, 7, 10, 14, and 28 after transplantation. Donor-specific anti-class I MHC monoclonal antibodies were used to verify the donor origin of the keratinocytes. We report that the keratinocyte allografts are acutely rejected but, in contrast to the conventional allografts, do not evoke alloantibody responses. Rejection of the keratinocytes at the renal subcapsular site was as rapid as that of conventional skin grafts. However, rejection of keratinocyte grafts on the body surface was delayed by a few days when compared with conventional skin grafts. Immunosuppression with cyclosporine prevented the rejection of DA keratinocyte layers placed at the renal subcapsular site of PVG rats, but rejection followed soon after cessation of cyclosporine therapy. These data suggest that rejection is a major constraint for the clinical application of cultured keratinocytes, and that autografts must be used if permanent cover is required. Moreover, the findings have interesting theoretical implications relating to the much greater vulnerability to rejection of skin grafts compared with organ grafts. Our current and previous data also suggest that class II positive dendritic cells are the major stimulus to alloantibody production after tissue transplantation.

Cultured keratinocytes as biological wound dressings

Human epidermal keratinocytes now can be grown reliably and reproducibly in vitro to form multilayered epithelium. These sheets of cultured keratinocytes have been used successfully to autograft patients with severe burns, leg ulcers and following excision of extensive congenital naevi. Whilst the technique carries the obvious advantage of huge expansion of the initial skin biopsy, thus removing the need for painful and slow healing donor sites, problems have been encountered. The take rate has been lower than with conventional split skin grafts. The take rate can be increased by the provision of a dermis. This may be achieved by providing an allodermis or by the use of a highly meshed autologous split skin graft. The wound is then covered with autologous cultured keratinocyte grafts. Manufactured dermis has been under investigation for some years and animal work suggests this may be an alternative approach. There is a delay of 2 to 3 weeks for culture of the autologous sheets of keratinocytes. This has led to the use of allogeneic grafts in a number of patients. The long term survival of these grafts has been attributed to the loss of antigen presenting cells during tissue culture. However some grafts have been rejected. Studies currently in progress may help resolve these anomalies. Whilst a number of problems remain to be solved the technique of cultured keratinocyte grafting takes wound care into an exciting new era. Skin banks may now become more than a surgeon's dream.

A simple method of taking skin grafts from the avulsed flap in degloving injuries

A simple method is described to facilitate the cutting of skin grafts from degloved skin flaps with a conventional hand dermatome or skin grafting knife.

GRAFTING OF BURNS WITH CULTURED EPITHELIUM PREPARED FROM AUTOLOGOUS EPIDERMAL CELLS

The cells from a small piece of epidermis can be grown into a large number of cultured epithelia. Such epithelia, generated from autologous skin, were grafted onto full-thickness burn wounds in two patients. The cultured epithelia acquired an epidermal structure resembling that achieved with conventional split-thickness skin grafts, and survived for the period of observation (up to 8 months). Since the method of cultivation can generate large amounts of epithelium, the procedure is applicable to the grafting of large areas, as in severe burns.

PROLONGED SURVIVAL OF ALYMPHATIC SKIN ALLOGRAFTS IN THE RAT A HUMORAL COMPONENT

Immunological mechanisms of increased graft survival in "immunologically privileged" sites were defined by comparing host responses against orthotopic and alymphatic skin allografts in rats. The conventional skin grafts reject by day 8; grafts placed on alymphatic skin pedicles heal in normally, but begin by day 16 to 18 to contract inexorably until only a scar remains by day 35 to 40. Lymphocyte-mediated cytotoxicity rose significantly in spleen and draining lymph nodes 8 to 10 days after orthotopic grafting, but was absent as long as 35 days after skin transplantation to alymphatic pedicles. No significant activity in antibody-dependent lymphocyte-mediated cytotoxicity was noted in either recipient group, while complement-dependent cytotoxicity was slightly elevated 8 to 10 days postoperatively in both groups. Passive transfer of serum from recipients of alymphatic skin grafts, taken 8 and 12 days after grafting, prolonged survival of test cardiac allografts significantly, although neither control serum from recipients of orthotopic skin allografts, or serum taken 28 days after alymphatic skin grafting increased test heart survival. We conclude that prolonged survival of skin grafts on alymphatic sites may be based, at least partially, on the development of host humoral factors.

A new dermatome for preparing large free skin grafts.

The defatting of large skin grafts from detached tissue presents technical problems due to the nature of conventional skin grafting knives and dermatomes. Such free grafts are required following degloving injuries, or in the surgical correction of lymphoedema of the legs.