Composite Skin Grafts Research Articles

Rekonstruktive Nasenchirurgie – das Problem der Innenauskleidung

Careful internal defect coverage is important for a well vascularised internal base for the transplant in reconstructive nasal surgery. Secondary healing of intranasal wounds often results in nostril contracture and scar stenosis. The choice of methods for surgical coverage depends on the location of the defect and the condition of surrounding elements. For example, the double-stemmed "pot handle" flap is suitable for small defects of the internal lining of the nasal lobule. The septal mucosa flap can be used for larger and more complex defects of the internal nasal lining. Using composite skin and cartilage grafts from the ear, three-layered nasal defects can be treated in a variety of ways. The turn-in flap is a tilt flap and is very versatile for the treatment of inner defects of the lower nasal half.

The long-term efficacy and clinical application of acellular allograft dermal with autogenous skin grafts in wound repair

Objective To find an ideal cover material for repairing of deep-burned functional part and scar deformity. Methods The wound of ulcer,scar and wound of the deep-burned functional part excised were covered with acellular allograft derma plus autogenous split-thickness skin graft. Results 30 cases were included in this study. The survival rate of the composite skin grafts was 100%. All the composite skin grafts were smooth and soft,had good elasticity, and the joint functions were good. Conclusion Acellular allograft dermal with autologous skin is an ideal covering material for repairing wound of function parts Key words: Acellular allograft dermal; Autogenous split-thickness skin; Wound repair

A Preliminary Study of the Effect of Poly(Methacrylic Acid-Co-Methyl Methacrylate) Beads on Angiogenesis in Rodent Skin Grafts and the Quality of the Panniculus Carnosus

Inadequate blood supply can limit tissue graft size and thickness. As a result, there is considerable interest in vascularization strategies that might extend these limits. Beads of a copolymer of methacrylic acid and methyl methacrylate were used to enhance rat composite myocutaneous skin graft vascularization and to assess the effect on the gross morphology of the panniculus carnosus. Beads (45 or 65 mol% methacrylic acid (n = 8) or control 100 mol% methyl methacrylate (n = 6) were spread over the wound bed and covered with the composite myocutaneous graft and analyzed 11 days later in comparison with a no-bead control group (n = 22). Microvessel density counts were significantly higher (p < 0.001) for grafts treated with either 45 mol% methacrylic acid or 65 mol% methacrylic acid beads compared with grafts treated with methyl methacrylate beads or no beads. There was no significant difference between grafts treated with 45 mol% methacrylic acid or 65 mol% methacrylic acid beads, and no significant differences between grafts treated with methyl methacrylate beads and no beads. Most importantly, the panniculus carnosus was significantly thicker (p < 0.001) for grafts treated in either methacrylic acid bead group compared with grafts treated with either methyl methacrylate beads or no beads. The data provide supporting evidence that methacrylic acid beads augment graft vascularization and the health of the panniculus carnosus.

Preparation of laser micropore porcine acellular dermal matrix for skin graft: An experimental study

In our previous study, we used composite grafts consisting of meshed porcine acellular dermal matrix (PADM) and thin split-thickness autologous epidermis to cover full thickness burn wounds in clinical practice. However, a certain degree of contraction might occur because the distribution of dermal matrix was not uniform in burn wound. In this study, we prepare a composite skin graft consisting of PADM with the aid of laser to improve the quality of healing of burn wound. PADM was prepared by the trypsin/Triton X-100 method. Micropores were produced on the PADM with a laser punch. The distance between micropores varied from 0.8, 1.0, 1.2 to 1.5mm. Full thickness defect wounds were created on the back of 144 SD rats. The rats were randomly divided into six groups: micropore groups I-IV in which the wound were grafted with PADM with micropores, in four different distances, respectively and split-thickness autograft; mesh group rats received meshed PADM graft and split-thickness autograft; control group received simple split-thickness autografting. The status of wound healing was histologically observed at regular time points after surgery. The wound healing rate and contraction rate were calculated. The wound healing rate in micropore groups I and II was not statistically different from that in control group, but was significantly higher than that in mesh group 6 weeks after grafting. The wound healing rate in micropore groups III and IV was lower than that in mesh and control groups 4 and 6 weeks after grafting. The wound contraction rate in micropore groups I and II was remarkably lower than that in control group 4 and 6 weeks after surgery and it was significantly much lower than that in mesh group 6 weeks after surgery. Histological examination revealed good epithelization, regularly arranged collagenous fibers and integral structure of basement membrane. Laser micropore PADM (0.8 or 1.0mm in distance) grafting in combination with split-thickness autografting can improve wound healing. The PADM with laser micropores in 1.0mm distance is the better choice.

An Evidence-Based Appraisal of the Use of Hyperbaric Oxygen on Flaps and Grafts

Hyperbaric oxygen has been advocated, both as an adjunctive or primary form of treatment, for a variety of disorders, including gas gangrene, osteoradionecrosis, and carbon monoxide poisoning. It has also been used to improve ischemic wounds before skin grafting and to support ischemic flaps. In this review, we analyze the available literature that investigates the use of hyperbaric oxygen for composite grafts, skin grafts, random flaps, distant flaps, and free flaps. An appraisal of the level of evidence for each of these uses of hyperbaric oxygen is offered. Although there are a significant amount of animal data supporting the application of hyperbaric oxygen for grafts and flaps, there is very little clinical information other than case reports and series to sustain its choice over other modalities of therapy. Multicenter prospective clinical studies are clearly needed comparing hyperbaric oxygen to other mechanical or pharmacologic interventions to improve wound healing for grafting or to support flap survival.

Evaluation of a composite skin substitute to treat venous stasis ulcers: a pilot study

Introduction: Venous leg ulcers represent a therapeutic challenge, and they are associated to significant morbidity and cost. Many advances have been made to develop and apply biological skin substitutes, showing they can be beneficial for patients with burns, leg ulcers, and other skin lesions. Autologous cultivated keratinocytes have been demonstrated to be useful in leg ulcer treatment, but the lack of a dermal component may compromise their effects and the quality of the scar. Purpose: To evaluate a composite skin graft of human acellular dermis and autologous keratinocyte culture to treat leg ulcer. Methods: Two patients with four long-term chronic ulcers were treated with a composite skin graft of human acellular dermis and autologous keratinocyte culture for a month in this pilot study. Results: The four ulcers had a surface reduction of 72.21%, 36.36%, 60.93%, and 15.90% after one month of treatment. No adverse tissue reactions were observed. Histology and immunohistochemistry showed that humam acellular dermis was free of donor’s cells, and the composite skin substitute preserved the architecture of the normal skin, including the basement membrane components and stratified epidermis. Conclusions: These preliminary observations suggest that such composite skin substitute could be an alternative to recalcitrant leg ulcers.

Authentic fibroblast matrix in dermal equivalents normalises epidermal histogenesis and dermo-epidermal junction in organotypic co-culture

Besides medical application as composite skin grafts, in vitro constructed skin equivalents (SEs) or organotypic co-cultures represent valuable tools for cutaneous biology. Major drawbacks of conventional models, employing collagen hydrogels as dermal equivalents (DEs), are a rather poor stability and limited life span, restricting studies to early phases of skin regeneration. Here we present an improved stabilised in vitro model actually providing the basis for skin-like homeostasis. Keratinocytes were grown on dermal equivalents (DEs) reinforced by modified hyaluronic acid fibres (Hyalograft-3D) and colonised with skin fibroblasts, producing genuine dermis-type matrix. These SEs developed a superior epidermal architecture with regular differentiation and ultrastructure, which occurred also faster than in SEs based on collagen-DEs. Critical aspects of differentiation, still unbalanced in early stages, were perfectly re-normalised, most strikingly the co-expression of keratins K1/K10 and downregulation of regeneration-associated keratins such as K16. The restriction of integrin and K15 distribution as well as keratinocyte proliferation to the basal layer underlined the restored tissue polarity, while the drop of growth rates towards physiological levels implied finally accomplishment of homeostasis. This correlated to faster basement membrane (BM) formation and ultrastructurally defined dermo-epidermal junction including abundant anchoring fibrils for strong tissue connection. Whereas the fibroblasts in the scaffold initially secreted a typical provisional regenerative matrix (fibronectin, tenascin), with time collagens of mature dermis (type I and III) were accumulating giving rise to an in vivo-like matrix with regularly organised bundles of striated collagen fibrils. In contrast to the more catabolic state in conventional DEs, the de novo reconstruction of genuine dermal tissue seemed to be a key element for maintaining prolonged normal keratinocyte proliferation (followed up to 8 wks), fulfilling the criteria of tissue-homeostasis, and possibly providing a stem cell niche.

Composite skin grafts for basal cell carcinoma defects of the nose.

Basal cell carcinoma is the most frequent cutaneous cancer of the nose and is characterized by its local spreading and exceptionally rare tendency to metastasize. Since a significant advantage has been seen in surgery compared to other treatments, surgical excision ensuring the highest chance of cure is frequently employed. Excision defects of the nose may be covered with either local flap or a full-thickness skin graft. In resurfacing such defects following excision of basal cell carcinomas, we favor the technique of composite-skin grafting which involves the harvesting of composite-skin graft including the epidermis, dermis and superficial layers of subcutaneous tissue to obtain the required thickness in the recipient site. This technique was used for defects remaining after the excision of basal cell carcinomas in a series of 15 patients. The areas involved were lateral nasal region (5 cases), nasal tip (4 cases), dorsum (3 cases), alar lobule (2 cases), and soft triangle (1 case). The mean follow-up was 14.2 months. The color, texture and thickness of the composite-skin graft harvested from the preauricular site and the neck compare favorably with the skin of the nose region. Satisfactory results, both clinically and in patient appreciation, have been obtained in both the reconstruction site and the appearance of the donor site in all patients.

Fibroblasts Improve Performance of Cultured Composite Skin Grafts on Athymic Mice

Fibroblasts Improve Performance of Cultured Composite Skin Grafts on Athymic Mice

Experimental model of cultured keratinocytes

The bioengineering research is essential in the development of ideal combination of biomaterials and cultured cells to produce the permanent wound coverage. The experimental model of cultured keratinocytes presents all steps of the culture, since the isolation of the keratinocytes, preparation of the human acellular dermis, preparation of the composite skin graft and their elevation to the air-liquid interface. The research in cultured keratinocytes model advances in two main ways: 1. optimization of the methods in vitro to the skin cells culture and proliferation and 2. developing biomaterials that present similar skin properties.

Contraction of the composite skin graft and autograft

Wound contraction as a result of a delay in grafting or second intention healing in an area that there was no graft take is a serious problem because of the sequela to the burned patient. The objective of the present study was to evaluate the contraction of the cultured keratinocytes and human acellular dermis composite graft by tracing the graft with transparent film after transplantation to the back of athymic mice. The evaluation of the contraction of the composite skin grafts and autografts in relation to the original wound area on the back of the athymic mice demonstrated greater contraction of the grafts after the dressings were removed on the seventh day. The composite skin graft contraction was significantly bigger than the autograft contraction. The experimental data suggested that the contraction appeared after dressing removal, but that the macroscopic aspect of the composite skin graft remained normal with no distortion of the graft or the surrounded murine skin.

Differentiation and barrier formation of a cultured composite skin graft.

The differentiation and barrier formation of cultured composite skin grafts (CSGs) were assessed by histology and measurements of surface electrical capacitance (SEC) in vitro and in vivo. Keratinocytes cultured on the surface of acellular dermis were lifted to the air-liquid interface and analyzed for 30 days in vitro. Initially, SEC measurements of CSGs (n = 11) were high but quickly dropped between days 4 and 6 and remained steady for 30 days, indicating barrier formation by the epidermis. Histology of the CSGs (n = 6) demonstrated stratification of the epidermal cells and partial formation of the stratum corneum by day 3 that was complete by day 7. CSGs (n = 5) were transplanted to athymic mice, where they formed a stratified and differentiated epidermis. SEC measurements of CSGs remained low after transplant, suggesting that exposure to the air-liquid interface improved the maturation of CSGs in vitro prior to transplant.

Integra as a dermal replacement in a meshed composite skin graft in a rat model: a one-step operative procedure.

Current use of Integra, the collagen-based dermal analogue, requires a two-step grafting procedure to achieve wound closure with an "ultrathin" autograft. A one-step operative procedure of meshed composite skin graft (MCSG) using Integra as a dermal template for a meshed split thickness autograft was developed in rats. The silicon layer of Integra was removed, the resulting dermal analogue was meshed (1:1.5), expanded, and placed on excised full thickness wound and covered with a meshed (1:1.5 or 1:6) split thickness autograft. Grafted wounds were dressed with BioBrane, Vaseline gauze, silver-impregnated nylon, or silver-nylon and direct current (SNDC). At scheduled intervals up to 3 months postgrafting, wounds were examined for epithelialization, collagen deposition and fibrosis, hair growth, and contraction. The results of wound closure and healing following the one-step procedure were compared with the outcome of the two-step grafting procedure where application of meshed Integra (step one) was followed in 14 days by removal of the silicon layer and application of the meshed autograft (step two). The one-step procedure applied to meshed autograft/Integra (1:1.5/1:1.5) composite graft accelerated wound closure by 6-19 days when compared with the two-step procedure. At 3 months postgrafting, the contraction of the healed wound dressed with SNDC, BioBrane, or Vaseline gauze was reduced by 13-16% following the one-step procedure compared with the two-step procedure (p < 0.05). The one-step procedure allowed the expansion of the autograft layer to 1:6 while achieving wound healing results similar to grafting with 1:1.5 meshed autograft layer using the two-step grafting procedure. Single-step application of meshed, thin, split thickness autograft over meshed Integra-derived dermal substitute allows more rapid wound closure with less contraction and more efficient use of graft donor skin than can be obtained with the commonly used two-step grafting procedure.

The Use of Transplantable Dermis from Incompatible Hosts in Composite Skin Grafts

The Use of Transplantable Dermis from Incompatible Hosts in Composite Skin Grafts

Accelerated healing with a mesh autograft/allodermal composite skin graft treated with silver nylon dressings with and without direct current in rats.

Evaluation of the healing and persistence of a meshed composite skin graft applied without immunosuppression. The contraction of wounds grafted with 9:1 split-thickness autograft/1.5:1 allodermal mesh composite skin grafts (auto/allo MCSGs) was investigated. No immunosuppressive agent was applied. Male ACI rats and female Lewis rats reciprocally served as allodermis graft donors and recipients. Autograft/dermal autograft and allograft/dermal allograft MCSGs were the controls. AT 3 months after grafting, when epithelized auto/allo MCSG wounds were measured by computerized morphometric analysis, the silver nylon (SN) dressing group displayed less contraction than the Vaseline (petroleum jelly) dressing group (p < 0.003), and direct current treatment (SNDC) was more effective than SN (p < 0.005). The histologic structures of the hair follicles appear to confine the rejection process to the allogeneic follicles of the graft. The focal nature of the rejection process and the relatively low antigenicity of the dermal matrix allowed the survival of the allodermis layer. Although direct current significantly enhanced MCSG healing, SN and SNDC were not the immunosuppressive agents that were confirmed. This type of MCSG can heal without immunosuppressive treatment.

Results of 1018 digital replantations in 552 patients

To find out the influencing factors of the immediate and late outcome of replantation and revascularization of the digits the study was carried out as a prospective survey research during 1983 to 1995 with at least 2 year follow up. Traumatic total or subtotal amputation with inadequate circulation of the digits distal to the metacarpal head were included in the study. There were 552 patients with 366 males (675 digits) and 186 females (343 digits). Successful operation was found in 508 patients (92%) with 946 digits (92.9%). Type of injury was the most important factor influencing immediate and late outcome. Regular cigarette smoking resulted in poor immediate survival rate. Prolonged ischaemia had a significant influence in final functional outcome. Using composite skin and subcutaneous vein graft gave good survival rate. Injury at the no man's land area resulted in poor range of movement of the digit. Connecting the profundus tendon stump of the proximal part to the superficialis tendon of the amputated part gave a better result than 2 tendon repair and repairing only the profundus tendon. Replantation should be carried out even if only one digit is involved. At the 2 year follow up 195 patients (38%) were classified in grade I of Chen et al., functional outcome, while 153 (31%) were in grade II, 124 (24%) were in grade III and 36 (7%) were in grade IV.

Computer controlled bioreactor for large-scale production of cultured skin grafts.

KERATOR--an automated membrane bioreactor--was developed to produce Autologous Wound Dressing (AWD) at significantly reduced cost and time of transplantation down to two weeks time. At the same time, the risk of human error is largely eliminated. The computer-controlled reactor is modular, allowing the production of up to 0.5 m2 AWD at one time. A special feature of the reactor is a hydrophilic polymeric support membrane on which the human keratinocytes attach and proliferate. Recently developed serum-free medium is used to culture keratinocytes as a monolayer without a feeder layer of murine fibroblasts. The use of composite skin grafts consisting of a subconfluent keratinocyte layer on a polymeric support film is a very promising method for skin transplantation owing to the high activity of non-differentiated keratinocyte cells and reduction of the time needed to prepare the skin grafts. A microscopic video system with image analysis was developed for on-line monitoring of the cell growth and morphology in the KERATOR. The computer uses the obtained information to control medium change and to predict the end of cultivation.

Snowblower injuries to the hand.

A retrospective review of 22 patients who sustained snowblower injuries to the hand was performed. There were 17 men and 5 women, ranging in age from 20 to 68 years (average age, 39.7 years). Fifty percent were manual laborers, 25% were unemployed, 15% were office workers, and 10% were not categorized. The dominant hand was involved in 86% of patients. In all patients, injuries occurred during an attempt to unclog manually the snowblower of wet snow. Patients were evaluated initially in the emergency room, where their wounds were irrigated and debrided, subungual hematomas drained, and nail bed lacerations repaired. Patients with more extensive injuries were taken to the operating room for definitive treatment including open or closed reduction of fractures, fingertip replacement as composite grafts or skin grafts, revision amputations, tenorrhaphies, and digital nerve repairs. All injuries occurred distal to the metacarpophalangeal joints. Only 1 patient sustained an injury to the proximal phalanx. Ten patients injured only 1 finger, 6 patients injured 2 fingers, and 6 patients injured 3 fingers. The middle and ring fingers were most commonly injured (39.6% and 33.3% respectively), followed by the index and little fingers (16.7% and 8.3% respectively), and the thumb (2.1%). Phalangeal fractures were the most common type of injury, occurring in 29.2% of patients, and usually involved the distal phalanx. This was followed in frequency by nail bed injuries (22.9%), amputations (22.9%), tendon lacerations (14.6%), soft-tissue avulsions (6.3%), and digital nerve injuries (4.2%). Snowblower injuries can involve bone, soft tissue, nail bed structures, nerves, and tendons, and may even result in amputation of one or several fingers. These injuries are localized to the distal portions of the fingers. The middle and ring fingers are most commonly involved, with relative sparing of the thumb. Fractures are the most frequent injury, followed by nail bed injuries and amputations. Snowblower injuries are often managed as open fractures with intravenous antibiotics; irrigation and debridement; and repair of bone, soft tissue, and nail bed structures.

Automated Culture of Human Keratinocytes in Bioreactor with Image Analysis for Production of Autologous Skin Grafts

The culture conditions for production of composite skin grafts consisting of keratinocyte monolayer grown on a hydrophilic foil support were optimized. The skin grafts were produced in a special bioreactor automating the culture operations such as cell seeding, medium change, and harvesting. For the purpose of the reactor control, a method for on-line monitoring cell confluence and cell concentration of the keratinocyte cultures was established using the technique of image analysis.

Genetically modified human keratinocytes overexpressing PDGF-A enhance the performance of a composite skin graft.

Skin loss due to burns and ulcers is a major medical problem. Bioengineered skin substitutes that use cultured keratinocytes as an epidermal layer with or without analogues of the dermis are one strategy for skin repair. However, none can achieve definitive wound closure, function, or cosmesis comparable to split-thickness autografts. Moreover, autograft donor sites, which require time to heal, may be limited or have attendant problems such as infection or functional/cosmetic deficiencies. To determine if the performance of composite skin grafts of keratinocytes on a dermal analogue could be enhanced, human keratinocytes were genetically modified to overexpress platelet-derived growth factor A chain (PDGF-A). Composite grafts of modified keratinocytes seeded onto acellular dermis, prepared from cryopreserved cadaver skin, secreted PDGF-AA protein in vitro [90 ng/graft (1.5 x 1.5 cm)/24 hr]. To test their performance in a wound healing model, composite grafts were transplanted to full-thickness excisional wounds on the back of athymic mice. PDGF-A grafts formed a stratified differentiated epidermis similar to control grafts. The acellular dermis was repopulated with host fibrovascular cells and by day 7, the PDGF-A grafts had significantly more cells in the dermis and increased staining for murine collagen types I and IV. At this early time point, wound contraction was also significantly inhibited in PDGF-A grafts versus control grafts. Thus, PDGF-A overexpression improves graft performance during the first critical week after transplantation.