Biomedical subjects

S T Boyce

Publications and source records attributed to S T Boyce.

At least 55 records · Page 3Linked to original sources

PubMed1989

Burn wound closure with cultured autologous keratinocytes and fibroblasts attached to a collagen-glycosaminoglycan substrate.

Improved survival of patients with extensive burn injuries requires the development of better techniques for timely and permanent closure of the full-thickness wound. We developed procedures for establishing confluent, stratified layers of cultured, autologous keratinocytes on the surface of a modified collagen-glycosaminoglycan membrane that contains autologous fibroblasts. We transferred the composite grafts onto limited areas of excised full-thickness burn wounds of four patients with extensive burn injuries. Our results indicate that this composite graft material has acceptable "take," with formation of a basement membrane within 9 days of graft placement. Use of this technique for major wound coverage may offer a significant advance in the care of extensively burned patients and also may be useful for providing skin for reconstructive surgery.

Adult↗

PubMed1989

Attachment of peptide growth factors to implantable collagen.

Ingrowth of fibrovascular tissue from the woundbed into collagen-based dermal substitutes and survival of cultured epithelium after transplantation may be enhanced by attachment of heparin binding growth factor 2 (HBGF2) and epidermal growth factor (EGF) to collagen. Biotinylation of collagen and the growth factors allows immobilization of HBGF2 and EGF by high affinity binding of tetravalent avidin. Biotinylated HBGF2 and EGF (B-GF) were exposed to complexes of biotinylated collagen (B-COL)-avidin (A) and detected with peroxidase-labeled avidin (AP) followed by chromagen formation on nitrocellulose paper. Binding of biotinylated HBGF2 and EGF was specific (*, P less than 0.05), proportional to the concentration of biotinylated collagen, and resistant to ionic (NaCl) displacement. Data are expressed as mean percentages of maximum binding +/- SEMs: (table; see text) Growth response of cultured human epidermal keratinocytes to HBGF2 (population doubling time, PDT = 0.70 population doublings (PD)/day) confirmed the retention of mitogenic activity after biotinylation (PDT = 0.80 PD/day). Specific binding of biotinylated HBGF2, EGF, or other biologically active molecules (antibiotics, NSAIDs) to implantable collagen may provide a mechanism for positive therapeutic modulation of wound healing, including repair of full-thickness skin wounds with cultured cell-collagen composite grafts.

Cell Division↗

PubMed1988

Structure of a collagen-GAG dermal skin substitute optimized for cultured human epidermal keratinocytes.

Collagen and glycosaminoglycan (GAG) dermal skin substitutes (membranes) were studied as substrates for cultured human epidermal keratinocytes. Structure of dermal substitutes was optimized for pore size to promote ingrowth of fibrovascular tissue from the wound bed and for culture of human keratinocytes of the membrane's surface. Pore size of the freeze-dried material was regulated by control of the temperature of freezing between -50 degrees C and -20 degrees C and by concentration of starting materials between 0.17% and 1.62% wt/vol. A nonporous surface of collagen-GAG was laminated to the membranes to provide a planar substrate for cultured epidermal keratinocytes. Thickness of dermal substitutes was regulated by control of the volume and concentration of starting materials. Biotin was conjugated to solubilized collagen for binding with avidin of specific quantities of biologically active molecules. The optimized membranes are suitable substrates for the culture of human epidermal keratinocytes, and together with the cells yield a composite material that is histologically similar to skin.

Artificial Organs↗

PubMed1988

Biologic attachment, growth, and differentiation of cultured human epidermal keratinocytes on a graftable collagen and chondroitin-6-sulfate substrate.

Repair of full-thickness burns requires replacement of both the dermal and the epidermal components of the skin. Use of tissue culture methods allows very large expansions of surface area to be covered by cultured normal human epidermal keratinocytes (HK). Porous and resorbable materials, such as collagen and chondroitin-6-sulfate membranes, may be expected to adhere to wounds and promote fibrovascular ingrowth better than grafts of cultured epidermal keratinocytes alone. This article demonstrates the in vitro formation of biologic attachments between HK and a collagen and chondroitin-6-sulfate dermal skin replacement. Dermal membranes are prepared as generic acellular sheets and stored in the dry state for extended periods. Subconfluent HK cultures in logarithmic phase growth can attach quickly to dermal membranes in vitro, form a confluent epithelial sheet on the surface of each membrane, and exhibit mitotic cells for at least 1 week in vitro. Transmission electron microscopy demonstrates the formation of hemidesmosomes, extracellular matrix, and banded collagen at the interface of the epidermal cells and the dermal membrane. By comparison, HK cultures as confluent sheets released enzymatically with Dispase do not attach to the dermal membranes in vitro, under the conditions tested, although complete coverage of the membrane by the cell sheets is obtained. Growth assays show that subconfluent HK cells retain sufficient growth potential to maintain logarithmic phase growth, but that HK cells disaggregated from confluent sheets become growth arrested in comparison. The composite material has discrete dermal and epidermal compartments, has total thickness comparable to split-thickness skin graft, and can be applied to full-thickness skin defects in a single procedure.

Burns↗

PubMed1986

Study of HLA-DR synthesis in cultured human keratinocytes.

Within the normal human epidermis only Langerhans and indeterminate cells express HLA-DR. Human keratinocytes (HK), however, may also express HLA-DR in certain disease states characterized by mononuclear cell infiltrates. Previous studies have shown that HK synthesize HLA-DR in response to stimulation by interferon gamma (INF-gamma). The purposes of this study were to define conditions under which cultured HK might express HLA-DR and to compare the HLA-DR synthesis of HK with that of monocytes. HLA-DR expression by HK as determined by indirect immunofluorescence of HK cultures was absent under standard low calcium conditions and remained absent with the addition of calcium, serum, mitogens, and supernatants from Pam-212 cells containing epidermal thymocyte-activating factor. HLA-DR expression in HK was induced by cocultivation with concanavalin A-stimulated peripheral blood mononuclear cells (PBMC), but not unstimulated PBMC. This effect was time-dependent and directly related to the number of PBMC. HLA-DR expression was also induced in a time- and dose-dependent manner by addition of supernatant from stimulated PBMC (SS) or by addition of recombinant INF-gamma but not by addition of interleukin (IL)-1 or IL-2. Induction by either SS or INF-gamma was blocked by an antiserum to INF-gamma. As determined by a semiquantitative immunoprecipitation technique, HLA-DR synthesis by HK was directly related to INF-gamma concentration. The pattern of HLA-DR peptides produced by HK was similar to that of monocytes, but the relative quantity synthesized was far less than that of monocytes.

Cells, Cultured↗

PubMed1985

Systematic comparison of antibody-mediated mechanisms of keratinocyte lysis in vitro.

We have conducted a systematic comparison of lysis of TNP-coated keratinocyte targets by TNP-specific antibody, by antibody plus complement, by antibody-dependent cellular cytotoxicity (ADCC), and by natural killing with the use of monocyte, lymphocyte, and neutrophil effectors. With chromium-release assays, human keratinocytes, HEp-2 cells (transformed human keratinocytes), PAM 212 cells (transformed mouse keratinocytes), and RSC (transformed rabbit keratinocytes) were all susceptible to monocyte- and lymphocyte-mediated ADCC (p less than 0.01 to p less than 0.02). All trypsinized keratinocyte targets were also susceptible to natural killing by monocyte or lymphocyte effectors (p = 0.05 to p less than 0.001). Antibody and antibody plus complement were poor mediators of keratinocyte lysis. If protein and complex lipid synthesis of keratinocytes were inhibited by 16-hr cycloheximide preincubation, then keratinocytes were susceptible to complement-mediated lysis, implying that the resistance of these cells to complement may be due to repair of transmembrane pores. Comparison of chromium-release assays with fluorescein diacetate dye uptake viability assays showed that human keratinocytes were still susceptible to monocyte and lymphocyte ADCC but not to antibody, antibody plus complement, or natural killing. The reproducible and uniform susceptibility of normal and transformed keratinocyte targets from three different species to monocyte and lymphocyte ADCC supports the hypothesis that this mechanism of cellular lysis may be important in antibody-associated diseases of epidermal cytotoxicity.

Animals↗

PubMed1984

Ultraviolet light induces binding of antibodies to selected nuclear antigens on cultured human keratinocytes.

Antibodies which bind to different nuclear antigens in tissue sections or in permeabilized cell cultures are useful markers of subsets of connective tissue disease, especially of lupus erythematosus (LE), but whether these antibodies are able to react with these intracellular sequestered antigens in vivo and cause immunologic tissue damage has been a matter of much debate. We report experiments which show that ultraviolet light-irradiated, cultured human keratinocytes bind IgG antibodies from the sera of LE patients with either monospecific anti-SSA/Ro, anti-RNP, or anti-Sm activity, which implies that these antigens have been made accessible on the cell surface by ultraviolet irradiation. Normal human sera or LE patient's sera with anti-double-stranded DNA, anti-single-stranded DNA, or antihistone activity do not bind to the surface of irradiated human keratinocytes. In control experiments, all antisera produced the expected patterns of nuclear and cytoplasmic staining of fixed permeabilized, unirradiated keratinocytes. Careful study of the viability and permeability of irradiated keratinocytes by several techniques showed that this apparent cell membrane expression of extractable nuclear antigens (SSA/Ro, RNP, and Sm) following irradiation was seen on injured keratinocytes whose cell membranes were intact, but not on dead cells. It is particularly significant that all six monospecific anti-SSA/Ro sera bound to irradiated keratinocytes, since this antibody antigen system is highly associated with photosensitive cutaneous LE.

Antibodies, Antinuclear↗

PubMed1983

Calcium-regulated differentiation of normal human epidermal keratinocytes in chemically defined clonal culture and serum-free serial culture.

An improved serum-free culture system has been developed for normal human epidermal keratinocytes (HK). Short-term clonal growth and differentiation studies are routinely performed in a defined medium consisting of optimized nutrient medium MCDB 153 supplemented with epidermal growth factor, insulin, hydrocortisone, ethanolamine, and phosphoethanolamine. A small amount of whole bovine pituitary extract (wBPE) is added for initiation of primary cultures, for frozen storage, and for serial culture. The need for feeder layers, conditioned medium, serum, and specialized culture surfaces has been eliminated entirely. With an optimal level of calcium ion (0.3 mM), colony-forming efficiency is about 30 percent and cellular multiplication rate is 0.96 doublings per day in the defined medium. A high-calcium concentration (1.0 mM) induces stratification and terminal differentiation, which can be quantified by counting cornified envelopes that are resistant to boiling in sodium dodecyl sulfate plus dithiothreitol. Under optimal conditions with wBPE present, cellular senescence occurs after about 40 population doublings. Scanning electron microscopy (SEM) has verified the occurrence of stratification during differentiation in the defined medium with high calcium. High-voltage electron microscopy (HVEM) after detergent extraction of human epidermal keratinocyte (HK) colonies grown in the defined medium with low and high calcium has revealed specific changes in the intermediate filament network and keratohyalin granules corresponding to changes in cellular differentiation. Indirect immunofluorescence studies have verified that the intermediate filament network observed with HVEM is composed of keratin proteins.

Blood↗

PubMed1981

Rapid clonal growth and serial passage of human diploid fibroblasts in a lipid-enriched synthetic medium supplemented with epidermal growth factor, insulin, and dexamethasone.

A serum-free, hormone-supplemented medium, enriched with a mixture of lipids, has been developed that supports rapid clonal growth of human diploid fetal lung fibroblasts (Flow 2000, WI-38, MRC-5, and IMR-90) and of low-passage human foreskin fibroblasts. The medium, which contains less than 1 microgram of total protein per ml, also supports serial passage of Flow 2000 cells under totally serum-free conditions. It provides lipid at a total of 10 micrograms/ml as a liposome prepared from a mixture of soybean lecithin, cholesterol, sphingomyelin, vitamin E, and vitamin E acetate. The soybean lecithin, which contains a variety of naturally occurring phospholipids, can be replaced with a mixture of highly purified phospholipids. Except for possible contaminants in the substances used in its preparation, the serum-free medium is fully defined chemically. It consists of an optimized basal nutrient medium, MCDB 110, supplemented with insulin, epidermal growth factor, dexamethasone, prostaglandins E1 and F2 alpha, phosphoenolpyruvate, dithiothreitol, glutathione, and the lipids listed above.

Cell Division↗

PubMedDate not supplied

Capillary morphogenesis during healing of full-thickness skin grafts: an ultrastructural study.

Biologic mechanisms by which skin grafts become revascularized after transplantation are poorly understood. To investigate graft revascularization, we examined the pattern of capillary growth in full-thickness skin grafts at serial time points. Full-thickness skin (2 x 2 cm) was excised to muscle fascia from the bilateral hind limbs of adult male Lewis rats. The graft/wound base boundary was identified by placement of a polypropylene mesh on the wound beneath the graft. Excised skin was replaced in its original orientation and secured with silk sutures tied over a gauze bolster dressing. After 3, 5, 7, and 10 days, animals were killed, and their aortas were cannulated and infused with an acrylic polymer to generate vascular casts. Grafts were excised, tissues were digested, and casts were examined with the use of scanning electron microscopy. Transmission electron microscopy was performed on tissues infused with the acrylic polymer that were not digested. At day 3, an immature lobular pattern was observed extending from the neovascular plexi on the graft side of the polypropylene mesh. At day 5, defined vessels with lobular ends occurred with high frequency. At day 7, the number of observed lobular structures was greatly reduced, and high frequencies of depressions in acrylic casts suggested protrusion of endothelial cell nuclei. By day 10, lobular structures were rare, well-defined microvascular plexi were contiguous with larger vessels, and depressions from endothelial cell nuclei appeared more shallow and less frequent. These findings suggest that (1) an immature lobular pattern representing either capillary outgrowth or extracapillary leakage occurs at day 3; (2) these immature lobules decrease, and more discrete capillaries increase by day 5; (3) vascular integrity is reestablished by day 7; (4) vascular plexi has regained full continuity, and there are suggestions that endothelial cell proliferation has subsided by day 10.

Journal Article↗

PubMedDate not supplied

Surface electrical capacitance as an index of epidermal barrier properties of composite skin substitutes and skin autografts.

Restoration of the epidermal barrier is a requirement for burn wound closure. A rapid, reliable, and noninvasive measure of the rate of restoration of the epidermal barrier is not readily available. To monitor the reformation of the epidermal barrier, we measured surface electrical capacitance on cultured skin substitutes (human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan substrates) and split-thickness skin autografts grafted to patients. Data were collected from four patients with burns and one pediatric patient with a congenital hairy nevus comprising > 60% total body surface area. Capacitance measurements were performed at days 7, 10, 12, 14, and 28 by direct contact of the capacitance probe for 10 seconds to the cultured skin substitutes or split-thickness autograft. On postoperative days 7, 10, 12, 14, 21, and 28, the surface electrical capacitance of cultured skin substitutes after 10 seconds of sampling was 2468 +/- 268, 1443 +/- 439, 129 +/- 43, 200 +/- 44, 88 +/- 20, and 74 +/- 19 picofarads (mean +/- standard error of the mean), respectively. Surface electrical capacitance for split-thickness autograft on the same days was 1699 +/- 371, 1914 +/- 433, 125 +/- 16, 175 +/- 63, 110 +/- 26, 271 +/- 77 picofarads, respectively. Surface electrical capacitance in all of the grafts decreased with time. Cultured skin substitutes had approximately the same 10-second capacitance values as split-thickness autograft during 3 weeks of healing and approached values for uninjured skin (32 +/- 5 picofarads) by 12 days. Measurement of surface electrical capacitance is a direct, inexpensive, and convenient index for noninvasive monitoring of epidermal barrier formation.

Journal Article↗

PubMedDate not supplied

Incubation of cultured skin substitutes in reduced humidity promotes cornification in vitro and stable engraftment in athymic mice.

Cultured skin substitutes have been used successfully for adjunctive treatment of excised burns and chronic skin wounds. However, limitations inherent to all models of cultured skin include deficient barrier function in vitro, and delayed keratinization after grafting in comparison to native skin autografts. Experimental conditions for incubation of skin substitutes were tested to stimulate barrier development before grafting, and measure responses in function and stability after grafting. Cultured skin substitutes consisted of human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan biopolymer substrates. Parallel cultured skin substitutes were incubated at the air-liquid interface in ambient (48-61%) or saturated (79-91%) relative humidity, and grafted to athymic mice on culture day 14. Additional cultured skin substitutes were incubated in the experimental conditions for a total of 28 days. Cadaveric human skin and acellular biopolymer substrates served as controls. Epidermal barrier was evaluated as the change in surface hydration by surface electrical capacitance with the NOVA Dermal Phase Meter. Cultured skin substitutes and cadaveric skin incubated in ambient humidity had lower baseline surface electrical capacitance and less change in surface electrical capacitance than parallel samples incubated in saturated humidity at all time points in vitro. Data from healing cultured skin substitutes at 2, 4, 8 and 12 weeks after grafting showed an earlier return to hydration levels comparable to native human skin, and more stable engraftment for skin substitutes from ambient humidity. The data indicate that cultured skin substitutes in ambient humidity have lower surface electrical capacitance and greater stability in vitro, and that they reform epidermal barrier more rapidly after grafting than cultured skin substitutes in saturated humidity. These results suggest that restoration of functional epidermis by cultured skin substitutes is stimulated by incubation in reduced humidity in vitro.

Animals↗

PubMedDate not supplied

Assessment of the potential for microbial resistance to topical use of multiple antimicrobial agents.

The goal of this study was to reduce the likelihood of the generation and/or persistence of bacterial resistance to some antimicrobial components contained in a topical antimicrobial mixture (neomycin, polymyxin B, mupirocin and ciprofloxacin) for use with cultured skin grafts, by substitution of alternative antimicrobials, specifically fusidic acid for mupirocin and ofloxacin for ciprofloxacin. The alternative agents failed to serve that purpose. However, with the exception of specific genera of bacteria, Proteus sp. and Providencia stuartii, 90% or more of all other bacteria tested were susceptible to the action of one or more of the individual antimicrobial agents contained in the original mixture. This was true when bacteria were highly susceptible to the antimicrobials, generally, or when bacteria resistant to specific antimicrobials such as penicillin-class antibiotics and ciprofloxacin, were tested. These results suggest that the redundancy of antimicrobials contained in this mixture reduces the chance that resistant bacteria generated by the use of this mixture or already present on wounds would persist when the mixture is used clinically.

Administration, Topical↗

PubMedDate not supplied

Genetic modification of cultured skin substitutes by transduction of human keratinocytes and fibroblasts with platelet-derived growth factor-A.

Gene therapy promises the potential for improved treatment of cutaneous wounds. This study evaluated whether genetically modified cultured skin substitutes can act as vehicles for gene therapy in an athymic mouse model of wound healing. Human keratinocytes and fibroblasts were genetically engineered by retroviral transduction to overexpress human platelet-derived growth factor-A chain. Three types of skin substitutes were prepared from collagen-glycosaminoglycan substrates populated with fibroblasts and keratinocytes: HF-/HK-, containing both unmodified fibroblasts and keratinocytes; HF-/HK+, containing unmodified fibroblasts and modified keratinocytes; and HF+/HK-, containing modified fibroblasts and unmodified keratinocytes. Skin substitutes were cultured for two weeks before grafting to full-thickness wounds on athymic mice. The modified skin substitutes secreted significantly elevated levels of platelet-derived growth factor throughout the culture period. Expression of retroviral platelet-derived growth factor-A mRNA was maintained after grafting to mice, and was detected in all HF-/HK+ grafts and one HF+/HK- graft at two weeks after surgery. Although no differences were seen between control and modified grafts, the results suggest that genetically modified cultured skin substitutes can be a feasible mechanism for cutaneous gene therapy. The cultured skin model used for these studies has advantages over other skin analogs containing only epidermal cells; because it contains both fibroblasts and keratinocytes, it therefore offers greater opportunities for genetic modification and potential modulation of wound healing.

Animals↗

PubMedDate not supplied

Reduced wound contraction after grafting of full-thickness burns with a collagen and chondroitin-6-sulfate (GAG) dermal skin substitute and coverage with biobrane.

Full-thickness burns destroy both the epidermal and dermal tissues of the skin. This study evaluates a collagen and chondroitin-6-sulfate dermal skin substitute (graft) that was applied to excised full-thickness burns and covered with Biobrane. Experimental conditions included: (a) no burn, subcutaneous implantation of the graft; (b) burn, excision, graft, coverage with Biobrane and bandages; (c) burn, excision, no graft, coverage with Biobrane and bandages; (d) burn only. forty-one days post-surgery, subcutaneous implantation (N = 3) of the graft caused no detectable contraction or necrosis of the overlying skin, whereas all burn wounds contracted. Measurements of wounds (percentage of original wound size) showed statistically significant differences between the following treatments; (a) graft plus Biobrane (N = 10), 34%; (b) no graft plus Biobrane (N = 9), 25%; (c) untreated burns (N = 6), 16%. Semi-quantitative evaluation of time to healing indicated by spontaneous detachment of Biobrane from wounds showed that grafted, excised wounds healed in an average of 2.7 weeks, while ungrafted, excised wounds required an average of 4.3 weeks to heal. Histological appearance of healed wounds after grafting and coverage with Biobrane resembles undamaged skin without epidermal adnexal structures. Excision of full-thickness burn eschar, followed by grafting with a collagen and chondroitin-6-sulfate dermal skin substitute and coverage with Biobrane provides reduced wound contraction within a six-week period of observation compared to non-excised wounds. Both more rapid and more complete wound healing took place compared to excised wounds that were not grafted.

Animals↗

PubMedDate not supplied

Delivery and activity of antimicrobial drugs released from human fibrin sealant.

Engraftment and healing of native or cultured skin grafts depend on adherence, vascularization, and control of microbial contamination in the wound bed. Fibrin sealant is a biocompatible polymer that may be used to promote skin engraftment by serving as a delivery vehicle for antimicrobial drugs. Human fibrin sealant (25 mg/ml) was polymerized with antibacterial agents (mupirocin [32 micrograms/ml], nitrofurazone [0.02% wt/vol], polymyxin B [400 U/ml], or norfloxacin [20 micrograms/ml]) on nitrocellulose (nc) backing and was prepared as 6 mm diameter discs with skin punches. Discs (n = 6) were applied in the Wet Disc Assay to clinical isolates of Staphylococcus aureus (mupirocin, nitrofurazone) or Pseudomonas aeruginosa (polymyxin B, norfloxacin). Controls included drug applied to 6 mm paper discs (25 microliter) and nitrocellulose discs submerged in each drug, blotted, and applied to bacterial cultures on agar in petri dishes. Data were expressed as zone of clearing (mm diameter +/- SEM) after overnight incubation at 35 degrees C. Significant differences (ANOVA and Turkey's test, p < 0.05) were found for each drug released from the disc of fibrin sealant compared with other vehicles. Release from filter paper discs compared with nitrocellulose was significant for nitrofurazone and norfloxacin. Serial transfer of fibrin discs to fresh bacterial cultures after 24 hours showed no zones of clearing. The data show that fibrin sealant releases topical drugs with no inhibition of antimicrobial activity on burn organisms. Greater zones of clearing from fibrin sealant may result from passive fluid retention or from active binding to fibrin followed by protease digestion by burn organisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗

PubMedDate not supplied

Cytotoxicity testing of topical antimicrobial agents on human keratinocytes and fibroblasts for cultured skin grafts.

Cultured epidermal skin has become an adjunctive therapy for treatment of major burn injuries, but its effectiveness is greatly limited because of destruction by microbial contamination. To evaluate candidate antimicrobial agents for use with cultured skin, a combined cytotoxicity-antimicrobial assay system was developed for determination of toxicity to cultured human keratinocytes and fibroblasts and for determination of susceptibility or resistance of common burn wound organisms. Candidate agents including chlorhexidine gluconate, polymyxin B, mupirocin, sparfloxacin, or nitrofurazone were tested separately for inhibition of growth of human cells and for inhibitory activity to microorganisms with the wet disk assay. The data showed that (1) chlorhexidine gluconate (0.05%) was uniformly toxic to both cultured human cells and microorganisms; (2) nitrofurazone (0.02%) had dose-dependent toxicity to human cells and limited effectiveness against gram-negative microorganisms; (3) sparfloxacin (30 micrograms/ml) had low toxicity to human cells and retained antimicrobial activity against both gram-positive and gram-negative bacteria; (4) polymyxin B (400 U/ml) was not toxic to human cells and had intermediate effectiveness on gram-negative bacteria; and (5) mupirocin (48 micrograms/ml) had no toxicity to skin cells and had uniform effectiveness against Staphylococcus aureus including methicillin-resistant Staphylococcus aureus. Selection of topical antimicrobial drugs by these assays may improve effectiveness of cultured skin for burns and may be used to control other surgical wound infections.

Administration, Topical↗

PubMedDate not supplied

Topical sulfamylon reduces engraftment of cultured skin substitutes on athymic mice.

Sulfamylon (mafenide acetate) remains extremely valuable for the control of the bacterial contamination of burn wounds, but it is cytotoxic to cultured keratinocytes used for wound closure. Because composite skin substitutes develop a partial epidermal barrier in vitro, they may hypothetically tolerate the use of topical Sulfamylon. To test this hypothesis, cultured skin substitutes were prepared from cultured human fibroblasts; keratinocytes were attached to these collagen-based substrates, which were grafted to full-thickness wounds in athymic mice (n = 8 per group). Wounds were irrigated twice daily with 5% (wt/vol) Sulfamylon solution or with a formulation of noncytotoxic antimicrobials (0% Sulfamylon). On day 9 after grafting, the wounds were treated with dry dressings and assessed at 4 weeks for expression of human leukocyte antigens-A, B, C and at 2, 3, and 4 weeks for percentage of original wound area and surface electrical capacitance in picofarads (pF). Data were analyzed for statistical significance (P < .05) by Fisher's exact test, Student's t test, and repeated measures analysis of variance: [table: see text] The data demonstrate that irrigation of cultured skin substitutes with a solution of 5% Sulfamylon results in smaller wound area, fewer wounds that contain human cells, and greater surface hydration (higher surface electrical capacitance) than irrigation with noncytotoxic antimicrobial agents. These results support the conclusion that cultured skin substitutes of this type do not tolerate the chemical toxicity of Sulfamylon as well as skin autografts. Further improvements in the properties of the epidermal barrier of cultured skin substitutes may facilitate the use of Sulfamylon or other potent antimicrobial agents for the management of microbial contamination during engraftment of transplanted skin cells.

Animals↗