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PubMedDate not supplied

Use of peracetic acid to sterilize human donor skin for production of acellular dermal matrices for clinical use.

We previously reported methods for sterilizing human skin for clinical use. In a comparison of gamma-irradiation, glycerol, and ethylene oxide, sterilization with ethylene oxide after treatment with glycerol provided the most satisfactory dermis in terms of structure and its ability to produce reconstructed skin with many of the characteristics of normal skin. However, the use of ethylene oxide is becoming less common in the United Kingdom due to concerns about its possible genotoxicity. The aim of this study was to evaluate peracetic acid as an alternative sterilizing agent. Skin sterilized with peracetic acid was compared with skin sterilized using glycerol alone or glycerol with ethylene oxide. The effect of subsequently storing peracetic acid sterilized skin in glycerol or propylene glycol was also examined. Acellular dermal matrices were produced after removal of the epidermis and cells in the dermis, processed for histological and ultrastructural analysis, and the biological function was evaluated by reconstitution with keratinocytes and fibroblasts. Results showed that sterilized acellular matrices retained the integrity of dermal structure and major components of the basement membrane. There were no overall significant differences in the ability of these matrices to form reconstructed skin, but peracetic acid alone gave a lower histologic score than when combined with glycerol or propylene glycol. We conclude that peracetic acid sterilization followed by preservation in glycerol or propylene glycol offers a convenient alternative protocol for processing of human skin. It is suggested that this sterile acellular dermis may be suitable for clinical use.

Dermis↗

PubMed2004

[Effect of expression of platelet-derived growth factor B gene on blood vessel reconstruction after tissue engineering skin grafting].

OBJECTIVE: To study the effect of PDGF on dermal blood vessel reconstruction by transplanted tissue-engineering skin containing PDGF-B gene to rats. METHODS: The recombined eukaryotic expression vector, pcDNA3.1-hPDGF-B, was constructed and transfected into fibroblasts mediated by LipofectAMINE. Keratinocytes + acellular dermal matrix (group A), keratinocytes + acellular dermal matrix + fibroblasts (group B), keratinocytes + acellular dermal matrix + fibroblasts with PDGF gene (group C) were recombined respectively, then transplanted them to rat dorsum and evaluated the reconstruction of blood vessels in the dermis after 2, 4, 6 week postoperation. RESULTS: In 2-4 weeks after skin grafting the vascularization rate in group C was higher than that of group B and group A. The vascularization rates in all groups had no significant differences in six weeks (P > 0.05). CONCLUSION: PDGF-B gene plays an important role in reconstruction of blood vessels in the dermis at early tissue-engineering skin grafting, which ensures the take of grafted tissue-engineering skin.

Acellular Dermis↗

PubMed1988

[Structure of the dermo-epidemic junction].

The basement membranes are extracellular proteic matrixes involved mainly in cell-substrate interactions. The dermo-epidermal junction (DEJ) is defined as the region formed by the dermal pole of the basal cell layer, the intercellular spaces, the lamina densa or basal lamina and the acellular fibrous components of the papillary dermis. The functions of the DEJ are to bind the epithelia to the connective tissue, and to preserve the viability of the epidermis by means of connecting it to the dermis. which is in charge of providing the necessary nutrients for its normal proliferation. The purpose of the present communication is to provide a concise review of the recent knowledges about the ultrastructure of the DEJ, with special emphasis on its antigenic components.

Antigens↗

PubMed1986

Structural and functional changes of normal aging skin.

Solar-induced cutaneous changes are more prevalent and profound in older persons and, thus, are often inappropriately attributed to the aging process, per se. Structural and functional alterations caused by intrinsic aging and independent of environmental insults are now recognized in the skin of elderly individuals. Structurally the aged epidermis likely becomes thinner, the corneocytes become less adherent to one another, and there is flattening of the dermoepidermal interface. The number of melanocytes and Langerhans cells is decreased. The dermis becomes atrophic and it is relatively acellular and avascular. Dermal collagen, elastin, and glycosaminoglycans are altered. The subcutaneous tissue is diminished in some areas, especially the face, shins, hands, and feet, while in others, particularly the abdomen in men and the thighs in women, it is increased. The number of eccrine glands is reduced and both the eccrine and apocrine glands undergo attenuation. Sebaceous glands tend to increase in size but paradoxically their secretory output is lessened. The nail plate is generally thinned, the surface ridged and lusterless, and the lunula decreased in size. There is a progressive reduction in the density of hair follicles per unit area on the face and scalp, independent of male-pattern alopecia. The hair shaft diameter is generally reduced but in some areas, especially the ears, nose, and eyebrows of men and the upper lip and chin in women, it is increased as vellus hairs convert to cosmetically compromising terminal hairs. Functional alterations noted in the skin of elderly persons include a decreased growth rate of the epidermis, hair, and nails, delayed wound healing, reduced dermal clearance of fluids and foreign materials, and compromised vascular responsiveness. Eccrine and apocrine secretions are diminished. The cutaneous immune and inflammatory responses are impaired, particularly cell-mediated immunity. Clinical correlates of these intrinsic aging changes of the skin include alopecia, pallor, xerosis, an increased number of benign and malignant epidermal neoplasms, increased susceptibility to blister formation, predisposition to injury of the dermis and underlying tissues, delayed onset and resolution of blisters and wheals, persistent contact dermatitis, impaired tanning response to ultraviolet light, increased risk for wound infections, prolongation of therapy necessary for onychomycosis, and thermoregulatory disturbances.

Adult↗

PubMed1999

Promising therapy for congenital giant pigmented nevi using acellular autograft nevi-dermal matrix.

As promising new therapy for congenital giant pigmented nevi, the authors investigated the potential use of an acellular autograft nevi-dermal matrix in combination with a split-thickness skin graft. To address whether the processed acellular nevi-dermal matrix from frozen skin could be reconstituted as a viable dermal base, the authors grafted it onto full-thickness skin defects in nude rats. Fibroblast infiltration and neovascularization into the acellular nevi-dermal matrix were observed. However, because the disappearance of the residual melanotic granules of the grafted dermis took 16 weeks, the authors excised with scissors the superficial layer of the acellular nevi-dermal matrix containing a large quantity of melanin. The appearance after using this method was relatively superior even compared with the full-thickness skin graft. The success of their experimental animal model using the acellular nevi-dermal matrix covered with split-thickness skin grafts confirms the potential value for the clinical application of this treatment for congenital giant nevi.

Animals↗

PubMed1999

The use of an acellular dermal skin graft to gain keratinized tissue.

For decades, free gingival grafting has been a predictable and widely used procedure to gain keratinized tissue around teeth with mucogingival problems. Recently, a biocompatible, acellular, connective tissue material (AlloDerm) made from human dermis has been introduced as an alternative to the conventional use of autogenous tissue. This material eliminates the need for donor sites, and it minimizes postoperative discomfort and complications. It also integrates well to the recipient site, and it provides an excellent color match with the surrounding tissues, making it esthetically pleasing.

Biocompatible Materials↗

PubMed1999

Recent advances in soft tissue augmentation.

Soft tissue augmentation has become increasingly important as more individuals seek aesthetic improvement without major surgical procedures. The choice of an appropriate subcutaneous implant, whether solid or injectable, requires a thorough understanding of the materials available. This review of the literature addresses autologous fat and dermis transplantation, autologous and allogeneic human collagen, bovine collagen, acellular dermal allograft, hyaluronic acid derivatives, expanded polytetrafluoroethylene, polymethyl-methacrylate microspheres, and other potential biomaterials. The search for the perfect material to eradicate rhytids, smooth scars, and fill traumatic detects continues. New products appear, sometimes with great fanfare, which fail to fulfill the promise of a better alternative to what we use now. For this reason, an in-depth understanding of implant materials is necessary for any physician performing soft-tissue augmentation procedures.

Adipose Tissue↗

PubMed2002

Structure and spatio temporal expression of the full length DNA complementary to RNA coding for alpha2 type I collagen of zebrafish.

Twenty distinct genetic types of collagen have been identified up to now. Their structure and function are not completely elucidated. We have chosen zebrafish as a model to bring information about the role of collagen during embryogenesis. In the present study, we isolated four overlapping DNA complementary to RNA clones covering the 4879 nucleotides of a zebrafish messenger RNA (mRNA) encoding a fibrillar procollagen chain. The comparison of its primary structure with known other vertebrate collagens allowed to conclude that it encodes collagen pro-alpha2(I) chain. The 5' untranslated region showed a typical stem-loop structure with three ATG codons which is found in mammals types I and III collagen chains (but not in type II), which are expressed in the same tissues. This suggests that the supposed regulatory role of the stem loop structure could be tissue specific. The comparison of the Gly-Gly doublets found along the helical domain of several species allowed to speculate that the Gly-Gly repeats could be a poikilotherm feature. Expression of pro-alpha2(I) was examined during zebrafish development by reverse transcriptase-polymerase chain reaction and in situ hybridization on whole embryo and tissue section. Col1a2 was expressed as early as stage10 h post fertilization (hpf) and two peaks of expression were observed at 20 and 48 hpf. alpha2 mRNAs, whose presence suggests a collagen synthesis, were detected principally in the superficial cell layers surrounding 20-72 hpf embryos which are characterized by an acellular collagen stratum. At 26-30 days, fibroblasts invade the dermis and take over from the epithelial cells to synthesize collagen. This suggests a fine regulation of collagen synthesis in these cells that remains to be elucidated. alpha2 mRNA were also detected in other tissues such as the tail fin primordium and the notochord primordium suggesting a participation of type I collagen in a pathway for notochord and tail formation.

5' Untranslated Regions↗

PubMed1981

Malignant external otitis: early histopathologic changes and pathogenic mechanism.

The histopathologic changes during the early stage of malignant external otitis (MEO) were studied in two patients, one a non-diabetic. The specimens were obtained by an en bloc excision of the diseased tissue of the external ear canal through a retroauricular approach. The most prominent histologic features of the early stage of MEO consist of a thick layer of almost acellular, partly degenerated, collagen extending from the cartilage into the dermis, which most likely existed prior to the penetration of the microorganism. This finding supports our concept that MEO is a disease which develops as a results of invasion of opportunistic organisms into tissue previously devitalized, probably due to vascular compromise and that these latter features constitute the basic mechanism of the entire disease process.

Aged↗

PubMed1995

Use of an acellular allograft dermal matrix (AlloDerm) in the management of full-thickness burns.

Scarring and contracture are major long-term sequelae of meshed split-thickness autografting for full-thickness skin injury. In the absence of dermis, mature fibroblasts secrete collagen in the altered pattern of scar. This case report illustrates the use of an acellular dermal matrix processed from human allograft skin (AlloDerm) in the treatment of a full-thickness burn injury. The processing technique results in an acellular dermal matrix with normal collagen bundling and organization and an intact basement membrane complex. In these patients, AlloDerm exhibited a high percentage 'take' and supported an overlying meshed split-thickness skin autograft, applied simultaneously. The clinical observations of 'take' were confirmed with histological and electron-microscopic evaluation of biopsies which demonstrated host cell infiltration and neovascularization of the AlloDerm. No specific immune response was detected, either by histology or by lymphocyte proliferation assay. By providing a dermal replacement, the grafted dermal matrix permitted the use of a thin, widely meshed autograft from the donor site, without the undesirable scarring and contracture at the wound site that commonly results from this technique. If effective, this approach would markedly reduce the amount of donor skin required for split-thickness autografts in full-thickness burn injuries.

Adult↗

PubMed1999

The use of composite acellular allodermis-ultrathin autograft on joint area in major burn patients--one year follow-up.

Scar contracture is a major long-term sequelae of meshed split-thickness skin grafts in the case of full-thickness burn injuries, and especially in joint areas. Severe contracture around joints may lead to loss of mobility. The thickness of the dermis in the autograft plays a major role in the functional and cosmetic outcomes of the third degree burn. How to replace lost dermis is a major problem in skin restoration following severe burns. The human allograft skin (AlloDerm) is an acellular dermal matrix with normal collagen bundling organization and intact basement membrane complex. We present 12 cases of clinical application of a composite grafting technique in which the allogeneic skin (AlloDerm) provided source of dermis, and an ultrathin autograft (0.004-0.006 inch in thickness) provided epidermis. In these patients, The composite grafts were applied to full-thickness burn wounds over various articular skin surfaces. The average skin graft take rate was 91.5%. These ultrathin autografts allow the donor sites to heal faster. The mean time of donor site reepithelization was 6 days. All patients had a nearly normal range of joint motion (average 95% of normal) after one year's follow up. Wound assessment over time has shown supple skin that has been resistant to trauma and infection. The cosmetic results were judged to be fair to good by surgeons and patients after one year's follow up.

Adult↗

PubMed2003

Bio-artificial skin composed of gelatin and (1-->3), (1-->6)-beta-glucan.

Porous scaffolds composed of gelatin and beta-glucan were prepared using the freeze-drying method. The scaffold had an inter-connected pore structure with average pore size of 90-150 microm. Results for the contact angle and cell attachment revealed that a high gelatin content was suitable for cellular attachment and distribution in two- or three-dimensional fibroblast cultures, because the gelatin had acidic residues, and arginine-glycine-aspartic acid groups. To prepare a stratified wound dressing to mimic the normal human skin, fibroblasts and keratinocyte cells were isolated from a child's foreskin, and were co-cultured in gelatin/beta-glucan scaffolds were cross-linked using 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride. An in vivo study showed that after 1 week, the artificial dermis containing the fibroblasts enhanced the re-epithelialization of a full-thickness skin defect rather than the acellular scaffold.

Animals↗

PubMed2006

Autologous full-thickness skin substitute for healing chronic wounds.

BACKGROUND: Chronic wounds represent a major problem to our society. Therefore, advanced wound-healing strategies for the treatment of these wounds are expanding into the field of tissue engineering. OBJECTIVES: To develop a novel tissue-engineered, autologous, full-thickness skin substitute of entirely human origin and to determine its ability to heal chronic wounds. METHODS: Skin substitutes (fully differentiated epidermis on fibroblast-populated human dermis) were constructed from 3-mm punch biopsies isolated from patients to be treated. Acellular allodermis was used as a dermal matrix. After a prior 5-day vacuum-assisted closure therapy to prepare the wound bed, skin substitutes were applied in a simple one-step surgical procedure to 19 long-standing recalcitrant leg ulcers (14 patients; ulcer duration 0.5-50 years). RESULTS: The success rate in culturing biopsies was 97%. The skin substitute visibly resembled an autograft. Eleven of the 19 ulcers (size 1-10 cm2) healed within 8 weeks after a single application of the skin substitute. The other eight larger (60-150 cm2) and/or complicated ulcers healed completely (n = 5) or continued to decrease substantially in size (n = 3) after the 8-week follow-up period. Wound healing occurred by direct take of the skin substitute (n = 12) and/or stimulation of granulation tissue/epithelialization (n = 7). Skin substitutes were very well tolerated and pain relief was immediate after application. CONCLUSIONS: Application of this novel skin substitute provides a promising new therapy for healing chronic wounds resistant to conventional therapies.

Adult↗

PubMed2005

Simultaneous in vivo regeneration of neodermis, epidermis, and basement membrane.

Full-thickness skin loss does not undergo complete spontaneous regeneration in mammals. To restore the normal function of skin, dermal and epidermal components can be supplied by grafting various substrates, concurrently or in stages. A tissue-engineering technique that combines disaggregated autologous keratinocytes and a highly porous, acellular collagen-glycosaminoglycan matrix has been shown in a porcine model to regenerate a dermis and epidermis in vivo. During regeneration, a basement membrane of normal appearance forms at the dermoepidermal junction, and vascularization of the construct occurs. Cell-seeded grafts can be produced with either uncultured or cultured keratinocytes and can be immediately applied in a single grafting procedure. The seeding process itself and the cell culture, when used, markedly expand the donor epithelial surface area, allowing large skin defects to be repaired using grafts created from very little donor tissue. This skin-substitute technology may have useful clinical applications.

Animals↗

PubMed2003

Effect of collagen matrices on dermal wound healing.

Dermal substitution and wound healing are areas of medicine in which there have been many recent advances, but neither the commercially available products nor the products currently described in experimental studies are able to fully substitute for natural living skin. There is an overall consensus that to heal wounds, the substitution of connective tissue matrix, the main component of each wound, is necessary. Both artificial and natural polymers have been used to reconstitute dermis. Nowadays, collagen has been discovered again. Collagen is a natural substrate for cellular attachment, growth and differentiation, and promotes cellular proliferation and differentiation. Once dermis reconstruction is done, the covering of the wound surface with both in vitro expanded epidermis and autologous split-skin transplants is significantly easier and has an improved chance of success. Nowadays, many commercial and experimental products have been introduced to improve cutaneous wound healing. This review discusses some of both acellular and cell-containing products used in the treatment of skin wounds.

Animals↗

PubMed1999

Surgical treatment of pseudosyndactyly of the hand in epidermolysis bullosa: histological analysis of an acellular allograft dermal matrix.

Recessive dystrophic epidermolysis bullosa is an inherited mechanobullous disorder of skin and mucous membranes. The most striking clinical characteristic of the disease is the formation of blisters following trivial trauma. Repeated cycles of blistering and scarring result in gradual encasement of the hand in an epidermal "cocoon." The authors treated an 11-year-old boy with recessive dystrophic epidermolysis bullosa who presented with hand contractures and interdigital pseudosyndactyly. Treatment included release of contractures and application of a biosynthetic dermal analog. This report is a histological analysis of the dermal matrix 1 year after initial placement of the allograft. Fibroblasts repopulating the dermal allograft had a normal synthetic phenotype and lacked the myofibroblastic features seen in the ungrafted control biopsy. Collagen and elastin in the repopulated dermal allograft had normal dermal orientation and maturity in contrast to the sparse, immature collagen and lack of elastin compared with the dermis of an ungrafted control region. Results of this histological study indicate that treatment of recessive dystrophic epidermolysis bullosa with an acellular human dermal allograft may restore some features of normal dermal architecture. Although the initial results are encouraging, longer follow-up is required before definitive conclusions can be made.

Child↗

PubMed2005

Comparison of dermal substitutes in wound healing utilizing a nude mouse model.

BACKGROUND: Dermal skin substitutes have become a standard of care in burn treatment. OBJECTIVE: To compare and assess wound contracture reduction and histologic incorporation into the wound, dermal substitutes were implanted into full-thickness skin wounds in nude mice. MATERIALS AND METHODS: Thirty-seven mice received a full-thickness 2 x 2 cm dorsal skin wound, and were either implanted with an acellular dermal matrix, Alloderm, Dermagraft-TC, Dermalogen, or Integra or assigned to the control group (with no dermal substitute). At 28 days postsurgery, the wounds were assessed for contraction, epithelialization, and other histological characteristics. RESULTS: Each dermal substitute decreased wound contracture, but Alloderm and the acellular dermal matrix did so significantly compared to the control (P < .01 and P < .03, respectively). Within-group and control comparisons showed no significant differences with respect to the presence of dystrophic calcification, squamous hyperplasia, infiltration of neutrophils, fibroblasts, and macrophages, epidermal keratinocyte stratification, or collagen fiber configuration. CONCLUSIONS: Integra elicited the greatest foreign body response. Although the Dermalogen group had the thickest elastin fiber fragments, Dermagraft may have initiated the earliest elastin fiber formation in the wounds. While all dermal substitutes were incorporated into the wound bed and wound contracture was decreased, acellular dermal matrix and Alloderm, both human skin-derived products, produced less contraction and the thickest new "dermis" in the healed wounds compared to the control or synthetic dermal substitutes.

Journal Article↗

PubMed1978

Ultrastructural characterization of the cuticle of Onchocerca volvulus microfilaria.

Previous ultrastructural studies on various microfilariae have suggested the presence of a trilaminar membrane at the parasite cuticle. In the present report, the formation of the cuticle of Onchocerca volvulus microfilariae was studied at different developmental stages by transmission electron microscopy of samples obtained from subcutaneous nodules of untreated patients. The cuticle is formed by the layering of surface coat fibrillar components of the hypodermal cells. No plasma membrane is found at the cuticle of the microfilaria. The use of freeze-fracture replication confirmed the absence of a classic plasma membrane at the parasite cuticle. Our results suggest that immunogenic determinants of the microfilaria cellular elements are hidden from the exterior by the acellular cuticle. This may explain the lack of cellular reaction usually found around living O. volvulus microfilariae in the dermis of onchocerciasis patients.

Animals↗