A topical cell therapy approach for diabetic chronic ulcers: Effects of mesenchymal stromal cells associated with platelet-rich plasma.

BACKGROUND: Diabetic cutaneous ulcers are subjected to several physiological and biochemical defects, which contribute to wound chronicity and therapeutic failure. Platelet-rich plasma (PRP) has been used for stimulating tissue regeneration, and mesenchymal stromal cells (MSCs) have demonstrated therapeutic properties in all phases of skin regeneration in cell therapy studies. AIMS: The objective of this study was to evaluate the therapeutic effects related to the use of a biomembrane composed of autologous MSCs and PRP on chronic wounds of diabetic patients (pre-post pilot study). PATIENTS/METHODS: Six diabetic patients with chronic wounds for more than 6 months were subjected to adipose tissue collection for isolation of MSCs, blood collection for PRP preparation, and topical administration of a biomembrane of MSCs and PRP on each chronic wound. The statistical difference regarding the evolution of ulcers was calculated by means of paired t test. RESULTS: There was granulation tissue formation starting from 7 days after topical application. Total re-epithelialization occurred in 5 of the 9 lesions treated, and the mean wound healing rate (WHR) was 74.55% (±32.55%) after 90 days. No cicatricial hypertrophy or retraction was observed. CONCLUSION: Mesenchymal stromal cells topical therapy associated with PRP is well-tolerated and able to provide a reduction in ulcer area of diabetic chronic wounds.

The effect of aging in primary human dermal fibroblasts.

Skin aging is a complex process, and alterations in human skin due to aging have distinct characteristic as compared to other organs. The aging of dermal cells and the biological mechanisms involved in this process are key areas to understand skin aging. A large number of biological mechanisms, such as decreasing of protein synthesis of extracellular matrix or increasing of degradation, are known to be altered through skin aging. However, environmental influence can accelerate this characteristic phenotype. In this study, we analyzed primary human dermal fibroblasts in three different in-vitro aging models-UVB irradiation and accelerated proliferation of human dermal fibroblasts from young donors as well as from elderly donors-for the gene expression of COL1A1, COL1A2, COL3A1, COL4A1, COL7A1, MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP12, MMP13, MMP14, TIMP1, TIMP2, TIMP3, TIMP4, IL1B, IL1A, IL6, IL8, IL10, PTGS2, TP53, CASP3, LMNA, SIRT1. We compared the gene expression levels with young control. Furthermore, the behavior of skin fibroblasts was also evaluated using cell growth rate. The findings reveal that the gene expression levels in skin fibroblasts was altered in the process of aging in all three in-vitro aging models, and the cell growth rate was reduced, suggesting that these methods can be employed to understand skin aging mechanisms as well as drug discovery screening method.

Terapia celular combinada com membranas de biopolímeros melhora a cicatrização de úlceras em paciente com dermatomiosite juvenil / Combining cell therapy with biopolymer films improves wound healing in a juvenile dermatomyositis patient

Introdução: Dermatomiosite juvenil (DMJ) é doença sistêmica que afeta a musculatura proximal e a pele de crianças. A doença ulcerada é um desafio terapêutico. Objetivo: Avaliar a melhora da doença ulcerada na DMJ, pelo uso de terapia celular. Métodos: Realização de cocultura de fibroblastos e queratinócitos autólogos e aplicação dessas células nas úlceras juntamente com cola de fibrina e colocação de membrana de quitosana-alginato ou quitosana-xantana sobre as lesões. Resultados: Menos de 12 horas após a terapia, o paciente referiu completa eliminação da dor e, dentro de dois dias, estava presente tecido de cicatrização. Algumas das úlceras estavam quase completamente cicatrizadas no final da primeira semana, e algumas das calcinoses desapareceram. Essa técnica não cura a doença, mas melhora a qualidade de vida, sendo possível criopreservar as células saudáveis do paciente para tratar novas lesões. Sendo as células de origem autóloga, elimina-se o risco de rejeição. Além disso, esse procedimento não necessita de debridamento das lesões nem hospitalização. Conclusões: A aplicação de culturas autólogas de fibroblastos e queratinócitos em úlceras já é considerada tratamento efetivo em pacientes com queimaduras e outras feridas cutâneas e, agora mostrou-se também eficaz no tratamento de feridas na DMJ.

Introduction: Juvenile dermatomyositis (JDM) is a systemic disease that affects children's proximal musculature and skin. The ulcerated stage of the disease is a therapeutic challenge. Objective: To evaluate the improvement of ulcerated stage of JDM caused by the use of cell therapy. Methods: Co-culture of autologous fibroblasts and keratinocytes, application of these cells in ulcers in conjunction with fibrin glue, and placement of chitosan-alginate or chitosan-xanthan membrane on the lesions. Results: Less than 12 hours after therapy, the patient reported complete cessation of pain and, within 2 days, healing tissue emerged. Some of the ulcers were almost completely healed by the end of the 1st week, and some of the calcinoses disappeared. This technique does not cure the disease, however it improves the patient's quality of life, and it is possible to cryopreserve healthy cells to treat new lesions. Given the fact that the cells are of autologous origin, the risk of rejection is eliminated. Furthermore, this procedure does not require debridement of the lesions or hospitalization. Conclusions: The application of autologous cultures of fibroblasts and keratinocytes in ulcers is already considered an effective treatment in patients with burns and other skin wounds, and has now also been proven effective in the treatment of wounds in JDM.

Frozen section evaluation of sentinel lymph nodes in breast carcinoma: a retrospective analysis.

OBJECTIVE: To determine the false-negative rate, sensitivity, and diagnostic accuracy of the frozen section analysis of the sentinel lymph node (SLN) biopsy in early-stage breast cancer compared to the definitive section and to identify the factors that could be associated with the appearance of false-negative cases. Secondarily, to evaluate the pathological results of cases submitted to completion axillary lymph node dissection (ALND) for positive SLN. METHODS: We performed a five-year review of cases (2011-2015), including patients with early-stage breast cancer undergoing SLN biopsy, with frozen section evaluation and subsequent definitive pathological analysis. These results were compared to calculate the false-negative rate and the factors associated with it. The histopathological findings were also evaluated in patients submitted to completion ALND. RESULTS: A total of 281 patients were evaluated, identifying 18 cases with frozen section results as false negative (false-negative rate: 23.7%), and 55.5% of these cases were micrometastases. The false-negative rate in SLN with macrometastasis was 13.1% and for micrometastasis cases was 66.7% (p < 0.001). True-positive patients that were submitted to completion ALND had additional axillary lymph nodes with metastases in 28% of cases, whereas the group of false negatives had additional positive axillary lymph nodes in 40% of patients (p = 0.62). CONCLUSION: Frozen section analysis had a false-negative rate acceptable in SLN biopsy in our institution, and the micrometastasis in the SLN was the most important factor associated with the appearance of this phenomenon.

Platelet-rich plasma (PRP) and adipose-derived mesenchymal stem cells: stimulatory effects on proliferation and migration of fibroblasts and keratinocytes in vitro.

The clinical use of tissue engineering associated with cell therapy is considered a new alternative therapy for the repair of chronic lesions with potential application in different medical areas, mostly in orthopedic and dermatological diseases. Platelet-rich plasma (PRP) is a rich source of growth factors and cytokines important for wound healing. Adipose-derived mesenchymal stem cells (ADSCs) have shown potential to accelerate the resolution of ulcers, to stimulate cell proliferation, and to benefit the quality of skin repair. This study aims to determine the effect of PRP and conditioned medium (CM) from ADSC on fibroblast and keratinocyte proliferation in vitro. Migration and proliferation assays were performed to evaluate the growth of fibroblasts and keratinocytes in the presence of PRP, CM, and CM + PRP. Significant proliferative stimulation was observed after 48 h of culture (p < 0.05) on mean absorbance of fibroblasts cultured with 10 and 25 % PRP, 100 % CM, and 25 % PRP + 25 % CM, if compared with control. Keratinocyte proliferation was stimulated after 48 h in cultures with 25, 50, and 100 % CM, and growth was compared with controls. The migration assay detected a significant migratory stimulus in fibroblasts cultured with 10 % PRP + 10 % CM after 48 h. These in vitro results suggest that PRP and ADSC have therapeutic potential for healing and re-epithelialization of chronic wounds in vivo.

Tetrasomy 3q26.32-q29 due to a supernumerary marker chromosome in a child with pigmentary mosaicism of Ito.

Pigmentary mosaicism of Ito (PMI) is a skin abnormality often characterized by hypopigmentation of skin, following, in most cases, the Blaschko lines, usually associated with extracutaneous abnormalities, especially abnormalities of the central nervous system (CNS). It is suggested that this pattern arises from the presence and migration of two cell lineages in the ectoderm layer during the embryonic period and embryonic cell migration, with different gene expression profiles associated with pigmentation. Several types of chromosomal aberrations, with or without mosaicism, have been associated with this disorder. This study comprised clinical description and cytogenetic analysis of a child with PMI. The G-banded karyotype analysis revealed a supernumerary marker chromosome in 76% of the analyzed metaphases from peripheral blood lymphocytes. Array genomic hybridization analysis showed a copy number gain between 3q26.32-3q29, of approximately 20.5 Mb. Karyotype was defined as 47,XX,+mar[38]/46,XX[12].arr 3q26.32-3q29(177,682,859- 198,043,720)x4 dn. Genes mapped in the overlapping region among this patient and three other cases described prior to this study were listed and their possible involvement on PMI pathogenesis is discussed.

Tissue therapy with autologous dermal and epidermal culture cells for diabetic foot ulcers.

A great part of diabetic ulcers on the lower extremities have difficult healing and represent the most common cause of non-traumatic amputation In case of patients unresponsive to the classical therapy with debridement, dressings and systemic antibiotic therapy, cell therapy may be an excellent indication. The objective of this study was to assess the efficacy of autologous skin cell (fibroblasts and keratinocytes) implants cultivated ex vivo and applied to long-standing (9-34 years) skin ulcers of five diabetic patients (4 DM2 and 1 DM1) with autologous fibrin glue. There were six ulcers of onset between 4 months and 20 years before and from 4.0 to 36.62 cm(2) in size, located on the lower limbs and unresponsive to the several conventional treatments. Complete healing was observed in five ulcers (83.3%), after 21-120 days. The patient who presented the largest ulcer had partial improvement in 40 days. It is believed that the more distal ulcer location is, the worse is its prognosis. There probably is a correlation between healing time, ulcer size and prior duration. No adverse reactions derived from the treatment occurred. It is concluded that this method is an excellent therapeutic option for diabetic ulcers, allowing faster healing. Its great advantage is being a minimally invasive procedure that can be carried out in an outpatient clinic.

Immunoarchitectural characterization of a human skin model reconstructed in vitro.

CONTEXT AND OBJECTIVE: Over the last few years, different models for human skin equivalent reconstructed in vitro (HSERIV) have been reported for clinical usage and applications in research for the pharmaceutical industry. Before release for routine use as human skin replacements, HSERIV models need to be tested regarding their similarity with in vivo skin, using morphological (architectural) and immunohistochemical (functional) analyses. A model for HSERIV has been developed in our hospital, and our aim here was to further characterize its immunoarchitectural features by comparing them with human skin, before it can be tested for clinical use, e.g. for severe burns or wounds, whenever ancillary methods are not indicated. DESIGN AND SETTING: Experimental laboratory study, in the Skin Cell Culture Laboratory, School of Medical Sciences, Universidade Estadual de Campinas. METHODS: Histological sections were stained with hematoxylin-eosin, Masson's trichrome for collagen fibers, periodic acid-Schiff reagent for basement membrane and glycogen, Weigert-Van Gieson for elastic fibers and Fontana-Masson for melanocytes. Immunohistochemistry was used to localize cytokeratins (broad spectrum of molecular weight, AE1/AE3), high molecular weight cytokeratins (34betaE12), low molecular weight cytokeratins (35betaH11), cytokeratins 7 and 20, vimentin, S-100 protein (for melanocytic and dendritic cells), CD68 (KP1, histiocytes) and CD34 (QBend, endothelium). RESULTS: Histology revealed satisfactory similarity between HSERIV and in vivo skin. Immunohistochemical analysis on HSERIV demonstrated that the marker pattern was similar to what is generally present in human skin in vivo. CONCLUSION: HSERIV is morphologically and functionally compatible with human skin observed in vivo.

Immunoarchitectural characterization of a human skin model reconstructed in vitro / Caracterização morfológica e imunoistoquímica de um modelo de pele humana reconstruída in vitro

CONTEXT AND OBJECTIVE: Over the last few years, different models for human skin equivalent reconstructed in vitro (HSERIV) have been reported for clinical usage and applications in research for the pharmaceutical industry. Before release for routine use as human skin replacements, HSERIV models need to be tested regarding their similarity with in vivo skin, using morphological (architectural) and immunohistochemical (functional) analyses. A model for HSERIV has been developed in our hospital, and our aim here was to further characterize its immunoarchitectural features by comparing them with human skin, before it can be tested for clinical use, e.g. for severe burns or wounds, whenever ancillary methods are not indicated. DESIGN AND SETTING: Experimental laboratory study, in the Skin Cell Culture Laboratory, School of Medical Sciences, Universidade Estadual de Campinas. METHODS: Histological sections were stained with hematoxylin-eosin, Masson's trichrome for collagen fibers, periodic acid-Schiff reagent for basement membrane and glycogen, Weigert-Van Gieson for elastic fibers and Fontana-Masson for melanocytes. Immunohistochemistry was used to localize cytokeratins (broad spectrum of molecular weight, AE1/AE3), high molecular weight cytokeratins (34βE12), low molecular weight cytokeratins (35βH11), cytokeratins 7 and 20, vimentin, S-100 protein (for melanocytic and dendritic cells), CD68 (KP1, histiocytes) and CD34 (QBend, endothelium). RESULTS: Histology revealed satisfactory similarity between HSERIV and in vivo skin. Immunohistochemical analysis on HSERIV demonstrated that the marker pattern was similar to what is generally present in human skin in vivo. CONCLUSION: HSERIV is morphologically and functionally compatible with human skin observed in vivo.

CONTEXTO E OBJETIVO: Nos últimos anos, diferentes modelos de pele humana reconstruída in vitro (PHRIV) foram descritos para uso clínico e aplicações em pesquisa na indústria farmacêutica. Antes de serem liberados para uso rotineiro como substitutos de pele humana, os modelos de PHRIV necessitam de testes (estudos) comparativos com a pele humana in vivo, por meio de análises morfológica (arquitetural) e imunoistoquímica (funcional). O objetivo deste trabalho é estudar as características imunoistoquímicas de um modelo de PHRIV desenvolvido em nosso serviço, comparando-as com a pele humana, para que esse modelo de PHRIV possa vir a ser testado clinicamente em casos de queimaduras e ulcerações de pele nos quais métodos tradicionais de tratamento não estejam indicados. TIPO DE ESTUDO E LOCAL: Estudo experimental laboratorial realizado no Laboratório de Cultura de Células da Pele da Faculdade de Ciências Médicas da Universidade Estadual de Campinas (FCM/Unicamp), Campinas, São Paulo, Brasil. MÉTODOS: Cortes histológicos foram corados com hematoxilina-eosina, tricrômio de Masson para fibras colágenas, ácido periódico-reagente de Schiff para membrana basal e glicogênio, Weigert-Van Gieson para fibras elásticas e Fontana-Masson para melanócitos. Estudo imunoistoquímico foi realizado para identificar citoqueratinas de amplo espectro de pesos moleculares (AE1/AE3), citoqueratinas de alto peso molecular (34βE12), citoqueratinas de baixo peso molecular (35βH11), citoqueratinas 7 e 20, vimentina, proteína S-100 (para melanócitos e células dendríticas), CD68 (KP1, histiócitos) e CD34 (QBend, endotélio). RESULTADOS: A histologia revelou similaridade satisfatória entre PHRIV e a pele in vivo. O estudo imunoistoquímico da PHRIV demonstrou padrão semelhante de marcadores usualmente presentes na pele humana in vivo. CONCLUSÃO: A PHRIV estudada é morfológica e funcionalmente compatível com a pele humana observada in vivo.

Model for human skin reconstructed in vitro composed of associated dermis and epidermis.

CONTEXT AND OBJECTIVE: The technique of obtaining human skin with dermis and epidermis reconstructed from cells isolated from patients can enable autologous skin grafting on patients with few donor sites. It also enables in vitro trials on chemicals and drugs. The objective of this work was to demonstrate a method for obtaining human skin composed of associated dermis and epidermis, reconstructed in vitro. DESIGN AND SETTING: Experimental laboratory study, in the Skin Cell Culture Laboratory of Faculdade de Ciências Médicas, Universidade Estadual de Campinas. METHODS: Cells from human fibroblast cultures are injected into bovine collagen type I matrix and kept immersed in specific culturing medium for fibroblasts. This enables human dermis reconstruction in vitro. On this, by culturing human keratinocytes and melanocytes, differentiated epidermis is formed, leading to the creation of human skin composed of associated dermis and epidermis, reconstructed in vitro. RESULTS: We showed that human skin composed of associated dermis and epidermis can be successfully reconstructed in vitro. It is histologically formed in the same way as human skin in vivo. Collagen tissue can be identified in the dermis, with cells and extracellular matrix organized in parallel to multilayer epidermis. CONCLUSIONS: It is possible to obtain completely differentiated human skin composed of associated dermis and epidermis, reconstructed in vitro, from injection of human fibroblasts into bovine collagen type I matrix and culturing of human keratinocytes and melanocytes on this matrix.

Texture analysis of the epidermis based on fast Fourier transformation in Sjögren-Larsson syndrome.

OBJECTIVE: To investigate whether image analysis of routine hematoxylin-eosin (H-E) skin sections using fast Fourier transformation (FFT) could detect structural alterations in patients with Sjögren-Larsson syndrome (SLS) diagnosed by molecular biology. STUDY DESIGN: Skin punch biopsies of 9 patients with SLS and 17 healthy volunteers were obtained. Digital images of routine histologic sections were taken, and their gray scale luminance was analyzed by FFT. The inertia values were determined for different ranges of the spatial frequencies in the vertical and horizontal direction. To get an estimation of anisotropy, we calculated the resultant vector of the designated frequency ranges. RESULTS: In the prickle cell layer, SLS patients showed more intense amplitudes in spatial structures with periods between 1.2 and 3.6 microm in the vertical direction, which correlated in part with accentuated nuclei and nucleoli and perinucleolar halos in the H-E sections. In a linear discriminant analysis, the variables derived from the FFT images correctly discriminated 84.6% of the patients. Texture features derived from the gray level cooccurrence matrix were not able to separate the groups. CONCLUSION: Exploratory texture analysis by FFT was able to detect discrete alterations in the prickle cell layer in routine light microscopy slides of SLS patients. The structural changes identified by FFT may be related to abnormal cellular components associated with aberrant lipid metabolism.

Model for human skin reconstructed in vitro composed of associated dermis and epidermis

CONTEXTO E OBJETIVO: A técnica para obtenção de pele humana que apresente derme e epiderme, reconstruída a partir de células isoladas de pacientes, pode possibilitar a realização de enxertos autólogos de pele reconstruída em laboratório em pacientes com áreas doadoras escassas, além de permitir ensaios com substâncias químicas e drogas in vitro e não mais in vivo. O objetivo do trabalho é demonstrar um método de obtenção de pele humana reconstruída in vitro composta de derme e epiderme associadas. TIPO DE ESTUDO E LOCAL: Estudo experimental laboratorial realizado no Laboratório de Cultura de Células da Pele da Faculdade de Ciências Médicas da Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. MÉTODOS: A partir da cultura de fibroblastos humanos, é possível obter um número suficiente de células que podem ser injetadas em uma matriz de colágeno bovino tipo I que, mantida imersa em meio de cultura específico para fibroblastos, permite a formação de uma derme humana reconstruída in vitro. Sobre essa derme, por meio de cultura de queratinócitos e melanócitos humanos, forma-se epiderme diferenciada, levando à formação de pele humana reconstruída in vitro, composta de derme e epiderme associadas. RESULTADOS: Demonstramos que é possível reproduzir pele humana reconstruída in vitro, composta de derme e epiderme associadas. Essa pele humana formada é, histologicamente, semelhante à pele humana in vivo. Na derme, identifica-se o tecido colágeno, com suas células, e a matriz extracelular organizados paralelamente à epiderme. Esta se desenvolve em várias camadas. CONCLUSÃO: É possível obter pele humana reconstruída in vitro, completamente diferenciada, composta de derme e epiderme, associadas, a partir da injeção de fibroblastos humanos em uma matriz de colágeno bovino tipo I e da cultura seqüencial de queratinócitos e melanócitose humanos sobre essa matriz contendo fibroblastos em seu interior.

Scalp lesions in Turner syndrome: a result of lymphoedema?

Lymphoedema and skin naevi are common in children with Turner syndrome (TS). Lymphoedema in the early stages of fetal life is thought to cause several of the phenotypic characteristics in patients with TS such as nuchal folds and pterygium colli. We present two patients with TS who have unusual lesions on the scalp. The first patient had an oval circumscribed lesion. Two biopsies were obtained from the lesion. Increased numbers of collagen fibres were seen in the reticular dermis suggesting the diagnosis of connective tissue naevus. The second patient presented with an area with skin folds on the scalp, similar to cutis verticis gyrata. Although unusual in TS, both lesions could be considered as resolving stages of lymphoedema. We suggest that karyotyping should be performed in cases of female infants presenting with similar lesions.

Model of human epidermis reconstructed in vitro with keratinocytes and melanocytes on dead de-epidermized human dermis.

CONTEXT: Recent progress in the field of epithelial culture techniques has allowed the development of culture systems in which the reconstructed epidermis presents characteristics of morphological differentiation similar to those seen in vivo. Human epidermis reconstructed in vitro may be used as the best alternative for the in vitro testing of the toxicology and efficiency of products for topical use, as well as in the treatment of skin burns and chronic skin ulcers. OBJECTIVE: To demonstrate a method for obtaining human epidermis reconstructed in vitro, using keratinocytes and melanocytes cultivated on dead de-epidermized human dermis. TYPE OF STUDY: Experimental/laboratory. SETTING: Skin Cell Culture Laboratory of the Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil. PROCEDURE: Human keratinocytes and melanocytes cultured in vitro were grown on a biological matrix (dead de-epidermized human dermis) and the system was kept at an air-liquid interface, in a suitable culturing medium, until a stratified human epidermis was formed, maintaining the histological characteristics of the epidermis in vivo. RESULTS: It was histologically demonstrated that it is possible to reproduce a differentiated epidermis through keratinocytes and melanocytes cultured on dead de-epidermized human dermis, thus obtaining a correctly positioned human epidermis reconstructed in vitro with functional keratinocytes and melanocytes that is similar to in vivo epidermis. CONCLUSIONS: It is possible to obtain a completely differentiated human epidermis reconstructed in vitro from keratinocyte and melanocyte cultures on a dead de-epidermized human dermis.

Model of human epidermis reconstructed in vitro with keratinocytes and melanocytes on dead de-epidermized human dermis

CONTEXTO: Recentes progressos no campo das técnicas de cultura epitelial têm levado ao desenvolvimento de sistemas de cultura nos quais a epiderme reconstruída obtida exibe características de diferenciação morfológica semelhantes àquelas vistas in vivo. Uma epiderme humana reconstruída in vitro pode ser utilizada como melhor alternativa para testes toxicológicos e de eficácia de produtos de uso tópico in vitro e ainda no tratamento de queimaduras e úlceras crônicas de pele. OBJETIVO: Demonstrar um método de obtenção de epiderme humana reconstruída in vitro, utilizando queratinócitos e melanócitos cultivados sobre uma derme humana morta desepidermizada. TIPO DE ESTUDO: Experimental Laboratorial. LOCAL: Laboratório de Cultura de Células da Pele da Faculdade de Ciências Médicas da Universidade Estadual de Campinas, Campinas, São Paulo, Brasil. PROCEDIMENTOS: Queratinócitos e melanócitos humanos cultivados in vitro foram semeados sobre uma matriz biológica (derme humana morta desepidermizada) e o sistema foi mantido em interface ar-líquido, em meio de cultura adequado, até haver a formação de uma epiderme humana estratificada, mantendo as características histológicas da epiderme in vivo. RESULTADOS: Demonstramos, histologicamente, que é possível reproduzir uma epiderme diferenciada, a partir da cultura de queratinócitos e melanócitos sobre uma derme humana morta desepidermizada, obtendo uma epiderme humana reconstruída in vitro, com queratinócitos e melanócitos funcionais, corretamente posicionados, equivalente à epiderme in vivo. CONCLUSÕES: É possível obter uma epiderme humana reconstruída in vitro completamente diferenciada a partir da cultura de queratinócitos e melanócitos sobre uma derme humana morta desepidermizada.