Project description:Autologous skin grafting is a standard treatment for skin defects such as burns. No artificial skin substitutes are functionally equivalent to autologous skin grafts. The cultured epidermis lacks the dermis and does not engraft deep wounds. Although reconstituted skin, which consists of cultured epidermal cells on a synthetic dermal substitute, can engraft deep wounds, it requires the wound bed to be well-vascularized and lacks skin appendages. In this study, we successfully generate complete skin grafts with PSC-derived epidermis with appendages on p63 knockout embryos' dermis. Donor PSC-derived keratinocytes encroach the embryos' dermis by eliminating p63 knockout keratinocytes based on cell-extracellular matrix adhesion mediated cell competition. Although the chimeric skin contains allogenic dermis, it is engraftable as long as autologous grafts. Furthermore, we could generate semi-humanized skin segments by human keratinocytes injection into the amnionic cavity of p63 knockout mice embryos. Niche encroachment opens the possibility of human skin graft production in livestock animals.
Project description:Cultured skin substitutes, prepared using keratinocytes, fibroblasts and biopolymers, can facilitate closure of massive burn wounds by increasing the availability of autologous tissue for grafting. However, because they contain only two cell types, skin substitutes cannot replace all of the functions of native human skin. To better understand the physiological and molecular differences between cultured skin substitutes and native skin, we undertook a comprehensive analysis of gene expression in native skin, cultured keratinocytes, cultured fibroblasts, and skin substitutes using Affymetrix gene chip microarrays. Goals: Our analysis focused on identifying gene signatures that were highly characteristic of each cell and tissue type, and those that are regulated by the formation of cultured skin substitute from the individual components. Normalization: We used a normalization and referencing strategy that consisted of BioConductor/RMA Express RMA processing of the entire series of cel files followed by a per gene normalization in which the median value of expression for each gene was derived from the cultured samples only, and this was used as a reference for all samples including the cultured skin substitute. This approach allowed for the identification of genes that were higher and lower-expressed in the cultured skin relative to the individual cell types that were also expressed strongly or weakly in normal skin relative to the median value established by the three cell types. Results Summary:We identified six major clusters of coordinately regulated genes that were the most differentially expressed between groups. These clusters correspond to biomarker pools representing expression signatures for native skin, fibroblasts, keratinocytes, and cultured skin. The expression analysis revealed that entire clusters of genes were either up-regulated or down-regulated upon combination of fibroblasts and keratinocytes in cultured skin grafts. Further, several categories of genes were overexpressed in cultured skin substitutes compared with native skin, including genes associated with hyperproliferative skin or activated keratinocytes. The observed pattern of expression indicates that cultured skin substitutes in vitro, which display a well-differentiated epidermal layer, exhibit skin-like differentiation relative to gene expression patterns in the individual cells. This consists of both the activation of normal skin signature genes and the suppression of keratinocyte and fibroblast signatures. There is also a signature consistent with a hyperproliferative phenotype similar to wounded native skin. Keywords: Cell interaction and co-culture response expression profile
Project description:Cultured skin substitutes, prepared using keratinocytes, fibroblasts and biopolymers, can facilitate closure of massive burn wounds by increasing the availability of autologous tissue for grafting. However, because they contain only two cell types, skin substitutes cannot replace all of the functions of native human skin. To better understand the physiological and molecular differences between cultured skin substitutes and native skin, we undertook a comprehensive analysis of gene expression in native skin, cultured keratinocytes, cultured fibroblasts, and skin substitutes using Affymetrix gene chip microarrays. Goals: Our analysis focused on identifying gene signatures that were highly characteristic of each cell and tissue type, and those that are regulated by the formation of cultured skin substitute from the individual components. Normalization: We used a normalization and referencing strategy that consisted of BioConductor/RMA Express RMA processing of the entire series of cel files followed by a per gene normalization in which the median value of expression for each gene was derived from the cultured samples only, and this was used as a reference for all samples including the cultured skin substitute. This approach allowed for the identification of genes that were higher and lower-expressed in the cultured skin relative to the individual cell types that were also expressed strongly or weakly in normal skin relative to the median value established by the three cell types. Results Summary:We identified six major clusters of coordinately regulated genes that were the most differentially expressed between groups. These clusters correspond to biomarker pools representing expression signatures for native skin, fibroblasts, keratinocytes, and cultured skin. The expression analysis revealed that entire clusters of genes were either up-regulated or down-regulated upon combination of fibroblasts and keratinocytes in cultured skin grafts. Further, several categories of genes were overexpressed in cultured skin substitutes compared with native skin, including genes associated with hyperproliferative skin or activated keratinocytes. The observed pattern of expression indicates that cultured skin substitutes in vitro, which display a well-differentiated epidermal layer, exhibit skin-like differentiation relative to gene expression patterns in the individual cells. This consists of both the activation of normal skin signature genes and the suppression of keratinocyte and fibroblast signatures. There is also a signature consistent with a hyperproliferative phenotype similar to wounded native skin. Experiment Overall Design: The sample series consists of native human skin (NHS) samples isolated from female donors undergoing reduction mammoplasty (breast skin) or abdominoplasty (abdomen skin). Skin samples from donors that were used to establish cultures of fibroblasts (CF) and keratinocytes (CK) were assigned donor numbers in the order they were processed in the laboratory, for example: 633, 634, etc. An additional human skin sample (C-1-Ref) was used only to make RNA as a standard control, and was therefore not assigned a donor number. Cultured skin substitutes (CSS) were prepared using isogenic CF and CK from each donor, and were cultured for 2 weeks in vitro to permit development of a stratified and cornified epidermal layer (confirmed by histology). For microarray analysis, RNA was isolated from intact NHS, from CF and CK in monolayer cultures, and from CSS. Samples are labeled indicating the sample type and donor number; for example, CF633 represents cultured fibroblasts from donor 633. To control for variation between individuals, four donors (= biological replicates) were used for each sample type: NHS, CF, CK, and CSS. Efforts were made to have complete sets of 4 samples from each donor, but intact RNA was not obtainable from 2 of the NHS samples (donors 634 and 651); these were replaced with NHS RNA from similar donors (donors C-1-Ref and 636). To check the fidelity of the microarray analysis, 2 of the RNA samples (CK639 and CSS651) were analyzed in duplicate (= technical replicates)
Project description:Constitutively active RAS plays a central role in the development of skin cancer in the classical two stage skin carcinogenesis in mice and in a number of human cancers. Ras-mediated tumor formation is commonly associated with upregulation of cytokines and chemokines that mediate an inflammatory response considered relevant to oncogenesis. MyD88 is a crucial intermediate in the expression of multiple innate immune responders through signaling from the Toll-like/IL-1R family. We report that mice ablated for MyD88 or the IL-1R are resistant to topical skin carcinogenesis, and cultured MyD88-/- keratinocytes transduced with an oncogenic ras vector form only a few small tumors in orthotopic grafts. Initiated keratinocytes arising from oncogenic activation of ras are hyperproliferative but also resist signals for induced differentiation and upregulate a host of pro-inflammatory genes. Ras-transduced MyD88-/- keratinocytes are also hyperproliferative but the differentiation response is intact and pro-inflammatory genes are not upregulated. Using both genetic and pharmacological approaches, we find that in keratinocytes, the differentiation and immune regulation functions mediated by oncogenic ras require the establishment of an autocrine loop through IL-1α and its receptor leading to NF-κB activation. In the absence of MyD88 or IL-1R, this loop cannot be established. Further, blocking the IL-1a mediated NF-κB activation in ras-transduced wildtype keratinocytes corrects the defect in both differentiation response and proinflammatory gene expression. Collectively, these results demonstrate that ras activation converts normal keratinocytes to an initiated phenotype through a series of potentially reversible feedback signals that provide therapeutic opportunities through inhibition of IL-1 signaling. Gene expression comparison of wild type ras-transformed keratinocytes untreated (n=3) or treated (n=3) in vitro with the IL1R antagonist Anakinra.
Project description:Constitutively active RAS plays a central role in the development of skin cancer in the classical two stage skin carcinogenesis in mice and in a number of human cancers. Ras-mediated tumor formation is commonly associated with upregulation of cytokines and chemokines that mediate an inflammatory response considered relevant to oncogenesis. MyD88 is a crucial intermediate in the expression of multiple innate immune responders through signaling from the Toll-like/IL-1R family. We report that mice ablated for MyD88 or the IL-1R are resistant to topical skin carcinogenesis, and cultured MyD88-/- keratinocytes transduced with an oncogenic ras vector form only a few small tumors in orthotopic grafts. Initiated keratinocytes arising from oncogenic activation of ras are hyperproliferative but also resist signals for induced differentiation and upregulate a host of pro-inflammatory genes. Ras-transduced MyD88-/- keratinocytes are also hyperproliferative but the differentiation response is intact and pro-inflammatory genes are not upregulated. Using both genetic and pharmacological approaches, we find that in keratinocytes, the differentiation and immune regulation functions mediated by oncogenic ras require the establishment of an autocrine loop through IL-1α and its receptor leading to NF-κB activation. In the absence of MyD88 or IL-1R, this loop cannot be established. Further, blocking the IL-1a mediated NF-κB activation in ras-transduced wildtype keratinocytes corrects the defect in both differentiation response and proinflammatory gene expression. Collectively, these results demonstrate that ras activation converts normal keratinocytes to an initiated phenotype through a series of potentially reversible feedback signals that provide therapeutic opportunities through inhibition of IL-1 signaling.
Project description:To investigate whether skin bacteria might influence the expression of selected genes, we co-cultured human keratinocytes with S. epidermidis, an abundant commensal in human skin and performed RNA sequencing analysis.
Project description:We established a culture method of human keratinocytes from the bulge region of a plucked hair follicle, that contains multipotent epithelial stem cells with high proliferative potential. Using our method, keratinocyte cultures were successfully obtained from all subjects without invasive skin biopsies. We compared the gene expression profiles between the cultured keratinocytes derived from human hair-follicle-bulge (bulge–derived keratinocytes; BDKs) and neonatal human epidermal keratinocytes (NHEKs), and between BDKs from donors with atopic dermatitis and non-atopic controls using microarray analysis. Keywords: expressin profiling
Project description:The epidermis, outermost layer of the skin, forms a barrier and is involved in innate and adaptive immunity in an organism. Keratinocytes participate in all these three protective processes. However, a regulator of keratinocyte protective responses against external dangers and stresses remains elusive. We found that upregulation of the orphan gene 2610528A11Rik was a common factor in the skin of mice with several types of inflammation. In the human epidermis, peptide expression of G protein-coupled receptor 15 ligand (GPR15L), encoded by the human ortholog C10orf99, was highly induced in the lesional skin of patients with atopic dermatitis or psoriasis. C10orf99 gene transfection into normal human epidermal keratinocytes (NHEKs) induced the expression of inflammatory mediators and reduced the expression of barrier-related genes. Gene ontology analyses showed its association with translation, mitogen-activated protein kinase (MAPK), mitochondria, and lipid metabolism. Treatment with GPR15L reduced the expression levels of filaggrin and loricrin in human keratinocyte 3D cultures. Instead, their expression levels in mouse primary cultured keratinocytes did not show significant differences between the wild-type and 2610528A11Rik deficient keratinocytes. Lipopolysaccharide-induced expression of Il1b and Il6 was less in 2610528A11Rik deficient mouse keratinocytes than in wild-type, and imiquimod-induced psoriatic dermatitis was blunted in 2610528A11Rik deficient mice. Furthermore, repetitive subcutaneous injection of GPR15L in mouse ears induced skin inflammation in a dose-dependent manner. These results suggest that C10orf99/GPR15L is a primary inducible regulator that reduces the barrier formation and induces the inflammatory response of keratinocytes.