Recessive Dystrophic Epidermolysis Bullosa Patients Research Articles

401 Dermal fibroblasts with loss of TSC2 express increased galectin-3, a potential biomarker for tuberous sclerosis complex

400 Amlexanox: Efficacy and mechanism for potential therapy for RDEB V Atanasova, Q Jiang, J Uitto and A South Thomas Jefferson University, Philadelphia, PA Recessive dystrophic epidermolysis bullosa (RDEB) is a severe skin blistering disorder caused by loss-of-function mutations in the COL7A1 gene, which encodes type VII collagen (ColVII). ColVII is the main, if not exclusive, component of anchoring fibrils that adhere the epidermis to the dermal layer of the skin. Mutations in COL7A1 lead to defective anchoring fibrils and subsequent perturbed adhesion between the two skin layers resulting in severe skin fragility and constant wounding without ability to heal. A subgroup of RDEB patients harbors nonsense mutations in COL7A1 which create premature termination codons (PTCs) of translation in the mRNA molecule. This leads to mRNA instability and lack of functional protein synthesized. A group of drugs have been reported for their ability to induce “readthrough” and allow for insertion of an amino acid at the site of PTC, thus producing fulllength protein. The mechanism by which these drugs act is currently not known. Here we focus on a PTC read-through drug, amlexanox, previously approved by the FDA for mouth ulcers. Our data show that amlexanox is able to induce full-length synthesis of ColVII in HpV immortalized RDEB patient derived keratinocytes and fibroblasts, as shown by western blotting. After 48 hours of treatment keratinocytes showed up to 14 fold increase in full-length ColVII protein synthesis as compared to non-treated controls. The same treatment in HpV fibroblasts led up to 3 fold increase in ColVII as compared to non-treated controls, or 25% of normal human fibroblasts. While the mechanism by which amlexanox is able to recover protein synthesis from the PTC containing COL7A1 gene is currently unclear, activation of UPF1 by its phosphorylation has been shown to be required for assembly of mRNA degradation machinery. Our data show that amlexanox treatment increases UPF1 phosphorylation, which may be part of the PTC read-through mechanism. In conclusion, we present data to support amlexanox as a read-through agent for the treatment of RDEB in cases with PTC in COL7A1. 401 Dermal fibroblasts with loss of TSC2 express increased galectin-3, a potential biomarker for tuberous sclerosis complex P Klover, R Thangapazham, J Kato, J Wang, S Li, C Dalgard, M Wilkerson, E Mccart, J Moss and T Darling 1 Dermatology, Uniformed Services University of the Health Sciences, Bethesda, MD, 2 Cardiovascular and Pulmonary Branch, NIH/NHLBI, Bethesda, MD and 3 Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD Tuberous sclerosis complex (TSC) is an autosomal genetic disorder in which tumors form in multiple organs due to biallelic inactivating mutations in TSC1 or TSC2 and increased mTORC1 signaling. In order to discover biomarkers for TSC, we studied our mouse model of TSC with conditional deletion of Tsc2 in dermal mesenchyme (Tsc2cKO), testing the potential clinical relevance of findings using human TSC skin tumors. RNA-sequencing analysis of cultured Tsc2-null and wild-type mouse dermal fibroblasts identified galectin-3 as overexpressed by the mutant cells. Levels of both intracellular and secreted galectin-3 protein were approximately 3-fold greater in Tsc2-null fibroblasts than wild-type fibroblasts. Tsc2-null cells incubated in the presence of 20 nM sirolimus, an mTORC1-inhibitor, showed decreased galectin-3 expression but not to the level of wild-type fibroblasts, suggesting that overexpression of galectin-3 is only partially mTORC1-dependent. Serum levels of galectin-3 were 68% greater (p1⁄40.0015) in Tsc2 cKO than wild-type mice and sirolimus treatment for 4 weeks decreased galectin-3 serum levels 25% (p1⁄40.036) in the Tsc2cKO. Fibroblast-like cells grown from human TSC skin tumors, including angiofibromas, fibrous cephalic plaque, and periungual fibromas, showed greater intracellular and secreted galectin-3 levels than patient normal fibroblasts. Immunohistochemical analysis showed abundant galectin-3 positive dermal cells in TSC skin tumors but nearly absent dermal staining in paired samples of patient normal-appearing skin. Our results demonstrate that loss of TSC2 in dermal fibroblasts is associated with increased galectin-3 and suggest that this molecule should be investigated as a biomarker for TSC and possibly other diseases associated with increased mTORC1 activation.

Gene-Corrected Fibroblast Therapy for Recessive Dystrophic Epidermolysis Bullosa using a Self-Inactivating COL7A1 Retroviral Vector

Patients with recessive dystrophic epidermolysis bullosa (RDEB) lack type VII collagen and therefore have severely impaired dermal-epidermal stability causing recurrent skin and mucosal blistering. There is currently no specific approved treatment for RDEB. We present preclinical data showing that intradermal injections of genetically corrected patient-derived RDEB fibroblasts using a Good Manufacturing Practices grade self-inactivating COL7A1 retroviral vector reverse the disease phenotype in a xenograft model in nude mice. We obtained 50% transduction efficiency in primary human RDEB fibroblasts with an average low copy number (range= 1-2) of integrated provirus. Transduced fibroblasts showed strong type VII collagen re-expression, improved adhesion properties, normal proliferative capabilities, and viability invitro. We show that a single intradermal injection of 3× 10(6) genetically corrected RDEB fibroblasts beneath RDEB skin equivalents grafted onto mice allows type VII collagen deposition, anchoring fibril formation at the dermal-epidermal junction, and improved dermal-epidermal adherence 2 months after treatment, supporting functional correction invivo. Gene-corrected fibroblasts previously showed no tumorigenicity. These data show the efficacy and safety of gene-corrected fibroblast therapy using a self-inactivating vector that has now been good manufacturing grade-certified and pave the way for clinical translation to treat nonhealing wounds in RDEB patients.

Pseudosyndactyly - an inflammatory and fibrotic wound healing disorder in recessive dystrophic epidermolysis bullosa.

A genetic blistering skin disease, recessive dystrophic epidermolysis bullosa (RDEB), is marked by severe wound healing defects and finger contractures. The purpose of this investigation was to elucidate the mechanisms of impaired wound healing and pseudosyndactyly occurring in RDEB patients by studying the role of known inflammation and fibrosis markers in RDEB pseudosyndactyly tissue. We studied the expression of the fibrosis and/or inflammation markers tenascin-C, α-smooth muscle actin, transforming growth factor-β1, interleukin-1β, and interleukin-6 in scarring and nonscarring tissue from healthy donors and RDEB patients by semiquantitative real time-PCR and, where applicable, by immunoblots. Furthermore, the distribution pattern of α-smooth muscle actin and tenascin-C were assessed by immunofluorescence microscopy. Based on mRNA and protein analysis, we found upregulation of tenascin-C, interleukin-1β, and interleukin-6 - but not of transforming growth factor-β1 - in recessive dystrophic epidermolysis bullosa scar samples taken from pseudosyndactyly hands. Unexpectedly, α-smooth muscle actin was not upregulated. Our results confirm inflammation and fibrosis in recessive dystrophic epidermolysis bullosa, especially in scars, suggesting major roles for these processes in pseudosyndactyly. Our data therefore suggests the potential use of antiinflammatory and antifibrotic drugs in the prevention of pseudosyndactyly.

Lysyl Hydroxylase 3 Localizes to Epidermal Basement Membrane and Is Reduced in Patients with Recessive Dystrophic Epidermolysis Bullosa.

Recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in COL7A1 resulting in reduced or absent type VII collagen, aberrant anchoring fibril formation and subsequent dermal-epidermal fragility. Here, we identify a significant decrease in PLOD3 expression and its encoded protein, the collagen modifying enzyme lysyl hydroxylase 3 (LH3), in RDEB. We show abundant LH3 localising to the basement membrane in normal skin which is severely depleted in RDEB patient skin. We demonstrate expression is in-part regulated by endogenous type VII collagen and that, in agreement with previous studies, even small reductions in LH3 expression lead to significantly less secreted LH3 protein. Exogenous type VII collagen did not alter LH3 expression in cultured RDEB keratinocytes and we show that RDEB patients receiving bone marrow transplantation who demonstrate significant increase in type VII collagen do not show increased levels of LH3 at the basement membrane. Our data report a direct link between LH3 and endogenous type VII collagen expression concluding that reduction of LH3 at the basement membrane in patients with RDEB will likely have significant implications for disease progression and therapeutic intervention.

Medical cell technologies for treatment of patients suffering from recessive dystrophic epidermolysis bullosa. Method of intracutaneous administration of fibroblasts

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe inherited disease developing due to genetic abnormalities in the synthesis of Type VII collagen by fibroblasts. A low production rate of Type VII collagen and abnormalities related to the formation of anchoring fibrils weaken the epidermis and derma adhesion strength, which results in the formation of blisters or erosions in case of any mechanical injury. Fibroblasts and keratinocytes belong to the key sources of Type VII collagen in the skin. Application of allogeneic fibroblasts is a promising cell technique for treating RDEB patients. The therapeutic effect of fibroblasts intradermal administration is stipulated by high stability of newly synthesized Type VII collagen and its ability to form anchoring fibrils in the area of the dermoepidermal junction. According to experimental and clinical studies, it is possible to boost the content of Type VII collagen in the dermoepidermal junction area and heal long-term skin defects in RDEB patients by means of intradermal administration of allogeneic fibroblasts.

666. A Phase-1 Safety Study Protocol for Lentiviral-Mediated COL7A1 Gene-Modified Autologous Fibroblasts in Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a debilitating genodermatosis caused by loss-of-function mutations in COL7A1, the gene encoding type VII collagen (C7), a protein central to anchoring fibril formation at the dermal-epidermal junction (DEJ). Presently there are no curative treatments for this condition. We have been developing the gene therapy protocol for locally injection of lentiviral mediated COL7A1 gene-modified autologous fibroblasts into the patients with RDEB. Primary fibroblasts were isolated from a 6mm skin biopsy. Cells are expanded and transduced with a GMP compliant lenti-viral vector containing codon optimised COL7A1 gene cDNA under the control of the human PGK promoter. Transduced cells were further expended to reach appropriate cell numbers and cryopreserved until patients are ready. Scale up studies carried out in our GMP compliance laboratory showed C7 expression and stable integration of vector into cells. In-situ immunostaining and western blot analysis confirmed the expression of collagen VII protein (C7) not only in transduced RDEB fibroblasts but also in the culture media, indicating there is secreted C7 from transduced cells. The primary objective of our proposed Phase-I study is to determine the safety and tolerability of treatment with autologous gene modified cells administered to RDEB patients. Fibroblasts expressing codon-optimised COL7A1 will be injected intra-dermally in 5-10 adults with RDEB. The secondary objectives are to assess the efficacy of this treatment and its impact on skin and reversion of gene expression. Each study participant will receive three intradermal injections of ex-vivo transduced autologous fibroblasts expressing codon-optimised COL7A1 as the IMP and three intradermal injections of non-transduced autologous fibroblasts as control. Each injection (both IMP and control) will be administered into separate 1cm2 areas of intact skin sites. Participants will be followed up with study interventions for a total of 36-month period at various time points. If successful, a similar approach could be used to modify autologous epidermal sheets for localised treatment of blisters as well as systemic cell therapies.

HEK293-based production platform for γ-retroviral (self-inactivating) vectors: application for safe and efficient transfer of COL7A1 cDNA.

The clinical application of self-inactivating (SIN) retroviral vectors requires an efficient vector production technology. To enable production of γ-retroviral SIN vectors from stable producer cells, new targetable HEK293-based producer clones were selected, providing amphotropic, GALV, or RD114 pseudotyping. Viral vector expression constructs can reliably be inserted at a predefined genomic locus via Flp-recombinase-mediated cassette exchange. Introduction of a clean-up step, mediated by Cre-recombinase, allows the removal of residual sequences that were required for targeting and selection, but were dispensable for the final producer clones and eliminated homology-driven recombination between the tagging and the therapeutic vector. The system was used to establish GALV and RD114 pseudotyping producer cells (HG- and HR820) for a clinically relevant long terminal repeat-driven therapeutic vector, designed for the transfer of a recombinant TCR that delivered titers in the range of 2×10(7) infectious particles (IP)/ml. Production capacity of the amphotropic producer cell (HA820) was challenged by a therapeutic SIN vector transferring the large COL7A1 cDNA. The final producer clone delivered a titer of 4×10(6) IP/ml and the vector containing supernatant was used directly to functionally restore primary fibroblasts and keratinocytes isolated from recessive dystrophic epidermolysis bullosa patients. Thus, the combinatorial approach (fc-technology) to generate producer cells for therapeutic γ-retroviral (SIN) vectors is feasible, is highly efficient, and allows their safe production and application in clinical trials.

Beyond branching: multiknot structured polymer for gene delivery.

Polymer-based transfection vectors are increasingly becoming the preferred alternative to viral vectors thanks to their safety and ease of production, but low transfection potency has limited their application. Many polycationic vectors show high efficiency in vitro, but their excessive charge density makes them toxic for in vivo applications. Herein, we demonstrate the synthesis of new and unique disulfide-reducible polymeric gene nanocarriers that exhibit significantly enhanced transfection potency and low cytotoxicity, particularly in skin cells, surpassing the efficiency of the well-known transfection reagents polyethylenimine (PEI) and Lipofectamine2000. The unique three-dimensional (3D) "multiknot" vectors were synthesized from in situ deactivation enhanced atom transfer radical (co)polymerization (DE-ATRP) of multivinyl monomers (MVMs). The high transfection levels and low toxicity of this multiknot structured polymer in vitro, combined with its ability to mediate collagen VII expression in 3D skin equivalents made from cells of recessive dystrophic epidermolysis bullosa patients, demonstrates its use as a platform nanotechnology which should be investigated further for dermatological disease therapies. Our findings suggest that the marked improvements stem from the dense multiknot architecture and degradable property, which facilitate both the binding and releasing process of the plasmid DNA.

Preconditioning of mesenchymal stem cells for improved transplantation efficacy in recessive dystrophic epidermolysis bullosa.

IntroductionThe use of hematopoietic cell transplantation (HCT) has previously been shown to ameliorate cutaneous blistering in pediatric patients with recessive dystrophic epidermolysis bullosa (RDEB), an inherited skin disorder that results from loss-of-function mutations in COL7A1 and manifests as deficient or absent type VII collagen protein (C7) within the epidermal basement membrane. Mesenchymal stem cells (MSCs) found within the HCT graft are believed to be partially responsible for this amelioration, in part due to their intrinsic immunomodulatory and trophic properties and also because they have been shown to restore C7 protein following intradermal injections in models of RDEB. However, MSCs have not yet been demonstrated to improve disease severity as a stand-alone systemic infusion therapy. Improving the efficacy and functional utility of MSCs via a pre-transplant conditioning regimen may bring systemic MSC infusions closer to clinical practice.MethodsMSCs were isolated from 2- to 4-week-old mice and treated with varying concentrations of transforming growth factor-β (TGFβ; 5-20 ng/mL), tumor necrosis factor- α (TNFα; 10-40 ng/mL), and stromal cell-derived factor 1-α (SDF-1α; 30 ng/mL) for 24-72 hours.ResultsWe demonstrate that treating murine MSCs with exogenous TGFβ (15 ng/mL) and TNFα (30 ng/mL) for 48 hours induces an 8-fold increase in Col7a1 expression and a significant increase in secretion of C7 protein, and that the effects of these cytokines are both time and concentration dependent. This cytokine treatment also promotes a 4-fold increase in Tsg-6 expression, a gene whose product is associated with improved wound-healing and immunosuppressive features. Finally, the addition of exogenous SDF-1α to this regimen induces a simultaneous upregulation of Col7a1, Tsg-6, and Cxcr4 expression.ConclusionsThese data suggest that preconditioning represents a feasible method for improving the functional utility of MSCs in the context of RDEB stem cell transplantation, and also highlight the applicability of preconditioning principles toward other cell-based therapies aimed at treating RDEB patients.

Aminoglycosides Restore Full-length Type VII Collagen by Overcoming Premature Termination Codons: Therapeutic Implications for Dystrophic Epidermolysis Bullosa

Patients with recessive dystrophic epidermolysis bullosa (RDEB) have severe, incurable skin fragility, blistering, and multiple skin wounds due to mutations in the gene encoding type VII collagen (C7), the major component of anchoring fibrils mediating epidermal-dermal adherence. Nearly 10-25% of RDEB patients carry nonsense mutations leading to premature stop codons (PTCs) that result in truncated C7. In this study, we evaluated the feasibility of using aminoglycosides to suppress PTCs and induce C7 expression in two RDEB keratinocyte cell lines (Q251X/Q251X and R578X/R906) and two primary RDEB fibroblasts (R578X/R578X and R163X/R1683X). Incubation of these cells with aminoglycosides (geneticin, gentamicin, and paromomycin) resulted in the synthesis and secretion of a full-length C7 in a dose-dependent and sustained manner. Importantly, aminoglycoside-induced C7 reversed the abnormal RDEB cell phenotype and incorporated into the dermal-epidermal junction of skin equivalents. We further demonstrated the general utility of aminoglycoside-mediated readthrough in 293 cells transiently transfected with expression vectors encoding 22 different RDEB nonsense mutations. This is the first study demonstrating that aminoglycosides can induce PTC readthrough and restore functional C7 in RDEB caused by nonsense mutations. Therefore, aminoglycosides may have therapeutic potential for RDEB patients and other inherited skin diseases caused by nonsense mutations.

Promise of Human Induced Pluripotent Stem Cells in Skin Regeneration and Investigation

Induced pluripotent stem cell (iPSC) technology has initiated a new era in biomedical science. The skin has been realized as an ideal platform for iPSC applications; unlike other organs, the skin is easily accessible, highly proliferative, and reconstitutable. Currently, skin equivalents can be generated from iPSCs not only from healthy individuals but also from patients with genodermatoses, providing novel platforms for dissecting disease pathophysiology and establishing cell-based therapy. With their developmental plasticity, iPSCs may also enable the regeneration of skin appendages. The iPSC technology may provide novel remedies for intractable disorders, once key issues particularly, safety concerns, are cleared.

Prevalence of specific anti-skin autoantibodies in a cohort of patients with inherited epidermolysis bullosa

BackgroundInherited epidermolysis bullosa (EB) is a group of skin diseases characterized by blistering of the skin and mucous membranes.There are four major types of EB (EB simplex, junctional EB, dystrophic EB and Kindler syndrome) caused by different gene mutations. Dystrophic EB is derived from mutations in the type VII collagen gene (COL7A1), encoding a protein which is the predominant component of the anchoring fibrils at the dermal-epidermal junction.For the first time in literature, we have evaluated the presence of anti-skin autoantibodies in a wider cohort of patients suffering from inherited EB and ascertained whether they may be a marker of disease activity.MethodsSera from patients with inherited EB, 17 with recessive dystrophic EB (RDEB), 10 with EB simplex (EBS) were analysed. As much as 20 patients with pemphigus vulgaris, 21 patients with bullous pemphigoid and 20 healthy subjects were used as controls.Anti-skin autoantibodies were tested in all samples with the Indirect Immunofluorescence (IIF) method and the currently available ELISA method in order to detect anti-type VII collagen, anti-BP180 and anti-BP230 autoantibodies.ResultsThe mean concentrations of anti-type VII collagen autoantibodies titres, anti-BP180 and anti-BP230 autoantibodies were statistically higher in RDEB patients than in EBS patients.The sensitivity and specificity of the anti-type VII collagen ELISA test were 88.2% and 96.7%. The Birmingham Epidermolysis Bullosa Severity score, which is used to evaluate the severity of the disease, correlated with anti-skin autoantibodies titres.ConclusionsThe precise pathogenic role of circulating anti-skin autoantibodies in RDEB is unclear. There is a higher prevalence of both anti-type VII collagen and other autoantibodies in patients with RDEB, but their presence can be interpreted as an epiphenomenon.

Type VII Collagen Deficiency Causes Defective Tooth Enamel Formation due to Poor Differentiation of Ameloblasts

Recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in the gene encoding type VII collagen (COL7), a major component of anchoring fibrils in the epidermal basement membrane zone. Patients with RDEB present a low oral hygiene index and prevalent tooth abnormalities with caries. We examined the tooth enamel structure of an RDEB patient by scanning electron microscopy. It showed irregular enamel prisms, indicating structural enamel defects. To elucidate the pathomechanisms of enamel defects due to COL7 deficiency, we investigated tooth formation in Col7a1(-/-) and COL7-rescued humanized mice that we have established. The enamel from Col7a1(-/-) mice had normal surface structure. The enamel calcification and chemical composition of Col7a1(-/-) mice were similar to those of the wild type. However, transverse sections of teeth from the Col7a1(-/-) mice showed irregular enamel prisms, which were also observed in the RDEB patient. Furthermore, the Col7a1(-/-) mice teeth had poorly differentiated ameloblasts, lacking normal enamel protein-secreting Tomes' processes, and showed reduced mRNA expression of amelogenin and other enamel-related molecules. These enamel abnormalities were corrected in the COL7-rescued humanized mice expressing a human COL7A1 transgene. These findings suggest that COL7 regulates ameloblast differentiation and is essential for the formation of Tomes' processes. Collectively, COL7 deficiency is thought to disrupt epithelial-mesenchymal interactions, leading to defective ameloblast differentiation and enamel malformation in RDEB patients.

Human Umbilical Cord Blood (HUCB) Derived Pluripotent Stem Cells Enhances Wound Healing

Abstract 4824 Background:Recessive dystrophic epidermolysis bullosa (RDEB) is a severe inherited skin blistering disease caused by mutations in the type VII collagen (COL7A1) gene that encodes a major component in anchoring fibrils (Christiano et.al. Nat Gen 1993). Recently, iPSCs have been generated from RDEB patients, which provides promises on gene correction and future autologous Stem Cell Transplantation (SCT) (Itoh/Cairo/Christiano PNAS 2011). Currently, Allogeneic (Allo) SCT remains to be the best treatment for numerous malignant and non-malignant diseases in pediatric patients (Cairo et al BBMT 2008). This has also been supported by the first report on Allo-SCT in seven children with RDEB (Wagner et.al. N Engl J Med 2010). However no distinct anchoring fibrils were observed in the recipient skin. Moreover the functional cell populations are to be characterized. Stem cell populations with pluripotent properties, including unrestricted somatic stem cells (USSCs) have been isolated from HUCB, and may represent novel stem cells for the regenerative therapy for RDEB either by themselves, or by co-administration with BM or HUCB (Liao/Cairo et al, Exp. Hem, 2011). Goal:Determine the potential of USSCs in promoting wound healing and treating RDEB. Method:USSCs were isolated from HUCB in the presence of 30% FBS and 10−7M dexamethasone, and characterized by RT-PCR, bisulfate sequencing and immunocytochemistry. A 1cm2 full-thickness excisional wound was created at the dorsal of NSG mice, followed by intradermal injection of 1 million USSCs or PBS at a 1cm- distance from the margin of the created wound. The wound areas were photographed and quantitated using ImageJ. Skin biopsies were taken at selected days and characterized by H&E staining and immunohistochemistry. Results:USSCs transcribe a low level of Nanog, Oct4 and Sox2, as compared to ES cells. Their Nanog and Oct4 expression is about 20- and 400- fold higher than that in human fibroblasts, and could be further activated at least 10 fold by treatment of DNA methylation inhibitor, 5-azacytidine. Their level of DNA methylation at the regulatory regions of Oct4 and Nanog genes is also intermediate between ES and fibroblasts. This suggests that USSCs represent a cell type that is developmentally an intermediate between ES cells and somatic cells. In addition, flow cytometry analysis indicated that USSCs also express stem cell surface antigen SSEA4. USSCs express Col7a1, the protein that is missing in the RDEB patients, at a level that is comparable to human keratinocytes and fibroblasts (fig A). This implies a potential ability of USSCs to rescue the RDEB defect by secreting COL7a1. In the mouse wounding model, USSC-treated wounds closed at a faster rate and Bonferroni post-test showed a significant difference between USSC and PBS treatment on days 6– 10 (Fig B). Immunological staining of tissue sections for endothelial protein CD31 showed increased vasculature in USSC-treated wounds at as early as three days post wounding, compared with PBS-treated wounds. Using immunostaining against human specific α5 and/or β1 integrin that is expressed specifically in USSCs, we have detected the presence of human cells within the wounded, but not unwounded basal layer of the skin, up to 1 month post wounding (Fig C). This indicates specific migration of USSCs to the wounded area and such a directed migration is likely to be mediated by the chemotactic interaction between stroma-derived factor 1(SDF-1) and CXCR4 that is expressed at the surface of USSCs. H&E staining on the skin biopsies taken at different time points indicated that USSCs promoted epithelialization and facilitated the formation and remodeling of epidermis. The resultant USSC-treated skin was less fibrotic, and more importantly, demonstrated formation of normal skin appendages in the center of the wounded area (Fig D). However, human cells were not detected in the skin appendages by immunological analysis, suggesting that accelerated epithelialization in the wound following USSC treatment has created an optimal environment for the migration of follicle progenitor cells from the unwounded skin to the center of the wound. Conclusion:This study demonstrated the beneficial effect of HUCB derived USSCs in cutaneous regeneration and wound healing in a mouse wounding model. The ability of USSCs in secreting Col7A1 and promoting wound healing suggests their potential therapeutic application in treating RDEB. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Correction of Dog Dystrophic Epidermolysis Bullosa by Transplantation of Genetically Modified Epidermal Autografts

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe skin blistering condition caused by mutations in the gene coding for collagen type VII. Genetically engineered RDEB dog keratinocytes were used to generate autologous epidermal sheets subsequently grafted on two RDEB dogs carrying a homozygous missense mutation in the col7a1 gene and expressing baseline amounts of the aberrant protein. Transplanted cells regenerated a differentiated and vascularized auto-renewing epidermis progressively repopulated by dendritic cells and melanocytes. No adverse immune reaction was detected in either dog. In dog 1, the grafted epidermis firmly adhered to the dermis throughout the 24-month follow-up, which correlated with efficient transduction (100%) of highly clonogenic epithelial cells and sustained transgene expression. In dog 2, less efficient (65%) transduction of primary keratinocytes resulted in a loss of the transplanted epidermis and graft blistering 5 months after transplantation. These data provide the proof of principle for ex vivo gene therapy of RDEB patients with missense mutations in collagen type VII by engraftment of the reconstructed epidermis, and demonstrate that highly efficient transduction of epidermal stem cells is crucial for successful gene therapy of inherited skin diseases in which correction of the genetic defect confers no major selective advantage in cell culture.

Induced Pluripotent Stem Cells from Individuals with Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited blistering skin disorder caused by mutations in the COL7A1 gene-encoding type VII collagen (Col7), the major component of anchoring fibrils at the dermal-epidermal junction. Individuals with RDEB develop painful blisters and mucosal erosions, and currently, there are no effective forms of therapy. Nevertheless, some advances in patient therapy are being made, and cell-based therapies with mesenchymal and hematopoietic cells have shown promise in early clinical trials. To establish a foundation for personalized, gene-corrected, patient-specific cell transfer, we generated induced pluripotent stem (iPS) cells from three subjects with RDEB (RDEB iPS cells). We found that Col7 was not required for stem cell renewal and that RDEB iPS cells could be differentiated into both hematopoietic and nonhematopoietic lineages. The specific epigenetic profile associated with de-differentiation of RDEB fibroblasts and keratinocytes into RDEB iPS cells was similar to that observed in wild-type (WT) iPS cells. Importantly, human WT and RDEB iPS cells differentiated in vivo into structures resembling the skin. Gene-corrected RDEB iPS cells expressed Col7. These data identify the potential of RDEB iPS cells to generate autologous hematopoietic grafts and skin cells with the inherent capacity to treat skin and mucosal erosions that typify this genodermatosis.

A novel homozygous splice site mutation in COL7A1 in a Chinese patient with severe recessive dystrophic epidermolysis bullosa and squamous cell carcinoma

Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited blistering skin disorder caused by mutations in COL7A1 gene encoding type VII collagen, the major component of anchoring fibrils in the dermo-epidermal junction. The development of cutaneous squamous cell carcinoma (SCC) is one of the most serious complications of this disease. We report herein a Chinese patient with the severe generalized subtype of RDEB (RDEB-sev gen) complicated by SCC. Skin biopsies were examined for histology, basement membrane ultrastructure, and type VII collagen expression. Genomic DNA was extracted from the peripheral blood samples and subjected to polymerase chain reaction amplification and direct automated DNA sequencing. Histopathological examination of the patient's skin revealed an undetectable expression of type VII collagen polypeptides in the basement membrane zone. Mutation analysis identified a novel splice site mutation in intron 64 (IVS64+5g->a) of COL7A1 gene, which resulted in an in-frame deletion of exon 64 in both alleles. This report contributes to the expanding database of COL7A1 mutations and emphasizes the need to elucidate the underlying genetic mechanisms associated with the increased incidence of SCC in RDEB patients.

Immune reactivity to type VII collagen: implications for gene therapy of recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe genodermatosis caused by loss-of-function mutations in COL7A1 encoding type VII collagen, the component of anchoring fibrils. As exogenous type VII collagen may elicit a deleterious immune response in RDEB patients during upcoming clinical trials of gene therapies or protein replacement therapies, we developed enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunosorbent spot (ELISPOT) assays to analyze B- and T-cell responses, to the full-length type VII collagen. The ELISA was highly sensitive and specific when tested against sera from 41 patients with epidermolysis bullosa acquisita (EBA), and the IFN-gamma ELISPOT detected a cellular response that correlated with ongoing EBA manifestations. Both tests were next applied to assess the risk of an immune response to type VII collagen in seven RDEB patients with a range of type VII collagen expression profiles. Immune responses against type VII collagen were dependent on the expression of type VII collagen protein, and consequently on the nature and position of the respective COL7A1 mutations. These immunologic tests will be helpful for the selection of RDEB patients for future clinical trials aiming at restoring type VII collagen expression, and in monitoring their immune response to type VII collagen after treatment.

Response of Intractable Skin Ulcers in Recessive Dystrophic Epidermolysis Bullosa Patients to an Allogeneic Cultured Dermal Substitute

Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited skin disorder caused by mutations in the COL7A1 gene, which encodes collagen VII (COL7). Skin ulcers in RDEB patients are sometimes slow to heal. We describe here the therapeutic response of intractable skin ulcers in two patients with generalized RDEB to treatment with an allogeneic cultured dermal substitute (CDS). Skin ulcers in both patients epithelialized by 3-4 weeks after this treatment. Immunohistochemical studies demonstrated that the COL7 expression level remained reduced with respect to the control skin and that it did not differ significantly between graft-treated and untreated areas. Electron microscopy showed aberrant anchoring fibrils beneath the lamina densa of both specimens. In conclusion, CDS is a promising modality for treatment of intractable skin ulcers in patients with RDEB, even though it does not appear to increase COL7 expression.

Increased invasive behaviour in cutaneous squamous cell carcinoma with loss of basement-membrane type VII collagen

Type VII collagen (ColVII) is the main component of anchoring fibrils, attachment structures within the lamina densa of the basement membrane that are responsible for attachment of the epidermis to the dermis in skin. Mutations in the human ColVII gene, COL7A1, cause the severe inherited blistering disorder recessive dystrophic epidermolysis bullosa (RDEB) affecting skin and mucosae, associated with a greatly increased risk of skin cancer. In this study, we examined the effect of loss of ColVII on squamous cell carcinoma (SCC) tumourigenesis using RNAi in a 3D organotypic skin model. Our findings suggest that loss of ColVII promotes SCC migration and invasion as well as regulating cell differentiation with evidence for concomitant promotion of epithelial-mesenchymal transition (EMT). Immunostaining of RDEB skin and a tissue array of sporadic cutaneous SCCs confirmed that loss of ColVII correlates with decreased involucrin expression in vivo. Gene-expression-array data and immunostaining demonstrated that loss of ColVII increases expression of the chemokine ligand-receptor CXCL10-CXCR3 and downstream-associated PLC signalling, which might contribute to the increased metastatic potential of SCCs with reduced or absent ColVII expression. Together, these findings may explain the aggressive behaviour of SCCs in RDEB patients and may also be relevant to non-RDEB skin cancer, as well as other tumours from organs where ColVII is expressed.