From marrow to matrix: novel gene and cell therapies for epidermolysis bullosa

Skin Allograft after Bone Marrow Transplantation of Patient with Recessive Dystrophic Epidermolysis Bullosa

In this study, we present a 26-year-old woman with case presentation of recessive dystrophic epidermolysis bullosa who had developed squamous cell carcinoma. The patient underwent bone marrow transplant and skin grafting with the same bone marrow donor. After excision of squamous cell carcinoma and skin grafting, no tumor was observed; thus, chemotherapy and radiation were no longer needed.

Mesenchymal stromal cells in wound healing applications: role of the secretome, targeted delivery and impact on recessive dystrophic epidermolysis bullosa treatment

Mesenchymal stromal cells (MSCs) are multi-potent stromal-derived cells capable of self-renewal that possess several advantageous properties for wound healing, making them of interest to the field of dermatology. Research has focused on characterizing the unique properties of MSCs, which broadly revolve around their regenerative and more recently discovered immunomodulatory capacities. Because of ease of harvesting and expansion, differentiation potential and low immunogenicity, MSCs have been leading candidates for tissue engineering and regenerative medicine applications for wound healing, yet results from clinical studies have been variable, and promising pre-clinical work has been difficult to reproduce. Therefore, the specific mechanisms of how MSCs influence the local microenvironment in distinct wound etiologies warrant further research. Of specific interest in MSC-mediated healing is harnessing the secretome, which is composed of components known to positively influence wound healing. Molecules released by the MSC secretome can promote re-epithelialization and angiogenesis while inhibiting fibrosis and microbial invasion. This review focuses on the therapeutic interest in MSCs with regard to wound healing applications, including burns and diabetic ulcers, with specific attention to the genetic skin disease recessive dystrophic epidermolysis bullosa. This review also compares various delivery methods to support skin regeneration in the hopes of combating the poor engraftment of MSCs after delivery, which is one of the major pitfalls in clinical studies utilizing MSCs.

Collagen VII Expression Is Required in Both Keratinocytes and Fibroblasts for Anchoring Fibril Formation in Bilayer Engineered Skin Substitutes

The blistering disease recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in the gene encoding collagen VII (COL7), which forms anchoring fibrils that attach the epidermis to the dermis. Cutaneous gene therapy to restore COL7 expression in RDEB patient cells has been proposed, and cultured epithelial autograft containing COL7-modified keratinocytes was previously tested in clinical trials. Because COL7 in normal skin is expressed in both fibroblasts and keratinocytes, cutaneous gene therapy using a bilayer skin substitute may enable faster restoration of anchoring fibrils. Hypothetically, COL7 expression in either dermal fibroblasts or epidermal keratinocytes might be sufficient for functional anchoring fibril formation in a bilayer skin substitute. To test this, engineered skin substitutes (ESS) were prepared using four combinations of normal + RDEB cells: (1) RDEB fibroblasts + RDEB keratinocytes; (2) RDEB fibroblasts + normal keratinocytes; (3) normal fibroblasts + RDEB keratinocytes; and (4) normal fibroblasts + normal keratinocytes. ESS were incubated in vitro for 2 weeks prior to grafting to full-thickness wounds in immunodeficient mice. Biopsies were analyzed in vitro and at 1, 2, or 3 weeks after grafting. COL7 was undetectable in ESS prepared using all RDEB cells (group 1), and macroscopic blistering was observed by 2 weeks after grafting in ESS containing RDEB cells. COL7 was expressed, in vitro and in vivo, in ESS prepared using combinations of normal + RDEB cells (groups 2 and 3) or all normal cells (group 4). However, transmission electron microscopy revealed structurally normal anchoring fibrils, in vitro and by week 2 in vivo, only in ESS prepared using all normal cells (group 4). The results suggest that although COL7 protein is produced in engineered skin when cells in only one layer express the COL7 gene, formation of structurally normal anchoring fibrils appears to require expression of COL7 in both dermal fibroblasts and epidermal keratinocytes.

A rare case of skin blistering and esophageal stenosis in the course of epidermolysis bullosa - case report and literature review

BACKGROUND

Epidermolysis bullosa (EB) constitutes a heterogenous group of rare multisystem genetically transmitted disorders comprising several blistering muco-cutaneous diseases with a monogenic basis and either autosomal dominant or autosomal recessive mode of inheritance. EB manifestation is not only limited to the skin. Systemic signs might involve the nose, ear, eye, genitourinary tract and upper gastrointestinal tract. The presence of particular symptoms is directly determined by a type of altered skin protein. Gastrointestinal manifestation of EB is most commonly reflected by esophageal stenosis due to recurrent esophageal blistering, followed by consequent scarring.

CASE PRESENTATION

Here we present a case of a man with dystrophic EB and dysphagia, skin blistering, joints contractures and missing nails. To our knowledge, the presented man is the oldest one diagnosed with EB living in Poland.

CONCLUSIONS

Management of an esophageal stricture in such circumstances is based on endoscopic dilatation. However, in most severe cases, placement of a gastrostomy tube is required. Despite great advances in medicine, a targeted therapy in the course of EB has not been established yet.

A multitask clustering approach for single-cell RNA-seq analysis in Recessive Dystrophic Epidermolysis Bullosa

Single-cell RNA sequencing (scRNA-seq) has been widely applied to discover new cell types by detecting sub-populations in a heterogeneous group of cells. Since scRNA-seq experiments have lower read coverage/tag counts and introduce more technical biases compared to bulk RNA-seq experiments, the limited number of sampled cells combined with the experimental biases and other dataset specific variations presents a challenge to cross-dataset analysis and discovery of relevant biological variations across multiple cell populations. In this paper, we introduce a method of variance-driven multitask clustering of single-cell RNA-seq data (scVDMC) that utilizes multiple single-cell populations from biological replicates or different samples. scVDMC clusters single cells in multiple scRNA-seq experiments of similar cell types and markers but varying expression patterns such that the scRNA-seq data are better integrated than typical pooled analyses which only increase the sample size. By controlling the variance among the cell clusters within each dataset and across all the datasets, scVDMC detects cell sub-populations in each individual experiment with shared cell-type markers but varying cluster centers among all the experiments. Applied to two real scRNA-seq datasets with several replicates and one large-scale droplet-based dataset on three patient samples, scVDMC more accurately detected cell populations and known cell markers than pooled clustering and other recently proposed scRNA-seq clustering methods. In the case study applied to in-house Recessive Dystrophic Epidermolysis Bullosa (RDEB) scRNA-seq data, scVDMC revealed several new cell types and unknown markers validated by flow cytometry. MATLAB/Octave code available at https://github.com/kuanglab/scVDMC.

scRNA-seq enables detailed profiling of heterogeneous cell populations and can be used to reveal lineage relationships or discover new cell types. In the literature, there has been little effort directed towards developing computational methods for cross-population transcriptome analysis of multiple single-cell populations. The cross-cell-population clustering problem is different from the traditional clustering problem because single-cell populations can be collected from different patients, different samples of a tissue, or different experimental replicates. The accompanying biological and technical variation tends to dominate the signals for clustering the pooled single cells from the multiple populations. In this work, we have developed a multitask clustering method to address the cross-population clustering problem. The method simultaneously clusters each individual cell population and controls variance among the cell-type cluster centers within each cell population and across the cell populations. We demonstrate that our multitask clustering method significantly improves clustering accuracy and marker discovery in three public scRNA-seq datasets and also apply the method to an in-house Recessive Dystrophic Epidermolysis Bullosa (RDEB) dataset. Our results make it evident that multitask clustering is a promising new approach for cross-population analysis of scRNA-seq data.

Inside out: regenerative medicine for recessive dystrophic epidermolysis bullosa

Epidermolysis bullosa is classified as a genodermatosis, an inherited genetic skin disorder that results in severe, chronic skin blistering with painful and life-threatening complications. Although there is currently no cure for epidermolysis bullosa, concurrent advances in gene and stem cell therapies are converging toward combinatorial therapies that hold the promise of clinically meaningful and lifelong improvement. Recent studies using hematopoietic stem cells and mesenchymal stromal/stem cells to treat epidermolysis bullosa have demonstrated the potential for sustained, effective management of the most severe cases. Furthermore, advances in the use of gene therapy and gene-editing techniques, coupled with the development of induced pluripotent stem cells from patients with epidermolysis bullosa, allow for autologous therapies derived from a renewable population of cells that are patient-specific. Here we describe emerging treatments for epidermolysis bullosa and other genodermatoses, along with a discussion of their benefits and limitations as effective therapies.

The Molecular Revolution in Cutaneous Biology: Emerging Landscape in Genomic Dermatology: New Mechanistic Ideas, Gene Editing, and Therapeutic Breakthroughs

Stunning technological advances in genomics have led to spectacular breakthroughs in the understanding of the underlying defects, biological pathways and therapeutic targets of skin diseases leading to new therapeutic interventions. Next-generation sequencing has revolutionized the identification of disease-causing genes and has a profound impact in deciphering gene and protein signatures in rare and frequent skin diseases. Gene addition strategies have shown efficacy in junctional EB and in recessive dystrophic EB (RDEB). TALENs and Cripsr/Cas9 have emerged as highly efficient new tools to edit genomic sequences to creat new models and to correct or disrupt mutated genes to treat human diseases. Therapeutic approaches have not been limited to DNA modification and strategies at the mRNA, protein and cellular levels have also emerged, some of which have already proven clinical efficacy in RDEB. Improved understanding of the pathogenesis of skin disorders has led to the development of specific drugs or repurposing of existing medicines as in basal cell nevus syndrome, alopecia areata, melanoma and EB simplex. These discoveries pave the way for improved targeted personalized medicine for rare and frequent diseases. It is likely that a growing number of orphan skin diseases will benefit from combinatory new therapies in a near future.

Targeted Exon Skipping Restores Type VII Collagen Expression and Anchoring Fibril Formation in an In Vivo RDEB Model

Dystrophic epidermolysis bullosa is a group of orphan genetic skin diseases dominantly or recessively inherited, caused by mutations in COL7A1 encoding type VII collagen, which forms anchoring fibrils. Individuals with recessive dystrophic epidermolysis bullosa develop severe skin and mucosal blistering after mild trauma. The exon skipping strategy consists of modulating splicing of a pre-mRNA to induce skipping of a mutated exon. We have targeted COL7A1 exons 73 and 80, which carry recurrent mutations and whose excision preserves the open reading frame. We first showed the dispensability of these exons for type VII collagen function in vivo. We then showed that transfection of primary recessive dystrophic epidermolysis bullosa keratinocytes and fibroblasts carrying null mutations in exon 73 and/or 80, with 2'-O-methyl antisense oligoribonucleotides, led to efficient ex vivo skipping of these exons (50-95%) and resulted in a significant level (up to 36%) of type VII collagen re-expression. Finally, one or two subcutaneous injections of antisense oligoribonucleotides at doses ranging from 400 μg up to 1 mg restored type VII collagen expression and anchoring fibril formation in vivo in a xenograft model of recessive dystrophic epidermolysis bullosa skin equivalent. This work provides a proof of principle for the treatment of patients with recessive dystrophic epidermolysis bullosa by exon skipping using subcutaneous administration of antisense oligoribonucleotides.