Epidermolysis bullosa: prospects for cell-based therapies

Assessment of the Timing of Milestone Clinical Events in Patients With Epidermolysis Bullosa From North America

Importance

Children with epidermolysis bullosa (EB) comprise a rare population with high morbidity and mortality. An improved understanding of the clinical trajectory of patients with EB, including age at time of clinical diagnosis and major clinical events, is needed to refine best practices and improve quality of life and clinical outcomes for patients with EB.

Objectives

To describe demographics, clinical characteristics, milestone diagnostic and clinical events (such as initial esophageal dilation), and outcomes in patients with EB using the Epidermolysis Bullosa Clinical Characterization and Outcomes Database and to determine what characteristics may be associated with overall EB severity and/or disease progression.

Design, Setting, and Participants

This cohort study included data on patients with EB who were enrolled in the Epidermolysis Bullosa Clinical Characterization and Outcomes Database from January 1, 2011, to June 30, 2017; 17 participating EB centers in the United States and Canada contributed data to this study.

Exposures

Type of EB, including recessive dystrophic epidermolysis bullosa (RDEB), junctional epidermolysis bullosa (JEB), dominant dystrophic epidermolysis bullosa (DDEB), and epidermolysis bullosa simplex (EBS).

Main Outcomes and Measures

Demographic information, clinical characteristics (including age at onset of signs of EB and subsequent clinical diagnosis), types of diagnostic testing performed, and milestone clinical events for patients with RDEB.

Results

Of 644 enrolled patients from 17 sites included in this study, 323 were male (50.2%), with a mean (SD) age of 14.4 (11.7) years; 283 (43.9%) had RDEB, 194 (30.1%) had EBS, 104 (16.2%) had DDEB, and 63 (9.8%) had JEB. Signs of disease were present at birth in 202 patients with RDEB (71.4%), 39 with JEB (61.9%), 60 with DDEB (57.7%), and 74 with EBS (38.1%). For those with signs of disease at birth, a clinical diagnosis was made at the time of birth in 135 patients with RDEB (67.0%), 31 with DDEB (52.6%), 35 with EBS, (47.3%) and 18 with JEB (46.2%). Patients with JEB had the highest rate of any confirmatory testing (51 of 63 [81.0%]), followed by RDEB (218 of 283 [77.0%]), DDEB (71 of 104 [68.3%]), and EBS (100 of 194 [51.5%]). For all types of EB, both electron microscopy and immunofluorescence microscopy were performed at younger ages than genetic analysis. Among 283 patients with RDEB, 157 (55.5%) had esophageal dilation, 104 (36.7%) had gastrostomy tube placement, 62 (21.9%) had hand surgery, 18 (6.4%) developed squamous cell carcinoma, and 19 (6.7%) died.

Conclusions and Relevance

The findings suggest that diagnostic testing for EB is more common for patients with severe phenotypes. Earlier diagnostic testing may enable improved characterizations of patients so that appropriate counseling and clinical care may be offered, especially pertaining to milestone events for those with RDEB.

Unraveling the ECM-Immune Cell Crosstalk in Skin Diseases

The extracellular matrix (ECM) is a complex network of proteins and proteoglycans secreted by keratinocytes, fibroblasts and immune cells. The function of the skin ECM has expanded from being a scaffold that provides structural integrity, to a more dynamic entity that is constantly remodeled to maintain tissue homeostasis. The ECM functions as ligands for cell surface receptors such as integrins, dystroglycans, and toll-like receptors (TLRs) and regulate cellular signaling and immune cell dynamics. The ECM also acts as a sink for growth factors and cytokines, providing critical cues during epithelial morphogenesis. Dysregulation in the organization and deposition of ECMs lead to a plethora of pathophysiological conditions that are exacerbated by aberrant ECM-immune cell interactions. In this review, we focus on the interplay between ECM and immune cells in the context of skin diseases and also discuss state of the art therapies that target the key molecular players involved.

Accelerated Wound Healing by Fibroblasts Differentiated from Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells in a Pressure Ulcer Animal Model

Fibroblasts synthesize and secrete dermal collagen, matrix proteins, growth factors, and cytokines. These characteristics of fibroblasts provide a potential way for fibroblast therapy to treat skin ulcers more effectively than conventional therapies such as cytokine therapy and negative pressure wound therapy. However, the obstacle to the commercialization of fibroblast therapy is the limited supply of cells with consistent quality. In this study, we tested whether human embryonic stem cell-derived mesenchymal stem cells (hESC-MSCs) could be differentiated into fibroblasts considering that they have characteristics of high differentiation rates, unlimited proliferation possibility from a single colony, and homogeneity. As a result, hESC-MSC-derived fibroblasts (hESC-MSC-Fbs) showed a significant increase in the expression of type I and III collagen, fibronectin, and fibroblast-specific protein-1 (FSP-1). Besides, vessel formation and wound healing were enhanced in hESC-MSC-Fb-treated skin tissues compared to PBS- or hESC-MSC-treated skin tissues, along with decreased IL-6 expression at 4 days after the formation of pressure ulcer wound in a mouse model. In view of the limited available cell sources for fibroblast therapy, hESC-MSC-Fbs show a promising potential as a commercial cell therapy source to treat skin ulcers.

Molecular pathology of the basement membrane zone in heritable blistering diseases:: The paradigm of epidermolysis bullosa

Epidermolysis bullosa (EB), a phenotypically heterogeneous group of skin fragility disorders, is characterized by blistering and erosions with considerable morbidity and mortality. Mutations in as many as 18 distinct genes expressed at the cutaneous basement membrane zone have been shown to be associated with the blistering phenotype, attesting to the role of the corresponding proteins in providing stable association of the epidermis to the dermis through adhesion at the dermo-epidermal basement membrane zone. Thus, different forms of EB have been highly instructive in providing information on the physiological functions of these proteins as integral components of the supramolecular adhesion complexes. In addition, precise information of the underlying genes and distinct mutations in families with EB has been helpful in subclassification of the disease with prognostic implications, as well as for prenatal testing and preimplantation genetic diagnosis. Furthermore, knowledge of the types of mutations is a prerequisite for application of allele-specific treatment approaches that have been recently developed, including read-through of premature termination codon mutations and chaperone-facilitated intracellular transport of conformationally altered proteins to proper physiologic subcellular location. Collectively, EB serves as a paradigm of heritable skin diseases in which significant progress has been made in identifying the underlying genetic bases and associated aberrant pathways leading from mutations to the phenotype, thus allowing application of precision medicine for this, currently intractable group of diseases.

Ultrasound mediated transdermal drug delivery

Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injections. However, the stratum corneum serves as a barrier that limits the penetration of substances to the skin. Application of ultrasound (US) irradiation to the skin increases its permeability (sonophoresis) and enables the delivery of various substances into and through the skin. This review presents the main findings in the field of sonophoresis in transdermal drug delivery as well as transdermal monitoring and the mathematical models associated with this field. Particular attention is paid to the proposed enhancement mechanisms and future trends in the fields of cutaneous vaccination and gene therapy.

Pompholyx: a review of clinical features, differential diagnosis, and management

Pompholyx is a vesicobullous disorder of the palms and soles. The condition is hard to treat because of the peculiarities of the affected skin, namely the thick horny layer and richness of the sweat glands. In this article, we review the available therapies, and score the treatments according to the level of evidence. The cornerstones of topical therapy are corticosteroids, although calcineurin inhibitors also seem to be effective. Topical photochemotherapy with methoxsalen (8-methoxypsoralen) is as effective as systemic photochemotherapy or high-dose UVA-1 irradiation. Systemic therapy is often necessary in bullous pompholyx. Corticosteroids are commonly used although no controlled study has been published to date. For recalcitrant cases, corticosteroids are combined with immunosuppressants. Alitretinoin has efficacy in chronic hand dermatitis including pompholyx. Another evolving treatment seems to be the intradermal injection of botulinum toxin. Radiotherapy might be an option for selected patients not responding to conventional treatment. In practice, patients benefit most from a combination of treatments.

Bone marrow stem cell therapy for recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe inherited blistering disease caused by mutations in the type VII collagen gene, resulting in defective anchoring fibrils at the epidermal-dermal junction. At present, no curative treatment for RDEB exists. Mounting evidence on reprogramming of bone marrow stem cells into skin has prompted the authors and others to develop novel strategies for treatment of RDEB. The rationale for bone marrow stem cell therapies for RDEB is based on the evidence that bone marrow-derived cells are guided into becoming skin cells, given the right microenvironment. Preclinical studies in mouse models have shown that wild-type bone marrow-derived cells can ameliorate the phenotype of RDEB and improve survival by restoring the expression of type VII collagen and the anchoring fibrils. At present, several clinical studies are ongoing around the world to study the therapeutic effects of bone marrow stem cell transplantation for RDEB. These studies provide a framework for future development of standardized, effective methods for stem cell transplantation to cure severe inherited skin diseases, including RDEB.

Fibroblast-based cell therapy strategy for recessive dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa (DEB) is a severe skin fragility disorder associated with trauma-induced blistering, progressive soft tissue scarring, and increased risk of skin cancer. DEB is caused by mutations in the COL7A1 gene which result in reduced, truncated, or absent type VII collagen, and anchoring fibrils at the dermal-epidermal junction (DEJ). Because no topical wound-healing agents have shown unequivocal benefit in the treatment of DEB, alternative approaches are needed. The purpose of cell therapy for recessive DEB is to increase the amount of collagen VII in the basement membrane zone in order to heal wounds and prevent further wound formation. Fibroblast-based cell therapy is safe and easy to work with, has few side effects, can dramatically restore stable collagen VII at the DEJ, and can normalize the substructure changes of DEB for at least a few months. Even though the mechanism and the duration of newly produced collagen VII at the DEJ are still unknown, this form of cell therapy provides a new effective approach to the treatment of recessive DEB.

Dystrophic epidermolysis bullosa: pathogenesis and clinical features

Dystrophic epidermolysis bullosa (DEB) is relatively well understood. Potential therapies are in development. This article describes the pathogenesis and clinical features of DEB. It also describes therapeutic options and the future of molecular therapies.

Molecular genetics of the skin: the implications of understanding

During recent decades, discoveries in genetic skin disease have produced insights into the biology of the skin, and in some cases permitted preventive prenatal diagnosis, but application of this knowledge in palliation or cure remains a tantalising prospect.

Progress in heritable skin diseases: translational implications of mutation analysis and prospects of molecular therapies*

Epidermolysis bullosa, a group of blistering disorders, serves as the paradigm of the tremendous progress made in understanding the molecular genetics of heritable skin diseases. Mutations in 10 distinct genes have been disclosed in the classic forms of epidermolysis bullosa, and the level of expression of the mutated genes within the cutaneous basement membrane zone, the types and combinations of mutations and their consequences at the mRNA and protein levels, when placed in the context of the individual's genetic background and exposure to environmental trauma, all determine the subtype and the phenotypic severity in each case. The translational implications of mutation analysis include improved diagnosis and subclassification, refined genetic counseling of families at risk, and development of DNA-based pre natal and preimplantation genetic diagnosis. The prospects of molecular therapies for epidermolysis bullosa include further development of strategies for gene therapy, protein replacement therapy and cell-based therapies, including stem cell therapy and bone marrow transfer. Collectively, advances in the molecular genetics of heritable skin diseases clearly emphasize the value of basic research for improved diagnostics and patient care for genetic skin diseases.

Mechanisms of fibroblast cell therapy for dystrophic epidermolysis bullosa: high stability of collagen VII favors long-term skin integrity

Here, we report on the first systematic long-term study of fibroblast therapy in a mouse model for recessive dystrophic epidermolysis bullosa (RDEB), a severe skin-blistering disorder caused by loss-of-function of collagen VII. Intradermal injection of wild-type (WT) fibroblasts in >50 mice increased the collagen VII content at the dermal-epidermal junction 3.5- to 4.7-fold. Although the active biosynthesis lasted <28 days, collagen VII remained stable and dramatically improved skin integrity and resistance to mechanical forces for at least 100 days, as measured with a digital 3D-skin sensor for shear forces. Experiments using species-specific antibodies, collagen VII-deficient fibroblasts, gene expression analyses, and cytokine arrays demonstrated that the injected fibroblasts are the major source of newly deposited collagen VII. Apart from transitory mild inflammation, no adverse effects were observed. The cells remained within an area Collapse

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MESH Headings

• Animals
• Animals, Newborn
• Blotting, Western
• Cell- and Tissue-Based Therapy/methods
• Cells, Cultured
• Collagen Type VII/metabolism
• Epidermolysis Bullosa Dystrophica/metabolism
• Epidermolysis Bullosa Dystrophica/pathology
• Epidermolysis Bullosa Dystrophica/therapy
• Fibroblasts/metabolism
• Fibroblasts/physiology
• Fibroblasts/ultrastructure
• Flow Cytometry
• Humans
• In Situ Nick-End Labeling
• Mice
• Mice, Transgenic
• Microscopy, Electron, Transmission
• Reverse Transcriptase Polymerase Chain Reaction
• Skin/metabolism
• Skin/pathology

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Affiliation(s)

Johannes S Kern Deparment of Dermatology, University Medical Center Freiburg, Freiburg, Germany
Stefan Loeckermann
Anja Fritsch
Ingrid Hausser
Wera Roth
Thomas M Magin
Claudia Mack
Marcel L Müller
Oliver Paul
Patrick Ruther
Leena Bruckner-Tuderman

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Collagens

The collagens represent a family of trimeric extracellular matrix molecules used by cells for structural integrity and other functions. The three alpha chains that form the triple helical part of the molecule are composed of repeating peptide triplets of glycine-X-Y. X and Y can be any amino acid but are often proline and hydroxyproline, respectively. Flanking the triple helical regions (i.e., Col domains) are non-glycine-X-Y regions, termed non-collagenous domains. These frequently contain recognizable peptide modules found in other matrix molecules. Proper tissue function depends on correctly assembled molecular aggregates being incorporated into the matrix. This review highlights some of the structural characteristics of collagen types I-XXVIII.

Connective tissue and related disorders and preterm birth: clues to genes contributing to prematurity

To identify candidate genes contributing to preterm birth, we examined the existing literature on the association between known disorders of connective tissue synthesis and metabolism and related diseases and prematurity. Our hypothesis was that abnormal matrix metabolism contributes to prematurity by increasing risk of preterm premature rupture of membranes (PPROM) and cervical incompetence. Based on this review, we identified gene mutations inherited by the fetus that could predispose to preterm birth as a result of PPROM. The responsible genes include COL5A1, COL5A2, COL3A1, COL1A1, COL1A2, TNXB, PLOD1, ADAMTS2, CRTAP, LEPRE1 and ZMPSTE24. Marfan syndrome, caused by FBN1 mutations, and polymorphisms in the COL1A1 and TGFB1 genes have been associated with cervical incompetence. We speculate that an analysis of sequence variation at the loci noted above will reveal polymorphisms that may contribute to susceptibility to PPROM and cervical incompetence in the general population.