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.

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.

Genetische Ursachen für epidermale Fragilität

Bei epidermaler Fragilität führen geringfügige Verletzungen zur Blasenbildung der Haut und der hautnahen Schleimhäute. Verantwortlich für die Fragilität sind Mutationen in Genen, die Proteine der epidermalen und dermo-epidermalen Adhäsion kodieren. Die meisten Erkrankungen werden in der Gruppe der Epidermolysis bullosa zusammengefasst und sind sowohl klinisch als auch genetisch heterogen. Bei Neugeborenen und Kleinkindern, aber auch bei vielen erwachsenen Patienten kann der Subtyp der Epidermolysis bullosa aufgrund des Phänotyps nicht diagnostiziert werden. Die genaue Diagnosestellung ist nur durch spezifische Laboruntersuchungen, wie das Immunfluoreszenzmapping, die Elektronenmikroskopie und die Mutationsanalyse möglich. Die Behandlung ist symptomatisch und basiert auf allgemeinem Wundmanagement, während bei den schweren Formen mit Multisystembeteiligung interdisziplinäre medizinische Betreuung notwendig ist. Die neuen Erkenntnisse über molekulare Grundlagen und Pathomechanismen der Epidermolysis bullosa ermöglichen die Entwicklung neuartiger molekularen Therapien.

Basement membranes and human disease

In 1990, the role of basement membranes in human disease was established by the identification of COL4A5 mutations in Alport's syndrome. Since then, the number of diseases caused by mutations in basement membrane components has steadily increased as has our understanding of the roles of basement membranes in organ development and function. However, many questions remain as to the molecular and cellular consequences of these mutations and the way in which they lead to the observed disease phenotypes. Despite this, exciting progress has recently been made with potential treatment options for some of these so far incurable diseases.

Dominant-negative effects of COL7A1 mutations can be rescued by controlled overexpression of normal collagen VII

Dominant-negative interference by glycine substitution mutations in the COL7A1 gene causes dominant dystrophic epidermolysis bullosa (DDEB), a skin fragility disorder with mechanically induced blistering. Although qualitative and quantitative alterations of the COL7A1 gene product, collagen VII, underlie DDEB, the lack of direct correlation between mutations and the clinical phenotype has rendered DDEB less amenable to therapeutic targeting. To delineate the molecular mechanisms of DDEB, we used recombinant expression of wild-type (WT) and mutant collagen VII, which contained a naturally occurring COL7A1 mutation, G1776R, G2006D, or G2015E, for characterization of the triple helical molecules. The mutants were co-expressed with WT in equal amounts and could form heterotrimeric hybrid triple helices, as demonstrated by affinity purification and mass spectrometry. The thermal stability of the mutant molecules was strongly decreased, as evident in their sensitivity to trypsin digestion. The helix-to-coil transition, T(m), of the mutant molecules was 31-34 degrees C, and of WT collagen VII 41 degrees C. Co-expression of WT with G1776R- or G2006D-collagen VII resulted in partial intracellular retention of the collagen, and mutant collagen VII had reduced ability to support cell adhesion. Intriguingly, controlled overexpression of WT collagen VII gradually improved the thermal stability of the collective of collagen VII molecules. Co-expression in a ratio of 90% WT:10% mutant increased the T(m) to 41 degrees C for G1776R-collagen VII and to 39 degrees C for G2006D- and G2015E-collagen VII. Therefore, increasing the expression of WT collagen VII in the skin of patients with DDEB can be considered a valid therapeutic approach.

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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[Epidermolysis bullosa. An update]

Epidermolysis bullosa (EB) represents a group of diseases characterized by skin fragility usually developing blisters after minimal trauma. The clinical picture ranges from mild subtypes with minor skin reactions to severe forms with lethal outcome within the first months of life. In the severe generalized subtypes, complications such as aggressive squamous cell carcinoma of the skin, anemia, esophageal stenosis and cardiomyopathy can occur so that multidisciplinary patient care is necessary. EB can be divided in four types--EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB) and Kindler syndrome. All together 33 subtypes can be distinguished. In 2008 a revised EB classification was introduced. Several eponyms for EB subtypes were replaced by descriptive names. The review presents the EB subtypes based on the new EB classification system, the molecular background and new therapeutic options.

Forty-two novel COL7A1 mutations and the role of a frequent single nucleotide polymorphism in the MMP1 promoter in modulation of disease severity in a large European dystrophic epidermolysis bullosa cohort

BACKGROUND

Dystrophic epidermolysis bullosa (DEB) is a severe genetic skin blistering disorder caused by mutations in the gene COL7A1, encoding collagen VII. Recently, the MMP1 promoter single nucleotide polymorphism (SNP) rs1799750, designated as 1G 2G, was shown to be involved in modulation of disease severity in patients with recessive DEB (RDEB), and was proposed as a genetic modifier.

OBJECTIVES

To identify the molecular basis of DEB in 103 individuals and to replicate the results of the MMP1 promoter SNP analysis in an independent patient group, as verification is necessary in such a rare and heterogeneous disorder.

METHODS

To determine the molecular basis of the disease, we performed COL7A1 mutation screening, reverse transcription-polymerase chain reaction (PCR) and real-time quantitative PCR. The status of the MMP1 SNP was analysed by PCR and restriction enzyme digestion and verified by sequencing.

RESULTS

We disclosed 42 novel COL7A1 mutations, including the first large genomic deletion of 4 kb affecting only the COL7A1 gene, and three apparently silent mutations affecting splicing. Even though the frequency of the high-risk allele was increased in patients with RDEB, no statistically significant correlation between disease severity and genotype could be made. Also, no correlation was observed with development of squamous cell carcinoma, a severe complication of DEB.

CONCLUSIONS

Taken together, the results suggest that the MMP1 SNP is not the sole disease modifier in different forms of DEB, and other genetic and environmental factors contribute to the clinical phenotype.