Intradermal injection of lentiviral vectors corrects regenerated human dystrophic epidermolysis bullosa skin tissue in vivo

Hypoxia and Foxn1 alter the proteomic signature of dermal fibroblasts to redirect scarless wound healing to scar-forming skin wound healing in Foxn1-/- mice

BACKGROUND

Foxn1-/- deficient mice are a rare model of regenerative skin wound healing among mammals. In wounded skin, the transcription factor Foxn1 interacting with hypoxia-regulated factors affects re-epithelialization, epithelial-mesenchymal transition (EMT) and dermal white adipose tissue (dWAT) reestablishment and is thus a factor regulating scar-forming/reparative healing. Here, we hypothesized that transcriptional crosstalk between Foxn1 and Hif-1α controls the switch from scarless (regenerative) to scar-present (reparative) skin wound healing. To verify this hypothesis, we examined (i) the effect of hypoxia/normoxia and Foxn1 signalling on the proteomic signature of Foxn1-/- (regenerative) dermal fibroblasts (DFs) and then (ii) explored the effect of Hif-1α or Foxn1/Hif-1α introduced by a lentiviral (LV) delivery vector to injured skin of regenerative Foxn1-/- mice with particular attention to the remodelling phase of healing.

RESULTS

We showed that hypoxic conditions and Foxn1 stimulation modified the proteome of Foxn1-/- DFs. Hypoxic conditions upregulated DF protein profiles, particularly those related to extracellular matrix (ECM) composition: plasminogen activator inhibitor-1 (Pai-1), Sdc4, Plod2, Plod1, Lox, Loxl2, Itga2, Vldlr, Ftl1, Vegfa, Hmox1, Fth1, and F3. We found that Pai-1 was stimulated by hypoxic conditions in regenerative Foxn1-/- DFs but was released by DFs to the culture media exclusively upon hypoxia and Foxn1 stimulation. We also found higher levels of Pai-1 protein in DFs isolated from Foxn1+/+ mice (reparative/scar-forming) than in DFs isolated from Foxn1-/- (regenerative/scarless) mice and triggered by injury increase in Foxn1 and Pai-1 protein in the skin of mice with active Foxn1 (Foxn1+/+ mice). Then, we demonstrated that the introduction of Foxn1 and Hif-1α via lentiviral injection into the wounded skin of regenerative Foxn1-/- mice activates reparative/scar-forming healing by increasing the wounded skin area and decreasing hyaluronic acid deposition and the collagen type III to I ratio. We also identified a stimulatory effect of LV-Foxn1 + LV-Hif-1α injection in the wounded skin of Foxn1-/- mice on Pai-1 protein levels.

CONCLUSIONS

The present data highlight the effect of hypoxia and Foxn1 on the protein profile and functionality of regenerative Foxn1-/- DFs and demonstrate that the introduction of Foxn1 and Hif-1α into the wounded skin of regenerative Foxn1-/- mice activates reparative/scar-forming healing.

ALKBH5-mediated m6A demethylation fuels cutaneous wound re-epithelialization by enhancing PELI2 mRNA stability

BACKGROUND

Impaired wound re-epithelialization contributes to cutaneous barrier reconstruction dysfunction. Recently, N⁶-methyladenosine (m⁶A) RNA modification has been shown to participate in the determination of RNA fate, and its aberration triggers the pathogenesis of numerous diseases. Howbeit, the function of m⁶A in wound re-epithelialization remains enigmatic.

METHODS

Alkbh5^‒/‒ mouse was constructed to study the rate of wound re-epithelialization after ALKBH5 ablation. Integrated high-throughput analysis combining methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-seq was used to identify the downstream target of ALKBH5. In vitro and in vivo rescue experiments were conducted to verify the role of the downstream target on the functional phenotype of ALKBH5-deficient cells or animals. Furthermore, the interacting reader protein and regulatory mechanisms were determined through RIP-qPCR, RNA pull-down, and RNA stability assays.

RESULTS

ALKBH5 was specifically upregulated in the wound edge epidermis. Ablation of ALKBH5 suppressed keratinocyte migration and resulted in delayed wound re-epithelialization in Alkbh5^‒/‒ mouse. Integrated high-throughput analysis revealed that PELI2, an E3 ubiquitin protein ligase, serves as the downstream target of ALKBH5. Concordantly, exogenous PELI2 supplementation partially rescued keratinocyte migration and accelerated re-epithelialization in ALKBH5-deficient cells, both in vitro and in vivo. In terms of its mechanism, ALKBH5 promoted PELI2 expression by removing the m⁶A modification from PELI2 mRNA and enhancing its stability in a YTHDF2-dependent manner.

CONCLUSIONS

This study identifies ALKBH5 as an endogenous accelerator of wound re-epithelialization, thereby benefiting the development of a reprogrammed m⁶A targeted therapy for refractory wounds.

5'RNA Trans-Splicing Repair of COL7A1 Mutant Transcripts in Epidermolysis Bullosa

Mutations within the COL7A1 gene underlie the inherited recessive subtype of the blistering skin disease dystrophic epidermolysis bullosa (RDEB). Although gene replacement approaches for genodermatoses are clinically advanced, their implementation for RDEB is challenging and requires endogenous regulation of transgene expression. Thus, we are using spliceosome-mediated RNA trans-splicing (SMaRT) to repair mutations in COL7A1 at the mRNA level. Here, we demonstrate the capability of a COL7A1-specific RNA trans-splicing molecule (RTM), initially selected using a fluorescence-based screening procedure, to accurately replace COL7A1 exons 1 to 64 in an endogenous setting. Retroviral RTM transduction into patient-derived, immortalized keratinocytes resulted in an increase in wild-type transcript and protein levels, respectively. Furthermore, we revealed accurate deposition of recovered type VII collagen protein within the basement membrane zone of expanded skin equivalents using immunofluorescence staining. In summary, we showed for the first time the potential of endogenous 5′ trans-splicing to correct pathogenic mutations within the COL7A1 gene. Therefore, we consider 5′ RNA trans-splicing a suitable tool to beneficially modulate the RDEB-phenotype, thus targeting an urgent need of this patient population.

Dermal White Adipose Tissue (dWAT) Is Regulated by Foxn1 and Hif-1α during the Early Phase of Skin Wound Healing

Dermal white adipose tissue (dWAT) is involved in the maintenance of skin homeostasis. However, the studies concerning its molecular regulation are limited. In the present paper, we ask whether the introduction of two transcription factors, Foxn1 and Hif-1α, into the post-wounded skin of Foxn1-/- mice regulates dWAT during wound healing (days 3 and 6). We have chosen lentivirus vectors (LVs) as a tool to deliver Foxn1 and Hif-1α into the post-wounded skin. We documented that combinations of both transgenes reduces the number, size and diameter of dermal adipocytes at the wound bed area. The qRT-PCR analysis of pro-adipogenic genes, revealed that LV-Hif-1α alone, or combined with LV-Foxn1, increases the mRNA expression of Pparγ, Glut 4 and Fasn at post-wounding day 6. However, the most spectacular stimulatory effect of Foxn1 and/or Hif-1α was observed for Igf2, the growth factor participating in adipogenic signal transduction. Our data also shows that Foxn1/Hif-1α, at post-wounding day 3, reduces levels of CD68 and MIP-1γ mRNA expression and the percentage of CD68 positive cells in the wound site. In conclusion, the present data are the first to document that Foxn1 and Hif-1α cooperatively (1) regulate dWAT during the proliferative phase of skin wound healing through the Igf2 signaling pathway, and (2) reduce the macrophages content in the wound site.

The potential of gene therapy for recessive dystrophic epidermolysis bullosa

Epidermolysis bullosa (EB) encompasses a heterogeneous group of inherited skin fragility disorders with mutations in genes encoding the basement membrane zone (BMZ) proteins that normally ensure dermal-epidermal integrity. Of the four main EB types, recessive dystrophic EB (RDEB), especially the severe variant, represents one of the most debilitating clinical entities with recurrent mucocutaneous blistering and ulceration leading to chronic wounds, infections, inflammation, scarring and ultimately cutaneous squamous cell carcinoma, which leads to premature death. Improved understanding of the molecular genetics of EB over the past three decades and advances in biotechnology has led to rapid progress in developing gene and cell-based regenerative therapies for EB. In particular, RDEB is at the vanguard of advances in human clinical trials of advanced therapeutics. Furthermore, the past decade has witnessed the emergence of a real collective, global effort involving academia and industry, supported by international EB patient organisations such as the Dystrophic Epidermolysis Bullosa Research Association (DEBRA), amongst others, to develop clinically relevant and marketable targeted therapeutics for EB. Thus, there is an increasing need for the practising dermatologist to become familiar with the concept of gene therapy, fundamental differences between various approaches and their human applications. This review explains the principles of different approaches of gene therapy; summarises its journey and discusses its current and future impact in RDEB.

Future Perspectives of Oral Delivery of Next Generation Therapies for Treatment of Skin Diseases

Gene therapies have conspicuously bloomed in recent years as evidenced by the increasing number of cell-, gene-, and oligo-based approved therapies. These therapies hold great promise for dermatological disorders with high unmet need, for example, epidermolysis bullosa or pachyonychia congenita. Furthermore, the recent clinical success of clustered regularly interspaced short palindromic repeats (CRISPR) for genome editing in humans will undoubtedly contribute to defining a new wave of therapies. Like biologics, naked nucleic acids are denatured inside the gastrointestinal tract and need to be administered via injections. For a treatment to be effective, a sufficient amount of a given regimen needs to reach systemic circulation. Multiple companies are racing to develop novel oral drug delivery approaches to circumvent the proteolytic and acidic milieu of the gastrointestinal tract. In this review, we provide an overview of the evolution of the gene therapy landscape, with a deep focus on gene and oligonucleotide therapies in clinical trials aimed at treating skin diseases. We then examine the progress made in drug delivery, with particular attention on the peptide field and drug-device combinations that deliver macromolecules into the gastrointestinal tract. Such novel devices could potentially be applied to administer other therapeutics including genes and CRISPR-based systems.

Highly branched poly(β-amino ester)s for gene delivery in hereditary skin diseases

Non-viral gene therapy for hereditary skin diseases is an attractive prospect. However, research efforts dedicated to this area are rare. Taking advantage of the branched structural possibilities of polymeric vectors, we have developed a gene delivery platform for the treatment of an incurable monogenic skin disease - recessive dystrophic epidermolysis bullosa (RDEB) - based on highly branched poly(β-amino ester)s (HPAEs). The screening of HPAEs and optimization of therapeutic gene constructs, together with evaluation of the combined system for gene transfection, were comprehensively reviewed. The successful restoration of type VII collagen (C7) expression both in vitro and in vivo highlights HPAEs as a promising generation of polymeric vectors for RDEB gene therapy into the clinic. Considering that the treatment of patients with genetic cutaneous disorders, such as other subtypes of epidermolysis bullosa, pachyonychia congenita, ichthyosis and Netherton syndrome, remains challenging, the success of HPAEs in RDEB treatment indicates that the development of viable polymeric gene delivery vectors could potentially expedite the translation of gene therapy for these diseases from bench to bedside.

Gene Therapy and its Application in Dermatology

Gene therapy is an experimental technique to treat genetic diseases. It is based on the introduction of nucleic acid with the help of a vector, into a diseased cell or tissue, to correct the gene expression and thus prevent, halt, or reverse a pathological process. It is a promising treatment approach for genetic diseases, inherited diseases, vaccination, cancer, immunomodulation, as well as healing of some refractory ulcers. Both viral and nonviral vectors can be used to deliver the correct gene. An ideal vector should have the ability for sustained gene expression, acceptable coding capacity, high transduction efficiency, and devoid of mutagenicity. There are different techniques of vector delivery, but these techniques are still under research for assessment of their safety and effectiveness. The major challenges of gene therapy are immunogenicity, mutagenicity, and lack of sustainable therapeutic benefit. Despite these constraints, therapeutic success was obtained in a few genetic and inherited skin diseases. Skin being the largest, superficial, easily accessible and assessable organ of the body, may be a promising target for gene therapy research in the recent future.

Toward Combined Cell and Gene Therapy for Genodermatoses

To date, more than 200 monogenic, often devastating, skin diseases have been described. Because of unmet medical needs, development of long-lasting and curative therapies has been consistently attempted, with the aim of correcting the underlying molecular defect. In this review, we will specifically address the few combined cell and gene therapy strategies that made it to the clinics. Based on these studies, what can be envisioned for the future is a patient-oriented strategy, built on the specific features of the individual in need. Most likely, a combination of different strategies, approaches, and advanced therapies will be required to reach the finish line at the end of the long and winding road hampering the achievement of definitive treatments for genodermatoses.

Tissue Transparency In Vivo

In vivo tissue transparency in the visible light spectrum is beneficial for many research applications that use optical methods, whether it involves in vivo optical imaging of cells or their activity, or optical intervention to affect cells or their activity deep inside tissues, such as brain tissue. The classical view is that a tissue is transparent if it neither absorbs nor scatters light, and thus absorption and scattering are the key elements to be controlled to reach the necessary transparency. This review focuses on the latest genetic and chemical approaches for the decoloration of tissue pigments to reduce visible light absorption and the methods to reduce scattering in live tissues. We also discuss the possible molecules involved in transparency.

Gene Therapy for Epidermolysis Bullosa

Epidermolysis bullosa is a family of diseases characterized by blistering and fragility of the skin in response to mechanical trauma. Advances in our understanding of epidermolysis bullosa pathophysiology have provided the necessary foundation for the first clinical trials of gene therapy for junctional and dystrophic epidermolysis bullosa. These therapies show that gene therapy is both safe and effective, with the potential to correct the molecular and clinical phenotype of patients with epidermolysis bullosa. Improvements in gene delivery and in preventing immune reactions will be among the challenges that lie ahead during further therapeutic development.

Patent landscape of molecular and cellular targeted therapies for recessive dystrophic epidermolysis bullosa

INTRODUCTION

Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a monogenetic inherited genodermatosis associated with deleterious mutations in the gene encoding type VII collagen (COL7A1). COL7A1 is essential for promoting attachment of the epidermis to the dermis, and its dysfunction may lead to generalized mucosal and cutaneous blistering associated to severe deformities. Currently, management of RDEB patients is limited to supportive care, being aimed at treating and preventing common complications associated with this condition. There is a great demand to develop targeted therapies for this devastating disease and RDEB research advances are currently being translated into clinical trials.

AREAS COVERED

Based on the literature and patent search, the authors have grouped the RDEB targeted therapies into five categories: a) cell-based therapies; b) gene therapy; c) protein replacement therapy; d) molecular therapy based on exon skipping; and e) drug-mediated premature termination codon read-through. The patent searching strategy involved inquiring Google and USPTO patent databases to reveal companies and institutions that are active in the area of RDEB targeted therapies.

EXPERT OPINION

The patent landscape related to targeted therapies for RDEB is quite heterogeneous, with each targeted therapeutic approach being associated with its own challenges in achieving robust patent protection and identifying opportunities for future development.

Gentamicin induces functional type VII collagen in recessive dystrophic epidermolysis bullosa patients

BACKGROUND

Recessive dystrophic epidermolysis bullosa (RDEB) is an incurable disease caused by mutations in the gene encoding type VII collagen, the major component of anchoring fibrils (AF). We previously demonstrated that gentamicin produced functional type VII collagen in RDEB cells harboring nonsense mutations. Herein, we determined whether topical or intradermal gentamicin administration induces type VII collagen and AFs in RDEB patients.

METHODS

A double-blind, placebo-controlled pilot trial assessed safety and efficacy of topical and intradermal gentamicin in 5 RDEB patients with nonsense mutations. The topical arm tested 0.1% gentamicin ointment or placebo application 3 times daily at 2 open erosion sites for 2 weeks. The intradermal arm tested daily intradermal injection of gentamicin solution (8 mg) or placebo into 2 intact skin sites for 2 days in 4 of 5 patients. Primary outcomes were induction of type VII collagen and AFs at the test sites and safety assessment. A secondary outcome assessed wound closure of topically treated erosions.

RESULTS

Both topical and intradermal gentamicin administration induced type VII collagen and AFs at the dermal-epidermal junction of treatment sites. Newly created type VII collagen varied from 20% to 165% of that expressed in normal human skin and persisted for 3 months. Topical gentamicin corrected dermal-epidermal separation, improved wound closure, and reduced blister formation. There were no untoward side effects from gentamicin treatments. Type VII collagen induction did not generate anti-type VII collagen autoantibodies in patients' blood or skin.

CONCLUSION

Topical and intradermal gentamicin suppresses nonsense mutations and induces type VII collagen and AFs in RDEB patients. Gentamicin therapy may provide a readily available treatment for RDEB patients with nonsense mutations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02698735.

FUNDING

Epidermolysis Bullosa Research Partnership, Epidermolysis Bullosa Medical Research Foundation, NIH, and VA Merit Award.

Novel and emerging therapies in the treatment of recessive dystrophic epidermolysis bullosa

Epidermolysis bullosa (EB) is a clinically and genetically heterogeneous group of inherited blistering diseases that affects ∼ 500,000 people worldwide. Clinically, individuals with EB have fragile skin and are susceptible to blistering following minimal trauma, with mucous membrane and other organ involvement in some subtypes. Within the spectrum of EB, ∼ 5% of affected individuals have the clinically more severe recessive dystrophic (RDEB) variant with a prevalence of 8 per one million of the population. RDEB is caused by loss-of-function mutations in the type VII collagen gene, COL7A1, which leads to reduced or absent type VII collagen (C7) and a paucity of structurally effective anchoring fibrils at the dermal-epidermal junction (DEJ). Currently, there is no cure for RDEB, although considerable progress has been made in testing novel treatments including gene therapy (lentiviral and gamma retroviral vectors for COL7A1 supplementation in keratinocytes and fibroblasts), as well as cell therapy (use of allogeneic fibroblasts, mesenchymal stromal cells (MSCs), and bone marrow transplantation (BMT)). Here, we review current treatment modalities available as well as novel and emerging therapies in the treatment of RDEB. Clinical trials of new translational therapies in RDEB offer hope for improved clinical management of patients as well as generating broader lessons for regenerative medicine that could be applicable to other inherited or acquired abnormalities of wound healing or scarring.

A knot polymer mediated non-viral gene transfection for skin cells

A knot polymer, poly[bis(2-acryloyl)oxyethyl disulphide-co-2-(dimethylamino) ethyl methacrylate] (DSP), was synthesized, optimized and evaluated as a non-viral vector for gene transfection for skin cells, keratinocytes. With recessive dystrophic epidermolysis bullosa keratinocytes (RDEBK-TA4), the DSP exhibited high transfection efficacy with both Gaussia luciferase marker DNA and the full length COL7A1 transcript encoding the therapeutic type VII collagen protein (C7). The effective restoration of C7 in C7 null-RDEB skin cells indicates that DSP is promising for non-viral gene therapy of recessive dystrophic epidermolysis bullosa (RDEB).

CRISPR/Cas9-based genetic correction for recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe disorder caused by mutations to the COL7A1 gene that deactivate production of a structural protein essential for skin integrity. Haematopoietic cell transplantation can ameliorate some of the symptoms; however, significant side effects from the allogeneic transplant procedure can occur and unresponsive areas of blistering persist. Therefore, we employed genome editing in patient-derived cells to create an autologous platform for multilineage engineering of therapeutic cell types. The clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 system facilitated correction of an RDEB-causing COL7A1 mutation in primary fibroblasts that were then used to derive induced pluripotent stem cells (iPSCs). The resulting iPSCs were subsequently re-differentiated into keratinocytes, mesenchymal stem cells (MSCs) and haematopoietic progenitor cells using defined differentiation strategies. Gene-corrected keratinocytes exhibited characteristic epithelial morphology and expressed keratinocyte-specific genes and transcription factors. iPSC-derived MSCs exhibited a spindle morphology and expression of CD73, CD90 and CD105 with the ability to undergo adipogenic, chondrogenic and osteogenic differentiation in vitro in a manner indistinguishable from bone marrow-derived MSCs. Finally, we used a vascular induction strategy to generate potent definitive haematopoietic progenitors capable of multilineage differentiation in methylcellulose-based assays. In totality, we have shown that CRISPR/Cas9 is an adaptable gene-editing strategy that can be coupled with iPSC technology to produce multiple gene-corrected autologous cell types with therapeutic potential for RDEB.

Lentiviral Engineered Fibroblasts Expressing Codon-Optimized COL7A1 Restore Anchoring Fibrils in RDEB

Cells therapies, engineered to secrete replacement proteins, are being developed to ameliorate otherwise debilitating diseases. Recessive dystrophic epidermolysis bullosa (RDEB) is caused by defects of type VII collagen, a protein essential for anchoring fibril formation at the dermal-epidermal junction. Whereas allogeneic fibroblasts injected directly into the dermis can mediate transient disease modulation, autologous gene-modified fibroblasts should evade immunological rejection and support sustained delivery of type VII collagen at the dermal-epidermal junction. We demonstrate the feasibility of such an approach using a therapeutic grade, self-inactivating-lentiviral vector, encoding codon-optimized COL7A1, to transduce RDEB fibroblasts under conditions suitable for clinical application. Expression and secretion of type VII collagen was confirmed with transduced cells exhibiting supranormal levels of protein expression, and ex vivo migration of fibroblasts was restored in functional assays. Gene-modified RDEB fibroblasts also deposited type VII collagen at the dermal-epidermal junction of human RDEB skin xenografts placed on NOD-scid IL2Rgamma(null) recipients, with reconstruction of human epidermal structure and regeneration of anchoring fibrils at the dermal-epidermal junction. Fibroblast-mediated restoration of protein and structural defects in this RDEB model strongly supports proposed therapeutic applications in man.

Gene editing toward the use of autologous therapies in recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a disease caused by mutations in the COL7A1 gene that result in absent or dysfunctional type VII collagen protein production. Clinically, RDEB manifests as early and severe chronic cutaneous blistering, damage to internal epithelium, an increased risk for squamous cell carcinoma, and an overall reduced life expectancy. Recent localized and systemic treatments have shown promise for lessening the disease severity in RDEB, but the concept of ex vivo therapy would allow a patient's own cells to be engineered to express functional type VII collagen. Here, we review gene delivery and editing platforms and their application toward the development of next-generation treatments designed to correct the causative genetic defects of RDEB.

Intravenously Administered Recombinant Human Type VII Collagen Derived from Chinese Hamster Ovary Cells Reverses the Disease Phenotype in Recessive Dystrophic Epidermolysis Bullosa Mice

Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited disorder characterized by skin fragility, blistering, and multiple skin wounds with no currently approved or consistently effective treatment. It is due to mutations in the gene encoding type VII collagen (C7). Using recombinant human C7 (rhC7) purified from human dermal fibroblasts (FB-rhC7), we showed previously that intravenously injected rhC7 distributed to engrafted RDEB skin, incorporated into its dermal-epidermal junction (DEJ), and reversed the RDEB disease phenotype. Human dermal fibroblasts, however, are not used for commercial production of therapeutic proteins. Therefore, we generated rhC7 from Chinese hamster ovary (CHO) cells. The CHO-derived recombinant type VII collagen (CHO-rhC7), similar to FB-rhC7, was secreted as a correctly folded, disulfide-bonded, helical trimer resistant to protease degradation. CHO-rhC7 bound to fibronectin and promoted human keratinocyte migration in vitro. A single dose of CHO-rhC7, administered intravenously into new-born C7-null RDEB mice, incorporated into the DEJ of multiple skin sites, tongue and esophagus, restored anchoring fibrils, improved dermal-epidermal adherence, and increased the animals' life span. Furthermore, no circulating or tissue-bound anti-C7 antibodies were observed in the mice. These data demonstrate the efficacy of CHO-rhC7 in a preclinical murine model of RDEB.

Downregulation of TNIP1 Expression Leads to Increased Proliferation of Human Keratinocytes and Severer Psoriasis-Like Conditions in an Imiquimod-Induced Mouse Model of Dermatitis

Psoriasis is a chronic, inflammatory skin disease involving both environmental and genetic factors. According to genome-wide association studies (GWAS), the TNIP1 gene, which encodes the TNF-α–induced protein 3-interacting protein 1 (TNIP1), is strongly linked to the susceptibility of psoriasis. TNIP1 is a widely expressed ubiquitin sensor that binds to the ubiquitin-editing protein A20 and restricts TNF- and TLR-induced signals. In our study, TNIP1 expression decreased in specimens of epidermis affected by psoriasis. Based on previous studies suggesting a role for TNIP1 in modulating cancer cell growth, we investigated its role in keratinocyte proliferation, which is clearly abnormal in psoriasis. To mimic the downregulation or upregulation of TNIP1 in HaCaT cells and primary human keratinocytes (PHKs), we used a TNIP1 specific small interfering hairpin RNA (TNIP1 shRNA) lentiviral vector or a recombinant TNIP1 (rTNIP1) lentiviral vector, respectively. Blocking TNIP1 expression increased keratinocyte proliferation, while overexpression of TNIP1 decreased keratinocyte proliferation. Furthermore, we showed that TNIP1 signaling might involve extracellular signal-regulated kinase1/2 (Erk1/2) and CCAAT/enhancer-binding protein β (C/EBPβ) activity. Intradermal injection of TNIP1 shRNA in BALB/c mice led to exaggerated psoriatic conditions in imiquimod (IMQ)-induced psoriasis-like dermatitis. These findings indicate that TNIP1 has a protective role in psoriasis and therefore could be a promising therapeutic target.

Modern methods of the treatment of hereditary epidermolysis bullosa

Today there are no ethiopathogenetic treatment methods for treating hereditary epidermolysis bullosa. All available treatment methods are symptomatic and are mainly aimed at patient care. Since severe forms of hereditary epidermolysis bullosa affect multiple organs, patients need assistance of both dermatologists and skilled experts such as general practitioners (pediatricians), gastroenterologists and dentists or ophthalmologists, surgeons, hematologists, oncologists, etc. when needed. To take efficient therapeutic and preventive measures, clinical recommendations and treatment standards are needed. Promising therapeutic methods (protein replacement, cell and gene techniques) are currently at different development and implementation stages but they can solve problems related to the treatment of hereditary epidermolysis bullosa in the future.

Gene therapy: pursuing restoration of dermal adhesion in recessive dystrophic epidermolysis bullosa

The replacement of a defective gene with a fully functional copy is the goal of the most basic gene therapy. Recessive dystrophic epidermolysis bullosa (RDEB) is characterised by a lack of adhesion of the epidermis to the dermis. It is an ideal target for gene therapy as all variants of hereditary RDEB are caused by mutations in a single gene, COL7A1, coding for type VII collagen, a key component of anchoring fibrils that secure attachment of the epidermis to the dermis. RDEB is one of the most severe variants in the epidermolysis bullosa (EB) group of heritable skin diseases. Epidermolysis bullosa is defined by chronic fragility and blistering of the skin and mucous membranes due to mutations in the genes responsible for production of the basement membrane proteins. This condition has a high personal, medical and socio-economic impact. People with RDEB require a broad spectrum of medications and specialised care. Due to this being a systemic condition, most research focus is in the area of gene therapy. Recently, preclinical works have begun to show promise. They focus on the virally mediated ex vivo correction of autologous epithelium. These corrected cells are then to be expanded and grafted onto the patient following the lead of the first successful gene therapy in dermatology being a grafting of corrected tissue for junctional EB treatment. Current progress, outstanding challenges and future directions in translating these approaches in clinics are reviewed in this article.

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.

Gene therapy for skin diseases

The skin possesses qualities that make it desirable for gene therapy, and studies have focused on gene therapy for multiple cutaneous diseases. Gene therapy uses a vector to introduce genetic material into cells to alter gene expression, negating a pathological process. This can be accomplished with a variety of viral vectors or nonviral administrations. Although results are promising, there are several potential pitfalls that must be addressed to improve the safety profile to make gene therapy widely available clinically.

Allogeneic blood and bone marrow cells for the treatment of severe epidermolysis bullosa: repair of the extracellular matrix

Contrary to the prevailing professional opinion of the past few decades, recent experimental and clinical data support the fact that protein replacement therapy by allogeneic blood and marrow transplantation is not limited to freely diffusible molecules such as enzymes, but also large structural proteins such as collagens. A prime example is the cross-correction of type VII collagen deficiency in generalised severe recessive dystrophic epidermolysis bullosa, in which blood and marrow transplantation can attenuate the mucocutaneous manifestations of the disease and improve patients' quality of life. Although allogeneic blood and marrow transplantation can improve the integrity of the skin and mucous membranes, today's accomplishments are only the first steps on the long pathway to cure. Future strategies will be built on the lessons learned from these first transplant studies.

One goal, different strategies--molecular and cellular approaches for the treatment of inherited skin fragility disorders

Epidermolysis bullosa (EB) is a heterogeneous group of inherited diseases characterized by the formation of blisters in the skin and mucosa. There is no cure or effective treatment for these potentially severe and fatal diseases. Over the past few years, several reports have proposed different molecular strategies as new therapeutic options for the management of EB. From classical vector-based gene therapy to cell-based strategies such as systemic application of bone marrow stem cells or local application of fibroblasts, a broad range of molecular approaches have been explored. This array also includes novel methods, such as protein replacement therapy, gene silencing and the use of induced pluripotent stem cells (iPCs). In this review, we summarize current concepts of how inherited blistering diseases might be treated in the future and discuss the opportunities, promises, concerns and risks of these innovative approaches.

A reporter-based screen to identify potent 3' trans-splicing molecules for endogenous RNA repair

In the treatment of genetic disorders, repairing defective pre-mRNAs by RNA trans-splicing has become an emerging alternative to conventional gene therapy. Previous studies have made clear that the design of the binding domains of the corrective RNA trans-splicing molecules (RTMs) is crucial for their optimal functionality. We established a reporter-based screening method that allows for selection of highly functional RTMs from a large pool of variants. The efficiency and functionality of the screen were validated in the COL7A1 gene, in which mutations are the cause of the skin disease dystrophic epidermolysis bullosa. Comparison of RTMs containing different binding domains hybridizing to COL7A1 intron 64/exon 65 revealed highly different trans-splicing efficiencies. Isolated RTMs were then adapted for endogenous trans-splicing in a recessive dystrophic epidermolysis bullosa (RDEB) keratinocyte cell line expressing reduced levels of COL7A1 mRNA. Our results confirm the applicability and relevance of prescreening reporter RTMs, as significant levels of endogenous COL7A1 mRNA repair were seen with RTMs identified as being highly efficient in our screening system.

Topical application of recombinant type VII collagen incorporates into the dermal-epidermal junction and promotes wound closure

Patients with recessive dystrophic epidermolysis bullosa (RDEB) have incurable skin fragility, blistering, and skin wounds due to mutations in the gene that codes for type VII collagen (C7) that mediates dermal-epidermal adherence in human skin. In this study, we evaluated if topically applied human recombinant C7 (rC7) could restore C7 at the dermal-epidermal junction (DEJ) and enhance wound healing. We found that rC7 applied topically onto murine skin wounds stably incorporated into the newly formed DEJ of healed wounds and accelerated wound closure by increasing re-epithelialization. Topical rC7 decreased the expression of fibrogenic transforming growth factor-β2 (TGF-β2) and increased the expression of anti-fibrogenic TGF-β3. These were accompanied by the reduced expression of connective tissue growth factor, fewer α smooth muscle actin (α-SMA)-positive myofibroblasts, and less deposition of collagen in the healed neodermis, consistent with less scar formation. In addition, using a mouse model in which skin from C7 knock out mice was grafted onto immunodeficient mice, we showed that applying rC7 onto RDEB grafts with wounds restored C7 and anchoring fibrils (AFs) at the DEJ of the grafts and corrected the dermal-epidermal separation. The topical application of rC7 may be useful for treating patients with RDEB and patients who have chronic skin wounds.

Management of severe epidermolysis bullosa by haematopoietic transplant: principles, perspectives and pitfalls

People with severe forms of epidermolysis bullosa (EB) develop widespread blistering and progressively debilitating multisystem complications that may result in a shortened lifespan. As some wounds in EB individuals are difficult or impossible to access with topical therapy, we examined the potential of systemic therapy with normal haematopoietic stem cells. In both animal models and children with EB, healthy donor cells from the haematopoietic graft migrated to the injured skin; simultaneously, there was an increase in the production of skin-specific structural proteins deficient in EB, increased skin integrity and reduced tendency to blister formation. Even though the majority of evaluable individuals have had a positive response in skin healing, frequently changing their quality of life, the improvement in lifestyle has been varied and the overall clinical response incomplete. To change the current amelioration of disease into a full cure, we propose to (i) increase safety as well as efficacy of haematopoietic cell transplant (HCT) using co-infusion of mesenchymal stromal/stem cells with haematopoietic stem cells and non-myeloablative conditioning for transplant; (ii) optimize homing of donor cells into the skin erosions in animal models of EB; and (iii) discover and test new drugs for EB therapy using patient-specific induced pluripotent stem cells. We conclude that although HCT has always been a risky treatment restricted to those with serious life-threatening or debilitating diseases, by most benchmarks, the results of HCT in EB have shown that HCT has the potential of being a durable, systemic therapy for people with severe forms of EB.

Lentiviral vectors for cutaneous RNA managing

Post-transcriptional managing of RNA plays a key role in the intricate network of cellular pathways that regulate our genes. Numerous small RNA species have emerged as crucial regulators of RNA processing and translation. Among these, microRNAs (miRNAs) regulate protein synthesis through specific interactions with target RNAs and are believed to play a role in almost any cellular process and tissue. Skin is no exception, and miRNAs are intensively studied for their role in skin homoeostasis and as potential triggers of disease. For use in skin and many other tissues, therapeutic RNA managing by small RNA technologies is now widely explored. Despite the easy accessibility of skin, the natural barrier properties of skin have challenged genetic intervention studies, and unique tools for studying gene expression and the regulatory role of small RNAs, including miRNAs, in human skin are urgently needed. Human immunodeficiency virus (HIV)-derived lentiviral vectors (LVs) have been established as prominent carriers of foreign genetic cargo. In this review, we describe the use of HIV-derived LVs for efficient gene transfer to skin and establishment of long-term transgene expression in xenotransplanted skin. We outline the status of engineered LVs for delivery of small RNAs and their in vivo applicability for expression of genes and small RNA effectors including small hairpin RNAs, miRNAs and miRNA inhibitors. Current findings suggest that LVs may become key tools in experimental dermatology with particular significance for cutaneous RNA managing and in vivo genetic intervention.

Downregulation of endothelial microRNA-200b supports cutaneous wound angiogenesis by desilencing GATA binding protein 2 and vascular endothelial growth factor receptor 2

OBJECTIVE

MicroRNAs (miRs) regulate angiogenesis by posttranscriptional silencing of target genes. The significance of angiostatic miR-200b in switching on skin wound angiogenesis was tested.

METHODS AND RESULTS

Wounding caused imminent and transient downregulation of miR-200b in dermal wound-edge endothelial cells. Derailing this injury response by lentiviral delivery of miR-200b in vivo impaired wound angiogenesis. Computational prediction, target reporter luciferase assay, and Western blot analysis provided first evidence that miR-200b targets globin transcription factor binding protein 2 (GATA2) and vascular endothelial growth factor receptor 2 (VEGFR2). Overexpression of GATA2 or VEGFR2 in endothelial cells rescued the angiostatic effect of miR-200b in vitro. Downregulation of miR-200b derepressed GATA2 and VEGFR2 expression to switch on wound angiogenesis, which was disrupted in diabetic wounds. Treatment of endothelial cells with tumor necrosis factor-α, a proinflammatory cytokine abundant in diabetic wounds, induced miR-200b expression, silenced GATA2 and VEGFR2, and suppressed angiogenesis. These outcomes were attenuated using anti-miR-200b strategy. Neutralization of tumor necrosis factor-α in the diabetic wounds improved wound angiogenesis and closure, which was accompanied by downregulation of miR-200b expression and desilencing of GATA2 and VEGFR2.

CONCLUSIONS

Injury-induced repression of miR-200b turned on wound angiogenesis. In mice with diabetes mellitus,excessive tumor necrosis factor-α induced miR-200b blunting proangiogenic functions of GATA2 and VEGFR2.

Lentivirus shRNA Grb10 targeting the pancreas induces apoptosis and improved glucose tolerance due to decreased plasma glucagon levels

AIMS/HYPOTHESIS

The physiological significance of growth factor receptor-bound protein-10 (GRB10) in the pancreas is unclear. We hypothesised that GRB10 is involved in pancreatic apoptosis, as GRB10 binds with a family of cell-survival-related proteins implicated in apoptosis.

METHODS

Lentiviral vector small hairpin RNA (shRNA) targeting Grb10 was injected in vivo via an intraductal pancreatic route to target pancreatic tissues in adult mice, which were studied 2 weeks post-injection.

RESULTS

Using the TUNEL assay, we demonstrated for the first time that in vivo injection of lentivirus shRNA Grb10 directly into the adult mouse pancreas induced apoptosis in both exocrine and endocrine (alpha and beta) cells. This effect was more pronounced in alpha cells. Levels of the pro-apoptotic protein BCL2-interacting mediator of cell death (BIM) in islets was higher in lentivirus shRNA Grb10 than in lentivirus shRNA scramble mice. In the apoptotic pathway, BIM initiates apoptosis signalling, leading to activation of the caspase cascade. We propose that, when complexed with GRB10, BIM is inactive. On activation by stress signalling or, in the present study, following injection of lentivirus shRNA Grb10 into pancreas, BIM becomes unbound from GRB10 and activates the caspase cascade. Indeed, caspase-3 activity in islets was higher in the experimental than in the control group. Apoptosis induced by shRNA Grb10 resulted in a 34% decrease in fasting plasma glucagon. Mice injected with shRNA Grb10 had improved glucose tolerance despite reduced insulin secretion compared with shRNA scramble control mice.

CONCLUSIONS/INTERPRETATION

GRB10 is critically involved in alpha cell survival and, as a result, plays an important role in regulating basal glucagon secretion and glucose tolerance in adult mice.

Molecular organization of the basement membrane zone

The dermal-epidermal basement membrane is a complex assembly of proteins that provide adhesion and regulate many important processes such as development, wound healing, and cancer progression. This contribution focuses on the structure and function of individual components of the basement membrane, how they assemble together, and how they participate in human tissues and diseases, with an emphasis on skin involvement. Understanding the composition and structure of the basement membrane provides insight into the pathophysiology of inherited blistering disorders, such as epidermolysis bullosa, and acquired bullous diseases, such as the pemphigoid group of autoimmune diseases and epidermolysis bullosa acquisita.

Long-term type VII collagen restoration to human epidermolysis bullosa skin tissue

In spite of advances in the molecular diagnosis of recessive dystrophic epidermolysis bullosa (RDEB), an inherited blistering disease due to a deficiency of type VII collagen at the basement membrane zone (BMZ) of stratified epithelium, current therapy is limited to supportive palliation. Gene delivery has shown promise in short-term experiments; however, its long-term sustainability through multiple turnover cycles in human tissue has awaited confirmation. To characterize approaches for long-term genetic correction, retroviral vectors were constructed containing long terminal repeat-driven full-length and epitope-tagged COL7A1 cDNA and evaluated for durability of type VII collagen expression and function in RDEB skin tissue regenerated on immune-deficient mice. Type VII collagen expression was maintained for 1 year in vivo, or over 12 epidermal turnover cycles, with no abnormalities in skin morphology or self-renewal. Type VII collagen restoration led to correction of RDEB disease features, including reestablishment of anchoring fibrils at the BMZ. This approach confirms durably corrective and noninjurious gene delivery to long-lived epidermal progenitors and provides the foundation for a human clinical trial of ex vivo gene delivery in RDEB.

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.

Bone marrow transplantation for recessive dystrophic epidermolysis bullosa

BACKGROUND

Recessive dystrophic epidermolysis bullosa is an incurable, often fatal mucocutaneous blistering disease caused by mutations in COL7A1, the gene encoding type VII collagen (C7). On the basis of preclinical data showing biochemical correction and prolonged survival in col7 −/− mice, we hypothesized that allogeneic marrow contains stem cells capable of ameliorating the manifestations of recessive dystrophic epidermolysis bullosa in humans.

METHODS

Between October 2007 and August 2009, we treated seven children who had recessive dystrophic epidermolysis bullosa with immunomyeloablative chemotherapy and allogeneic stem-cell transplantation. We assessed C7 expression by means of immunofluorescence staining and used transmission electron microscopy to visualize anchoring fibrils. We measured chimerism by means of competitive polymerase-chain-reaction assay, and documented blister formation and wound healing with the use of digital photography.

RESULTS

One patient died of cardiomyopathy before transplantation. Of the remaining six patients, one had severe regimen-related cutaneous toxicity, with all having improved wound healing and a reduction in blister formation between 30 and 130 days after transplantation. We observed increased C7 deposition at the dermal-epidermal junction in five of the six recipients, albeit without normalization of anchoring fibrils. Five recipients were alive 130 to 799 days after transplantation; one died at 183 days as a consequence of graft rejection and infection. The six recipients had substantial proportions of donor cells in the skin, and none had detectable anti-C7 antibodies.

CONCLUSIONS

Increased C7 deposition and a sustained presence of donor cells were found in the skin of children with recessive dystrophic epidermolysis bullosa after allogeneic bone marrow transplantation. Further studies are needed to assess the long-term risks and benefits of such therapy in patients with this disorder. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00478244.)

Gene therapy for recessive dystrophic epidermolysis bullosa

Among the severe genetic disorders of the skin that are suitable for gene and cell therapy, most efforts have been made in the treatment of blistering diseases including dystrophic epidermolysis bullosa. This condition can be recessively or dominantly inherited, depending on the nature and position of the mutation or mutations in the gene encoding type VII collagen. At present, there is no specific treatment for recessive dystrophic epidermolysis bullosa, and gene and cell therapy approaches hold great promise. This article discusses the different gene therapy approaches that have been used for the treatment of this disease and the new perspectives that they open.

SIN retroviral vectors expressing COL7A1 under human promoters for ex vivo gene therapy of recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is caused by loss-of-function mutations in COL7A1 encoding type VII collagen which forms key structures (anchoring fibrils) for dermal-epidermal adherence. Patients suffer since birth from skin blistering, and develop severe local and systemic complications resulting in poor prognosis. We lack a specific treatment for RDEB, but ex vivo gene transfer to epidermal stem cells shows a therapeutic potential. To minimize the risk of oncogenic events, we have developed new minimal self-inactivating (SIN) retroviral vectors in which the COL7A1 complementary DNA (cDNA) is under the control of the human elongation factor 1alpha (EF1alpha) or COL7A1 promoters. We show efficient ex vivo genetic correction of primary RDEB keratinocytes and fibroblasts without antibiotic selection, and use either of these genetically corrected cells to generate human skin equivalents (SEs) which were grafted onto immunodeficient mice. We achieved long-term expression of recombinant type VII collagen with restored dermal-epidermal adherence and anchoring fibril formation, demonstrating in vivo functional correction. In few cases, rearranged proviruses were detected, which were probably generated during the retrotranscription process. Despite this observation which should be taken under consideration for clinical application, this preclinical study paves the way for a therapy based on grafting the most severely affected skin areas of patients with fully autologous SEs genetically corrected using a SIN COL7A1 retroviral vector.

Role of dermal-epidermal basement membrane zone in skin, cancer, and developmental disorders

The dermal-epidermal basement membrane zone is an important epithelial and stromal interface, consisting of an intricately organized collection of intracellular, transmembrane, and extracellular matrix proteins. The basement membrane zone has several main functions including acting as a permeability barrier, forming an adhesive interface between epithelial cells and the underlying matrix, and controlling cellular organization and differentiation. This article identifies key molecular players of the dermal-epidermal membrane zone, and highlights recent research studies that have identified structural and functional roles of these components in the context of various blistering, neoplastic, and developmental syndromes.

Keratinocyte-/fibroblast-targeted rescue of Col7a1-disrupted mice and generation of an exact dystrophic epidermolysis bullosa model using a human COL7A1 mutation

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe hereditary bullous disease caused by mutations in COL7A1, which encodes type VII collagen (COL7). Col7a1 knockout mice (COL7(m-/-)) exhibit a severe RDEB phenotype and die within a few days after birth. Toward developing novel approaches for treating patients with RDEB, we attempted to rescue COL7(m-/-) mice by introducing human COL7A1 cDNA. We first generated transgenic mice that express human COL7A1 cDNA specifically in either epidermal keratinocytes or dermal fibroblasts. We then performed transgenic rescue experiments by crossing these transgenic mice with COL7(m+/-) heterozygous mice. Surprisingly, human COL7 expressed by keratinocytes or by fibroblasts was able to rescue all of the abnormal phenotypic manifestations of the COL7(m-/-) mice, indicating that fibroblasts as well as keratinocytes are potential targets for RDEB gene therapy. Furthermore, we generated transgenic mice with a premature termination codon expressing truncated COL7 protein and performed the same rescue experiments. Notably, the COL7(m-/-) mice rescued with the human COL7A1 allele were able to survive despite demonstrating clinical manifestations very similar to those of human RDEB, indicating that we were able to generate surviving animal models of RDEB with a mutated human COL7A1 gene. This model has great potential for future research into the pathomechanisms of dystrophic epidermolysis bullosa and the development of gene therapies for patients with dystrophic epidermolysis bullosa.

[Orogenital and conjunctival involvement in hereditary and autoimmune blistering diseases]

Chronic involvement of orogenital and conjunctival mucosa in the course of either genetically based (epidermolysis bullosa hereditaria) or auto-immunologically mediated (as for example pemphigus vulgaris, mucous membrane pemphigoid or epidermolysis bullosa acquisita) blistering diseases can cause significant morbidity. To provide accurate care, recognition of clinical, pathogenic and diagnostic features as well as awareness of recent advances in the development of new therapeutic modalities are mandatory and thus will be discussed in this review.

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

Key Words Collapse

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

Collapse

Grants Collapse

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

Collapse