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Researchers have designed a local treatment in the form of a gel to treat children with a type of epidermolysis bullosa, a rare condition that can be very serious. The results of the study, published in the medical journal Nature, are “very encouraging, because they advance the treatment of this severe skin disease”, says Professor Alain Hovnanian, from the Genetics department at the hospital l Hôpital Necker, director of the Laboratory of Genetic Skin Diseases at INSERM and the University of Paris.
Epidermolysis bullosa, a rare and serious genetic disease
Recessive dystrophic epidermolysis bullosa (RDEB) is a type of epidermolysis, which is a very rare genetic disease. In 2011, the incidence of this skin pathology, all types and subtypes of diseases combined, was 1/125,000 in the United States, according to Orphanet.
Epidermolysis bullosa is characterized by very fragile skin, which can tear at the slightest touch. The skin is as fragile as the wings of a butterfly. This epidermal fragility leads to the appearance of blisters (bubbles) on the surface of the skin and causes the skin to fall off in flaps. According to Dr. Hovnanian, this disease is “clinically responsible for a very great fragility of the skin, it is responsible for bubbles and erosions leading to chronic inflammation and increasing the risk of skin cancer”.
The severity of the symptoms varies from one individual to another, as does the intensity of the pain. The disease usually manifests at birth or in infancy.
For the time being, the treatment of this type of epidermolysis bullosa is based on local and daily care of each wound as well as symptomatic treatment in the event of pain or infection.
In the most serious cases, there is an invasive technique based on the use of stem cells requiring a skin graft. This type of intervention is expensive and remains inaccessible to many patients. Indeed, Doctor Hovnanian, also an expert in the Dermatology department of Saint-Louis Hospital, specifies that to benefit from this surgical operation, “patients should be included in clinical trials. It is a major intervention that requires not only hospitalization, but also a biopsy of the skin, the culturing of keratinocytes to correct them and make them into epithelia.”.
In addition, the specialist in genetic skin diseases tells us that other therapeutic means are “during studies, such as intravenous injection”.
The scientific community is researching this rare disease in order to provide relief to patients. Among them, researchers have just developed a gel that helps heal wounds caused by epidermolysis bullosa. This gel can be applied locally to skin lesions when changing dressings.
A therapeutic gene encoding the collagen carried by the herpes virus
In patients with this type of epidermolysis bullosa, a protein is missing, it is collagen VII (C7). Present in all the fundamental structures of the body and the skin, collagen is an essential fiber for the elasticity of the skin and the maintenance of the dermis. In the case of this disease, the gene that codes for the protein is absent.
The gel developed by the team of researchers is based on “in-vivo gene therapy which delivers an active molecule to the patient’s skin”, explains Professor Hovnanian. In practice, the gel administers to the skin previously modified fibroblasts which will propagate on the skin tissue. Scientists have used the cold sore virus, HSV-1, to transport genes encoding collagen into the skin. Here, the advantage of the herpes virus is that it “infects the skin provided there is a wound, otherwise the virus is much less “effective”, especially when the skin is intact”. Besides, “it is able to transport a very large number of collagen”, continues the Professor. And to add that “the virus enters the cell nucleus, but does not integrate into the chromosome, this is the episomal principle”. “When “cells divide, they shed the herpes virus”.
Great patient comfort
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Not only does the gel close the wounds, but its effects last for a certain period of time. This is rather promising, because as Professor Hovnanian points out, epidermolysis bullosa is “painful for patients“and those of the Doctor”are already in demand”. According to him, “if you can achieve wound closure, even for several months, that’s a big step forward”. Indeed, good healing over time avoids the suffering caused by this disease, but could also reduce the risk of developing skin cancer.
In clinical trials, the gel was applied to the wounds of nine patients over the age of six with recessive dystrophic epidermolysis bullosa. After three months, all the lesions healed and healed. For a few weeks or even a few months after stopping treatment, the lesions did not return. According to Alain Hovnanian, this may be linked to the “collagen, which has a rather long lifespan. This protein is stable and degrades slowly. Maybe that’s why the effects are prolonged”.
On the other hand, the wounds of the patients who received the placebo closed up, but new blisters kept forming.
In addition, a local application gel is an accessible treatment, because it can be “applied at each dressing change”. Also, it would seem that no side effects have been identified during randomized trials.
The limits of this therapeutic gel
First, freezing requires a “repeated application on really injured areas”, says Professor Hovnanian. In the long term, the benefits remain to be assessed and that is why the “phase 3 of the clinical trial is underway”. It also remains to be defined.what will be the price of this gel, because that of the silicone dressing represents a very high societal cost”. Also, the gel has proven therapeutic benefits for “treat small wounds measuring 10 to 20 m², except for one of the patients, who had a lesion of 50 cm²”. It would be necessary to determine the benefits on larger wounds, but also to measure the effectiveness of the effects over time. Nevertheless, even ifthe correction is not definitive, it remains very interesting”, in particular to relieve patients, as Professor Hovnanian concludes.