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Potentiel thérapeutique des cellules stromales mésenchymateuses dans l'épidermolyse bulleuse dystrophique récessive

Abstract : Recessive dystrophic epidermolysis bullosa (RDEB) is a severe skin disease caused by loss-of-function mutations in COL7A1 encoding type VII collagen. Type VII collagen forms anchoring fibrils which are essential structures for dermal-epidermal adherence. Patients with RDEB suffer since birth from skin and mucosal blistering and develop severe complications. The development of aggressive squamous cell carcinomas is the first cause of demise of these young patients. To date, there is no treatment. Mesenchymal stromal cells (MSC) are multipotent cells, isolated from adult tissue (bone marrow, adipose tissue) or perinatal tissue (umbilical cord). Previous works have shown that local and systemic injections of allogeneic bone marrow-derived MSC (BM-MSC) have a potential to reduce skin inflammation and to improve wound healing in RDEB patients. However, clinical improvement was transient and the mechanisms of action of BM-MSC in RDEB and also their survival after injection are still poorly understood. BM-MSC could act through immunomodulation, anti-fibrotic and angiogenic proprieties, paracrine effects leading to type VII collagen production in the host tissues and/or type VII collagen secretion by injected BM-MSC. The aim of our work was to study the therapeutic potential of MSC for RDEB in preclinical models. We first showed that BM-MSC produce COL7A1 mRNA and type VII collagen levels comparable to healthy dermal fibroblasts in culture. We then assessed the long-term capacity of human BM-MSC to survive, produce and deposit type VII collagen at the dermal-epidermal junction (DEJ) after local injection in human RDEB skin equivalents transplanted onto nude mice. In vivo intradermal (ID) injection of a single dose of human BM-MSC led to the production and deposition of human type VII collagen at the DEJ and allowed anchoring fibrils formation for at least six months post-injection. Injected human BM-MSC were found in the skin at least four months post-injection. These data show that intradermally injected human BM-MSC have the potential to improve dermal-epidermal adhesion of RDEB skin equivalents through sustained deposit of type VII collagen molecules and subsequent anchoring fibrils formation. We then compared the efficacy of human Umbilical Cord Wharton's Jelly-MSC (UC-MSC) with BM-MSC using the same methodology as previously described. UC-MSC showed in vitro a significantly higher amount of COL7A1 mRNA and type VII collagen compared to BM-MSC and healthy dermal fibroblasts in culture. ID injection of a single dose of UC-MSC in vivo led to the production and deposition of low levels of human type VII collagen at the DEJ for four months post-injection. Injected human UC-MSC were found in the skin two months post-injection. These data disclosed a lower efficacy of UC-MSC to restore collagen VII at the DEJ compared to BM-MSC injected in the same xenograft RDEB model. These data open the perspective of using gene-corrected BM-MSC from a Col7a1-/- RDEB murine model to restore normal dermal-epidermal adhesion. Col7a1-/- mice reproduce cutaneous and mucosal lesions observed in RDEB patients. The life expectancy of these animals is very short. We could show that transduction of Col7a1-/- murine BM-MSC in culture using a COL7A1-expressing SIN retroviral vector led to type VII collagen expression levels which were 30-fold higher on average than in BM-MSC from WT mice. In vivo data are required to determine whether the injection of gene-corrected BM-MSC has the potential to treat skin and mucosal lesions in RDEB mice and to define the optimal dose and duration of the effect in vivo. Restoration of type VII collagen expression and anchoring fibrils formation in Col7a1-/- mice would represent an important step towards clinical translation.
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https://tel.archives-ouvertes.fr/tel-02518996
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  • HAL Id : tel-02518996, version 1

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Clarisse Ganier. Potentiel thérapeutique des cellules stromales mésenchymateuses dans l'épidermolyse bulleuse dystrophique récessive. Génétique humaine. Université Sorbonne Paris Cité, 2018. Français. ⟨NNT : 2018USPCB185⟩. ⟨tel-02518996⟩

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