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ePaper created 2014-09-15, 12:31:02 | version 1.32.01
In 2003 a new Laser Dissection Microscopy (LDM) technique was introduced in the Center for Blistering Diseases by cell biologist Anna Maria Gerdina (Marjon) Pasmooij. With this technique it became possible to immediately analyze frozen skin biopsies for their spontaneous correction event, thereby omitting the need for cell culturing. Although it was initially thought that only one reversion event had occurred in a patient, data obtained with LDM revealed that every single patch originated from a distinct genetic event.[2] At the time of the publication in 2005, the general opinion was that revertant mosaicism was rare. However, the identification of many more patients with EB and revertant mosaicism in the following years changed this, and led to the belief that revertant mosaicism is common.[3] Experiments were carried out on the possibility of culturing keratinocytes from a revertant skin area, creating a skin graft and subsequently transplanting back to affected skin.[4] Although the surgical method of the transplantation was successful, the amount of revertant keratinocytes was insufficient for obtaining fully functional skin with normal integrity. A hurdle still to overcome is the improvement of graft production, such that adequate percentages of revertant stem cells are present to secure functional repair of the skin.[5] Another exciting possibility, attracting the interest of many current researchers, is combining revertant mosaicism with induced pluripotent stem cell (iPSC) technology. Patient-specific keratinocytes from revertant mosaic patches that have been corrected spontaneously could be used as a source for patient- specific iPSCs and provide an essentially unlimited number of patient-specific cells for grafting. As revertant mosaicism seems to be common in EB, and the possibility of using the patient’s own naturally corrected keratinocytes is an appealing one, the first symposium on Natural Gene Therapy of the Skin was held in Barcelona in 2011 with financial support from the Dutch Butterfly Child Foundation (http://www.vlinderkind.nl), and prior to the 41st Annual Meeting of the European Society for Dermatological Research (ESDR).[6] 57 (A) Patient with EB caused by germ-line mutations in the COL17A1 gene. Due to the absence of collagen XVII, her skin is fragile and blisters easily. She has, however, several areas that are clinically normal and do not blister (dashed lines). (B) Skin biopsies taken from the affected skin show the absence of the green collagen XVII staining (arrows) compared to normal control skin. In contrast, the normal seeming revertant skin shows patchy re-expression of the deficient protein (double arrowhead). The figure is reprinted from Pasmooij et al., 2012, Discov Med, 14(76): 167-79. BWEADVSMGFINCORR:Opmaak 1 21-07-2014 17:40 Pagina 57