title: Cell membrane integrity in myotonic dystrophy type 1: implications for therapy.
abstract: Myotonic Dystrophy type 1 (DM1) is a multisystemic disease caused by toxic RNA from a DMPK gene carrying an expanded (CTG•CAG)n repeat. Promising strategies for treatment of DM1 patients are currently being tested. These include antisense oligonucleotides and drugs for elimination of expanded RNA or prevention of aberrant binding to RNP proteins. A significant hurdle for preclinical development along these lines is efficient systemic delivery of compounds across endothelial and target cell membranes. It has been reported that DM1 patients show elevated levels of markers of muscle damage or loss of sarcolemmal integrity in their serum and that splicing of dystrophin, an essential protein for muscle membrane structure, is abnormal. Therefore, we studied cell membrane integrity in DM1 mouse models commonly used for preclinical testing. We found that membranes in skeletal muscle, heart and brain were impermeable to Evans Blue Dye. Creatine kinase levels in serum were similar to those in wild type mice and expression of dystrophin protein was unaffected. Also in patient muscle biopsies cell surface expression of dystrophin was normal and calcium-positive fibers, indicating elevated intracellular calcium levels, were only rarely seen. Combined, our findings indicate that cells in DM1 tissues do not display compromised membrane integrity. Hence, the cell membrane is a barrier that must be overcome in future work towards effective drug delivery in DM1 therapy.
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands; Prosensa Therapeutics B.V., Leiden, The Netherlands.
authors: Anchel
authors: A
authors: González-Barriga
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors: Julia
authors: J
authors: Kranzen
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors: Huib J E
authors: HJ
authors: Croes
authors: Prosensa Therapeutics B.V., Leiden, The Netherlands.
authors: Suzanne
authors: S
authors: Bijl
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors: Walther J A A
authors: WJ
authors: van den Broek
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors: Ingeborg D G
authors: ID
authors: van Kessel
authors: Department of Neurology, Donders Centre for Neuroscience, Radboud university medical center, Nijmegen, The Netherlands.
authors: Baziel G M
authors: BG
authors: van Engelen
authors: Prosensa Therapeutics B.V., Leiden, The Netherlands.
authors: Judith C T
authors: JC
authors: van Deutekom
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors: Bé
authors: B
authors: Wieringa
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands; Prosensa Therapeutics B.V., Leiden, The Netherlands.
authors: Susan A M
authors: SA
authors: Mulders
authors: Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors: Derick G
authors: DG
authors: Wansink
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002648:Child; D016189:Dystrophin / Q000235:genetics / Q000378:metabolism; D005070:Evans Blue / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000188:drug therapy / Q000378:metabolism*
chemical_list: D016189:Dystrophin; D005070:Evans Blue; D002118:Calcium