QUANTIFICATION OF NORMAL DYSTROPHIN MESSENGER-RNA FOLLOWING MYOBLAST TRANSPLANTATION IN MDX MICE

A mutagenesis RT-PCR method was used to detect normal dystrophin mRNA following the injection of normal myoblasts in mdx mice using two immu nosuppressors, A specific sequence of the dystrophin mRNA (257 bp) was amplified by RT-PCR from the muscle total RNA, MaeIII digestion of th e amplified products allowed us to distinguish the normal messenger of dystrophin from the dystrophic one and to establish the percentage of normal and of dystrophic (mdx) dystrophin mRNA, Normal dystrophin mRN A was detected using this technique in mdx muscles transplanted with h istocompatible normal myoblasts, For this type of transplantation, no significant difference in the percentage of normal dystrophin mRNA was observed between immunosuppressed mice and those not immunosuppressed , No normal dystrophin mRNA was, however, observed in mdx mice followi ng histoincompatible normal myoblast transplantation without immunosup pression, When such transplantations were done in mice immunosuppresse d with cyclosporine or FK-506, normal dystrophin mRNA accounted for 31 % and 36% of the total dystrophin mRNA, respectively, In fact, one ani mal immunosuppressed with FK-508 expressed as much as 57% of normal dy strophin mRNA, These results thus show that FK-506 makes it possible t o restore dystrophin expression to a level comparable to that observed in DMD carriers that are usually asymptomatic. (C) 1995 John Wiley an d Sons, Inc.