Non-viral transfer of the growth hormone gene to different muscles of immunodeficient dwarf (lit/scid) mice is under study with the objective of improving phenotypic correction via this particular gene therapy approach. Plasmid DNA was administered into the exposed quadriceps or non-exposed tibialis cranialis muscle of lit/scid mice followed by electroporation, monitoring several growth parameters. In a 6-month bioassay, 50 μg DNA were injected three times into the quadriceps muscle of 80-day old mice. A 50% weight increase, with a catch-up growth of 21%, together with a 16% increase for nose-to-tail and tail lengths (catch-up = 19-21%) and a 24-28% increase for femur length (catch-up = 53-60%), were obtained. mIGF1 serum levels were ~. 7-fold higher than the basal levels for untreated mice, but still ~. 2-fold lower than in non-dwarf scid mice. Since treatment age was found to be particularly important in a second bioassay utilizing 40-day old mice, these pubertal mice were compared in a third bioassay with adult (80-day old) mice, all treated twice with 50 μg DNA injected into each tibialis cranialis muscle, via a less invasive approach. mIGF1 concentrations at the same level as co-aged scid mice were obtained 15 days after administration in pubertal mice. Catch-up growth, based on femur length (77%), nose-to-tail (36%) and tail length (39%) increases was 40 to 95% higher than those obtained upon treating adult mice. These data pave the way for the development of more effective pre-clinical assays in pubertal dwarf mice for the treatment of GH deficiency via plasmid-DNA muscular administration.
Bibliographical noteFunding Information:
This work was supported by FAPESP, São Paulo, Brazil ( 2011/21708-6 , 2013/03747-0 , 2014/04277-0 , 2014/07380-6 , 2014/18242-3 , 2014/19757-7 ) and by the National Research Council (CNPq), Brasilia, Brazil ( PQ 300473/2009-5 ).
© 2015 Elsevier Ltd.
- Gene therapy
- Growth hormone gene
- Immunodeficient dwarf mice
- Non-viral gene transfer
- Treatment age