Long-term human growth hormone expression and partial phenotypic correction by plasmid-based gene therapy in an animal model of isolated growth hormone deficiency.
BACKGROUND
A model for in vivo gene therapy based on electroporation of human growth hormone (hGH)-coding naked DNA in the muscle of dwarf (lit/lit) and immunodeficient dwarf (lit/scid) mice is described.


METHODS
A plasmid containing the ubiquitin C promoter and the genomic hGH sequence was administered to the exposed quadriceps muscle, followed by electrotransfer using eight 50-V pulses of 20 ms at a 0.5-s interval. Serum hGH levels were determined after various days of DNA administration and a long-term body weight gain experiment was carried out.


RESULTS
Serum hGH, determined 3 days after DNA administration, revealed a significant dose-response curve (p < 0.01) in the 0-50 microg range. Because 50 microg of plasmid DNA produced circulating hGH levels of 2-3 ng/ml for at least 12 days, a long-term body weight gain assay was carried out. After 60 days, the weight of treated lit/scid mice increased 33.1% compared to a 4.2% weight decrease for the control group. hGH circulating levels were of the order of 1.5-3 ng/ml throughout the experiment and the average weight increase during the first 10 days was comparable to that obtained upon regular daily injection of 10 microg of recombinant hGH per mouse, producing comparable circulating levels of the hormone. A lower, but still significant increase in body weight was obtained upon repeating the experiment in immunocompetent dwarf mice (lit/lit).


CONCLUSIONS
We report for the first time sustained levels of circulating hGH after intramuscular naked DNA administration and, consequently, a highly significant weight increase of dwarf 'little' mice.
Oliveira
Nélio A J
NA
Biotechnology Department, National Nuclear Energy Commission (IPEN-CNEN), Cidade Universitária, São Paulo, SP, Brazil.
Cecchi
Cláudia R
CR
Higuti
Eliza
E
Oliveira
João E
JE
Jensen
Thomas G
TG
Bartolini
Paolo
P
Peroni
Cibele N
CN
D000818:Animals; D001835:Body Weight; D004195:Disease Models, Animal; D004393:Dwarfism, Pituitary / Q000628:therapy*; D015316:Genetic Therapy; D019382:Human Growth Hormone / Q000172:deficiency / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009132:Muscles / Q000473:pathology; D009929:Organ Size; D010641:Phenotype; D010957:Plasmids / Q000235:genetics*; D013997:Time Factors
D019382:Human Growth Hormone