Oral gene therapy for hypoparathyroidism: a rat model

The use of nonionic polymeric micelles orally to protect and deliver plasmid DNA in vivo was investigated. Parathyroid hormone (PTH)(1-34) gene (179 bp) was inserted into a human cytomegalovirus promoter (PCMV) and E. coli competent cells were used to amplify the cDNA. Polymeric micelle formations (100 microl) formed from PCMV-PTH(1-34) cDNA (7.2 microg/microl) and 6% (w/v) polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) was administered at 8-hr intervals for 48 hr and then at 8-hr intervals for 24 hr weekly for 3 weeks. Parathyroidectomized rats receiving 150 microl of EDTA (10 mM) before each dose of formation served as the study group; rats receiving drinking water, EDTA (10 mM), PCMV-PTH(1-34) cDNA and PCMV-PTH(1-34) cDNA plus EDTA at the same amount and time intervals served as the control groups. Serum levels of calcium and PTH(1-34) were measured weekly for 4 weeks. Immunohistochemical stain for PTH(1-34), reverse transcriptase polymerase chain reaction for PTH(1-34) mRNA and the relative density of PTH(1-34) mRNA were performed at 2 and 4 weeks after oral gene therapy in different organs. One third to three of five rats in the control groups died after parathyroidectomy. Serum levels of calcium and PTH(1-34) were higher in the study than in the control groups. In the study group, positive stain of PTH(1-34) and PTH(1-34) mRNA could be found in those organs. Relative densities of PTH(1-34) mRNA were higher in the study than in the drinking water group in different organs. Oral gene therapy can maintain calcium and PTH(1-34) levels in parathyroidectomized rats.