USE OF NONAUTOLOGOUS MICROENCAPSULATED FIBROBLASTS IN GROWTH-HORMONE GENE-THERAPY TO IMPROVE GROWTH OF MIDGET SWINE

The aim of the present study was to investigate the expression activit y, both in vitro and in vivo, of the porcine growth hormone complement ary DNA (pGH cDNA) in porcine fetal fibroblast (PFF) cells, The pGH ge ne had been constructed inside the bicistronic retroviral vector PSN a nd subsequently transfected into PFF cells further encapsulated with i mmunoprotective microcapsules, This would provide a way to evaluate th e improvement in growth performance of Tao-Yuan swine by the use of no nautologous microencapsulated fibroblasts carrying the pGH cDNA via th e technique of somatic gene therapy. Results from Southern blot analys is confirmed that the full length of the pGH cDNA was completely integ rated into the genome of the PFF cells after they had been infected on e to four times using a PSN retroviral vector. Moreover, Northern blot analysis showed that high transcription activity was present in clone s infected twice, and exogenous pGH secretion was found when the pGH-i nfected PFF had been further cultured for 48 hr in vitro and subjected to immunoblot assay. Encapsulation of the pGH-PFF with an alginate-po ly-L-lysine-alginate membrane did not show any deterioration in their proliferation and survival both in vitro and in vivo. The pGH gene in encapsulated recombinant fibroblasts was fully expressed after it had been transplanted into the peritoneal cavity of the Tao-Yuan swine, an d reverse transcription-polymerase chain reaction (RT-PCR) analysis wa s performed on the microcapsules retrieved 1 month later. The feasibil ity of pGH gene therapy to improve midget Tao-Yuan swine growth enhanc ement is further supported by the fact that transplantation of the enc apsulated recombinant fibroblast cells resulted in a much more signifi cant increase in weight gain than in those swine in either the age-mat ched untreated control group or in those that had been transplanted wi th uncapsulated recombinant PFF cells (10.56 +/- 1.01 kg versus 6.95 /- 0.94 and 5.27 +/- 1.30 kg; p < 0.05), These experimental data sugge st that growth hormone gene therapy did provide an alternative approac h for growth improvement in midget Tao-Yuan swine.