Human Pro-insulin Transgenic Calf Derived from Somatic Cell Nuclear Transfer

The current study was undertaken to evaluate the possibility of producing a human pro-insulin transgenic cow by means of somatic cell nuclear transfer (SCNT). A double selection system, Neomycin resistance (Neo^r) gene and enhanced green fluorescent protein (EGFP) gene linked through an inner ibosomal entry site (IRES) sequence directed by a Cytomegalovirus(CMV) promoter, was used for enrichment and selection of the transgenic cells and preimplantation embryos. Transgenes were introduced into bovine fetal fibroblast cells (BFF) cultured in vitro through electroporation (900 V/cm, 5 ms). Transgenic bovine fibroblast cells (TBF) were enriched through addition of G418 in culture medium (800 μg/mL). Before being used as a nuclear donor, the TBF cells were either cultured in normal conditions (10% FBS) or treated with serum starvation (0.5% FBS for 2-4 days) followed by 10 hours recovery for G1 phase synchronization. Transgenic cloned embryos were produced through GFP-expressing cell selection and SCNT. The results were the percentage of blastocyst development following SCNT was lower using TBF than BFF cells (23.2% VS 35.2%, P<0.05). No difference in the percentage of cloned blastocysts between the two groups of transgenic nuclear donor of normal and starvation cultures were observed (23.2% VS 18.9%, PP>0.05). Two to four GFP-expressing blastocysts were transferred into the uterus of each synchronised recipient. One pregnancy from of seven recipients (21 embryos) was confirmed by rectum palpation 60 days after embryo transfer and one recipient has given birth to a calf at term. PCR and DNA sequencing analysis confirmed that the calf was produced using human proinsulin transgenic animal.

Keywords
Somatic cell nuclear transfer, Human pro-insulin, EGFP, Transgenic calf