Somatic cell cloning efficiency is determined by many factors. One of the most important factors is the structure-functional quality of nuclear donor cells. Morphologic criteria that have been used to date for qualitative evaluation of somatic cells may be insufficient for practical application in the cloning. Biochemical and biophysical changes that are one of the earliest symptoms in the transduction of apoptotic signal may be not reflected in the morphologic changes of somatic cells. For this reason, adult cutaneous or foetal fibroblast cells that, in our experiments, provided the source of genomic DNA for the cloning procedure had been previously analysed for biochemical and biophysical proapoptotic alterations with the use of live-DNA (YO-PRO-1) and plasma membrane (Annexin V-eGFP) fluorescent markers. In Groups IA and IB, the generation of nucleartransferred (NT) embryos using non-apoptotic/non-necrotic contact-inhibited or serum-starved adult cutaneous fibroblast cells yielded the morula and blastocyst formation rates of 125/231 (54.1%) and 68/231 (29.4%) or 99/237 (41.8%) and 43/237 (18.1%), respectively. In Groups IIA and IIB, the frequencies of embryos reconstituted with non-apoptotic/non-necrotic contact-inhibited or serum-starved foetal fibroblast cell nuclei that reached the morula and blastocyst stages were 171/245 (69.8%) and 97/245 (39.6%) or 132/227 (58.1%) and 63/227 (27.8%), respectively. In conclusion, contact inhibition of migration and proliferative activity among the subpopulations of adult dermal fibroblast cells and foetal fibroblast cells resulted in considerably higher morula and blastocyst formation rates of in vitro cultured cloned pig embryos compared to serum starvation of either type of fibroblast cell line. Moreover, irrespective of the methods applied to artificially synchronize the mitotic cycle of nuclear donor cells at the G0/G1 phases, developmental abilities to reach the morula/blastocyst stages were significantly higher for porcine NT embryos that had been reconstructed with non-apoptotic/non-necrotic foetal fibroblast cells than those for NT embryos that had been reconstructed with non-apoptotic/non-necrotic adult dermal fibroblast cells. To our knowledge, the generation of cloned pig embryos using abattoir-derived oocytes receiving cell nuclei descended from contact-inhibited or serum-deprived somatic cells undergoing comprehensive vital diagnostics for the absence of biochemical and biophysical proapoptotic alterations within their plasmalemmas has not been reported so far.
