Improving porcine SCNT efficiency by selecting donor cells size.

Considerable advancements have recently been achieved in porcine somatic cell nuclear transfer (SCNT), but the efficiency remains low. Donor cell size might play an important role in SCNT, but its effects in pigs remain unclear. This study aimed to evaluate the efficiency of porcine SCNT by selecting donor cells of suitable size. Porcine fetal fibroblasts (PFFs) were divided into three groups, group S (small, d ≤ 13 μm), group M (medium, 13 μm  18 μm), and their biological characteristics were analyzed. Next, SCNT was performed using PFFs of different sizes to evaluate the developmental potential of reconstructed embryos. The data showed that PFFs in groups S, M and L accounted for 17.5%, 47.7% and 34.8% of cells, respectively. Morphologically, cells in group S exhibited clear and regular cell membranes and nuclei, whereas cells in groups M and L displayed varying degrees of cell membrane protuberance, karyo-pyknosis, autophagy and mitochondrial abnormalities. In addition, the growth status and proliferation capabilities of cells in group S were significantly better than those of group M and group L. The percentage of cells at G0/G1 in group S and M were significantly greater than group L. The senescence rate of group S was lower than group M and group L. The apoptosis rate of group S was significantly lower than that of group L but comparable to that of group M . The cleavage rate of group S was also significantly greater than that of group M but comparable to that of group L . The blastocyst rate of group S was significantly greater than that of group M and group L. The blastocyst cell numbers of group S were also significantly greater than those of group M and group L. These findings suggested that small PFFs with a diameter of less than 13 μm are more suitable donor cells for SCNT in pigs.