Supplement of autologous ooplasm into porcine somatic cell nuclear transfer embryos does not alter embryo development

Abstract

Somatic cell nuclear transfer (SCNT) is considered as the technique in which a somatic cell is introduced into an enucleated oocyte to make a cloned animal. However, it is unavoidable to lose a small amount of the ooplasm during enucleation step during SCNT procedure. The present study was aimed to uncover whether the supplement of autologous ooplasm could ameliorate the oocyte competence so as to improve low efficiency of embryo development in porcine SCNT. Autologous ooplasm-transferred (AOT) embryos were generated by the supplementation with autologous ooplasm into SCNT embryos. They were comparatively evaluated with respect to embryo developmental potential, the number of apoptotic body formation and gene expression including embryonic lineage differentiation, apoptosis, epigenetics and mitochondrial activity in comparison with parthenogenetic, in vitro-fertilized (IVF) and SCNT embryos. Although AOT embryos showed perfect fusion of autologous donor ooplasm with recipient SCNT embryos, the supplement of autologous ooplasm could not ameliorate embryo developmental potential in regard to the rate of blastocyst formation, total cell number and the number of apoptotic body. Furthermore, overall gene expression of AOT embryos was presented with no significant alterations in comparison with that of SCNT embryos. Taken together, the results of AOT demonstrated inability to make relevant values improved from the level of SCNT embryos to their IVF counterparts.

Strategies to Improve the Efficiency of Somatic Cell Nuclear Transfer

“…In contrast, cytoplasm supplementation could not improve cloned porcine embryo development in regard to the blastocyst rate, total cell number, and apoptotic cells. The transcription levels of embryonic lineage differentiation genes (OCT4 and CDX2), pro-apoptotic genes (BAX and BAK), anti-apoptotic gene (BCL2), mitochondria activity-related genes (MFN and TFAM), and methylation-related genes (DNMT1 and DNMT3a) showed no significant differences between cytoplasm supplemented and non-supplemented cloned porcine embryos [79].…”

Does supplementation with mitochondria improve oocyte competence? A systematic review

“…Fertilization rate in mitochondrial supplementation group was higher than in control group in 9 out of 25 studies (Cohen et al 1998, Yi et al 2007, Chiaratti et al 2011, Hua et al 2012, Oktay et al 2015, Cagnone et al 2016, Wang et al 2017b. This rate was not significantly different in 16 studies (Huang et al 1999, Lanzendorf et al 1999, Nagai et al 2004, Takeda et al 2005, Van Thuan et al 2006, Hua et al 2007, Sansinena et al 2011, Takeda et al 2012, Gonzalez-Grajales et al 2016, Igarashi et al 2016, Lee et al 2017, Srirattana & St John 2018, Sheng et al 2019, and was not evaluated in the remaining studies (Petr et al 1994, Cohen et al 1997, Van Blerkom et al 1998, Brenner et al 2000, Barritt et al 2001b, Dale et al 2001, Kong et al 2003, Hoseini et al 2016, St John et al 2019.…”

“…Mitochondrial transcription factor A (TFAM) was expressed in similar range in mitochondrial supplementation groups, as well as mitochondrial transcription factor B1 (TFB1), Sirtuins , POLRMT (Hua et al 2012) and Mitochondrial Mitofusin-1 (Lee et al 2017), indicating no differences concerning mitochondrial-related genes expression. However, another study demonstrated that oocytes supplemented with mitochondria modulated methylation of POLG (hypomethylation) at metaphase II oocytes, leading to mtDNA replication prior to implantation .…”

“…Improved embryo development was reported in 12 out of 27 papers (Cohen et al 1997, 1998, Dale et al 2001, Hua et al 2007, Yi et al 2007, Chiaratti et al 2011, Hua et al 2012, Cagnone et al 2016, Wang et al 2017b. Embryo development was not different from controls in 15 studies (Huang et al 1999, Lanzendorf et al 1999, Nagai et al 2004, Takeda et al 2005, Van Thuan et al 2006, Sansinena et al 2011, Takeda et al 2012, Oktay et al 2015, Gonzalez-Grajales et al 2016, Igarashi et al 2016, Lee et al 2017, Srirattana & St John 2018, Labarta et al 2019b, Sheng et al 2019 and was not evaluated in the remaining (Petr et al 1994, Van Blerkom et al 1998, Brenner et al 2000, Barritt et al 2001b, Kong et al 2003, Hoseini et al 2016, St John et al 2019. Although not significant, one study reported a trend toward higher embryo grade on day 3 (Oktay et al 2015).…”

“…Concerning oocyte and embryo development related genes, no differences in pluripotency genes, such as OCT4 and SOX2, were reported (Hua et al 2012, Cagnone et al 2016, Lee et al 2017. Srirattana and St John (2018) found that 188 differentially expressed genes (DEGs) were upregulated and 321 DEGs were downregulated in the miNT blastocysts, being cellular development the most influenced molecular and cellular function, with increased expression.…”