52 EFFECT OF DONOR CELLS WITH VARIOUS DIFFERENTIATED STATUS ON THE DEVELOPMENTAL COMPETENCE OF PORCINE NUCLEAR TRANSFER EMBRYOS

Abstract

Adult stem cells are more desirable than somatic cells for nuclear transfer (NT) because of their easy reprogrammability to resemble the genome of the zygote (Zhu et al. 2004 Biol. Reprod. 70, 1088–1095). Mesenchymal stem cells (MSCs) are a heterogeneous population of uncommitted and lineage-committed cells and have a more flexible potential as donor cells for NT. The aim of this study was to compare the developmental potential of NT embryos using undifferentiated (MSCs) and differentiated cells in the same lineage (osteocyte, adipocyte, and chondrocyte) by assessing the cleavage and blastocyst rates. Fetal fibroblasts were used as NT control. MSCs obtained from the aspirated bone marrow of a neonatal pig were cultured in advanced-DMEM (ADMEM) supplemented with 5% FCS. The differentiation potential was demonstrated by culture of MSCs at passage 3 under the conditions that were favorable for adipogenic, osteogenic, and chondrogenic development (Pittenger et al. 1999 Science 284, 143–147). For NT, cells from passages 3–5 were transferred into the perivitelline space of enucleated MII oocytes that had been in vitro-matured after collection from slaughterhouse-derived ovaries. After fusion with a needle-type electrode, eggs were cultured in 7.5 µg mL⁻¹ cytochalasin B for 3 h, and subsequently cultured in PZM-3 medium for 6 days. Statistical significance was tested using ANOVA with Bonferroni and Duncan tests. The results are presented in Table 1. The rates of cleavage and development to blastocyst stage of NT embryos varied among donor cell sources. Most eggs (92.2 ± 2.7%) cloned with MSCs cleaved, and 47.8% of eggs developed to the blastocyst stage. In contrast, NT eggs using differentiated MSCs—osteocytes, adipocytes, chondrocytes, and controls (fetal fibroblasts)—revealed significantly (P < 0.05) lower cleavage (74.5, 63.4, 74.3, and 66.4%, respectively) and blastocyst development (33.7, 30.1, 36.5, and 25.5%, respectively) rates than those using undifferentiated MSCs. The results demonstrate that the genome of donor cells with different differentiated status supports embryonic development to various degrees, and multipotent MSCs might have a greater potential in producing viable cloned porcine embryos.

Table 1.  Development of NT embryos with undifferentiated and differentiated cells

This work was supported by Grant No. R05-2004-000-10702-0 from KOSEF, Republic of Korea.