In vitro and in vivo osteogenesis of human mesenchymal stem cells derived from skin, bone marrow and dental follicle tissues.

The present study evaluated the human mesenchymal stem cells (hMSCs) isolated from skin (hSMSC), bone marrow (hBMSC) and dental follicle (hDFMSC) tissues on their in vitro and in vivo osteogenic potential using demineralized bone matrix (DBM) and fibrin glue scaffold. Cells originated from three distinct tissues showed positive expressions of CD44, CD73, CD90, CD105 and vimentin, and differentiation ability into osteocytes, adipocytes and chondrocytes. hMSCs from all tissues co-cultured with a mixed DBM and fibrin glue scaffold in non-osteogenic induction media were positively stained by von Kossa and expressed osteoblast-related genes, such as osteocalcin (OC), osteonectin (ON), runt-related transcription factor 2 (Runx2) and osterix. For in vivo osteogenic evaluation, PKH26 labeled hMSCs were implanted into the subcutaneous spaces of athymic mice with a mixed scaffold. At 4 weeks of implantation, PKH26 labeled cells were detected in all hMSC-implanted groups. Bone formation with OC expression and radio-opacity intensity were observed around DBM scaffold in all hMSC-implanted groups. Interestingly, hDFMSCs-implanted group showed the highest OC expression and calcium content. These findings demonstrated that hDFMSCs could be a potential alternative autologous cell source for bone tissue engineering.

Effects of activation methods on DNA synthesis and development of parthenogenetic porcine embryos.

This study investigated the timing of DNA synthesis and patterns of pronuclear (PN) formation during the first cell cycle, and its influence on developmental competence, velocity and proliferation index of porcine parthenote blastocysts produced by different activation treatments. Oocytes were activated as follows: electrical stimulation (EST), EST combined with 7.5 µg/ml cytochalasin B (EST + CCB), 10 µg/ml cycloheximide (EST + CHX) and 1.9 mm 6-dimethylaminopurine (EST + 6-DMAP) for 3 h. DNA synthesis and PN formation were evaluated using 1 mm 5'bromo-2'deoxy-uridne (BrdU) at 2 h intervals from 1 to 13 h or 5 to 13 h of post-activation (hpa), respectively. In EST, DNA synthesis started at 3 hpa, reached the peak at 11 hpa and decreased at 13 hpa. Treatment with 6-DMAP resulted in an early increase of DNA synthesis at 3 hpa, whereas CCB delayed DNA synthesis for 2 h. In EST and EST + 6-DMAP, most of the eggs showed 1PN, whereas, incidence of 2PN in EST + CCB was higher than 1PN. EST + CHX was observed with 1PN, 2PN and multiple PN. Blastocyst rate in EST + CCB and EST + 6-DMAP were significantly (p<0.05) higher than EST + CHX. But, the developmental velocity was not different among groups. Proliferation index of blastocysts, as indicated the number of blastomere at S-phase of the cell cycle was low in all groups. In conclusion, CCB, CHX and 6-DMAP used for producing porcine parthenogenetic embryos induced different onset of DNA synthesis and PN, but they did not affect the subsequent embryo development.

Ultra-structural changes and developmental potential of porcine oocytes following vitrification.

This study evaluated the effects of exposure and/or vitrification of porcine metaphase II (MII) oocytes on their in vitro viability and ultra-structural changes with two experiments. Experiment 1 examined the effect of vitrified oocytes on microtubule localization, mitochondrial morphology, chromosome organization and the developmental rate in IVF control and vitrified oocytes. Oocytes matured for 44 h were subjected to IVF (IVF control). Oocytes matured for 42 h were exposed to cryoprotectants (CPA control), followed by 2h culture, and subjected to IVF. Oocytes vitrified at 42 h post-maturation were warmed, cultured for 2h, and subjected to IVF (vitrified). Experiment 2 evaluated the effect of oocytes freezing on development of ICSI with and without activation and parthenotes. Fresh and vitrified oocytes were subjected to ICSI with and without electrical activation. Cleavage and blastocyst rates were significantly (P<0.05) lower in vitrified IVF, parthenote and ICSI embryos than those in fresh counterparts. Between ICSI embryos from fresh oocytes and vitrified oocytes, the rates of blastocyst were significantly higher (P<0.05) in activated group than the group without activation. Significant differences (P<0.05) were observed in normal spindle configuration of vitrified (43.5%) compared to control (81.0%) oocytes, but no significant difference was observed between CPA exposed and control groups. In conclusion, porcine oocytes at MII stage are very sensitive to vitrification with altered microtubule localization and mitochondrial organization thus resulting in impaired fertilization and embryo development.

Developmental rate and ploidy of embryos produced by nuclear transfer with different activation treatments in cattle.

Bovine oocyte activation is one of the essential elements that determine the success of nuclear transfer and the subsequent development of cloned embryos. Three methods for oocyte activation, including 5 microM ionomycin (5 min, Group 1) alone, ionomycin+1.9 mM 6-dimethylaminopurine (DMAP, 3h, Group 2), and ionomycin+10 microg/ml cycloheximide (CHX, 3h, Group 3) were compared for the development of embryos produced by somatic nuclear transfer (SCNT) to parthenotes and IVF counterparts. At 19-h post-activation/insemination (hpa/hpi), 27.5% of oocytes in Group 2 cleaved and this rate was greater (P<0.05) than other groups (Group 1, 2.1%; Group 3, 3.0%). None of the oocytes in the IVF control group cleaved at 19-22 hpi. At 24 hpa, the rates of cleavage of oocytes in Group 2 (52.1%) were greater (P<0.05) than those in Groups 1 and 3 (7 and 38.3%, respectively). Only six oocytes (3.3%) in the IVF control group cleaved at 24 hpi. The overall cleavage rates of oocytes in Group 2 (85.5%) at 48 hpa were greater (P<0.05) than other treatments, but it did not show any difference when compared with the IVF control group (75.0%). The development rate to two-cell stage embryos of Group 2 was consistently greater at all observation points followed by Groups 3 and 1. Similar results were obtained in SCNT embryos, but the rates of cleavage at 48 hpi and blastocyst development in Group 2 (68.4 and 16.3%, respectively) did not differ from Group 3 (63.0 and 13.1%, respectively). The chromosomal composition in the parthenotes and SCNT embryos differed (P<0.05) among treatments. In Groups 1 and 3, greater percentages of haploid parthenotes (86 and 71%, respectively) were observed. In contrast, 84% of parthenotes in Group 2 had abnormal ploidy (44% polyploid and 40% mixoploid). In the case of SCNT embryos, Groups 1 and 3 had greater percentages of diploid chromosomal sets (77 and 70%, respectively), whereas 54% in Group 2 were polyploid or mixoploid. These results indicate that DMAP treatment after ionomycin greatly increases the developmental rates of parthenotes, but did not differ in blastocyst development compare with CHX treatment. However, DMAP treatment increased the time-dependent cleavage rate to two-cell stage embryos. Further, it greatly enhanced the incidence of chromosomal abnormalities in parthenotes and SCNT embryos. Hence, it is concluded that CHX combined with ionomycin is more desirable than DMAP for oocyte activation during nuclear transfer in cattle.

DNA methylation levels in porcine fetal fibroblasts induced by an inhibitor of methylation, 5-azacytidine.

Removal of the somatic DNA methylation pattern from donor cells and remodeling of embryonic status have been suggested as integral processes for successful nuclear transfer (NT) reprogramming. This study has investigated the effects of 5-azacytidine (5-azaC), a DNA methylation inhibitor, on global methylation changes in porcine fetal fibroblasts (PFF); this may improve NT attributable to the potential reprogramming of the methyl groups. PFF in 5th passage cultures were treated with 0, 0.5, 1.0, 2.0, and 3.0 microM 5-azaC for 96 h; 5-azaC inhibited the growth at all tested concentrations. At the higher concentrations of 5-azaC used, cells appeared to exhibit morphological changes and to become apoptotic as observed by TUNEL assay. Thus, cells were negatively affected by 5-azaC. Differences in cellular ploidy were also observed at higher concentrations. Analysis showed no considerable changes in the proportion of cells at the G1-phase of the cell cycle with 5-azaC concentrations. The fractional part of the methylated DNA of these cells was significantly reduced by 5-azaC treatment. Confocal microscopy confirmed the inhibition of methylation levels in PFF with increased concentrations of 5-azaC. Exposure to 5-azaC altered the expression of genes involved in imprinting (IGF2) or pro-apoptosis (BAX), whereas there was a reduction in the expression of the main enzyme responsible for replicating the DNA methylation pattern (DNMT1) and anti-apoptosis (BCL2L1). Therefore, 5-azaC induces a relative reduction in methylation in PFF, and cells treated with 0.5 microM 5-azaC may have enhanced potential for porcine NT.

Effects of confluent, roscovitine treatment and serum starvation on the cell-cycle synchronization of bovine foetal fibroblasts.

The present study was designed to examine the effects of cell-cycle synchronization protocols, such as confluent, roscovitine treatment and serum starvation, in bovine foetal fibroblasts on synchronization accuracy at G0/G1, viability, apoptosis, necrosis and ploidy for use as a nuclei donor. The cells in 5-10 passages were randomly allocated into three treated groups. Cells were cultured either in Dulbecco's modified Eagle's medium (DMEM) + 10% foetal bovine serum (FBS) until 90% confluent (group 1, confluent), in DMEM + 10% FBS + 30 microM roscovitine for 12 h (group 2, roscovitine), or in DMEM + 0.5% FBS for 5 days (group 3, serum starvation). Most of the cells (>80%) in all groups were arrested at the G0/G1 stage. Although the rates did not differ, cells in group 1 showed an increased cell population arrested at the G0/G1 phase. Significantly (p < 0.05) higher rates of apoptosis occurred in group 3 than in group 1 and 2 (10% vs 6% and 6%, respectively). No differences in chromosomal abnormality were observed among groups. However, by increasing the number of cell culture passages up to 15, significantly (p < 0.05) higher chromosomal abnormality was observed than in 5 and 10 passages (39% vs 28% and 23%, respectively) in group 1. The results clearly indicated that bovine foetal fibroblasts could be effectively synchronized at G0/G1 stages by all the three different treatments, confluent, roscovitine and serum starvation. However, cells in confluent showed reduced apoptosis and necrosis when they underwent 5-10 passages, exhibiting increased percentage of cells with stable chromosome diversity. Hence, cells in confluent merit further studies before they could be used as nuclear donors.