In Experiment 1, to determine the developmental potential of buffalo oocytes of different qualities, compact cumulus-oocyte complexes (COCs) with an unexpanded cumulus mass, and with homogeneous ooplasm were classified as Grade 1 (with > or =5 layers of cumulus cells) and Grade 2 less than 4 layers of cumulus cells). Grade-3 oocytes were either without cumulus cells or with expanded cumulus mass, and with irregular ooplasm. The oocytes were matured for 24 h at 38.5 degrees C, 5% CO2 in air in maturation medium (10% fetal bovine serum (FBS) in TCM-199 supplemented with 5 microg mL(-1) follicle stimulating hormone-P). The nuclear maturation and cleavage rates, and the proportion of cleaved embryos which developed to morula and blastocyst stage were in the order Grade 1>Grade 2>Grade 3 (P < 0.05). For Experiment 2, the maturation medium consisted of TCM-199 supplemented with one of the following sera at 10% concentration: (1) buffalo oestrus serum (BOS), (2) superovulated buffalo serum (SBS), (3) fetal bovine serum (FBS) and (4) steer serum (SS). After in vitro fertilization (IVF), the oocytes were co-cultured with buffalo oviductal epithelial cells in TCM-199 containing the respective sera at 10% concentration for the subsequent 9 days. The extent of cumulus expansion and nuclear maturation were not different among different groups. The cleavage rates were lower (P < 0.05) with FBS than with BOS, SBS and SS. The proportion of cleaved embryos which developed to blastocyst stage was higher (P < 0.05) with SBS than with BOS, FBS and SS.

This study was carried out to isolate and characterize buffalo embryonic stem (ES) cell-like cells from in vitro-produced embryos. Inner cell mass (ICM) cells were isolated either mechanically or by enzymatic digestion from 120 blastocysts whereas 28 morulae were used for the isolation of blastomeres mechanically. The ICM cells/ blastomeres were cultured on mitomycin-C-treated feeder layer. Primary cell colony formation was higher (P < 0.05) for hatched blastocysts (73.1%, 30/41) than that for early/expanded blastocysts (25.3%, 20/79). However, no primary cell colonies were formed when blastomeres obtained from morulae were cultured. Primary colonies were formed in 14.1% (12/85) of intact blastocyst culture, which was significantly lower (P < 0.05) than that of 41.6% for ICM culture. These colonies were separated by enzymatic or mechanical disaggregation. Using mechanical disaggregation method, the cells remained undifferentiated and two buffalo ES cell-like cell lines (bES1, bES2) continued to grow in culture up to eight passages. However, disassociation through enzymatic method resulted in differentiation. Undifferentiated cells exhibited stem cell morphological features, normal chromosomal morphology, and expressed specific markers such as alkaline phosphatase (AP) and Oct-4. Cells formed embryoid bodies (EBs) in suspension culture; extended culture of EBs resulted in formation of cystic EBs. Following prolonged in vitro culture, these cells differentiated into several types of cells including neuron-like and epithelium-like cells. Furthermore, the vitrified-thawed ES cell-like cells also exhibited typical stem cell characteristics. In conclusion, buffalo ES cell-like cells could be isolated from in vitro-produced blastocysts and maintained in vitro for prolonged periods of time.

Hand-made cloning (HMC) has proved to be an efficient alternative to the conventional micromanipulator-based technique in some domestic animal species. This study reports the development of an effective culture system for in vitro culture of zona-free cloned buffalo (Bubalus bubalis) embryos reconstructed using adult skin fibroblast cells as nucleus donor. Cleavage and blastocyst rates observed were 52 and 0% in modified Charles Rosenkrans 2 (mCR2), 61 and 4.6% in modified Synthetic Oviductal Fluid (mSOF), and 82 and 40.3% in Research Vitro Cleave (RVCL; Cook, Australia) medium, respectively. Similarly, higher blastocyst rates (24.5 +/- 4.1%) were observed when zona-free parthenotes were cultured in RVCL medium. Culturing zona-free cloned buffalo embryos on flat surfaces (FS) yielded significantly higher (p < 0.05) blastocyst rates than Well of the Wells (WOW) or microdrops (MD). Furthermore, development in WOW was found to be significantly better than MD culture. The quality of HMC blastocysts was examined using differential staining. This study establishes the application of zona-free nuclear transfer procedures for the production of hand-made cloned buffalo embryos and the development of efficient culture system and appropriate media requirements for enhancing their preimplantation development.

Somatic cells were isolated from cryopreserved semen of 4 buffalo bulls, 3 of which had died over 10 years earlier, and were established in culture. The cells expressed cytokeratin-18, keratin and vimentin indicating that they were of epithelial origin. The cells were used as nuclear donors for hand-made cloning for producing buffalo embryos. The blastocyst rate and quality, as indicated by apoptotic index, were comparable among embryos produced using cells obtained from fresh or frozen-thawed semen or those obtained from conventional cell sources such as skin. Examination of the epigenetic status revealed that the global level of H3K27me3 but not that of H3K9/14ac and H4K5ac differed significantly (P<0.05) among cloned embryos from different bulls. The relative mRNA abundance of HDAC1, DNMT1, P53 and CASPASE 3 but not that of DNMT3a differed in cells and in cloned embryos. Following transfer of 24 cloned embryos produced from fresh semen-derived cells to 12 recipients, one calf weighing 55 kg, which is now 6 months of age and is normal, was born through normal parturition. Following transfer of 20 embryos produced from frozen-thawed semen-derived cells to 10 recipients, 2 became pregnant, one of which aborted in the first trimester; the calf born was severely underweight (17 kg), and died 12 h after birth. The ability of cells derived from fresh and frozen-thawed semen to produce live offspring confirms the ability of these cells to be reprogrammed. Our findings pave the way for restoration of highly precious progeny-tested bulls, which has immense economic importance, and can also be used for restoration of endangered species.

A culture system capable of sustaining self-renewal of buffalo embryonic stem (ES) cell-like cells in an undifferentiated state over a long period of time was developed. Inner cell masses were seeded on KO-DMEM+15% KO-serum replacer on buffalo fetal fibroblast feeder layer. Supplementation of culture medium with 5 ng/mL FGF-2 and 1000 IU/mL mLIF gave the highest (p<0.05) rate of primary colony formation. The ES cell-like cells' colony survival rate and increase in colony size were highest (p<0.05) following supplementation with FGF-2 and LIF compared to other groups examined. FGF-2 supplementation affected the quantitative expression of NANOG, SOX-2, ACTIVIN A, BMP 4, and TGFβ1, but not OCT4 and GREMLIN. Supplementation with SU5402, an FGFR inhibitor (≥20 μM) increased (p<0.05) the percentage of colonies that differentiated. FGFR1-3 and ERK1, K-RAS, E-RAS, and SHP-2, key signaling intermediates of FGF signaling, were detected in ES cell-like cells. Under culture conditions described, three ES cell lines were derived that, to date, have been maintained for 135, 95, and 85 passages for over 27, 19, and 17 months, respectively, whereas under other conditions examined, ES cell-like cells did not survive beyond passage 10. The ES cell-like cells were regularly monitored for expression of pluripotency markers and their potency to form embryoid bodies.