PubMed Health⌕ Search

Biomedical subjects

Michelle Lane

Publications and source records attributed to Michelle Lane.

26 records · Page 2Linked to original sources
PubMed2003

Cryo-survival and development of bovine blastocysts are enhanced by culture with recombinant albumin and hyaluronan.

Recombinant albumin can be used to supplement culture medium for the maturation and fertilization of bovine oocytes and subsequent embryo development to the blastocyst stage. Recombinant albumin was able to support blastocyst development at rates equivalent to that of bovine serum albumin (BSA) supplemented media. Supplementation of media containing recombinant albumin and citrate stimulated blastocyst expansion. Culture with recombinant albumin and citrate significantly increased the ability of the resultant blastocysts to re-expand and hatch following cryopreservation. The further addition of the glycosaminoglycan hyaluronan to the culture medium containing either BSA or recombinant albumin also increased the ability of blastocysts to survive cryopreservation. Inclusion of recombinant albumin and hyaluronan in culture media facilitates the development of physiological defined culture conditions. For bovine embryos this has implications for both research and commercial applications where defined reproducible conditions are desirable.

Albumins↗
PubMed2003

Changing the start temperature and cooling rate in a slow-freezing protocol increases human blastocyst viability.

OBJECTIVE: To determine the effect of start temperature and cooling rate of a slow freezing protocol on human blastocyst viability. DESIGN: Controlled-rate freezing of human blastocysts using different start temperatures and cooling rates. SETTING: Private assisted reproductive technology unit. PATIENT(S): Patients donated with consent cryopreserved pronucleate embryos. INTERVENTION(S): Culture of thawed pronucleate embryos in G III series media, containing hyaluronan, followed by cryopreservation of 36 blastocysts with subsequent noninvasive analysis of embryo metabolism. MAIN OUTCOME MEASURE(S): Pyruvate and glucose consumption and blastocyst reexpansion and quality. RESULT(S): Glucose consumption and blastocyst reexpansion after thaw were significantly higher when a start temperature of -6 degrees C and a cooling rate of 0.5 degrees C/min to -32 degrees C were used compared with a start temperature of 20 degrees C and a cooling rate of 2 degrees C to -6 degrees C, followed by cooling at 0.3 degrees C to -35 degrees C. Pyruvate uptake after thaw was not affected by the freezing procedure. Clinical use of the lower start temperature and quicker cooling rate, combined with culture in hyaluronan-based media, has led to the establishment of a 30% implantation rate. CONCLUSION(S): Human embryos cultured to the blastocyst stage in hyaluronan-based sequential media are readily cryopreserved and maintain their viability after thaw.

Blastocyst↗
PubMed2003

Use of G1.2/G2.2 media for commercial bovine embryo culture: equivalent development and pregnancy rates compared to co-culture.

The expanded application of commercial bovine IVM, IVF, and IVC systems is dependent on the ability to produce embryos in culture that are capable of producing normal pregnancies. Because serum containing culture systems can induce neonatal and fetal problems there exists a definite need for a serum-free culture system that produces viable blastocysts. This study demonstrated that the physiological sequential media system G1.2/G2.2 could produce bovine blastocysts at rates equivalent to co-culture. Additionally, these blastocysts had equivalent or increased cell numbers and inner cell mass development. Blastocysts produced in the G1.2/G2.2 culture system produced pregnancies following both fresh transfer and cryopreservation at equivalent rates to co-culture. Finally, this study demonstrated that the media system G1.2/G2.2 could be used in a commercial OPU transfer program without any loss in the numbers of blastocysts produced or the numbers of pregnancies resulting following transfer from either fresh or cryopreserved blastocysts.

Animals↗
PubMed2003

Towards a single embryo transfer.

The delivery of a single, healthy child is the desired outcome of human assisted reproduction techniques. To attain this goal, there is an increasing movement toward single embryo transfer. The question is, therefore, at what stage to transfer the human embryo back to the uterus? Maximal implantation rates reported to date have come from the transfer of blastocysts (70% fetal heart rate). In any given cycle of treatment the probability of conceiving a child will be further increased by the ability to cryopreserve those embryos not transferred. It is therefore proposed that the transfer of a single blastocyst is the best treatment for most patients, given the high implantation rates of fresh transfers, and that it is now possible to cryopreserve supernumerary blastocysts effectively. The next decision is how to culture the human embryo to the blastocyst stage. The use of sequential culture media, designed not only to allow for changes in nutrient requirements and metabolism as development proceeds, but also to minimize intracellular trauma, can facilitate the development of highly viable blastocysts. Sequential culture media have been evaluated against a single-step culture system. It has been shown that sequential media (G1/G2) produce more viable blastocysts than those embryos cultured in a single medium formulation (simplex optimized medium with elevated potassium and with amino acids, KSOM(AA)) throughout the preimplantation period. Furthermore, even if KSOM(AA) is used for embryo culture, it is essential that the medium be renewed after 48 h to alleviate the toxicity associated with ammonium build-up. Of great significance, embryos cultured in sequential media G1 and G2 have the same rate of development as embryos developed in vivo.

Animals↗
PubMed2002

Vitrification of human blastocysts using the cryoloop method: successful clinical application and birth of offspring.

PURPOSE: The purpose was to investigate vitrification of human blastocysts using the cryoloop. METHODS: Thirteen couples elected to have blastocysts cryopreserved via vitrification (N = 54 blastocysts). Embryos were exposed to two vitrification solutions, pipetted onto the cryoloop then plunged into liquid nitrogen. On the day of embryo replacement, blastocysts were warmed by passage through three dilution media, and rinsed into culture medium. RESULTS: Four couples returned for cryopreserved embryo replacement. Fifteen blastocysts were warmed; all 15 (15/15; 100%) were recovered. Fifteen (15/15; 100%) blastocysts were deemed viable, and 13 were replaced. Two replacements did not result in pregnancy; one resulted in clinical pregnancy with a blighted ovum; one resulted in clinical pregnancy with the live, term birth of a healthy male infant. Two of 13 embryos implanted yielding an implantation rate of 15.4%. CONCLUSIONS: These preliminary data suggest that blastocysts can be successfully vitrified using the cryoloop method.

Blastocyst↗
PubMed2002

Addition of ascorbate during cryopreservation stimulates subsequent embryo development.

BACKGROUND: Embryo development following cryopreservation is reduced compared with fresh embryos. One of the traumas that cryopreservation imparts on embryos is an increase in oxidative stress. Therefore, this study investigated the effects of the addition of the antioxidant ascorbate to the cryopreservation solutions on subsequent embryo development. METHODS: Mouse embryos at the 2-cell and blastocyst stages were either slow-frozen or vitrified in solutions containing either no ascorbate or 0.1 or 0.5 mmol/l ascorbate. The effects on the levels of hydrogen peroxide and subsequent embryo development and physiology were assessed. RESULTS: Addition of ascorbate to the cryopreservation solutions reduced the levels of hydrogen peroxide in embryos. Furthermore, addition of 0.1 mmol/l ascorbate significantly enhanced inner cell mass development in blastocysts. Embryos cryopreserved with ascorbate had significantly lower levels of lactate dehydrogenase leakage, and increased rates of metabolism compared with those cryopreserved in the absence of ascorbate. The benefits of ascorbate were significantly greater in embryos that were slow-frozen compared with those that were vitrified. CONCLUSIONS: These data indicate that the addition of 0.1 mmol/l ascorbate to the cryopreservation solutions for the mammalian embryo would be of significant value.

Animals↗
PubMedDate not supplied

Physiology and culture of the human blastocyst.

The human embryo undergoes many changes in physiology during the first 4 days of life as it develops and differentiates from a fertilized oocyte to the blastocyst stage. Concomitantly, the embryo is exposed to gradients of nutrients within the female reproductive tract and exhibits changes in its own nutrient requirements and utilization. Determining the nature of such nutrient gradients in the female tract and the changing requirements of the embryo has facilitated the formulation of stage-specific culture media designed to support embryo development throughout the preimplantation period. Resultant implantation rates attained with the culture and transfer of human blastocysts are higher than those associated with the transfer of cleavage stage embryos to the uterus. Such increases in implantation rates have facilitated the establishment of high pregnancy rates while reducing the number of embryos transferred. With the introduction of new scoring systems for the blastocyst and the non-invasive assessment of metabolic activity of individual embryos, it should be possible to move to single blastocyst transfer for the majority of patients.

Blastocyst↗