BEDFORD, MA, June 24, 2025 /24-7PressRelease/ -- The study, titled "Ambient Temperature Transport of Human Oocytes: An Unexpected Research Resource," explored the potential of immature oocytes from young egg donors at The World Egg and Sperm Bank in Phoenix, AZ. A total of 432 oocytes, collected from controlled ovarian stimulation cycles, were shipped overnight in a specialized transport medium designed to mimic the follicular environment. The medium included caffeine, dibutyryl cyclic-AMP, estrogen, progesterone, and, in some cases, zinc sulfate (ZnSO4). Remarkably, over 95% of the oocytes remained viable upon arrival, with many demonstrating meiotic progression or spontaneous activation after culture.
Key Findings:
High Viability: More than 95% of oocytes survived ambient temperature transport, whether supplemented with zinc or not, showcasing the robustness of the transport protocol.
Meiotic Competence: Transported oocytes exhibited meiotic progression, with some advancing to metaphase II or undergoing spontaneous activation, particularly when zinc was included in the transport medium.
Spontaneous Activation: Oocytes transported with zinc showed a higher incidence of spontaneous activation and cleavage activity, progressing to 2-, 4-, and even 8-cell stages during extended culture, as observed through time-lapse imaging.
Research Potential: The study highlights the potential of using "discard" oocytes—typically unsuitable for clinical use—as a valuable resource for studying oocyte biology and developing parthenogenetic stem cells, which could offer ethical and practical advantages over embryonic stem cells.
"This work demonstrates that immature human oocytes can be transported at ambient temperature without compromising their viability or research potential," said lead author Dr. Maria G. Gervasi, a collaborating Bedford Research Scientist. "These findings provide a novel, experimentally tractable resource that could transform our understanding of human oocyte biology and enhance stem cell research."
The transport protocol was designed for simplicity, requiring minimal effort from clinical teams. Oocytes were placed in cryotubes with the ambient temperature transport medium (ATTM), packaged in insulated Styrofoam boxes, and shipped overnight. Temperature sensors ensured conditions remained within a safe range (32–45°C). Upon arrival, oocytes were either fixed for immediate analysis or cultured for up to 5 days, with time-lapse and fluorescence imaging used to monitor viability, meiotic status, and activation.
The study also underscores the role of zinc in enhancing oocyte behavior. Oocytes transported with zinc exhibited increased spontaneous activation and cleavage, suggesting that zinc may influence meiotic maturation and early developmental processes. These findings align with prior research on zinc's role in reproductive physiology and warrant further investigation.
Implications for Reproductive Medicine and Stem Cell Research: This research addresses a critical gap in human oocyte studies, where access to viable research material has been limited. By repurposing immature oocytes from egg banking, the study offers a sustainable and ethical source for advancing assisted reproductive technologies (ART) and stem cell therapies. Potential applications include improving clinical outcomes for ART, understanding causes of meiotic arrest, and developing parthenote stem cells, which have fewer ethical concerns and reduced tissue antigen complexity compared to embryonic stem cells.
"We are grateful to The World Egg and Sperm Bank and the donors whose contributions made this research possible," said co-author Dr. Ann A. Kiessling of the Bedford Research Foundation. "This collaboration highlights the potential to transform discarded biological material into a powerful tool for scientific discovery."
Limitations and Future Directions: The study acknowledges variability in oocyte behavior, likely due to differences in donor responses to ovarian stimulation. Future research will focus on optimizing the transport medium and systematically studying patient-specific factors to enhance meiotic competence and activation outcomes. The researchers also aim to explore the mechanisms behind zinc's effects and the potential for scaling up parthenote stem cell derivation.
Availability: The study, published on June 21, 2025, is available online at https://doi.org/10.1007/s10815-025-03548-9. Supplementary materials, including time-lapse videos, can be accessed through the journal's website.
About Bedford Research Foundation: The Bedford Research Foundation is dedicated to advancing biomedical research, with a focus on reproductive biology and stem cell technologies. Supported by the ESHE Fund, the Foundation collaborates with leading institutions to address critical challenges in human health.
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