Researchers at Tel Aviv University have developed a new imaging method that enables detailed three-dimensional mapping of live human sperm cells without damaging them or using chemical stains, a breakthrough they say could improve sperm selection for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).
The research was led by Prof. Natan T. Shaked of the School of Biomedical Engineering at the Iby and Aladar Fleischman Faculty of Engineering, with support from the Zimin Institute for Engineering Solutions Advancing Better Lives.
Current sperm selection for assisted reproduction relies largely on two-dimensional microscopy and the visual assessment of embryologists. Because sperm cells are nearly transparent, their internal structure cannot be directly examined, while chemical staining cannot be used because the cells must remain viable for fertilization.
The new technique combines optical tomography with interferometric imaging to generate high-resolution, three-dimensional images of live sperm cells as they swim freely. By mapping each cell’s refractive index, the system reveals internal structures that cannot be observed using existing clinical imaging methods.
Using the technology, the researchers produced detailed refractive-index maps of live human sperm cells and identified key intracellular structures, including the nucleus and the acrosome, the cap-like structure containing enzymes that allow sperm to penetrate the egg. The method also visualized the midpiece and regions associated with the centrioles, which play an important role in embryo development.
To validate the findings, the researchers combined the label-free imaging approach with fluorescence microscopy during the study. The findings were published in the journal Biomedical Optics Express.
The team also incorporated an artificial intelligence model trained on spatial, morphological and textural features extracted from the three-dimensional images. According to the researchers, the model identified intracellular structures with 89% sensitivity and 94% specificity, demonstrating the technology’s potential for automated sperm assessment in future clinical applications.
“Our goal is to provide fertility specialists with information that has never before been available,” said Shaked. “Instead of relying solely on the external appearance of a sperm cell, clinicians may eventually be able to evaluate its internal structure without compromising its viability.”
“Such information could enable more informed sperm selection and potentially improve the success rates of assisted reproduction,” he added.
The research team is now investigating whether the technology can detect DNA fragmentation in sperm cells, which is associated with reduced male fertility and lower IVF success rates. If confirmed in future studies, the researchers say the method could become an important tool for fertility diagnostics and personalized reproductive medicine.
According to the researchers, male factors contribute to approximately half of all infertility cases worldwide, making accurate and objective sperm assessment a major challenge in reproductive medicine.
The research results have been licensed to a commercial company under a licensing agreement with Tel Aviv University for the development of sperm-selection technology.
Source:
www.jpost.com
