Unraveling sperm kinematic heterogeneity with machine learning.

The management of data from computer-aided sperm analysis (CASA) systems is crucial for understanding sperm motility. CASA systems generate motility parameters derived from tracking individual sperm cells, producing raw data as spermatozoa coordinates, which form the basis for sperm trajectory construction. These parameters and trajectories allow statistical descriptions of motility and identification of sperm heterogeneity. The substantial information provided by CASA enables the application of artificial intelligence (AI) techniques to interpret their biological significance. However, the type and format of CASA data, whether raw or condensed, pose challenges for analysis using conventional statistical methods. Advances in machine learning and deep learning have addressed these limitations by leveraging motility parameters and trajectory representations for automated classification and clustering of motility patterns. These methods, including supervised and unsupervised learning, have been employed to identify kinematic subpopulations within sperm samples, offering deeper insights into sperm dynamics. Open-source tools and CASA systems have facilitated this progress by providing accessible platforms for AI applications in sperm motility analysis. Although the use of machine learning in this field remains limited, integrating CASA-derived data with AI techniques shows potential for automating sperm classification and identifying motility patterns, advancing reproductive biology and fertility assessments. This work reviews the traditional use of CASA data, the analytical constraints, and the promising role of machine learning in enhancing the understanding of the heterogeneity of sperm kinematics.