In vitro fertilization (IVF) is the standard clinical treatment for infertility, which is a growing global health issue with psychological, social, and economic implications. DNA fragmentation of the sperm used in IVF treatments deterministically lowers the fertilization rate, causes embryo arrest in development, increases the miscarriage rate, and results in genetic disorders in the offspring. Current clinical practice of sperm selection either destroys the sperm for invasive DNA assessment or assumes that sperm motility and morphology are correlated with sperm DNA integrity. However, this correlation has never been proved due to the lack of single-cell manipulation and characterization techniques.
Targeting non-invasive selection of high DNA integrity sperm, this thesis focuses on (1) developing enabling robotic manipulation techniques for pick-place of single sperm for subsequent DNA analysis, and (2) establishing, for the first time, the correlation between sperm motility and morphology parameters and the same sperm's DNA integrity. Closed-loop visual servo control algorithms were developed to adjust sperm position and orientation, based on which robotic immobilization of motile sperm were achieved via two approaches: tapping the sperm tail with a micropipette or firing laser pulses to ablate the motor proteins on the sperm tail. Computer vision algorithms were also developed to non-invasively measure sperm motility and morphology parameters in real-time. The same sperm, with its motility and morphology characteristics recorded, was transferred for DNA integrity analysis. These robotic techniques not only free human from tedious labor operation, but also bring state of the art population-based sperm analysis to the single-cell level. Experimental results confirmed the long-hypothesized correlation that sperm with normal motility and normal morphology have low DNA fragmentation. Finally, based on the established correlation, a set of quantitative criteria was formulated for automated, objective, and non-invasive selection of sperm with high DNA integrity.Ph.D
