The Effect of Phosphodiesterase Inhibitors on Improving the Outcomes of Assisted Reproductive Technologies

Abstract

In assisted reproductive technology (ART), phosphodiesterase (PDE) inhibitors such as pentoxifylline (PTX) and theophylline (THEO) are widely used to enhance sperm motility. By increasing intracellular cAMP, these agents stimulate movement, yet concerns persist regarding potential embryotoxicity. Robust experimental evidence is therefore required to balance their clinical utility against possible risks. This study investigated the developmental impact of PTX and THEO using a mouse model of human pre‑implantation development. Zygotes were microinjected with PTX or THEO using a technique that closely mimics intracytoplasmic sperm injection (ICSI), then cultured in vitro under standardised conditions. Embryo development was assessed alongside total cell number following propidium iodide staining. Multiple control groups, including non‑injected embryos, medium‑injected embryos, and PVP‑injected embryos, were included to distinguish compound‑specific effects from procedural artefacts.

Early developmental outcomes were broadly comparable across groups. There was no significant difference in cleavage rate between the groups.

Total cell‑number analysis showed that PTX‑injected embryos exhibited a significant reduction in total cell number compared with untreated controls. In contrast, THEO‑injected embryos displayed cell numbers indistinguishable from controls.

Time‑lapse imaging showed no significant morphokinetic differences between groups when normalised to pronuclear fading. Neither PTX nor THEO disrupted cleavage‑cycle duration or synchrony.

Taken together, these findings demonstrate that PTX and THEO differ in their effects on pre‑implantation development. Both compounds supported normal cleavage and blastocyst formation, and neither disrupted the fundamental kinetic architecture of early development. However, PTX exerted a clear suppressive effect on proliferative capacity, reducing total cell number. THEO, by contrast, appeared benign across all measured endpoints.