Men with no spermatozoa may benefit by combining round spermatid injection (ROSI) and artificial oocyte activation (AOA).
Injection of round spermatids in patients with non-obstructive azoospermia (NOA) yields generally poor pregnancy and life birth outcomes compared to regular ICSI using mature sperm, although around 100 healthy babies have been born as a result of ROSI. Some recent studies in mice, however, have found that injection of round spermatids can produce epigenetic modifications in embryos resulting from ROSI.
This review by Yong Tao, published in Reproductive Biomedicine Online, highlights that some evidence suggests that the low success of ROSI, may be due to the absence of oocyte activation and looks at various techniques applied to compensate for this, including calcium ionophore exposure, vigorous cytoplasmic aspiration and electroporation.
Tao concludes by stating that due to outcomes remaining suboptimal by combining ROSI and AOA, the technique should not yet be offered routinely. Further research is necessary, which could allow ROSI to become a valid technique for patients with NOA.
Reference: 1. Tao Y. Oocyte activation during round spermatid injection: state of the art. Reprod Biomed Online. 2022 Aug;45(2):211-218. doi: 10.1016/j.rbmo.2022.03.024. Epub 2022 Apr 1. PMID: 35534395.