Is there a future for spermatid injections?

Abstract

Microinjection of spermatids into oocytes has proven to be a successful assisted reproduction procedure in the animal model. In the human, low fertilization and cleavage to the 4-cell stage were reported after intracytoplasmic sperm injection (ICSI) with round spermatids. In comparison with a conventional ICSI-testicular sperm extraction (TESE) programme, the implantation rate after round spermatid injection is dramatically low. Different problems have been encountered during the development of the spermatid injection technique and they could be partially responsible for the lower outcome when using round spermatids. Compared with the round spermatid cells, spermatids in the elongation phase are easy to isolate and identify from other round cells present in a wet preparation. The morphological identification does not reveal anything about the viability or the genetic normality of the round spermatids. Severe testicular dysfunction may have consequences on the quality of the few spermatogenic cells present. Others factors, such as the pathology of the patient, play an important role in the successful treatment. Even if the results are extremely low, spermatid injection seems more favourable for men who have already proven their capacity to produce some spermatozoa. A spermatogenic block at the round spermatid level has led to early abortions, increasing the suspicion of the role of a genetic factor. In order for this technique to be safe for use in clinics, more intensive work is needed to improve the selection and handling of cells and to ascertain the genomic imprinting and gene expression necessary for embryonic development. Hence, when using immature cells for conception, the screening of the patient and the follow-up of the pregnancies and babies should be mandatory.

The employment of strontium to activate mouse oocytes: effects on spermatid-injection outcome

“…This has led to the advocacy of complete dismissal of ROSI (Silber et al 1997) and to the procedure being completely banned in the UK (Ezeh et al 1999). In the context of disappointing outcomes, critiques of ROSI's failings have ensued (Devroey 1998, Silber & Johnson 1998, Vanderzwalmen et al 1998, with focus being placed upon oocyte activation inadequacies in addition to genetic concerns.…”

Fourteen babies born after round spermatid injection into human oocytes

“…Since the first ROSI human babies were obtained by Tesarik et al (15,16), additional pregnancies have been reported (17)(18)(19). However, there have been very few similar reports in recent years, perhaps because many clinical investigators have become pessimistic as to the efficiency, safety, and practical value of ROSI (20)(21)(22)(23). Indeed, both the Practice Committee of American Society for Reproductive Medicine and the Practice Committee of Society for Assisted Reproductive Technology (24) considered ROSI as an experimental rather than a recommended practice.…”

Establishment of male-specific epigenetic information

“…These include a genetic risk due to the possible transmission of a genetic defect associated with the paternal infertility, as well as a risk linked to potential bepigeneticQ consequences on the development of the embryo and the future individual. Concerning the latter, it is worth noticing that successful fertilizations have been obtained by injecting spermatozoa with an abnormal nuclear structure, or immature spermatozoa, or even their precursors, the spermatids (Ogura and Yanagimachi, 1995;Tesarik et al, 1995;Vanderzwalmen et al, 1998;Ogura et al, 1999;Yanagimachi, 1999). Moreover, recent studies have pointed out possible epigenetic abnormalities in children conceived by ICSI (Cox et al, 2002;De Rycke et al, 2002;DeBaun et al, 2003).…”