Experimental Round Spermatid Injection (ROSI) to Treat Infertile Couples

Azoospermia is defined as the absence of sperm in the ejaculate. Around 1% of general population suffers from azoospermia. Men who were rendered infertile due to a non-obstructive azoospermia, who have been subjected to Testicular Sperm Extraction (TESE) surgery and found to be lacking elongated spermatids or spermatozoa, are commonly advised to consider utilizing a sperm donor or apply for adoption. It is reported that ~30% of men with non-obstructive azoospermia lack elongated spermatids and spermatozoa but may still produce round spermatids (less mature form of haploid germ cells) in their testicles. Round Spermatid Injection (ROSI) technology to fertilize oocytes is not a brand-new technology, however, it is plagued with notoriously low efficiency. Despite this limitation, it has been reported that most of these patients still desire to have the ROSI procedure instead of applying directly for other options, i.e. sperm donation or adoption.

High failure rate of traditional ROSI has been attributed to a few potential causes:

1. Incorrect selection of round spermatids (to distinguish from diploid spermatogonia cells)
2. Using round spermatids that were already in the process of degeneration
3. Incomplete imprinting in the round spermatid
4. Incomplete activation of oocytes Recently Tanaka and colleagues in Japan established a new ROSI method and reported over 90 babies born via this method1. They described a new method of round spermatid selection and oocyte activation using NEPA21 super electroporator (10 minutes prior to round spermatid injection).

Babies born from this new ROSI method in Japan have been evaluated for developmental and cognitive differences for 2 years1. Babies conceived with ROSI were found to have a shorter gestation times, and lower body weight at 12 and 18 months when compared to their naturally conceived counterparts, but also showed an increased birth weight and showed no body weight differences at 24 months of age. No diseases resulting from genetic anomalies have been reported thus far, but the relatively small sample sizes present in the literature needs to be tested in larger cohorts. Therefore, this effective ROSI method should still be considered as an "experimental fertility treatment".