ROSI (round spermatid injection)

ROSI (round spermatid injection)

ROSI (round spermatid injection) is a method in which precursors of mature sperm obtained by ejaculated specimens or testicular sperm extraction (TESE) are injected directly into oocytes and used in the place of mature spermatozoa in the cases of last resort as treatment for male infertility.

Men with azoospermia are commonly referred to male fertility specialists who may recommend surgical sperm extraction procedures in order to obtain spermatozoa for use in fertilization. Unfortunately, even with these extraction procedures, many men do not possess mature spermatozoa which can be successfully isolated.

1 out of 100 healthy men is azoospermicand that about 70–80% of those are nonobstructive azoospermia cases. Micro‐TESE is the sole treatment to find spermatozoa. The incidence of detecting testicular spermatozoa is about 30–60%,but about half of those spermatozoa found are immotile or have deformities.

Among men with nonobstructive azoospermia where neither mature spermatozoa nor late-stage spermatids were isolated from testicular samples, it has been reported that approximately 30% of patients will possess round spermatids in their surgical samples.

The rationale of ROSI is that round spermatids  develop after two times of meiosis and have the same number of chromosomes and same contents of DNA as those of matured spermatozoa.

Round spermatid has a haploid set of chromosomes 23 and 1N DNA content just as a mature spermatozoa. So, if round spermatid can be injected directly into the oocyte with the same technique as ICSI, it can fertilize the oocyte and deliver a baby.

Round spermatid is found in the ejaculate or testis. Those  in ejaculate are considered to be an inadequate sample for ROSI in comparison with testicular one due to the high possibility of apoptotic change of round spermatid

Studies showed that the pregnancy rate per couple was 13.4% and delivery rate per couple was 8.1% .

ROSI has resulted in clinical pregnancies and live births, but success rates are considerably lower than those achieved with mature spermatozoa

ROSI appears to result in offspring without any unusual physical, mental, or epigenetic problems

Follow up of ROSI babies (physical and cognitive development) showed that their development was the same as naturally conceived babies except the baby’s response to parental interaction between 12-18 months, furthermore the weight gain of ROSI babies was the same as naturally conceived babies but we noticed that male babies were somehow lighter at the age of 1.5 years old compared to their naturally conceived counterparts, they eventually caught up at the age of 2 years old.

ROSI babies are not at increased risk of chromosomal/genetic or congenital anomalies and they give a proportion of infertile men the chance to propagate their genetic material throughout generations.

Dr Najeeb Layyous  F.R.C.O.G

Consultant Obstetrician, Gynecologist and Infertility Specialist