FIRST REGISTERED PILOT TRIAL TO VALIDATE THE SAFETY AND EFFECTIVENESS OF MATERNAL SPINDLE TRANSFER TO OVERCOME INFERTILITY ASSOCIATED WITH POOR OOCYTE QUALITY

Abstract

Poor quality oocytes frequently fail to fertilise or produce embryos that arrest during their first days of culture in vitro. Oocyte cytoplasmic dysfunctions (including, but not limited to mitochondria) have been indicated as a major cause of this problem. Since maternal spindle transfer (MST) allows replacement of the entire cytoplasm of an affected oocyte, it holds promise for the enhancement of embryonic development. Recent studies in the mouse and in human oocytes donated for research have confirmed the technical feasibility of MST and provided reassurance concerning safety. Here we present results from the first registered pilot trial aiming to reveal whether MST has potential to overcome infertility caused by poor oocyte quality. This pilot trial (ISRCTN 11455145) was restricted to 25 patients, selected based on their multiple previous failed IVF attempts, in each case associated with massive embryo development arrest. Female age over 40y/o and severe male factor were exclusion criteria. Procedures were authorized by the National Authority of Assisted Reproduction (437/23.9.2016) and approved by the Hospital’s IRB. Informed consent was obtained from patients and donors to conduct all procedures and follow-up the children born. The meiotic spindle from patient’s oocytes was isolated in a minimal cytoplasmic volume and transferred to a previously enucleated donor oocyte. MST oocytes were inseminated by ICSI and cultured up to 6 days in a time-lapse incubator. Good morphology blastocysts underwent biopsy, aneuploidy testing and analysis of mitochondrial DNA (mtDNA) carryover levels. SNPs analysis and DNA fingerprints were used to confirm the origin of the nuclear genome and mtDNA in biopsied samples, amniotic fluid and somatic tissues of resulting children. A total of 25 MST cycles were performed in patients with an average age of 37.1 y/o and a mean number of previous failed IVF attempts of 5.7 (min 3 and max 11). The mean number of MII oocytes used for MST per patient was 4.4. MST was applied successfully in 113 of 123 oocytes (91.9%) used. Normal fertilization was confirmed in 76.1% (86/113) of injected oocytes and 52 of these developed into good quality blastocysts (60.5%). Genetic screening revealed 50% (26/52) of embryo biopsy specimens to be euploid and mtDNA carryover levels <1%. In 16/25 cases, at least one euploid blastocyst of good morphology was obtained. Thus far, single blastocyst transfers were performed in 9 patients, resulting in 6 clinical pregnancies (66.7%). Two patients have delivered a healthy child and 3 more pregnancies are ongoing. Genetic analyses of the biopsied cells, amniotic fluid and samples collected after birth (blood, urine, saliva, cord blood, placenta) confirmed the parentage of the children and the origin of the donated mtDNA. Follow-up studies are being performed on the children born. Given the difficult reproductive history of the patients, results are encouraging. However, more carefully controlled pilot trials and follow-up studies are needed to provide more insights into the efficacy of MST to overcome infertility.