Z. Rosenwaks’s research while affiliated with Reproductive Medicine Associates of New York and other places

Study question Is there a way to assess seminal plasma of NOA men to predict a successful sperm retrieval at testicular biopsy? Summary answer Multi-omics approach in seminal plasma of NOA men provides reliable prediction on the spermatogenic activity within the seminiferous tubule. What is known already Microdissection testicular sperm extraction (m-TESE) in NOA men successfully retrieved spermatozoa in about 60% of the cases. While several algorithms have been investigated aiming at estimating spermatogenic progress such as age, serum FSH, inhibin B, and genetics, there is no specific assay that can do so reliably. Even histopathology is often inconclusive while equally invasive. Recently, epigenetic analysis on testicular biopsy specimens has shown a differential gene expression in relation to the origin of azoospermia and spermatogenic function (Cheung, et al, 2024, in press). Study design, size, duration Over a 4-year period, twenty-eight men were deemed azoospermic following several failed extensive semen analyses. Transcriptomic analysis was performed by RNAseq on seminal fluid and the specific gene expression were evaluated and compared. In addition, DNAseq and proteomics were carried out to confirm our findings. These patients then underwent micro-TESE by a single surgeon and were divided into two cohorts based on whether spermatozoa was successfully retrieved or not. Participants/materials, setting, methods RNA and DNA were isolated from seminal plasma using a commercial kit and sequenced by Illumina HiSeq3000/4000 platform. Differentially expressed genes (DEGs) were assessed and compared to a fertile donor control using DESeq2 and Gene Ontology analysis. An absolute log2fold change of > 1 and a P-value of < 0.0005 were considered statistically significant. Gene mutations were detected by CLC Genomic Server 9.0. Main results and the role of chance Transcriptomic in 28 ejaculates from iNOA men browsed 21,855 genes against a fertile donor. Of 3,505 imbalanced genes, 12 were consistently imbalanced in 12 men, while 19 genes were imbalanced in remaining 16. Among the 2 cohorts, 8 common imbalanced genes were found. Particularly TPTE2, a testis-specific gene that regulates spermatogenesis, was overexpressed in 10/12 men (OE-12-cohort), while underexpressed in the remainder 16 (UE-16-cohort). DNAseq showed that TPTE2 was conserved in the OE-12-cohort, while exhibiting a frameshift mutation in the UE-16-cohort. Most interestingly, NEU1, a gene involved in acrosome development and fertilization, was found to be consistently and concurrently overexpressed in the OE-12-cohort, while being convserly underexpressed in all the men in the UE-16 cohort. DNAseq confirmed the NEU1 gene exhibited a synonymous mutation in the OE-12 and a frameshift mutation in the UE-16-cohort. About 1-2 months after the DEG analysis was completed, all of the patients underwent m-TESE. The 12 men from the OE-12-cohort all had successful retrieval of spermatozoa at m-TESE, conversely the 16 men from the UE-16-cohort all consistently failed to yield spermatozoa at testicular surgery in spite of extensive search for several hours and by multiple embryologists. Moreover, histopathology confirmed spermatogenic status in both OE-12&UE-16-cohorts. Limitations, reasons for caution Using non-invasive RNAseq and DNAseq on the seminal plasma has allowed us to identify DEGs that may be used to predict whether a patient with iNOA would have a successful or failed sperm retrieval with micro-TESE. However, these results are preliminary and should be further validated in larger study cohort. Wider implications of the findings Transcriptomics on the ejaculates of men with iNOA represents a noninvasive tool to detect presence of residual spermatogenesis. If confirmed by further studies, this precision medicine method may be utilized in order to properly counsel patients regarding their future prognosis. Trial registration number Not applicable

Study question Can poor fertilization with testicular spermatozoa be rescued by oocyte activation? We propose a more physiological approach to the standard method. Summary answer Couples who utilized testicular spermatozoa benefitted from assisted oocyte activation (AOA), particularly when a more physiological approach such as recombinant human phospholipase-C-zeta (rhPLCζ) was utilized. What is known already ICSI overcomes sperm acrosomal dysfunction and other inherent defects of the male gamete. However, partial or complete fertilization failure may still occur, often attributable to the absence of PLCζ. These cases are often treated by calcium ionophore, a very popular method that is considered quite safe, however it still raises concerns because it induces intracellular calcium oscillations in a very aspecific manner. Testicular spermatozoa are particularly at risk of suboptimal fertilization; therefore, the availability of a more physiological method would be welcome. Study design, size, duration Over a period of 12 months, 21 couples utilizing testicular spermatozoa for ICSI, that resulted in poor fertilization, were identified and treated in subsequent ICSI cycles with assisted oocyte activation (AOA), either by exposure to ionomycin or co-injection of rhPLCζ at the time of ICSI. Embryology and clinical outcomes were recorded and compared between the two AOA methods as well as the couples’ historical and subsequent cycles. Participants/materials, setting, methods Couples with a history of poor/absent fertilization after undergoing ICSI using testicular spermatozoa were counseled for AOA in subsequent cycles (IRB 0712009553). For consenting couples, AOA was performed either by exposing post-ICSI oocytes to 50mM of ionomycin (Ionomycin-AOA), or by co-injecting spermatozoa with 0.4pL of rhPLCζ (5mg/mL) during ICSI (rhPLCζ-AOA). Fertilization, embryo development, and clinical outcomes were compared between the couples’ historical and AOA cycles. Main results and the role of chance We included 21 couples (maternal age, 35.1±4 yrs; paternal age, 36.8±7 yrs). Female partners all had negative infertility workups that consisted of a comprehensive review of their medical history as well as a targeted physical examination and tests assessing ovarian reserve, ovulatory function, and absence of uterine and tubule structural abnormalities. The couples underwent 53 historical ICSI cycles using poor testicular spermatozoa (concentration, 0.04±0.1x106/ml, 0.5±1% motility) that yielded a 22.5% (94/417) fertilization and only an 11.5% (3/26) clinical pregnancy rate. All couples subsequently underwent ICSI-AOA cycles. Fourteen couples (maternal age, 35.5±4 yrs; paternal age, 37.6±6 yrs) who were treated with Ionomycin-AOA obtained a higher fertilization of 44.4% (99/223) (P<0.00001), which resulted in a clinical pregnancy rate of 26.3% (5/19). Thus far, four couples have delivered 1 boy and 3 girls, with no major or minor congenital malformations. The remaining 7 couples (maternal age, 35.8±4 yrs; paternal age, 37.9±7 yrs) underwent subsequent ICSI cycles with rhPLCζ-AOA, which yielded a remarkably higher fertilization of 50.0% (50/134) (P<0.00001). These couples went on to achieve a clinical pregnancy rate of 27.3% (3/11), resulting in the delivery of 1 girl and 2 boys. Initial follow-up has confirmed normal neonatal development. Limitations, reasons for caution The effectiveness of AOA in ICSI cycles with testicular spermatozoa is very encouraging, particularly when a more physiological method is utilized. Nonetheless, these findings need to be validated in a larger cohort, confirming successful outcome and children health. Wider implications of the findings ICSI utilizing surgically retrieved spermatozoa, particularly testicular, are plagued by suboptimal fertilization, and using AOA may represent a way to normalize the generation of conceptuses. Moreover, a broader adoption of AOA would certainly benefit from the use of a recombinant cytosolic factor normally present in the sperm perinuclear theca. Trial registration number n/a

Study question Can de novo male gamete from embryonic stem cell contribute to the full pre-implantation development? Summary answer Gametes generated after 29 days of differentiation in our three-dimensional (3D) culture system can support consistent fertilization and normal embryo development to the blastocyst stage. What is known already In regenerative medicine, several 3D culture systems have been proposed and are capable of producing functional tissue implants. In reproductive biology, recent studies have reported preliminary success in generating functional de novo gametes through soft-agar culture and testicular organoids from mouse embryonic stem cells. However, in order to achieve successful fertilization and satisfactory embryo development, an heterologous transplantation in a host seminiferous tubule is required to allow proper spermiogenesis to obtain functional gametes. Here we attempt to perform neogametogensis in a novel 3D niche to generate de novo gamete ready to be used for ICSI. Study design, size, duration Mouse ESCs were first cultured on a gelatin coated 6-well plate with fibroblasts in monolayer and later spherified using sodium alginate. Spheres were submerged in specifically designed conditioned media to encourage differentiation of the mESCs into germ-like cells. Over the course of differentiation, cells were assessed for germ cell differentiation biomarkers. Considering that a normal spermatogenesis occur in 30 days, utilization of the de novo gametes was planned for day-15, 22, 29 and 36. Participants/materials, setting, methods Mouse ESCs were differentiated by submerging the spheres in EpiLC medium containing Activin A, bFGF and KSR for 3 days followed by PGCLC medium containing BMP4, LIF, SCF and EGF for up to 36 days. Differentiation was assessed for markers DAZL (spermatogonium), VASA (spermatocyte), BOULE (post-meiotic stage) and acrosin (spermatid). Differentiated cells were then injected into oocytes and activated by calcium ionophore. Embryo development was monitored in a time-lapse incubator. Main results and the role of chance The evaluation of germline-specific markers through immunofluorescence revealed consistent levels of Vasa expression, a ubiquitous germline marker, with percentages at 15% on day-3, 18% on day-10, 17% on day-15, 19% on day-22, 20% on day-29, and 13% on day-36. Dazl, a specific marker for spermatogonia, exhibited a peak expression of 45% on day-10 in spherified cells. Boule, expressed by secondary spermatocytes, reached its highest level of 10% on day-15 but progressively decreased to 8% on day-22. Acrosin, a marker for spermatids, initially manifested at day-10 at 2% positivity and increased to 5% on day-15, reaching 7% on day-22, and peaked at 20% on day-29. According to spermatogenic marker expression, the neogametes follows a maturational profile similar to in vivo mouse spermatogenesis. To prove neogametes competence, we inject the neogametes into mature oocytes. The control ICSI cohort achieved 89.2% fertilization and 77.8% blastocyst rates. Neogametes generated on day-15, 22, 29 and 36, achieved fertilization rates of 35.0%, 61.1%, 81.8% and 75.0%, respectively, and yielded blastulation rates of 5.0%, 16.7%, 36.4% and 8.3%, respectively. Resulting embryos had morphokinesis comparable to control up to the 8-cell stage, but a delay was observed from compaction to blastocyst hatching. Limitations, reasons for caution In spite of the ability to fertilize normally and support blastulation, efficiency rate remained suboptimal. More importantly, the ability to generate live offspring still has to be proven. Wider implications of the findings This novel 3D differentiation model is capable of generating competent gametes and obviate the need for allo-/xeno-geneic transplantation. Once reproducibility and ability to obtain healthy offspring are confirmed, this method may represent a novel treatment option for azoospermic men Trial registration number N/A

Study question Can we utilize a more physiological compound to induce oocyte activation in couples with history of complete/partial fertilization failure with ICSI? Summary answer Recombinant human phospholipase-C-zeta (rhPLCζ) successfully activated oocytes with same efficiency as ionomycin, consistently normalized fertilization and enhanced clinical outcomes. What is known already While ICSI overcomes most aspects of male gamete dysfunction, partial or complete fertilization failure may seldomly occur mostly due absence of sperm-specific protein, known as PLCζ, which is required to trigger oocyte activation. Assisted oocyte activation (AOA), most often performed with an antibiotic (ionomycin), activates oocytes by triggering calcium release from intracellular storage. This agent induces indiscriminate permeabilization of ooplasmic membrane-bound organelles. This action has been considered nonspecific and may have possible deleterious effects on subsequent embryo development. Therefore, we propose a physiological alternative that employs a recombinant form of PLCζ, the native protein residing in the sperm perinuclear theca. Study design, size, duration In the past 12 months, couples with poor ICSI fertilization were included. PLCζ were assessed to confirm sperm-related oocyte activation deficiency with a normal threshold of ≥ 30%. In a preliminary comparison, sibling oocytes were equally allocated to AOA by ionomycin or to rhPLCζ at time of ICSI. Fertilization, embryo development, and clinical outcomes between the two cohorts. Subsequently, we describe the clinical outcomes of couples treated solely by rhPLCζ. Participants/materials, setting, methods Thirty couples, confirmed with low level of PLCζ in the ejaculates, were offered AOA with their subsequent ICSI cycles (IRB#0712009553). Conventional AOA was performed by exposing post-ICSI oocytes to 50 µM ionomycin. The rhPLCζ-AOA method was performed by co-injecting spermatozoa with 0.4pL of a rhPLCζ (5 µg/µL) during ICSI. Chi-square tests were utilized to compare rhPLCζ-AOA versus ionomycin-AOA and rhPLCζ-AOA versus history cycles. Main results and the role of chance In the preliminary study, 9 patients were included (maternal age: 35.7 ± 6, paternal age: 36.7 ± 6). PLCζ positivity was 11.7±3.6% confirming a sperm-related oocyte activation deficiency. A total of 123 oocytes were retrieved in 9 cycles, with maturity of 78.0% (96/123). The 96 MII oocytes were allocated to be treated with ionomycin-AOA (n = 58) or rhPLCζ-AOA (n = 38). While conventional ionomycin-AOA yielded a fertilization rate at 55.2% (32/58), rhPLCζ-AOA resulted in 63.1% (24/38). Both compounds generated embryos at similar rates and one pregnancy was achieve in each cohort. On the bases of such comparable outcomes, 21 couples had 40 previous cycles that generated a fertilization rate of 18.3% (60/327), cleavage rate of 51.7% (31/60), Following the replacement of 23 embryos in 14 transfer cycles, these cycles yielded 2 clinical pregnancies, but all resulted in pregnancy loss. In the subsequent cycles with rhPLCζ-AOA (n = 32), an enhanced fertilization rate was achieved at 41.1% (116/280, P<0.00001). The treatment cycle yielded a higher cleavage rate at 80.2% (93/116, P<0.0001), and after replacing 25 embryos in 17 embryo transfer cycles, yielded 6 pregnancies and 5 of them resulted in delivered or are ongoing. Limitations, reasons for caution We demonstrated that physiological rhPLCζ-AOA achieved an excelled fertilization and clinical outcomes comparing to the traditional ionomycin method. Although further observation is needed to confirm its safety, this approach represents a more physiological method capable of achieving fertilization, higher embryo cleavage and ultimately better pregnancy outcomes. Wider implications of the findings While ICSI has gained large popularity, poor fertilization may occasionally occur. The availability of an assisted oocyte activation that utilize a native compound capable of restoring fertilization capability of the male gamete is appealing and holds great promises. Trial registration number N/A

Study question We wonder whether it is possible to edit a specific gene in individual mammalian spermatozoa as well as embryo by using CRISPR-Cas9? Summary answer We were able to successfully edit the coat pigment gene on individual spermatozoa as well as embryos by injecting CRISPR-Cas9 during Piezo-ICSI. What is known already Earlier investigations into embryo genome editing with CRISPR-Cas9 were conducted during the S-phase or zygote stage, encountering obstacles such as mosaicism and loss of heterozygosity. To overcome these challenges, performing genome editing at the gamete level is considered more favorable. While it may be achievable in oocytes, sperm genome editing can be ambitious due to the tightly supercoiled DNA around the protamine cores. In initial attempts, simple permeabilization of the sperm membrane allowed CRISPR-Cas9 penetration into the cell; however, the attempts at genomic editing proved to be unsuccessful. Study design, size, duration In the past several months, oocytes were divided into two groups: half of them were used to perform embryo genome editing, whilst the other half was used to edit exclusively the sperm genome through oocyte-mediated sperm decondensation (OMSD), where a single spermatozoon was injected into an enucleated oocyte and used the ooplasmic machinery for DNA decondensation and editing. In both models, CRISPR-Cas9 was used to knock out Tyr gene to create an albino phenotype. Participants/materials, setting, methods B6D2F1 mice were used to retrieve oocytes and spermatozoa. A cohort of oocytes used for the OSMD approach were enucleated, whilst the others were maintained with an intact nucleus. All oocytes, enucleated or not, were injected with a single spermatozoon with Tyr-sgRNA and Cas9 protein. Embryos were cultured until the 8-cell stage and processed for T7E1 cleavage analysis. Genome editing efficiency was calculated following the manufacturer protocol. Main results and the role of chance Of the 40 oocytes used for the study, 20 intact oocytes were used to perform embryo genome editing in the standard fashion, while 20 were enucleated for OMSD experiments. After undergoing Piezo-ICSI with CRISPR-Cas9 solution, 90.0% (18/20) of intact oocytes fertilized. After 48 hours in culture, diploid embryos reached the 8-cell stage at 88.9% (16/18). The 584-bp region of the target site of extracted DNA was amplified and gene modification of the edited diploid embryo cohort was confirmed in 87.5% (14/16). Compared to the OMSD cohort, enucleated oocytes fertilized at 85.0% (17/20) while cleavage rate was lower at 64.7% (11/17) and sperm genome modification at 81.8% (9/11). Both diploid embryos and haploid androgenetic embryos evidence an editing efficiency of 36.8%. Therefore, we verified that genome editing on embryos and sperm achieved the same editing yield. Limitations, reasons for caution While the experimental observations are still limited, it is important to note that these results in the embryo model may be underestimated by the T7E1 cleavage assay that only recognize heterozygous modification. The technique needs further refinement to optimize targeting and editing efficiency. Wider implications of the findings Sperm genome decondensation through an OMSD approach allows CRISPR-Cas9 to edit the sperm genome in order to correct eventual pathogenic mutations present in the gamete. Moreover, these would be the only method to absolutely ensure uniform generation of resulting embryos. Trial registration number not applicable

Study question Is it possible to generate genotyped oocytes by utilizing accessible somatic cells in a somatic cell nuclear transfer model? Summary answer Genotyped oocytes generated through haploidization of endometrial somatic cells exhibited reliably completed embryo development and yielded healthy offspring. What is known already The generation of genotyped oocytes through neogametogensis or somatic cell nuclear transfer (SCNT) would be the ultimate solution to treat female infertility due to primary ovarian insufficiency or agonadism. Among the various approaches, somatic cell haploidization appears more feasible (Lee, et al 2022). Unfortunately, this approach has only been successful in a murine model using cumulus cells. However, this donor cell type is not ideal when translated into clinical setting, due to the absence of cumulus cells in patients who are void of oocytes, which arguably is the patient population that would potentially benefit the most from this technique. Study design, size, duration In a mouse SCNT model, endometrial stromal cells (EMSCs) were injected into enucleated oocytes. Cumulus cells (CCs) were used as another source of nuclear donor. Intact MII oocytes were used as control. Post-SCNT oocytes and controls were inseminated by spermatozoa from B6-EGFP mice to monitor paternal genome presence through embryo development and offspring. Embryos were cultured in a time-lapse microscope. To prove gamete competence, blastocysts were transferred into pseudo-pregnant recipients and offspring health was assessed. Participants/materials, setting, methods Endometrial stromal cells were cultured for 4 days and exposed to aphidicolin overnight to synchronize at G1 phase of cell cycle. Cumulus cells were collected after denudation. Oocytes from B6D2F1 mice were enucleated under polarized light microscope. SCNT was performed with CCs or EMSCs by lipofectamine-mediate fusion. Oocytes were inseminated with spermatozoa from GFP-positive transgenic mice. Embryos morphokinesis were assessed by a time-lapse system. Blastocysts were transferred into 2.5-dpc surrogate CD1 mice. Main results and the role of chance Control oocytes(n = 75) fertilized at 93.3%(70/75) and progressed to 2-cell stage at 93.3%(70/75), 8-cell at 93.3%(70/75) and blastocyst at 89.3%(67/75). The control embryos started syngamy at 14.4±1h, reaching the 4-cell stage at 37.3±3h and blastulation at 80.6±8h. A total of 484 oocytes were enucleated, 470(97.1%) survived and underwent SCNT using CCs(n = 85) or EMSCs(n = 385). Fusion rate was 95.5% for CC with a haploidization rate of 70.9%(56/79) that led to a fertilization rate of 64.3%(36/56). The CC cohort developed to 2-cell, 8-cell, and morula at 47.4%, 35.4%, and 22.8%, with a delay in development at syngamy at 19.0±8h(P<0.0001). In the EMSC cohort, fusion rate was 96.0%(361/376). Haploidization rate was 65.4%(236/361), comparable to the CC cohort(P = 0.35). Fertilization was lower in the EMSC cohort at 47.0%(P<0.01) compared to the CC cohort. Subsequently, EMSC cohort yielded similar cleavage rates to 2-cell stage at 30.7%, 8-cell stage at 29.4%, and morula stage at 28.5%. The blastocyst rate was higher in the EMSC cohort at 28.0%(P<0.05). The EMSC cohort yielded similar developmental timing comparing to controls from pronuclear appearance to 4-cell cleavage but a delay manifested afterward at 37.3±3h(P<0.0001). In the EMSC cohort, 42 blastocysts were transferred, yielding 3 healthy pups(2 male,1 female). Limitations, reasons for caution While we generated consistent haploidization and satisfactory fertilization, full pre-implantation development remained low. Even more limited was the live birth rate, which probably related to subtle factors such as an imprinting issue due to insufficient reprogramming of the somatic cell donor. Wider implications of the findings The SCNT model described to generate genotyped oocytes, although still with limited efficiency, represents a feasible reproductive option for women with agonadism and compromised ovarian reserve. This model is still a better approach to complete neogametogenesis. Trial registration number not applicable

Study question Can a multi-bioassay approach identify a specific male gamete dysfunction often overlooked by a standard semen analysis? Summary answer In cases of persistent fertilization failure, additional testing may assist in pinpointing underlying factors contributing to compromised sperm embryo developmental competence and tailor treatment. What is known already Conventional semen analysis, while informative, ineffectively captures the complete spectrum of male gamete dysfunction. Despite adequate sperm concentration and motility, some couples may still experience fertilization failure with Intracytoplasmic Sperm Injection (ICSI). This highlights the complexity of male infertility, that extends beyond standard parameters. In addressing sperm-related fertilization challenges, various assisted oocyte activation (AOA) methods have been proposed to trigger intracellular Ca2+ release, leading to calcium spikes and meiosis initiation. Study design, size, duration In the past 10 months, we identified couples (n = 50) with a history of poor ICSI fertilization, exhibiting suboptimal head morphology. Screening for acrosomal dysfunction involved assessing the presence of PLCxand related gene mutations. We measured the degree of chromatin compaction by histone-to-protamine ratio and evaluated sperm chromatin fragmentation (SCF). To correct for eventual acrosomal dysfunction, couples were counseled to undergo subsequent ICSI cycles with AOA. Clinical outcome was compared between historical and treatment cycles. Participants/materials, setting, methods Fifty men with a history of poor ICSI fertilization were included. A standard semen analysis was conducted according to WHO guidelines. The presence of PLCx was measured through immunofluorescent staining (normal threshold, ≥ 30%), corroborated by gene mutation detection though DNA-seq. Sperm histone-to-protamine ratio was evaluated by Aniline Blue (normal threshold, <15% histone retention). SCF was assessed utilizing the TUNEL assay (normal threshold, ≤15%). AOA was performed using ionomycin or recombinant PLCx protein. Main results and the role of chance Fifty men experienced a poor clinical outcome following ICSI with a fertilization of 7.4% (48/647), embryo implantation of 6.6% (1/15), clinical pregnancy of 6.6% (1/15), and pregnancy loss rate of 100% (1/1). Their semen analysis, interestingly, revealed the following semen parameters: 3.0±1 mL volume, 50.0±20 x106/mL concentration, 41.4±21% motility, and 1.9±1% normal morphology. Nonetheless, PLCx content was diminished, with values ranging from 2-27%. Genomic assessment confirmed mutations in PLCx, DPY19L2, SPATA16 and PICK1 genes, all implicated in sperm nuclear remodeling and acrosome formation. An elevated histone content at 29.7% was positively correlated with an increased SCF at 18.0% (R2=0.6, P<0.001). In subsequent cycles employing AOA, the normal fertilization increased to 42.3% (305/721), the embryo implantation reached 13.0% (9/69), the clinical pregnancy rose to 21.1% (8/38), and the delivery rate was 21.1% (8/38), without any pregnancy loss. (P<0.001). Limitations, reasons for caution While this study affirms the effectiveness of a multifaceted assessment in pinpointing specific sperm dysfunctions and customizing treatment, it is still a retrospective observation requiring independent validation in a larger population. Wider implications of the findings Semen analysis alone fails to address specific aspects of male gamete dysfunction. Incorporating additional bioassays to assess chromatin structure, integrity, and acrosomal function offers valuable insights for fertility management in tailoring personalized treatments. This comprehensive approach enhances the understanding of male reproductive health, maximizing the potential for successful clinical outcome. Trial registration number not applicable

Study question Can a genetic assessment of cell-free DNA, isolated from seminal plasma of nonobstructive azoospermic (NOA) men, predict successful sperm extraction at testicular biopsy? Summary answer Seminal cell-free DNA (cfDNA) isolated from the ejaculates of NOA men with failed testicular sperm retrieval outcomes concurrently and consistently displayed mutations on three genes. What is known already The most puzzling form of azoospermia is the testicular type, where the chances of successful microdissection testicular sperm extraction (micro-TESE) are unpredictable. Therefore, developing a method that could identify or predict individuals with absent spermatogenesis would be most useful. While histopathology is considered the most reliable method for predicting successful micro-TESE, it is invasive and often inconclusive. Recently, cfDNA testing has been gaining momentum as a noninvasive method for prenatal screening and even with the potential for eventually replacing PGT-A. However, the prognostic value of using cfDNA to predict the presence/absence of spermatozoa in men undergoing micro-TESE is relatively unknown. Study design, size, duration Over a period of 8 months, we recruited azoospermic men with normal peripheral karyotypes and for whom an extensive semen analysis did not identify spermatozoa. For consenting patients (n = 12), we performed genetic assessments on cfDNA from their ejaculates (IRB 1006101085). These patients subsequently underwent micro-TESE, and their cfDNA mutation profiles were compared according to whether spermatozoa were successfully retrieved ((+)Sperm, n = 5), or not ((-)Sperm, n = 7). Participants/materials, setting, methods Using a commercially available kit, circulating cfDNA was eluted from the ejaculates of consenting NOA men, as well as a normozoospermic control (n = 2). The isolated cfDNA specimens subsequently underwent whole exome sequencing (WES) on an Illumina HiSeq at 2x150bp. Gene mutations were detected by CLC Genomic Server 9.0 and compared within, as well as between, the +Sperm and -Sperm cohorts in comparison to the control group. Main results and the role of chance All 12 men (35.5±4yrs) had normal peripheral karyotypes and tested negative for Y-microdeletions. They had no history of genetic diseases and were off any supplements, medications, and/or hormones before or during the study. Genetic assessment on cfDNA from the +Sperm cohort (n = 5; 38.3±2yrs) identified 8 genes (ADAMTS7, ATP9B, CBFA2T3, FAM20C, FCGBP, PEBP4, PHF2, RPS9) that were concurrently mutated among all NOA men from this group. Although ADAMTS7 plays a potential role in sperm-egg fusion, the remaining genes are unrelated to sperm production. Whole exome sequencing of cfDNA from the -Sperm cohort (n = 7; 33.5±4yrs) consistently detected mutations on 3 genes, including one involved in spermatogenesis (CFAP54), one essential for oxidative regulation of spermatozoa (GSTT4), and one that encodes testis antigens that are normally expressed during spermatogenesis (BAGE2). Moreover, we concurrently and consistently identified pathogenic mutations on an additional gene in the -Sperm cohort. This gene (MUC2) is involved in the epithelial coating of mucus membrane-containing organs, and its expression has been correlated with spermatogenesis. Interestingly, these genes were all unaffected in men with successful micro-TESE outcomes. Limitations, reasons for caution Although we detected candidate gene mutations that correlate with micro-TESE outcome, these are preliminary findings that need further validation in a larger study cohort. Furthermore, while cfDNA analysis has shown great promise, it is not specific enough on its own and should be corroborated by epigenetic testing. Wider implications of the findings Genetic screening of seminal cfDNA provides a noninvasive alternative to histopathology and can be used to predict the absence of spermatogenesis, sparing these men from unnecessary surgery and cost. This novel biomarker approach lays the groundwork for precision medicine in male infertility testing. Trial registration number n/a

Study question Can microfluidic sperm sperm selection (MFSS) contribute to isolating spermatozoa with higher genomic integrity and cryostress resistance, while retaining embryo developmental competence? Summary answer In comparison to conventional density gradient (DG), MFSS yielded a higher proportion of motile spermatozoa coupled with enhanced genomic integrity and resistance to cryostress. What is known already The cryopreservation of human spermatozoa has long been a cornerstone in reproductive treatments, serving as a pivotal method for preserving male fertility for several decades. Despite the unlimited storage time of cryopreserved semen specimens, the thawing process inevitably diminishes the number of viable spermatozoa. The implementation of a technique capable of enhancing the motility of spermatozoa cryopreserved would yield a higher proportion of gametes with higher kinetics and genomic integrity at thawing. Study design, size, duration Since 2017, 183 men underwent cryopreservation utilizing MFSS. Post-processing semen parameters, including Sperm Chromatin Fragmentation(SCF), and post-thaw motility were compared with a DG control(n = 1979). Additionally, post-thaw parameters for 30 men who had previously employed DG and subsequently adopted MFSS for semen cryopreservation were included. In 12 specimens, a paired analysis was carried out on a same ejaculate. Moreover, we explored pregnancy outcomes with MFSS-selected specimens in some men that underwent ART. Participants/materials, setting, methods Semen parameters were analyzed, and DG was performed according to WHO 2021 guidelines. MFSS was carried out following manufacture’s protocol (ZyMōt® Multi 850µL). Cryoprotectant (Test Yolk Buffer) was added to the final sample before being immersed in liquid nitrogen. A minute aliquot of the processed sample, cryopreserved separately, was thawed for post-thaw motility. TUNEL assay was used to measure SCF (≤ 15% normal threshold). Main results and the role of chance In this study, 1979 men (40.0±7y) underwent DG prior to cryopreservation, resulting in a 44.3±25x106/mL concentration, 88.2±4% motility, and 2.9±1% normal morphology, serving as control. The remaining 183 men of a similar age underwent MFSS prior to cryopreservation. Despite a lower concentration at 26.1±15x106/mL(P < 0.001), MFSS resulted in a higher post-processing motility(97.8±2%, P < 0.001) and normal morphology(3.4±1%, P < 0.001). Post-thaw analysis revealed a remarkably higher post-thaw motility in MFSS (51.2±7% vs 43.6%±4%,P < 0.001). SCF averaged 17%(raw), 11%(DG) and 2%(MFSS,P<0.001). To confirm research hypothesis, a pilot study was done in 12 men (37.3±3y,3.0±2d abstinence) with their semen specimen equally aliquoted for DG or MFSS and cryopreserved. The post-thaw motility increased from 45.4±8%(DG) to 61.3±13%(MFSS,P<0.001). Subsequently, in men(n = 30, 40.8±6y, 3.0±2d abstinence) who underwent semen cryopreservation previously by DG and subsequent by MFSS, a similar trend was observed with a higher post-thaw motility (53.2±6% vs 43.2%±6%,P < 0.001). Among the 36 patients who utilized DG cryopreserved specimen for reproductive purposes, 11/19 (57.9%) patients achieved pregnancy in ICSI cycles. while 5/17 (29.4%) achieved pregnancy in an IUI cycle, Among the 18 couples who used MFSS cryopreserved specimen for ICSI, a pregnancy rate was reported (8/18,44.4%). A IUI pregnancy rate was also reported (4/18,22.2%) using MFSS cryopreserved specimen. Limitations, reasons for caution While MFSS has proven to increase post-thaw survival rate and maintain a lower SCF, it did not necessarily trend in a higher pregnancy in IUI cycles, possibly due to the borderline elevated SCF. This finding needs to be confirmed in a larger population. Wider implications of the findings In reproductive medicine, we strive to identify new techniques aimed at providing more competent gametes. MFSS was capable of isolating the most motile potion of spermatozoa with a higher genomic integrity. The utilization of MFSS for specimens to be cryopreserved appears promising in generating higher post-thaw recovery of motile spermatozoa. Trial registration number not applicable

Study question Can we identify an alternative method to Sendai-Virus fusion for somatic cell nuclear transfer (SCNT) aiming at generating artificial oocyte? Summary answer The utilization lipofectamine proved itself as a valid alternative method to virus-mediated SCNT, allowing successful membrane fusion and supporting proper embryo development. What is known already SCNT involves transferring a diploid cell’s nucleus into an enucleated oocyte. Early attempts of SCNT involves direct injection and electrofusion but both approaches can affect oolemma integrity. To avoid mechanical damage to oolemma, fusogenic agents have been employed for SCNT including polyethylene glycol (PEG) and more efficient Hemagglutinating Virus of Japan Envelope (HVJ-E). However, despite its high efficiency, HVJ-E is difficult to be used in human because it is a virus derivative, and a recent shortage of this compound made it not readily available. On the other hand, cationic phospholipid is fusogenic and is widely utilized in transfection experiments. Study design, size, duration In the past 4 months, SCNT was carried out through PEG-mediated, HVJ-E-mediated, or novel lipofectamine-mediated fusion using cumulus cells as nuclear donor. Post-SCNT oocytes were inseminated and cultured up to the blastocyst stage. Embryo development and morphokinetics were assessed and compared among the three SCNT experimental cohorts. In some cases, blastocysts were transferred into pseudo-pregnant mice, post-natal development were monitored. Fertilization, embryo development, and offspring wellbeing were monitored. Participants/materials, setting, methods Oocytes from B6D2F1 mice were enucleated by micromanipulation. The ooplasts were allocated to 3 cohorts: 1) exposure to 45% PEG, 2) subzonal transfer of donor cell with HVJ-E, or 3) subzonal transfer the donor cell exposed to 1.75% lipofectamine. Reconstructed oocytes were monitored for fusion 30 minutes after exposure to fusogens and inseminated by spermatozoa from B6-EGFP mice to confirm paternal genome provenance. Fertilization and embryo development were monitored in a time-lapse system. Main results and the role of chance A total of 165 oocytes were enucleated and 160 (97.0%) survived and allocated to PEG-fusion (n = 50), Sendai-virus-fusion (n = 41) and lipofecamine-fusion (n = 80) cohorts. Fusion rate was 56.0% (28/50) for the PEG-fusion cohort, while Sendai-virus and lipofectamine-fusion cohorts yielded higher fusion rate at 92.7%(38/41) and 86.3%(69/80), respectively (P<0.0001). Control oocytes yielded 96.7% (145/150) fertilization rate and developed to 2-cell stage at 93.8% (136/145), and yielded an eventual blastocyst rate at 80.7% (117/145). Despite a lower oocyte reconstruction rate, PEG-fusion cohort fertilized at 89.3% (25/28), but cleavage rate to 2-cell stage was lower at 48.0% (12/25, P<0.0001) and did not yield any blastocyst. The HVJ-E cohort yielded a fertilization rate of 94.7% (36/38) and cleavage rate at 97.2% (35/36) similar to control. The blastocyst rate was observed at 22.9% (8/35, P<0.0001) when comparing to control. Lipofectamine-fusion cohort yielded 91.3% (63/69) fertilization rate and subsequent cleavage rate at 95.2% (60/63). Albeit at a lower blastocyst development rate comparing to control, the lipofectamine cohort yielded similar full-preimplantation rate at 19.0% (12/63) when comparing to HVJ-E cohort. All blastocysts (n = 20) were transferred into 2 pseudo-pregnant mice and 3 healthy female offspring were yielded to date. Limitations, reasons for caution HVJ-E mediated membrane fusion has been well established with proven safety record; however, its recent shortage has led to a temporary cessation of its utilization. Our lipofectamine-mediated cell fusion technique yielded satisfactory fusion, fertilization, blastocyst formation and some live offspring, however the safety and efficacy still remain to be validated. Wider implications of the findings This novel lipofectamine-mediated cell fusion has broader implications for advancing cloning technologies. Lipofection is a non-viral approach, overcomes shortage of HVJ-E and therefore propose itself as a more appealing cell fusion method for human SCNT. Trial registration number N/A