Artificial oocytes through haploidization of mouse endometrial stromal cells and bone marrow-derived mesenchymal stem cells.
Academic Article
Overview
abstract
OBJECTIVE: To evaluate the feasibility of using endometrial stromal cells (EmSCs) and bone marrow-derived mesenchymal stem cells (BM-MSCs) as alternative sources of donor nuclei for somatic cell haploidization. DESIGN: To perform somatic cell haploidization, mouse metaphase II oocytes were enucleated and injected with the nucleus of cumulus cells (CCs), EmSCs or BM-MSCs. Intact metaphase II oocytes served as controls. Oocytes after haploidization and controls were inseminated and cultured up to 96 hours in a time-lapse incubator to assess embryo development and morphokinesis. Blastocysts were either cryopreserved for future genetic analysis or transferred to surrogate pseudo-pregnant mice. SUBJECTS: Female B2D2F1 mice (ooplasm donor), male B6-EGFP mice (spermatozoa donor), CD-1 female mice (surrogate) EXPOSURE: Enucleated oocytes underwent somatic cell nuclear transfer using the nucleus of CCs, EmSCs or BM-MSCs to generate functional oocytes. These oocytes are fertilized to generate conceptuses. MAIN OUTCOME MEASURES: The primary outcome compared embryo development in the experimental groups vs. control. The secondary outcome was embryo morphokinetics evaluated with time-lapse microscopy. RESULTS: A total of 811 oocytes were enucleated, with a survival rate of 97.5%. Somatic cell nuclear transfer (SCNT) was performed using CCs (n = 90), EmSCs (n = 394), or BM-MSCs (n = 327), resulting in comparable somatic cell fusion rates of 95.2%, 96.0%, and 96.5%, respectively. Comparing the different SCNT groups, the CC cohort had a higher fertilization rate (45.6%) than the EmSC (30.8%) and BM-MSC (26.5%) cohorts. However, subsequent embryo development showed significant attrition in the CC cohort, where only 14.4% of CC embryos developed into blastocysts compared with 25.6% of EmSC embryos and 19.6% of BM-MSC embryos. In terms of embryo morphokinetics, all SCNT groups had slower embryo progression than the control group. However, EmSC and BM-MSC embryo development was faster than CC embryos from syngamy to the 8-cell stage (48.8 vs. 48.5 vs. 58.5 hours, respectively). All EmSC embryos and eight out of nine BM-MSC embryos displayed heterozygosity, confirming biparental contribution from the somatic cell and sperm genome. In the EmSC cohort, 42 blastocysts were transferred, yielding three healthy mouse pups (2 male, 1 female). All three pups displayed biparental inheritance, grew to adulthood and produced three healthy first-generation litters. CONCLUSION: Somatic cell haploidization of EmSCs and BM-MSCs generated oocytes capable of full preimplantation development and yielded healthy offspring. The utilization of genotyped donor nuclei for neogametogenesis may represent a feasible fertility treatment option for individuals with complete absence of oocytes.
