Exploring the impacts of senescence on implantation and early embryonic development using totipotent cell-derived blastoids

INTRODUCTION

Advanced maternal age is associated with reduced implantation and pregnancy rates, yet the underlying mechanisms remain poorly understood, and research models are limited.

OBJECTIVES

Here, we aim to elucidate the impacts of senescence on implantation ability by employing blastoids to construct a novel research model.

METHODS

We used a novel three-dimensional system with totipotent blastomere-like cells (TBLCs) to construct TBL-blastoids and established senescence-related embryo models derived from oxidative stress-induced TBLCs.

RESULTS

Morphological and transcriptomic analyses revealed that TBL-blastoids exhibited characteristic blastocyst morphology, cell lineages, and a higher consistency in developmental rate. TBL-blastoids demonstrated the ability to develop into postimplantation structures in vitro and successfully implanted into mouse uteri, inducing decidualization and forming embryonic tissues. Importantly, senescence impaired the implantation potential of TBL-blastoids, effectively mimicking the impaired implantation ability and reduced pregnancy rates associated with advanced age. Furthermore, analysis of differentially expressed genes (DEGs) in human homologous deciduae revealed enrichment in multiple fertility-related diseases and other complications of pregnancy. The genes implicated in these diseases and the common DEGs identified in the lineage-like cells of the two types of TBL-blastoids and deciduae may represent potential targets for addressing impaired implantation potential.

CONCLUSION

These results unveiled that TBL blastoids are an improved model for investigating implantation and early postimplantation, offering valuable insights into pregnancy-related disorders in women with advanced age and potential targets for therapeutic interventions.

Cloning by SCNT: Integrating Technical and Biology-Driven Advances

Somatic cell nuclear transfer (SCNT) into enucleated oocytes initiates nuclear reprogramming of lineage-committed cells to totipotency. Pioneer SCNT work culminated with cloned amphibians from tadpoles, while technical and biology-driven advances led to cloned mammals from adult animals. Cloning technology has been addressing fundamental questions in biology, propagating desired genomes, and contributing to the generation of transgenic animals or patient-specific stem cells. Nonetheless, SCNT remains technically complex and cloning efficiency relatively low. Genome-wide technologies revealed barriers to nuclear reprogramming, such as persistent epigenetic marks of somatic origin and reprogramming resistant regions of the genome. To decipher the rare reprogramming events that are compatible with full-term cloned development, it will likely require technical advances for large-scale production of SCNT embryos alongside extensive profiling by single-cell multi-omics. Altogether, cloning by SCNT remains a versatile technology, while further advances should continuously refresh the excitement of its applications.

Spatio-temporal localization of selected pectic and arabinogalactan protein epitopes and the ultrastructural characteristics of explant cells that accompany the changes in the cell fate during somatic embryogenesis in Arabidopsis thaliana

During somatic embryogenesis (SE), explant cells undergo changes in the direction of their differentiation, which lead to diverse cell phenotypes. Although the genetic bases of the SE have been extensively studied in Arabidopsis thaliana, little is known about the chemical characteristics of the wall of the explant cells, which undergo changes in the direction of differentiation. Thus, we examined the occurrence of selected pectic and AGP epitopes in explant cells that display different phenotypes during SE. Explants examinations have been supplemented with an analysis of the ultrastructure. The deposition of selected pectic and AGP epitopes in somatic embryos was determined. Compared to an explant at the initial stage, a/embryogenic/totipotent and meristematic/pluripotent cells were characterized by a decrease in the presence of AGP epitopes, b/the presence of AGP epitopes in differentiated cells was similar, and c/an increase of analyzed epitopes was detected in the callus cells. Totipotent cells could be distinguished from pluripotent cells by: 1/the presence of the LM2 epitope in the latest one, 2/the appearance of the JIM16 epitope in totipotent cells, and 3/the more abundant presence of the JIM7 epitope in the totipotent cells. The LM5 epitope characterized the wall of the cells that were localized within the mass of embryogenic domain. The JIM8, JIM13 and JIM16 AGP epitopes appeared to be the most specific for the callus cells. The results indicate a relationship between the developmental state of the explant cells and the chemical composition of the cell walls.