Double sperm cloning (DSC) is a promising strategy in mammalian genetic engineering and stem cell research

Abstract

Embryonic stem cells (ESCs) derived from somatic cell nuclear transfer (SCNT) and induced pluripotent stem cells (iPSCs) are promising tools for meeting the personalized requirements of regenerative medicine. However, some obstacles need to be overcome before clinical trials can be undertaken. First, donor cells vary, and the reprogramming procedures are diverse, so standardization is a great obstacle regarding SCNT and iPSCs. Second, somatic cells derived from a patient may carry mitochondrial DNA mutations and exhibit telomere instability with aging or disease, and SCNT-ESCs and iPSCs retain the epigenetic memory or epigenetic modification errors. Third, reprogramming efficiency has remained low. Therefore, in addition to improving their success rate, other alternatives for producing ESCs should be explored. Producing androgenetic diploid embryos could be an outstanding strategy; androgenic diploid embryos are produced through double sperm cloning (DSC), in which two capacitated sperms (XY or XX, sorted by flow cytometer) are injected into a denucleated oocyte by intracytoplasmic sperm injection (ICSI) to reconstruct embryo and derive DSC-ESCs. This process could avoid some potential issues, such as mitochondrial interference, telomere shortening, and somatic epigenetic memory, all of which accompany somatic donor cells. Oocytes are naturally activated by sperm, which is unlike the artificial activation that occurs in SCNT. The procedure is simple and practical and can be easily standardized. In addition, DSC-ESCs can overcome ethical concerns and resolve immunological response matching with sperm providers. Certainly, some challenges must be faced regarding imprinted genes, epigenetics, X chromosome inactivation, and dosage compensation. In mice, DSC-ESCs have been produced and have shown excellent differentiation ability. Therefore, the many advantages of DSC make the study of this process worthwhile for regenerative medicine and animal breeding.

Cloning in action: can embryo splitting, induced pluripotency and somatic cell nuclear transfer contribute to endangered species conservation?

“…Term offspring have yet to be generated using this technique and it appears that the main challenges here pertain to an inability to replicate the pattern of maternal and paternal gene imprinting in the absence of crucial genetic and epigenetic contributions from the oocyte (Tucci et al ., 2019). Nonetheless double sperm cloning has been flagged as a promising approach to generate stem cells and may facilitate novel strategies for genetic rescue and conservation in the future (Zhang et al ., 2020). Live mice have been obtained following injection of hypomethylated haploid ESCs into MII oocytes (bimaternal offspring) or tetraploid complementation of ESCs from diploid androgenetic embryos obtained by double sperm cloning (bipaternal offspring) (Li et al ., 2018).…”

Double Sperm Cloning: Could Improve the Efficiency of Animal Cloning

“…2). This strategy mimics the fertilization process which possesses superiority over other reprogramming approaches and proposes a promising method for animal breeding and regenerative medicine (Zhang et al, 2020). The various studies revealed that the oocyte has the magical power to reprogram differentiated cells into a pluripotent state, but it is more efficiently reprogramming sperm cells during fertilization than somatic cells by SCNT (Matoba et al, 2018).…”