Vascular alterations underlie developmental problems manifested in cloned cattle before or after birth

Area of Science:

• Reproductive biology
• Developmental biology
• Veterinary medicine

Background:

• Assisted reproductive techniques (ART) are widely used but often result in developmental deficits and reduced viability.
• Nuclear transfer (NT), a highly invasive ART, is particularly associated with abnormalities in cloned offspring.

Purpose of the Study:

• To characterize the developmental abnormalities in bovine clones produced via nuclear transfer.
• To identify the primary causes of reduced viability in cloned cattle.

Main Methods:

• Detailed necropsy examinations of 13 neonatal bovine clones that died shortly after birth.
• Inclusion of data from prematurely terminated bovine embryos and fetuses produced by NT.

Main Results:

• Bovine clones exhibited significant quantitative and qualitative differences compared to in-vivo-derived cattle.
• Alterations were observed across multiple organs, including the heart, lung, and liver.
• A strong association was found between cloning and aberrant vascular development during early intrauterine stages.

Conclusions:

• Vascular problems are identified as key developmental alterations induced by bovine cloning.
• Epigenetic modifications are presumed to be the underlying mechanism driving these vascular abnormalities.