The micro-RNAome in full-term placentas of babies born small-for-gestational age

Children born after fetal growth restriction (FGR) have an increased risk of neonatal morbidity and mortality as well as an increased risk of morbidity later in life, especially in the spectrum of the metabolic syndrome. FGR can be caused by many different things. There are both genetic causes and causes from the environment, which makes FGR a heterogenic condition. FGR most often results in the birth of a child that is small for gestational age (SGA).

The placenta has a great impact on fetal growth. Environmental factors influence placental gene expressions, which influence placental structure and function, which in turn influence the growth and development of the fetus. The environment can influence the genome by epigenetic mechanisms. One epigenetic mechanism is the production of microRNAs (miRNAs), which are shorter than the usual mRNAs. miRNAs regulate the expression of almost 30 % of all human genes and influence all fundamental cell processes. They act mainly by inhibiting mRNAs to produce proteins. So far, more than 1,000 different miRNAs have been found in humans, and the number is still increasing.

It has been shown that the miRNAs have a great impact on the development of the placenta. Earlier studies have examined the placental expression of a few different miRNAs and found different changes. In this research project, the total miRNA expression (the miRNAome) in full-term placentas will be examined for the first time in children born SGA in comparison with control groups.

The overall propose of this project is to increase our knowledge on molecular biological mechanisms behind pathological SGA births, in order to increase the possibility of introducing new and better treatments for these patients.

From a sample collection of about 10,000 placenta biopsies at the University Hospital in Örebro we have carefully chosen a number of samples fulfilling our stringent inclusion but no exclusion criteria. These biopsies will be analyzed for total miRNA expression by Next Generation Sequencing. The data will then be processed by bioinformatic technics and finally presented in a scientific article.