Effects of maternal body weight on Wharton’s Jelly mesenchymal stromal cells (Pilot study)

Abstract

To investigate whether the maternal metabolic environment affects the DNA methylation of mesenchymal stromal/stem cells (MSCs) from umbilical cord (UC) Wharton’s Jelly (WJ), potentially rendering them unsuitable for clinical use in multiple recipients, a pilot study was conducted on fourteen UCs obtained post partum from healthy non-obese (BMI=19-25; n=7) and obese (BMI≥30; n=7) donors receiving elective Caesarean sections.

The time of first WJ-MSCs outgrowth from UC explants was similar in samples from obese and non-obese donors. However, the cells from non-obese donors proliferated faster after 34 hours of culture than cells from obese donors. Differentiation into adipogenic, osteogenic and chondrogenic lineages was similar between obese and non-obese donor samples as demonstrated by tissue-specific staining and RT-PCR for lineage markers. However, WJ-MSCs from obese donors exhibited stronger immunosuppressive activity than those from non-obese donors.

Genome-wide DNA methylation of triple-positive (CD73+CD90+CD105+) WJ-MSCs sorted from the first passage of a mixed population of cells was assessed. Samples from the obese and non-obese donors clustered separately, and 5,767 of the analysed CpG sites (1%) exhibited different methylation. Sixty-seven genes were observed with at least one CpG site with a methylation difference ≥0.2 in four or more obese donors. These 67 genes were further refined based on a list of polymorphic CpG sites and segmental duplications. In 18 of the 67 genes with a different CpG methylation pattern, the CpG sites were in non-polymorphic regions. However, two genes (DCAF6 and ZNF714) resided in segmentally duplicated regions.

To determine whether methylation differences altered gene expression, the samples were analysed using a HumanHT-12 Expression BeadChip array and, of the 18 genes, only PNPLA7 was significantly affected at the mRNA level, which was confirmed independently by RT-PCR and Western blotting.

Although the number of analysed donors was limited, the data suggest that an abnormal metabolic environment related to excessive body weight might alter the properties of WJ-MSCs used for cellular therapy.

Date of Award	2017
Original language	English
Awarding Institution	King's College London
Supervisor	Dusko Ilic (Supervisor) & Richard Siow (Supervisor)