Table 3.

Studies assessing the effect of pre-gestational diabetes on placental and offspring miRNAs.

Author Year [Reference]	Species	miRNA	Target Gene	Methods	Tissue	Results	Comments
Dong 2016 [87]	Mice	149 miRNAs	2111 potential target genes	RNA microarrays/RT-qPCR	Heart	Cardiac development-related pathways (STAT3 and IGF-1) and transcription factors associated to altered miRNAs, leading to CHDs	Oxidative stress as responsible for dysregulation of miRNAs
Dong D 2016 [88]	Mice	miR-17 downregulated	Thioredoxin interactive protein upregulated	RT-qPCR	Neural stem cells	Proapoptotic hyperglycaemia (via ASK1 pathway)	ASK1 leads to NTDs
Ibarra 2018 [85]	Human	miR-125-5p miR-20a-5p		RNA-Seq/qPCR	Placenta	Classifiers composed by 2–3 miRNAs were identified	miR-125-5p and miR-20a-5p were present in classifiers for type 1 and type 2 diabetes
Jiangs 2017 [89]	Human	miR130b-3p upregulated	PGC-1 downregulation	RT-qPCR	Placental trophoblastic cell line (Be Wo cells)	Impaired mitochondrial function and oxidative stress which affects foetal development	Inhibition of miR-130b-3p reverted effects found.
Ramya, 2017 [90]	Mice	miRNA-30 family miR-30b upregulated	Sirtuin gene downregulated	RNA microarrays/RT-qPCR	Neural stem cells	Decreased Sirt 1 protein: altered neuron/glia ratio	Diabetic induced NTDs via miRNAs
Shi 2017 [91]	Mice	Exosomal miRNA		RNA-Seq analysis	Blood	Maternal exosomal miRNAs in diabetes contribute to cardiac development deficiency leading to CHDs	Maternal exosomal miRNAs in diabetes could cross the maternal-foetal barrier
Shyama sundar 2013 [92]	Mice	miR-200a, miR-200b, miR-466a-3p, miR-466d-3p Downregulated	Dcx and Pafah1b1 upregulated	RT-qPCR	Neural stem cells	Knock down of miRs increases gliogenesis and neurogenesis which if impaired may form the basis of NTDs	Hyperglycaemia alters epigenetic-reversible mechanisms in NSCs.
Wang 2017 [93]	Mice	miR192-2 upregulated	PGC-1 gene upregulated	RT-qPCR	Neuroepithelial cells	Less NTDs by diminishing autophagy	These regulate the teratogenicity of hyperglycaemia
Zhao 2017 [94]	Mice	miR-505-5p, miR-770-5p and miR-1a-1-5p differentially expressed	Association with diabetic embryopathy was sought	NGS	Embryos (9.5 days)	Putative target genes under-represented in a database of genes associated with cardiovascular and neural malformations	No differences in miRNA expression at 8.5 days
Zhao 2018 [95]	Mice	miR-27a upregulated	Nuclear factor erythroid 2-related factor 2 downregulated	RT-qPCR	Neural stem cells	Increased oxidative stress that suppresses Nuclear factor erythroid 2-related factor 2 and its responsive antioxidant enzymes resulting in diabetic embryopathy	Protein reduction also followed a (glucose) dose and time dependent-manner

C: control. CHDs: Congenital heart defects. D: diabetes. N: number. NS: Not specified. NSC: neural stem cells. NTDs: Neural tube defects. CHD: Congenital heart defects. NGS: Next generation sequencing. RT-qPCR: Real-time, quantitative PCR.