Differential expression of microRNAs in cord blood exosomes regulating fetal haemoglobin expression

Cord blood contains an array of microRNAs (miRNAs) regulating gamma globulin expression. However, miRNAs in exosomes from cord blood have not been reported yet. This study aims to analyse the differential expression of miRNA regulating fetal haemoglobin expression in cord blood exosomes and exosomes of maternal sample as control.

This study includes exploration of putative gene targets for upregulation of fetal haemoglobin by bioinformatic tools such as MicroRNA Base (miRBase), MicroRNA Regulatory Network Analysis (miRNet) and MicroRNA Prediction (miRmap). The exosomes were isolated from EDTA sample of cord blood using a commercially available kit (Qiagen, GmbH, Germany). Total RNA was isolated from the exosome pellet by miRNA easy Mini Kit and SYBR green miRNA quantitative reverse transcription polymerase chain reaction (qRT-PCR) kit was used to validate the expression of miRNAs. The miRNAs of exosomes were analysed to see their presence or absence and fold changes in their expression in cord blood compared to the maternal sample as control.

The cord blood exosomes showed a significantly increased expression of miRNA 15a-5p, 381-3p, 210-3p, 326 and 103a-3p in cord blood exosomes compared to exosomes of maternal plasma sample. However, the differential expression was not significant for miRNA 486-3p, 23a-3p, 27a-5p, 96-5p, 34a-5p, 23b-3p and let-7a-5p. Bioinformatically, significantly increased miRNA expression responsible for increased fetal haemoglobin (HbF) level was associated with B-cell lymphoma/leukemia 11A (BCL11A), Myeloblastosis (MYB), Kruppel-like factor-1 (KLF-1), Testicular Rreceptor 4 (TR4), Specificity Protein 1 (SP1) and SRY-Box Transcriptor Factor 6 (SOX6) genes.

This study finds the presence of potential miRNAs in cord blood exosomes regulating HbF level in cord blood. The results of this study may serve as the basis for future clinical trials to reactivate the HbF expression in sickle cell disease (SCD).