Background: Human umbilical cord blood (HUCB) is an acceptable and readily accessible source of stem cells. There is an ongoing interest in cord blood stem cell therapies; however, little is known about the possible unfavorable effects of laboratory modifications on the isolated HUCB cells. The involvement of miRNAs in several biological processes has been shown. The aim of this study was to evaluate the possible changes in miRNA expression profiles in CD133+ hematopoietic cells after in vitro culture.Methods: HUCBCD133+ hematopoietic stem cells were isolated by magnetic-activated cell sorting, and then the cells were counted using flow cytometry. The cells were divided into 2 groups. In the first group, RNA was extracted and the cells of the second group were cultured in vitro for 12 days and then these cells were used to assay miRNAs expression using real-time qPCR. Results: The results showed that the expression of 349 out of 1,151 screened miRNAs was upregulated following a 12-day in vitro culture of CD133+ cells, whereas the expression of 293 miRNAs was downregulated. In addition, the expression of 509 miRNAs was not significantly altered. Another in-silico analysis involving the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to the selected miRNAs was also conducted. Conclusion: Based on our results, the in vitro expansion of HUCB resulted in altered expression levels of miRNAs. This study provides information on the effects of 2-dimensional culture of hematopoietic cells prior to transplantation for more successful transplantation.