Human perinatal tissue is an abundant source of mesenchymal stromal cells(MSCs) and lacks the ethical concerns. Perinatal MSCs can be obtained from various tissues as like amnion, chorion, and umbilical cord. Still, little is known of the distinct nature of each MSC type. In this study, we successfully isolated and cultured MSCs from amnion(AMSCs), chorion(CMSCs), and umbilical cord(UC-MSCs). Proliferation potential was different among them, that AMSCs revealed the lowest proliferation rate due to increased Annexin V and senescence-associated β-galactosidase positive cells. We demonstrated distinct characteristic gene expression according to the source of the original tissue using microarray. In particular, genes associated with apoptosis and senescence including CDKN2A were up-regulated in AMSCs. In CMSCs, genes associated with heart morphogenesis and blood circulation including HTR2B were up-regulated. Genes associated with neurological system processes including NPY were up-regulated in UC-MSCs. Quantitative RT-PCR confirmed the gene expression data. And in vitro differentiation of MSCs demonstrated that CMSCs and UC-MSCs had a more pronounced ability to differentiate into cardiomyocyte and neural cells, respectively. This study firstly demonstrated the innate tissue-specific differentiation potency of perinatal MSCs which can be helpful in choosing more adequate cell sources for better outcome in a specific disease.

Park DJ, et al. Blood Res. 2020 Mar;55(1):17-26. https://doi.org/10.5045/br.2020.55.1.17

Kim Y, et al. Blood Res. 2017 Jun;52(2):84-94. https://doi.org/10.5045/br.2017.52.2.84

Human mesenchymal stromal cells (MSCs) have served as a major cellular resource for cell-based immunomodulatory and regenerative therapies. However, genomic instability may accumulate during ex vivo expansion of MSCs, thereby increasing the potential of malignant transformation. Here, we performed whole genome sequencing of two peripheral blood-derived MSC lines (MSC1 and MSC2) at various passages (passage 1 [P1] to P9). The majority of single-nucleotide variations (SNVs) occurred in later passages; specifically, 90% and 70% of all SNVs in MSC1 and MSC2 were observed in P9 and P7/P9, respectively. These late-occurring SNVs were enriched with C > A transversions and were overrepresented in intronic regions compared to intergenic regions, suggesting that the mutational forces are not constant across the passages. Clonality analyses also distinguished early-occurring, subclonal SNVs from late-occurring, clonally fixed SNVs. In addition, MSCs were largely devoid of copy number alterations (CNAs) (i.e., 0–2 CNAs per passage), with one exception (MSC2-P3) harboring 29 passage-specific CNAs. Our findings suggest that the SNVs found to be abundant at later passages likely resulted from the accumulation of replication stress, which can be associated with proliferation activity. Thus, the genomic instability associated with proliferation records should be considered for clinical applications of MSCs.

Mutation of the fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), which is one of the most frequent genetic alterations, strongly contributes to an increased risk of treatment failure and to poor prognosis. In this study, we established quantitative fragment analysis of FLT3-ITD simultaneously measuring mutant allele burden and length, verified the analytical performance and evaluated the clinical significance in adult acute myeloid leukemia (AML) patients. FLT3-ITD was detected in 73 of 363 adult AML patients (20.1%) and high mutant allelic burden (⩾50%, n=13) and long ITD length (⩾70 base pairs, n=15) were significantly associated with inferior overall survival (OS; P=0.002 and 0.005, respectively) and event-free survival (EFS; P=0.004 and 0.007, respectively). FLT3-ITD poor prognostic group was identified as patients with high allele burden or long ITD length (n=24), which revealed significant adverse clinical outcome for both OS (P<0.001) and EFS (P<0.001). In cytogenetically normal AML, even FLT3-ITD low allele burden and short length was associated with poorer OS (P=0.037) and EFS (P=0.044) than wild type, whose influence was overcome when hematopoietic stem cell transplantation was performed. In minimal residual disease monitoring, FLT3-ITD negativity after consolidation therapy was a valuable predictor of better OS (P<0.001) and EFS (P<0.001). FLT3-ITD poor prognostic group with high mutant allele burden or long ITD length is efficiently identified by quantitative fragment analysis.