Quiescent Human Mesenchymal Stem Cells Are More Resistant to Heat Stress than Cycling Cells.

Quiescence is the prevailing state of many cell types under homeostatic conditions. Yet, surprisingly, little is known about how quiescent cells respond to environmental challenges. The aim of the present study is to compare stress responses of cycling and quiescent mesenchymal stem cells (MSC). Human endometrial mesenchymal cells (eMSС) were employed as adult stem cells. eMSC quiescence was modeled by serum starvation. Sublethal heat shock (HS) was used as a stress factor. Both quiescent and cycling cells were heated at 45°C for 30 min and then returned to standard culture conditions for their recovery. HS response was monitored by DNA damage response, stress-induced premature senescence (SIPS), cell proliferation activity, and oxidative metabolism. It has been found that quiescent cells repair DNA more rapidly, resume proliferation, and undergo SIPS less than proliferating cells. HS-enforced ROS production in heated cycling cells was accompanied with increased expression of genes regulating redox-active proteins. Quiescent cells exposed to HS did not intensify the ROS production, and genes involved in antioxidant defense were mostly silent. Altogether, the results have shown that quiescent cells are more resistant to heat stress than cycling cells. Next-generation sequencing (NGS) demonstrates that HS-survived cells retain differentiation capacity and do not exhibit signs of spontaneous transformation.

Molecular Genetic Analysis of Human Endometrial Mesenchymal Stem Cells That Survived Sublethal Heat Shock.

High temperature is a critical environmental and personal factor. Although heat shock is a well-studied biological phenomenon, hyperthermia response of stem cells is poorly understood. Previously, we demonstrated that sublethal heat shock induced premature senescence in human endometrial mesenchymal stem cells (eMSC). This study aimed to investigate the fate of eMSC-survived sublethal heat shock (SHS) with special emphasis on their genetic stability and possible malignant transformation using methods of classic and molecular karyotyping, next-generation sequencing, and transcriptome functional analysis. G-banding revealed random chromosome breakages and aneuploidy in the SHS-treated eMSC. Molecular karyotyping found no genomic imbalance in these cells. Gene module and protein interaction network analysis of mRNA sequencing data showed that compared to untreated cells, SHS-survived progeny revealed some difference in gene expression. However, no hallmarks of cancer were found. Our data identified downregulation of oncogenic signaling, upregulation of tumor-suppressing and prosenescence signaling, induction of mismatch, and excision DNA repair. The common feature of heated eMSC is the silence of MYC, AKT1/PKB oncogenes, and hTERT telomerase. Overall, our data indicate that despite genetic instability, SHS-survived eMSC do not undergo transformation. After long-term cultivation, these cells like their unheated counterparts enter replicative senescence and die.

[INDUCTION OF DECIDUAL DIFFERENTIATION OF ENDOMETRIAL MESENCHYMAL STEM CELLS].

In this study, we compared the ability of human mesenchymal stem cells derived from menstrual blood (eMSCs) and mesenchymal stem cells (MSCs) from other tissues to differentiate into decidual cells in vitro. It was demonstrated that during differentiation secretion of decidualization markers (prolactin and insulin-like growth factor binding protein-1) increases in eMSCs from adipose tissue (MSC-AD). Thus, the ability of eMSCs to differentiate into decidual cells is much higher than MSC-BM or MSC-AD. It makes eMSCs promising for application in cellular therapy of infertility associated with decidualzation insufficiency.

Monoclonal antibodies reveal structural similarity between cytoskeletal filaments and a model nucleopeptide.

The cytoskeleton is considered to be a very important cellular component, playing a role in the interactions between different organelles. However, in many cases the true biochemical functions and some of the structural aspects of cytoskeletal filaments are still unknown. Several hybridoma cell lines producing monoclonal antibodies (Mab) against a complex of linear DNA with the tridecapeptide Dns-NH2-VVTGVKTGVKTVT-CO2H have been established. (Dns is 5-methylaminonaphthalene-1-sulphonic acid.) The organization of this complex, in which the DNA is in a compact form, has been well-characterized previously by physicochemical methods and electron microscopy. A monoclonal antibody, Mab 66/9, was selected for further study on the basis of its reactivity with the immunizing DNA-peptide complex and minimal reaction with DNA alone. In immunofluorescence studies with cultured cells, this Mab did not recognize any nuclear structures, but reacted with cytoskeletal intermediate filaments and with nuclear lamins. Thus, Mab 66/9 appears to define an epitope present in the immunizing DNA-peptide complex and in cytoskeletal elements. The epitope is probably determined by the conformation of the oligopeptide since it was not detected in denatured cell lysates. Our observations provide some indirect evidence in support of the DNA-binding properties of cytoskeletal components which have been hypothesized in some recent publications.