DNA Methylation Changes duringIn VitroPropagation of Human Mesenchymal Stem Cells: Implications for Their Genomic Stability?

Abstract

Mesenchymal stem cells (MSCs) hold great promise for the treatment of numerous diseases. A major problem for MSC therapeutic use is represented by the very low amount of MSCs which can be isolated from different tissues; thus ex vivo expansion is indispensable. Long-term culture, however, is associated with extensive morphological and functional changes of MSCs. In addition, the concern that they may accumulate stochastic mutations which lead the risk of malignant transformation still remains. Overall, the genome of human MSCs (hMSCs) appears to be apparently stable throughout culture, though transient clonal aneuploidies have been detected. Particular attention should be given to the use of low-oxygen environment in order to increase the proliferative capacity of hMSCs, since data on the effect of hypoxic culture conditions on genomic stability are few and contradictory. Furthermore, specific and reproducible epigenetic changes were acquired by hMSCs during ex vivo expansion, which may be connected and trigger all the biological changes observed. In this review we address current issues on long-term culture of hMSCs with a 360-degree view, starting from the genomic profiles and back, looking for an epigenetic interpretation of their genetic stability.

Avoidance of total knee arthroplasty in early osteoarthritis of the knee with intra-articular implantation of autologous activated peripheral blood stem cells versus hyaluronic acid: A randomized controlled trial with differential effects of growth factor addition

“…Moreover, allogeneic sources are usually preferred for obvious commercial and patentrelated reasons and not due to ease of procurement or cost [30]. Isolated MSC of any source must invariably be expanded, and these manipulated allogeneic cells are prone to cytogenetic issues and infection/contamination risks as no uniform rules have been adopted [29][30][31]. We do yet not know which cell fraction(s) or specific cells are the most appropriate in regenerating cartilage.…”

“…Furthermore, a crucial and positive relationship between obesity and cancer is well known, and the purported immunomodulating and angiogenic properties of AT MSC raise suspicions about a possible causation [59,63]. Moreover, ex vivo expansion and long-term cultures with increased numbers of passages are associated with extensive morphological and functional changes of MSCs [31] and subsequently the concern that these cells may accumulate stochastic mutations which may lead to the risk of malignant transformation [31,61].…”

Correlation between telomere maintenance and stemness of mesenchymal stem/stromal cells

“…Previously, it has been shown that bone marrow MSCs loose replication capacity and differentiation potential during two months of in vitro cultivation [23] . There are opposite data about effects of extensive ex vivo expansion of MSCs in laboratories on their biology, where although a risk of malignant transformations was suggested [2] , there is evidence that long term cultivation of MSCs could not lead to transformation, because MSCs are not able to escape senescence [17,24,25] . Importantly, recent data showed a key role of telomere status in HSCs and bone marrow MSCs for the development of dyskeratosis congenita, a condition where shortened telomeres not only in HSCs, but also in bone marrow MSCs lead to disease development.…”

“…These processes require strict control of cell-cycle progression, followed by DNA replication, which are conditioned by chromosome stability provided by telomere replication and telomerase-mediated telomere extension in S phase. Due to the role in cell-cycle control and genome stability, telomere status is an important feature of stem, progenitor or precursor cells involved in maintenance of tissue homeostasis [1,2] .…”

Immunophenotypic characterisation and cytogenetic analysis of mesenchymal stem cells from equine bone marrow and foal umbilical cords during in vitro culture

“…The literature offers conflicting data regarding the risk of spontaneous transformation of mesenchymal stem cells during іn vitro culture (2)(3)(4)16). Therefore, investigations of the biological properties of mesenchymal stem cells from equine bone marrow and foal umbilical cords as well as their cytogenetic analysis are highly relevant and timely tasks (13).…”