Effects of IGFBP3 knockdown on human endometrial mesenchymal stromal cells stress-induced senescence.

Insulin-like growth factor binding protein 3 (IGFBP3) is known for its pleiotropic ability to regulate various cellular processes such as proliferation, apoptosis, differentiation etc. It has recently been shown that IGFBP3 is part of the secretome of senescent human endometrial mesenchymal stromal cells (MESCs) (Griukova et al., 2019) that takes part in paracrine propagation of senescence-like phenotype in MESCs (Vassilieva et al., 2020); however, mechanisms of pro-senescent IGFBP3 action in MESCs remain still unexplored. This study is aimed at elucidating the role of IGFBP3 upregulation in senescent MESCs. IGFBP3 knockdown in MESCs committed to H2O2-induced senescence led to partial abrogation of p21/Rb axis, to elevated ERK phosphorylation and to increase in SA-ß-gal activity. Additionally, MESCs derived from various donors were found to demonstrate different IGFBP3 regulation during stress-induced senescence. Obtained results suggest ambiguous role of IGFBP3 in stress-induced senescence of MESCs.

Chondrogenic differentiation followed IGFBP3 loss in human endometrial mesenchymal stem cells.

Insulin-like growth factor binding protein 3 (IGFBP3) is a multifunctional protein, able either to stimulate the cell growth or to promote apoptosis. In particular, IGFBP3 plays significant role in propagation of stress-induced senescence in human endometrium-derived mesenchymal stem cells (MESCs) (Vassilieva et al., 2020). We undertook CRISPR/Cas9-mediated IGFBP3 knockout in an effort to decelerate stress-induced senescence in MESCs, but, unexpectedly, IGFBP3-knockout MESCs culture acquired chondrocyte-like features, such as cell condensation and aggregation. We revealed that IGFBP3-knockout MESCs completely lost CD73 and CD90 MESCs positive surface markers, and significantly decreased expression of CD105 and CD146 MESCs positive surface markers. In addition, we found IGFBP3-knockout MESCs aggregates positively stained for Alcian Blue. We also detected expression of collagen type II in IGFBP3-knockout MESCs. The obtained results indicate that MESCs lost stemness after IGFBP3-knockout and underwent differentiation toward chondrogenic lineage. Our findings can enlighten IGFBP3 role in regulation of MESCs chondrogenesis.