High Throughput Transcriptome Profiling of Lithium Stimulated Human Mesenchymal Stem Cells Reveals Priming towards Osteoblastic Lineage

Abstract

Human mesenchymal stem cells (hMSCs) present in the bone marrow are the precursors of osteoblasts, chondrocytes and adipocytes, and hold tremendous potential for osteoregenerative therapy. However, achieving directed differentiation into osteoblasts has been a major concern. The use of lithium for enhancing osteogenic differentiation has been documented in animal models but its effect in humans is not clear. We, therefore, performed high throughput transcriptome analysis of lithium-treated hMSCs to identify altered gene expression and its relevance to osteogenic differentiation. Our results show suppression of proliferation and enhancement of alkaline phosphatase (ALP) activity upon lithium treatment of hMSCs under non-osteogenic conditions. Microarray profiling of lithium-stimulated hMSC revealed decreased expression of adipogenic genes (CEBPA, CMKLR1, HSD11B1) and genes involved in lipid biosynthesis. Interestingly, osteoclastogenic factors and immune responsive genes (IL7, IL8, CXCL1, CXCL12, CCL20) were also downregulated. Negative transcriptional regulators of the osteogenic program (TWIST1 and PBX1) were suppressed while genes involved in mineralization like CLEC3B and ATF4 were induced. Gene ontology analysis revealed enrichment of upregulated genes related to mesenchymal cell differentiation and signal transduction. Lithium priming led to enhanced collagen 1 synthesis and osteogenic induction of lithium pretreated MSCs resulted in enhanced expression of Runx2, ALP and bone sialoprotein. However, siRNA-mediated knockdown of RRAD, CLEC3B and ATF4 attenuated lithium-induced osteogenic priming, identifying a role for RRAD, a member of small GTP binding protein family, in osteoblast differentiation. In conclusion, our data highlight the transcriptome reprogramming potential of lithium resulting in higher propensity of lithium “primed” MSCs for osteoblastic differentiation.

Effects of thirty elements on bone metabolism

“…Some studies suggest that lithium causes bone loss that can predispose or aggravate osteoporosis [171,172], whereas other studies did not find any significant effects [173]. In contrast, several studies highlighted beneficial effects of lithium on bone metabolism, including inhibition of bone resorption and osteoclast formation, possibly via modulation of the canonical Wnt/␤-catenin pathway [174][175][176][177][178].…”

Transcriptomics of human multipotent mesenchymal stromal cells: Retrospective analysis and future prospects

“…MSC differentiation has been a focus of past comparative transcriptome approaches, which has included studies of functional differences in MSC populations (Jansen et al, 2010), characterization of MSC stemness (Gao et al, 2013;Steinert et al, 2015), and assessments of differentiation status (Brown et al, 2015;Granchi et al, 2010;Liu et al, 2014;Menssen et al, 2011;Modder et al, 2012;Satija et al, 2013;Skreti et al, 2014;Steinert et al, 2015;Wislet-Gendebien et al, 2012;Yu et al, 2013;Zhang et al, 2014). For example, temporal and spatial patterns of gene expression profiles were reported for chondrogenic differentiation (Skreti et al, 2014).…”

Development and characterization of lithium-releasing silicate bioactive glasses and their scaffolds for bone repair

“…Activation of this pathway through cell exposure to Li has been reported to promote osteoblastogenesis and inhibit osteoclastogenesis, leading to an increase in bone formation and volume in rats [13,14]. The effects of lithium on bone density have been investigated, with some authors observing that it might interfere with calcium transport within the body [15], enhance the proliferation, differentiation and cementogenic gene expression in human periodontal ligament-derived cells [16] and osteogenic differentiation in mesenchymal stem cells (MSCs) [17]. A study investigating the effects of lithium in patients treated with lithium carbonate found that such treatment may enhance or preserve bone mass [18].…”