The Expression Profile of Dental Pulp-Derived Stromal Cells Supports Their Limited Capacity to Differentiate into Adipogenic Cells

Abstract

Mesenchymal stromal cells (MSCs) can self-renew, differentiate into specialised cells and have different embryonic origins-ectodermal for dental pulp-derived MSCs (DPSCs) and mesodermal for adipose tissue-derived MSCs (ADSCs). Data on DPSCs adipogenic differentiation potential and timing vary, and the lack of molecular and genetic information prompted us to gain a better understanding of DPSCs adipogenic differentiation potential and gene expression profile. While DPSCs differentiated readily along osteogenic and chondrogenic pathways, after 21 days in two different types of adipogenic induction media, DPSCs cultures did not contain lipid vacuoles and had low expression levels of the adipogenic genes proliferator-activated receptor gamma (PPARG), lipoprotein lipase (LPL) and CCAAT/enhancer-binding protein alpha (CEBPA). To better understand this limitation in adipogenesis, transcriptome analysis in undifferentiated DPSCs was carried out, with the ADSC transcriptome used as a positive control. In total, 14,871 transcripts were common to DPSCs and ADSCs, some were unique (DPSCs: 471, ADSCs: 1032), and 510 were differentially expressed genes. Detailed analyses of overrepresented transcripts showed that DPSCs express genes that inhibit adipogenic differentiation, revealing the possible mechanism for their limited adipogenesis.

Similar Features, Different Behaviors: A Comparative In Vitro Study of the Adipogenic Potential of Stem Cells from Human Follicle, Dental Pulp, and Periodontal Ligament

“…Due to existing reports indicating that DPSCs have a limited capacity to differentiate into adipocytes [ 22 , 23 , 24 ], we first explored the conditions to induce the adipogenic response in those stem cells by comparing them in five adipogenic cocktails ( Table 1 ). As the starting point, we used an adipogenic induction medium 1 (AIM-1, see Table 1 ), which was enriched with 10 μM of INS and 200 μM of INDO, potent adipogenic agents that stimulate the proliferation and differentiation of preadipocytes by triggering the expression of essential transcriptional factors governing adipogenesis [ 25 , 26 , 27 ].…”

“…The inhibition of this protein by bpV (pic) or the PTEN knockdown induces the expression of PPAR γ and LPL , and increases the adipogenic response of DPSCs by suppressing the osteogenic pathway [ 60 ]. More recently, despite the fact that DPSCs exhibit MSCs and stemness features, this cell population is unable to differentiate into adipocytes [ 22 ] even by using a commercial culture induction media [ 23 ]. The detailed analysis of the transcriptomic data showed that DPSCs, when cultured under adipogenic conditions, express genes that inhibit adipogenic differentiation, including the wingless-type member 10 ( WNT10B ) or MSH-like homeobox ( MSX2 ) [ 23 ], which can prevent adipogenesis by blocking the expression of PPAR γ and the C/EBP family [ 6 ].…”

Dental-Derived Mesenchymal Stem Cells: State of the Art

“…Meanwhile, DPSCs cultured in the adipogenic induction medium did not show cytoplasmic lipid accumulation and had low expression levels of adipogenic-related genes (Fracaro et al, 2020). A recent study disclosed the gene expression profile of DMSCs, which supported their limited capacity of differentiating into adipocytes (Fracaro et al, 2020). However, it seems that the adipogenic limitation is not insurmountable.…”

“…Although some studies have reported that DMSCs can achieve adipogenic differentiation as efficiently as other MSCs, sometimes their conclusions were based solely on microscopic images of a few differentiated cells without further confirmation (Gronthos et al, 2000;Isobe et al, 2016). Meanwhile, DPSCs cultured in the adipogenic induction medium did not show cytoplasmic lipid accumulation and had low expression levels of adipogenic-related genes (Fracaro et al, 2020). A recent study disclosed the gene expression profile of DMSCs, which supported their limited capacity of differentiating into adipocytes (Fracaro et al, 2020).…”

Higher Expression of DNA (de)methylation-Related Genes Reduces Adipogenicity in Dental Pulp Stem Cells

“…In this regard, DPSCs exhibit higher mineralization capacity than other MSCs, including BMSCs, ATSCs, and different DT-MSCs (Xu et al, 2013;Padial-Molina et al, 2019;Shen et al, 2019;Mucientes et al, 2021). Thus, not surprisingly, the hypomethylation of the WNT10B locus (Figure 1G) facilitates its expression in DPSCs (Fracaro et al, 2020) to favor osteogenesis over adipogenesis, which suggests that DNA methylation is a mechanism underlying adipocyte and bone cell development. Together, these findings allow us to hypothesize that both the DNA methylation and gene expression established in DPSCs tend to be preserved, which suggests that the higher DNMT expression in DPSCs but not in PLSCs may be an important mechanism of cell identity that maintains the integrity of the epigenetic memory of DPSCs even under adipogenic conditions.…”