Potassium dihydrogen phosphate promotes the proliferation and differentiation of human periodontal ligament stem cells via nuclear factor kappa B pathway

A Review of Novel Strategies for Human Periodontal Ligament Stem Cell Ex Vivo Expansion: Are They an Evidence-Based Promise for Regenerative Periodontal Therapy?

Periodontitis is a gingiva disease sustained by microbially associated and host-mediated inflammation that results in the loss of the connective periodontal tissues, including periodontal ligament and alveolar bone. Symptoms include swollen gingiva, tooth loss and, ultimately, ineffective mastication. Clinicians utilize regenerative techniques to rebuild and recover damaged periodontal tissues, especially in advanced periodontitis. Human periodontal ligament stem cells (hPDLSCs) are considered an appealing source of stem cells for regenerative therapy in periodontium. hPDLSCs manifest the main properties of mesenchymal stem cells, including the ability to self-renew and to differentiate in mesodermal cells. Significant progress has been made for clinical application of hPDLSCs; nevertheless, some problems remain, including the small number of cells isolated from each sample. In recent decades, hPDLSC ex vivo expansion and differentiation have been improved by modifying cell culture conditions, especially with the supplementation of cytokines' or growth factors' mix, chemicals, and natural compounds, or by using the decellularized extracellular matrix. Here, we analyzed the changes in stemness properties and differentiation potential of hPDLSCs when culturing in alternative media. In addition, we focused on the possibility of replacing FBS with human emoderivates to minimize the risks of xenoimmunization or zoonotic transmission when cells are expanded for therapeutic purposes.

Integrative Analysis of ceRNA Networks in human periodontal ligament stem cells under hypoxia

OBJECTIVE

This study aims to investigate the regulatory effect of hypoxia on human periodontal ligament stem cells (PDLSCs) through RNA sequencing (RNA SEQ). Human PDLSCs were cultured in normoxia (20% O₂ ) or hypoxia (2% O₂ ).

MATERIAL AND METHODS

Total RNA was extracted and sequenced. The expression profiles of circRNAs, lncRNAs, and miRNAs were determined, and the lncRNA/circRNA-miRNA-mRNA networks were analyzed.

RESULTS

In total, 15 miRNAs, 449 lncRNAs, and 53 circRNAs were differentially expressed. Among them, 21 circRNAs, 262 lncRNAs, 5 miRNAs, and 5 mRNAs were selected to construct competing endogenous RNA (ceRNA) networks. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were carried out to explore potential related pathways and regulatory functions. Several ceRNA axes (lncRNA-FTX/circRNA-FAT1-hsa-miR-4781-3p-SMAD5 and circRNA LPAR1-hsa-miR-342-3p-ADAR) may provide a theoretical basis on the study of osteogenic differentiation of PDLSCs under hypoxia.

CONCLUSION

This study revealed that the expression profiles of circRNAs, lncRNAs, and miRNAs had changed significantly in PDLSCs cultured in 2% O₂ ; specific circRNAs/lncRNAs may play a competitive role in the differentiation of PDLSCs.

Low-intensity pulsed ultrasound enhances immunomodulation and facilitates osteogenesis of human periodontal ligament stem cells by inhibiting the NF-κB pathway

Human periodontal ligament stem cells (hPDLSCs) are vital in cellular regeneration and tissue repair due to their multilineage differentiation potential. Low intensity pulsed ultrasound (LIPUS) has been applied for treating bone and cartilage defects. This study explored the role of LIPUS in the immunomodulation and osteogenesis of hPDLSCs. hPDLSCs were cultured in vitro, and the effect of different intensities of LIPUS (30, 60, and 90 mW/cm²) on hPDLSC viability was measured. hPDLSCs irradiated by LIPUS and stimulated by lipopolysaccharide (LPS) and LIPUS (90 mW/cm2) were co-cultured with peripheral blood mononuclear cells (PBMCs). Levels of immunomodulatory factors in hPDLSCs and inflammatory factors in PBMCs were estimated, along with determination of osteogenesis-related gene expression in LIPUS-irradiated hPDLSCs. The mineralized nodules and alkaline phosphatase (ALP) activity of hPDLSCs and levels of IκBα, p-IκBα, and p65 subunits of NF-κB were determined. hPDLSC viability was increased as LIPUS intensity increased. Immunomodulatory factors were elevated in LIPUS-irradiated hPDLSCs, and inflammatory factors were reduced in PBMCs. Osteogenesis-related genes, mineralized nodules, and ALP activity were promoted in LIPUS-irradiated hPDLSCs. The cytoplasm of hPDLSCs showed increased IκBα and p65 and decreased p-IκBα at increased LIPUS intensity. After LPS and LIPUS treatment, the inhibitory effect of LIPUS irradiation on the NF-κB pathway was partially reversed, and the immunoregulation and osteogenic differentiation of hPDLSCs were decreased. LIPUS irradiation enhanced immunomodulation and osteogenic differentiation abilities of hPDLSCs by inhibiting the NF-κB pathway, and the effect is dose-dependent. This study may offer novel insights relevant to periodontal tissue engineering.

A Novel Perspective on Tissue Engineering Potentials of Periodontal Ligament Stem Cells

It is challenging to completely and predictably regenerate the missing periodontal tissues caused by the trauma or disease. To regenerate the periodontium, there is a need to consider several aspects that co-occur with periodontal development. This study provides an overview of the most up-to-date investigations on the characteristics and immunomodulatory features of Periodontal Ligament Stem Cells (PDLSCs) and the recent interventions performed using these cells, focusing on cell survival, proliferation, and differentiation. Keeping in mind the relationship between age and potency of PDLSCs, this work also demonstrates the necessity of establishing dental-derived stem cell banks for tissue regeneration applications. The data were collected from Pubmed and Google Scholar databases with the keywords of periodontal ligament stem cells, tissue engineering, characteristics, and stem cell therapy. The results showed the presence of wide-ranging research reports supporting the usability of PDLSCs for periodontal reconstruction. However, a better understanding of self-restoration for adequate regulation of adult stem cell growth is needed for various applied purposes.

Nano-Based Drug Delivery Systems for Periodontal Tissue Regeneration

Periodontitis is a dysbiotic biofilm-induced and host-mediated inflammatory disease of tooth supporting tissues that leads to progressive destruction of periodontal ligament and alveolar bone, thereby resulting in gingival recession, deep periodontal pockets, tooth mobility and exfoliation, and aesthetically and functionally compromised dentition. Due to the improved biopharmaceutical and pharmacokinetic properties and targeted and controlled drug release, nano-based drug delivery systems have emerged as a promising strategy for the treatment of periodontal defects, allowing for increased efficacy and safety in controlling local inflammation, establishing a regenerative microenvironment, and regaining bone and attachments. This review provides an overview of nano-based drug delivery systems and illustrates their practical applications, future prospects, and limitations in the field of periodontal tissue regeneration.

P75 neurotrophin receptor positively regulates the odontogenic/osteogenic differentiation of ectomesenchymal stem cells via nuclear factor kappa-B signaling pathway

p75NTR, a neural crest stem cell marker, is continuously expressed in mesenchymal cells during tooth development. Importantly, high expression of p75NTR in the late bell stage implicates its involvement in odontogenesis and mineralization. However, the regulatory mechanisms underlying p75NTR involvement in odonto/osteogenic differentiation remain unclear. Here, we investigate the effect and potential mechanisms underlying p75NTR involvement in odonto/osteogenic differentiation. We dissected EMSCs from the first branchial arches of mice embryo and compared the proliferation and migration of p75NTR+/+ and p75NTR-/-EMSCs by transwell, scratch and cell counting kit 8(CCK8)assays. The differentiation ability and the involvement of nuclear factor kappa-B (NF-κB) pathway were investigated through alkaline phosphatase and immunofluorescence assay, real-time PCR, and western blot. During induction of dental epithelium conditioned medium, p75NTR+/+ EMSCs exhibited deeper Alkaline phosphatase (ALP) staining and higher expression of odonto/osteogenic genes/proteins (e.g., dentin sialoprotein (DSPP) than p75NTR+/+ EMSCs. Moreover, p75NTR+/+ EMSCs exhibited higher nuclear P65 expression than p75NTR-/-EMSCs. Inhibition of NF-κB pathway with Bay11-7082 in p75NTR+/+EMSCs substantially decreased DSPP expression level. However, activation of NF-κB pathway with Bay11-7082 in p75NTR-/-EMSCs enhanced DSPP expression level. Thus, p75NTR possibly plays a paramount role in the proliferation and differentiation of EMSCs via NF-κB pathway.

miR-200a-3p represses osteogenesis of human periodontal ligament stem cells by targeting ZEB2 and activating the NF-κB pathway

OBJECTIVES

Human periodontal ligament stem cells (hPDLSCs) bear multilineage differentiation potential and represent the cytological basis of periodontal tissue regeneration. microRNA (miR) is accepted as a critical regulator of cell differentiation. This study explored the molecular mechanism of miR-200a-3p in osteogenesis of hPDLSCs.

MATERIAL AND METHODS

hPDLSCs were cultured and identified in vitro. miR-200a-3p expression during osteogenic differentiation of hPDLSCs was detected. hPDLSCs were transfected with miR-200a-3p mimic or miR-200a-3p inhibitor. Alkaline phosphatase (ALP) activity, calcified nodules and osteogenesis-related genes of hPDLSCs were measured. The binding relationship between miR-200a-3p and ZEB2 was predicted and verified. hPDLSCs were infected with sh-ZEB2, and then the osteogenic capacity was examined. miR-200a-3p inhibitor-transfected hPDLSCs were infected with sh-ZEB2. The key proteins of the NF-κB pathway were measured.

RESULTS

miR-200a-3p expression was downregulated during osteogenic differentiation of hPDLSCs. Upregulation of miR-200a-3p reduced ALP activity, calcified nodules and osteogenesis-related genes of hPDLSCs, while downregulation of miR-200a-3p facilitated the osteogenesis of hPDLSCs. miR-200a-3p targeted ZEB2. ZEB2 silencing repressed osteogenesis of hPDLSCs. ZEB2 silencing attenuated the promoting effect of miR-200a-3p inhibitor on osteogenesis of hPDLSCs. miR-200a-3p activated the NF-κB pathway by targeting ZEB2.

CONCLUSION

miR-200a-3p repressed osteogenesis of hPDLSCs by targeting ZEB2 and activating the NF-κB pathway. This study may offer insights for periodontal tissue regeneration engineering.

MicroRNA Hsa-Let-7b Regulates the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Targeting CTHRC1

Let-7 miRNA family has been proved as a key regulator of mesenchymal stem cells' (MSCs') biological features. However, whether let-7b could affect the differentiation or proliferation of periodontal ligament stem cells (PDLSCs) is still unknown. Here, we found that the expression of hsa-let-7b was visibly downregulated after mineralization induction of PDLSCs. After transfected with hsa-let-7b mimics or inhibitor reagent, the proliferation ability of PDLSCs was detected by cell counting kit-8 (CCK-8), flow cytometry, and 5-ethynyl-2-deoxyuridine (EdU) assay. On the other hand, the osteogenic differentiation capacity was detected by alkaline phosphatase (ALP) staining and activity, alizarin red staining, Western blot, and quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). We verified that hsa-let-7b did not significantly impact the proliferation ability of PDLSCs, but it could curb the osteogenic differentiation of PDLSCs. Besides, we predicted CTHRC1 acts as the downstream gene of hsa-let-7b to affect this process. Moreover, the combination of CTHRC1 and hsa-let-7b was verified by dual luciferase reporter assay. Our results demonstrated that the osteogenic differentiation of PDLSCs was enhanced after inhibiting hsa-let-7b, while was weakened after cotransfection with Si-CTHRC1. Collectively, hsa-let-7b can repress the osteogenic differentiation of PDLSCs by regulating CTHRC1.

Betulinic acid promotes the osteogenic differentiation of human periodontal ligament stem cells by upregulating EGR1

Periodontitis is one of the most common chronic inflammations of the oral cavity, which eventually leads to tooth loss. Betulinic acid (BetA) is an organic acid that has anti-inflammatory effects and is derived from fruits and plants, but its effect on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) is still unclear. This study aimed to explore the effect of BetA on the osteogenic differentiation of hPDLSCs and its mechanism. Our results revealed that BetA not only promoted the viability of hPDLSCs but also induced their osteogenic differentiation in a dose-dependent manner. In addition, RNA sequencing was used to screen the differentially expressed genes (DEGs) after hPDLSCs were treated with BetA, and 127 upregulated and 138 downregulated genes were identified. Gene Ontology enrichment analysis showed that DEGs were mainly involved in the response to lithium ions and the positive regulation of macrophage-derived foam cell differentiation. The Kyoto Encyclopedia of Genes and Genomes analysis results revealed that DEGs were enriched in the nuclear factor-κB and interleukin-17 signaling pathways. More importantly, we confirmed that early growth response gene 1 (EGR1), one of the three DEGs involved in bone formation, significantly promoted the expression of osteogenic markers and the mineralization of hPDLSCs. Knockdown of EGR1 obviously limited the effect of BetA on the osteogenic differentiation of hPDLSCs. In conclusion, BetA promoted the osteogenic differentiation of hPDLSCs through upregulating EGR1, and BetA might be a promising candidate in the clinical application of periodontal tissue regeneration.