Comparative evaluation of proliferative potential and replicative senescence associated changes in mesenchymal stem cells derived from dental pulp and umbilical cord

OGA promotes human dental pulp stem cell senescence and inhibits mitophagy by inhibition of O-GlcNAcylation of KLF2

BACKGROUND

Dental pulp stem cells (DPSCs) aging impedes its application in tooth regeneration techniques, involving abnormal mitophagy. O-GlcNAcylation is a post-translational modification that regulates various cellular processes. Here, we aimed to investigate the role of O-GlcNAcylation in mitophagy and senescence.

METHODS

DPSCs were cultured and passaged in vitro, and the 7th (p7) and 15th (p15) generation cells were collected. OGA and KLF2 were knocked down in p15 cells. Cell senescence was evaluated using senescence associated β-galactosidase staining, enzyme-linked immunosorbent assay, and western blotting; mitophagy was evaluated using western blotting. The regulation of OGA on the O-GlcNAcylation of KLF2 was analyzed using immunoprecipitation and western blotting.

RESULTS

The results showed that p15 cells were more senescent than p7 cells and had poor mitophagy, with the higher expression of OGA. Knockdown of OGA inhibited senescence and promoted mitophagy in DPSCs. Moreover, silencing of KLF2 reversed the effects on senescence and mitophagy mediated by OGA knockdown. Additionally, OGA suppressed the O-GlcNAcylation of KLF2 at S177 site and thus reduced its stability.

CONCLUSION

Silencing of OGA promotes mitophagy and inhibits DPSC senescence by promoting the O-GlcNAcylation of KLF2, suggesting a novel mechanism underlying DPSC senescence.

Comparison of infant bone marrow- and umbilical cord-derived mesenchymal stem cells in multilineage differentiation

We compared infant bone marrow-derived mesenchymal stem cells (infant BMSCs) with umbilical cord-derived mesenchymal stem cells (UCSCs) by assessing multilineage differentiation. Proliferation was gauged through changes in cell numbers and doubling time. Senescence-related genes (p16, p21, and p53), senescence-associated β-galactosidase (SA-β-gal), and γH2AX immunofluorescence determined senescence presence. Superoxide dismutases (SODs) and genes related to various differentiations were analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Differentiation was confirmed through histochemical, immunohistochemical, and immunofluorescence staining. Infant BMSCs surpassed UCSCs in proliferation. Infant BMSCs exhibited lower senescence-related gene expression at late passages, upregulated antioxidant enzymes during early passages, and reduced SA-β-gal staining. Chondrogenic gene expression (SOX9, COL2, and COL10) was enhanced in infant BMSCs, along with improved immunohistochemical staining. Infant BMSCs showed higher expression of osteogenic (ALP and OCN) and adipogenic (PPARγ and LPL) genes, confirmed by histochemical staining. However, UCSCs had higher expression of tenogenic genes (MMP3, SCX, DCN, and TNC). Hepatogenic differentiation potential was similar, with no significant difference in hepatogenic gene expression (ALB and TAT). Compared to UCSCs, infant BMSCs demonstrated superior proliferation, reduced senescence, increased antioxidant capacity, and enhanced differentiation potential toward chondrogenic, osteogenic, and adipogenic lineages.

Vitamin D3-incorporated chitosan/collagen/fibrinogen scaffolds promote angiogenesis and endothelial transition via HIF-1/IGF-1/VEGF pathways in dental pulp stem cells

Effective vascularization during wound healing remains a critical challenge in the regeneration of skin tissue. On the other hand, mesenchymal stem cell (MSC) to endothelial phenotype transition (MEnDoT) is a potential phenomenon grossly underexplored in vascularized skin tissue engineering. Vitamin D3 has a proven role in promoting MEnDoT. Hence, a D3-incorporated scaffold made with biocompatible materials such as chitosan, collagen and fibrinogen should be able to promote endothelial lineage transition in vitro for tissue engineering purposes. In this study, we developed vitamin D3 incorporated chitosan-collagen-fibrinogen (CCF-D3) scaffolds physically crosslinked under UV and conducted thorough physicochemical and biological assays on it compared to a control scaffold without vitamin D3. Our study for the first time reports the potential vascularization property of the CCF-D3 scaffold by inducing the transitions of dental pulp MSC to endothelial lineage via the HIF-1/IGF-1/VEGF pathways. MSC seeded on UV-exposed CCF-D3 scaffolds had higher cell viability and transitioned towards endothelial lineage was observed by elevated proliferative and endothelial-specific gene expressions and flow cytometric analysis of SCA-1+ antibody. The difference in VEGF-A and α-SMA expressions was also observed in the D3-CCF scaffold compared to the scaffolds without D3.

Improved Method for Dental Pulp Stem Cell Preservation and Its Underlying Cell Biological Mechanism

Dental pulp stem cells (DPSCs) are considered a valuable cell source for regenerative medicine because of their high proliferative potential, multipotency, and availability. We established a new cryopreservation method (NCM) for collecting DPSCs, in which the tissue itself is cryopreserved and DPSCs are collected after thawing. We improved the NCM and developed a new method for collecting and preserving DPSCs more efficiently. Dental pulp tissue was collected from an extracted tooth, divided into two pieces, sandwiched from above and below using cell culture inserts, and cultured. As a result, the cells in the pulp tissue migrated vertically over time and localized near the upper and lower membranes over 2-3 days. With regard to the underlying molecular mechanism, SDF1 was predominantly involved in cell migration. This improved method is valuable and enables the more efficient collection and reliable preservation of DPSCs. It has the potential to procure a large number of DPSCs stably.

Stem cell sources from human biological waste material: a role for the umbilical cord and dental pulp stem cells for regenerative medicine

Stem cell research with biological waste material is an area that holds promise to revolutionize treatment modalities and clinical practice. The interest in surgical remnants is increasing with time as research on human embryonic stem cells remains controversial due to legal and ethical issues. Perhaps, these restrictions are the motivation for the use of alternative mesenchymal stem cell (MSC) sources in the regenerative field. Stem cells (SCs) of Umbilical Cord (UC) and Dental Pulp (DP) have almost similar biological characteristics to other MSCs and can differentiate into a number of cell lineages with enormous potential future prospects. A concise critical observation of UC-MSCs and DP-MSCs is presented here reviewing articles from the last two decades along with other stem cell sources from different biological waste materials.

Effect of Biodentine on Odonto/Osteogenic Differentiation of Human Dental Pulp Stem Cells

This study aims to compare the biological characteristics of human dental pulp stem cells (hDPSCs) isolated from different-aged populations and examine the effects of Biodentine on proliferation and odonto/osteogenic differentiation of hDPSCs isolated from the elderly in vitro. hDPSCs were isolated from three different-aged populations: group A (≤18 years old), group B (19−59 years old), and group C (≥60 years old). The adhesion, proliferation, odonto/osteogenesis, and senescence were compared. The optimal concentration of aqueous Biodentine extract was determined by CCK-8 assay, alkaline phosphatase (ALP), and alizarin red staining (ARS). The effect of Biodentine on odonto/osteogenic gene and protein expression of hDPSCs in each group was evaluated by quantitative real-time PCR (QRT-PCR) and Western blot. hDPSCs were successfully isolated from three different-aged populations. Flow cytometry revealed that all isolated hDPSCs were positive for CD73 (>90%), CD90 (>90%), CD146 (<30%), and negative for CD45 (<1%). There existed an age-related decline in proliferation, odonto/osteogenic gene expression, and S-phase fraction (p < 0.05), an increase in senescence genes and p21 and p16 expression, and time needed for cell adhesion. Biodentine promoted hDPSC proliferation and mineralization in each group, particularly at a concentration of 0.2 mg/mL. Biodentine markedly enhanced odonto/osteogenesis-related gene and protein expression in each group (p < 0.05). hDPSCs can be obtained from populations of all ages. Though there is an age-related decline in their biological properties, hDPSCs from the elderly still maintain certain proliferation and multidirectional differentiation abilities. Biodentine can significantly promote the proliferation and odonto/osteogenic differentiation of hDPSCs isolated from the elderly over 60 years old, which could be considered a pulp capping material for vital pulp therapy in the elderly. Nevertheless, the efficacy of Biodentine in clinical application has to be further studied.

Human Umbilical Cord Mesenchymal Stem Cells: Current Literature and Role in Periodontal Regeneration

Periodontal disease can cause irreversible damage to tooth-supporting tissues such as the root cementum, periodontal ligament, and alveolar bone, eventually leading to tooth loss. While standard periodontal treatments are usually helpful in reducing disease progression, they cannot repair or replace lost periodontal tissue. Periodontal regeneration has been demonstrated to be beneficial in treating intraosseous and furcation defects to varied degrees. Cell-based treatment for periodontal regeneration will become more efficient and predictable as tissue engineering and progenitor cell biology advance, surpassing the limitations of present therapeutic techniques. Stem cells are undifferentiated cells with the ability to self-renew and differentiate into several cell types when stimulated. Mesenchymal stem cells (MSCs) have been tested for periodontal regeneration in vitro and in humans, with promising results. Human umbilical cord mesenchymal stem cells (UC-MSCs) possess a great regenerative and therapeutic potential. Their added benefits comprise ease of collection, endless source of stem cells, less immunorejection, and affordability. Further, their collection does not include the concerns associated with human embryonic stem cells. The purpose of this review is to address the most recent findings about periodontal regenerative mechanisms, different stem cells accessible for periodontal regeneration, and UC-MSCs and their involvement in periodontal regeneration.