The odontoblastic differentiation of dental mesenchymal stem cells: molecular regulation mechanism and related genetic syndromes

[Effects of cell area on single odontoblast polarization and differentiation via microarray technology]

OBJECTIVES

This study aimed to explore the impact of cell spreading area on odontoblast polarization and differentiation using micropatterned surfaces ge-nerated by photolithography.

METHODS

Micropatterned surfaces with differential adhesive properties were prepared using polyethylene glycol diacrylate (PEGDA)-ba-sed photolithography. Human dental pulp stem cells (hD-PSCs) were isolated into single cells and cultured on micropatterned surfaces with areas of 1 800, 2 700, and 3 600 μm2. Immunofluorescence staining was used to observe cell morphology and analyze the relocating of the golgi apparatus and nucleus. Alkaline phosphatase staining was preformed to examine odontogenic differentiation.

RESULTS

The hDPSCs were successfully isolated and cultured on micropatterned surfaces mimicking the morphology of polarized odontoblasts. Phalloidin staining confirmed that the isolated hDPSCs successfully recapitulated the morphology of predesigned micropatterns. Immunofluorescence staining showed that the polarization and differentiation levels of the hDPSCs with a 3600 μm2 area were significantly higher than those with 1 800 and 2 700 μm2 areas (P<0.05).

CONCLUSIONS

The polarization and differentiation of single hDPSCs increased with the cell areas on micropatterned surfaces.

Exploring the cytotoxic effects of bioactive compounds from Alcea rosea against stem cell driven colon carcinogenesis

Seven compounds were isolated from ethyl acetate extract of Alcea rosea and were examined for their cytotoxicity against HCT116, HT29 and SW480 colon cancer cells. It was found that two compounds (C4 and C5) exhibited strong anti-colon cancer activities. These two compounds were used to study their properties that include MTT activity (with IC50 of C4 as 74.71, 129.0 and 131.4 µg/ml in HCT116, HT29 and SW480 respectively, whereas IC50 of C5 as 128.1, 168.4 and 225.8 µg/ml in HCT116, HT29 and SW480 cells respectively), colony formation activity, wound healing activity, spheroid formation activity, DAPI-PI staining, acridine-orange and ethidium bromide staining, ROS measurement, and rhodamine-123 staining in both HCT116 and HT29 colon cancer cells. Both the compounds showed significant increase in apoptosis as visualized by 4',6-diamidino-2-phenylindol/propidium iodide (DAPI-PI) and acridine orange/ethidium bromide (AO/EtBr) staining. The induction of apoptosis was further confirmed by the expressions of cleaved PARP and caspase 3. ROS generation and its effect on MMP were measured by staining cells with Dichloro-dihydro-fluorescein diacetate (DCFH-DA) and Rhodamine. Expression levels of EMT associated markers like Cyclin D1, Slug, Vimentin, and E-Cadherin were also studied. Both the compounds down regulate protein levels of Slug, Cyclin D1, and Vimentin in a concentration-dependent manner. Eeffect of C4 and C5 compounds on key signaling protein like Wnt3a, Notch1, and Shh were evaluated. Additionally, mRNA levels of these genes were also analyzed. C4 exhibited the best binding affinity when docked with Shh and Wnt3a and Notch1. Similarly, C5 exhibited - 8.8, -8.2 and - 7.6 kcal⋅mol- 1 with Shh, Wnt3a and Notch1. The present findings provide insight and immense scientific support and integrity to a piece of indigenous knowledge. However, validation in living organisms is necessary before progressing to clinical trials and advancing it into a marketable pharmaceutical product.

Fabrication of Hard Tissue Constructs from Induced Pluripotent Stem Cells for Exploring Mechanisms of Hereditary Tooth/Skeletal Dysplasia

Tooth/skeletal dysplasia, such as hypophosphatasia (HPP), has been extensively studied. However, there are few definitive treatments for these diseases owing to the lack of an in vitro disease model. Cells differentiated from patient-derived induced pluripotent stem cells (iPSCs) demonstrate a pathological phenotype. This study aimed to establish a method for fabricating hard tissue-forming cells derived from human iPSCs (hiPSCs) for the pathological analysis of tooth/skeletal dysplasia. Healthy (HLTH) adult-derived hiPSCs were cultured in a hard tissue induction medium (HM) with or without retinoic acid (RA) under 3D culture conditions, and mineralization and expression of dentinogenesis- and osteogenesis-related markers in 3D hiPSC constructs were evaluated. hiPSCs derived from patients with hypophosphatasia were also cultured in HM with RA. HLTH-derived hiPSCs formed mineralized 3D constructs and showed increased expression of dentinogenesis- and osteogenesis-related markers; addition of RA promoted the expression of these markers in hiPSC constructs. HPP-derived hiPSC constructs showed lower mineralization and expression of dentinogenesis- and osteogenesis-related markers than HLTH-derived hiPSCs, indicating an impaired ability to differentiate into odontoblasts and osteoblasts. This method for fabricating 3D hiPSC constructs allows for simultaneous assessment of dentinogenesis and osteogenesis, with HPP-derived hiPSC constructs recapitulating pathological phenotypes.

Roles of SP/KLF transcription factors in odontoblast differentiation: From development to diseases

OBJECTIVES

A zinc-finger transcription factor family comprising specificity proteins (SPs) and Krüppel-like factor proteins (KLFs) plays an important role in dentin development and regeneration. However, a systematic regulatory network involving SPs/KLFs in odontoblast differentiation has not yet been described. This review examined the expression patterns of SP/KLF gene family members and their current known functions and mechanisms in odontoblast differentiation, and discussed prospective research directions for further exploration of mechanisms involving the SP/KLF gene family in dentin development.

MATERIALS AND METHODS

Relevant literature on SP/KLF gene family members and dentin development was acquired from PubMed and Web of Science.

RESULTS

We discuss the expression patterns, functions, and related mechanisms of eight members of the SP/KLF gene family in dentin development and genetic disorders with dental problems. We also summarize current knowledge about their complementary or synergistic actions. Finally, we propose future research directions for investigating the mechanisms of dentin development.

CONCLUSIONS

The SP/KLF gene family plays a vital role in tooth development. Studying the complex complementary or synergistic interactions between SPs/KLFs is helpful for understanding the process of odontoblast differentiation. Applications of single-cell and spatial multi-omics may provide a more complete investigation of the mechanism involved in dentin development.

Developmental Anomalies in Human Teeth: Odontoblastic Differentiation in Hamartomatous Calcifying Hyperplastic Dental Follicles Presenting with DSP, Nestin, and HES1

Hyperplastic dental follicles (HDFs) represent odontogenic hamartomatous lesions originating from the pericoronal tissues and are often associated with impacted or embedded teeth. These lesions may occasionally feature unique calcifying bodies, known as calcifying whorled nodules (CWNs), characterized by stromal cells arranged in a whorled or spiral fashion. CWNs are typically observed in multiple calcifying hyperplastic dental follicles or regional odontodysplasia. In our study, we examined 40 cases of HDFs, including nine instances with characteristics of CWNs, referred to as calcifying hyperplastic dental follicles (CHDFs), which are infrequently accompanied by odontodysplasia. The median ages of the HDFs and CHDFs were 16 (ranging from 3 to 66) and 15 (ranging from 11 to 50) years, respectively. The lower third molars were the most frequently affected by HDSFs and CHDFs, followed by the upper canines. A histological examination was conducted on all 40 cases, with an immunohistochemical analysis performed on 21 of them. Among the cases with CWN, nine affected a single embedded tooth, with one exception. CWNs exhibited diverse calcifications featuring sparse or entirely deposited psammoma bodies, and some displayed dentinoid formation. Immunohistochemically, the stromal cells of HDFs were frequently positive for CD56 and nestin. By contrast, CWNs were negative for CD56 but positive for nestin as well as hairy and enhancer split 1 (HES1), with a few dentin sialoprotein (DSP)-positive calcified bodies. Our results revealed that hamartomatous CHDFs can impact multiple and single-embedded teeth. CWNs composed of nestin and HES1-positive ectomesenchymal cells demonstrated the potential to differentiate into odontoblasts and contribute to dentin matrix formation under the influence of HES1. This study is the first report documenting odontoblastic differentiation in HDFs. The rare occurrence of HDFs and CHDFs contributes to limited comprehension. To prevent misdiagnosis, a better understanding of these conditions is necessary.