Evaluation of the maintenance of stemness, viability, and differentiation potential of gingiva-derived stem-cell spheroids

Genetic and Functional Modifications Associated with Ovarian Cancer Cell Aggregation and Limited Culture Conditions

The aggregation of cancer cells provides a survival signal for disseminating cancer cells; however, the underlying molecular mechanisms have yet to be elucidated. Using qPCR gene arrays, this study investigated the changes in cancer-specific genes as well as genes regulating mitochondrial quality control, metabolism, and oxidative stress in response to aggregation and hypoxia in our progressive ovarian cancer models representing slow- and fast-developing ovarian cancer. Aggregation increased the expression of anti-apoptotic, stemness, epithelial-mesenchymal transition (EMT), angiogenic, mitophagic, and reactive oxygen species (ROS) scavenging genes and functions, and decreased proliferation, apoptosis, metabolism, and mitochondrial content genes and functions. The incorporation of stromal vascular cells (SVF) from obese mice into the spheroids increased DNA repair and telomere regulatory genes that may represent a link between obesity and ovarian cancer risk. While glucose had no effect, glutamine was essential for aggregation and supported proliferation of the spheroid. In contrast, low glucose and hypoxic culture conditions delayed adhesion and outgrowth capacity of the spheroids independent of their phenotype, decreased mitochondrial mass and polarity, and induced a shift of mitochondrial dynamics towards mitophagy. However, these conditions did not reduce the appearance of polarized mitochondria at adhesion sites, suggesting that adhesion signals that either reversed mitochondrial fragmentation or induced mitobiogenesis can override the impact of low glucose and oxygen levels. Thus, the plasticity of the spheroids' phenotype supports viability during dissemination, allows for the adaptation to changing conditions such as oxygen and nutrient availability. This may be critical for the development of an aggressive cancer phenotype and, therefore, could represent druggable targets for clinical interventions.

Effects of noni on cellular viability and osteogenic differentiation of gingiva-derived stem cells demonstrated by RNA sequencing and quantitative PCR

Noni fruit (Morinda citrifolia) has been widely used in traditional medicine across tropical and subtropical regions, and is now being paid more attention in Western medicine. The present study aimed to investigate the effects of noni extract on the change in the cellular morphology, maintenance of cellular viability and enhancement of osteogenic differentiation of stem cells. Stem cells obtained from gingiva were cultured where noni extracts existed at concentrations ranging from 10-200 ng/ml. Evaluations of cell morphology and cellular viability were performed. Alkaline phosphatase activity assays were performed to assess the osteogenic differentiation. Alizarin Red S staining was performed to evaluate the calcium deposits in the culture, with the addition of noni extract. Global gene expression was analyzed via next-generation mRNA sequencing. Gene ontology and pathway analyses were performed to determine the associated mechanisms. Validation procedures were performed via quantitative (q)PCR analysis. The addition of noni at concentrations ranging from 10-200 ng/ml did not produce significant morphological changes. There were significantly higher values of cellular viability, with the highest value at 100 ng/ml compared with the control (P<0.05). Furthermore, significantly higher values of alkaline phosphatase activity was noted in the 10 and 100 ng/ml groups compared with the 0 ng/ml group on day 7 (P<0.05). Alizarin Red S staining revealed calcium deposits in each group. In addition, the highest value for Alizarin Red S staining was observed at 100 ng/ml compared with the unloaded control (P<0.05). qPCR analysis demonstrated that the mRNA expression levels of RUNX2, BSP, OCN and COL1A1 increased following treatment with noni. Taken together, the results of the present study suggest that noni extract has enhancing effects on gingiva-derived mesenchymal stem cells, by enhancing cellular viability and osteogenic differentiation.

Vitamin D Enhanced the Osteogenic Differentiation of Cell Spheroids Composed of Bone Marrow Stem Cells

Background and Objectives: Vitamin D is a bone modulator widely used in regenerative medicine. This study aimed to analyze the effects of vitamin D on the osteogenic differentiation and mineralization of human mesenchymal stem cells. Materials and Methods: Spheroids were fabricated using human bone marrow-derived stem cells, and were cultured in the presence of vitamin D at concentrations of 0, 0.1, 1, 10, and 100 nM. Stem cell spheroids were fabricated and the morphological evaluation was conducted on days 1, 3, 7 and 14. Determination of qualitative cellular viability was performed with Live/Dead Kit assay on days 1 and 7. Quantitative cellular viability was evaluated with Cell Counting Kit-8 on days 1, 3, 7, and 14. To analyze the osteogenic differentiation of cell spheroids, alkaline phosphatase activity assays were performed with commercially available kit on days 7 and 14. Real-time polymerase chain reaction was used to determine the expression levels of RUNX2, BSP, OCN, and COL1A1 on days 7 and 14. Results: The stem cells produced well-formed spheroids, and addition of vitamin D did not result in any noticeable changes in the shape. The addition of vitamin D did not significantly change the diameter of the spheroids at 0, 0.1, 1, 10, or 100 nM concentrations. Quantitative cell viability results from days 1, 3, 7 and 14 showed no significant difference between groups (p > 0.05). There was significantly higher alkaline phosphatase activity in the 0.1 nM group when compared with the control group on day 14 (p < 0.05). Real-time polymerase chain reaction results demonstrated that the mRNA expression levels of RUNX2, OCN, and COL1A1 were significantly increased when vitamin D was added to the culture. Conclusions: Based on these findings, we concluded that vitamin D could be applied to the increased osteogenicity of stem cell spheroids.

Characteristics, Classification, and Application of Stem Cells Derived from Human Teeth

Since mesenchymal stem cells derived from human teeth are characterized as having the properties of excellent proliferation, multilineage differentiation, and immune regulation. Dental stem cells exhibit fibroblast-like microscopic appearance and express mesenchymal markers, embryonic markers, and vascular markers but do not express hematopoietic markers. Dental stem cells are a mixed population with different sensitive markers, characteristics, and therapeutic effects. Single or combined surface markers are not only helpful for understanding the subpopulation of mixed stem cell populations according to cell function but also for improving the stable treatment effect of dental stem cells. Focusing on the discovery and characterization of stem cells isolated from human teeth over the past 20 years, this review outlines the effect of marker sorting on cell proliferation and differentiation ability and the assessment of the clinical application potential. Classified dental stem cells from markers and functional molecules can solve the problem of heterogeneity and ensure the efficacy of cell therapy strategies including dentistry, neurologic diseases, bone repair, and tissue engineering.

Comparison of 2- and 3-Dimensional Cultured Periodontal Ligament Stem Cells; a Pilot Study

This study compared the characteristics of periodontal ligament stem cells (PDLSCs) cultured using 3-dimensional (3D) versus conventional 2-dimensional (2D) methods. PDLSCs were cultured in either a 3D culture with a non-adhesive culture plate (Stemfit 3D®) or a conventional 2D culture using a 6-well plate. Morphology, viability, proliferation ability, and osteogenic differentiation were analyzed to characterize the differences induced in identical PDLSCs by 3D and 2D culture environments. In addition, gene expression was analyzed using RNA sequencing to further characterize the functional differences. The diameter and the viability of the 3D-cultured PDLSCs decreased over time, but the shape of the spheroid was maintained for 20 days. Although osteogenic differentiation occurred in both the 2D- and 3D-cultured PDLSCs, compared to the control group it was 20.8 and 1.6 higher in the 3D- and 2D-cultured cells, respectively. RNA sequencing revealed that PDLSCs cultured using 2D and 3D methods have different gene expression profiles. The viability of the 3D-cultured cells was decreased, but they showed superior osteogenic differentiation compared to 2D-cultured cells. Within the limitations of this study, the results demonstrate that the structure and function of PDLSCs are influenced by the cell culture method.

Morphological stability, cellular viability and stem cell marker expression of three-dimensional cultures of stem cells from bone marrow and periodontium

The aim of the present study was to evaluate the morphology, cellular viability and stem cell marker expression of three-dimensional cultures of bone marrow and gingiva-derived stem cells in different ratios. Stem cell spheroids were made with bone marrow and gingiva-derived stem cells using ratios of 6:0 (Group 1), 4:2 (Group 2), 3:3 (Group 3), 2:4 (Group 4) and 0:6 (Group 5), respectively. The viability of cell spheroids was analyzed using a Live/Dead kit assay and a Cell Counting Kit-8 assay. Total RNA extraction and reverse transcription-quantitative PCR were performed to detect the mRNA expression levels of Nanog and β-actin in each group. Stem cell spheroids were well formed in silicone elastomer-based concave microwells with different ratios of bone marrow and gingiva-derived stem cells. The shape of the spheroids and their viability were maintained throughout the entirety of the experimental procedure. Statistically significant increases in spheroid diameters were noted in Groups 4 and 5 on day 1 when compared with Group 1 on day 1. There was a significant increase in the cell viability values seen in Group 3 on day 1 when compared with Group 1 on day 1. Highest levels of Nanog expression was seen in Group 3 on day 10, but the increase was not significant when compared with Group 1 on day 1. Co-culturing with higher ratios of gingiva-derived stem cells produced stem cell spheroids with larger diameters and increased cellular viability. This co-culture technique may be used in stem cell therapy with allogenic stem cell transplantation.

Gingiva-derived Mesenchymal Stem Cells and Their Potential Applications in Oral and Maxillofacial Diseases

BACKGROUND

Stem cells are undifferentiated cells with multilineage differentiation potential. They can be collected from bone marrow, fat, amniotic fluid, and teeth. Stem cell-based therapies have been widely used to treat multiple diseases, such as cardiac disease, and hematological disorders. The cells may also be beneficial for controlling the disease course and promoting tissue regeneration in oral and maxillofacial diseases. Oral-derived gingival mesenchymal stem cells are easy to access and the donor sites heal rapidly without a scar. Such characteristics demonstrate the beneficial role of GMSCs in oral and maxillofacial diseases.

OBJECTIVE

We summarize the features of GMSCs, including their self-renewal, multipotent differentiation, immunomodulation, and anti-inflammation properties. We also discuss their applications in oral and maxillofacial disease treatment and tissue regeneration.

CONCLUSION

GMSCs are easily harvestable adult stem cells with outstanding proliferation, differentiation, and immunomodulation characteristics. A growing body of evidence indicates that GMSCs have strong potential use in accelerating wound healing and promoting the regeneration of bone defects, periodontium, oral neoplasms, salivary glands, peri-implantitis, and nerves. Moreover, alginate, polylactic acid and polycaprolactone can be used as biodegradable scaffolds for GMSC encapsulation. Various growth factors can be applied to the corresponding scaffolds to obtain the desired GMSC differentiation and phenotypes. Three-dimensional spheroid culture systems could optimize GMSC properties and improve the performance of the cells in tissue engineering. The immunomodulatory property of GMSCs in controlling oral and maxillofacial inflammation needs further research.

Fibroblast growth factor-4 maintains cellular viability while enhancing osteogenic differentiation of stem cell spheroids in part by regulating RUNX2 and BGLAP expression

Fibroblast growth factors (FGFs) are growth factors that were initially identified as proteins that stimulate fibroblast proliferation. The aim of the present study was to examine the effects of FGF-4 on the morphology, cellular viability and osteogenic differentiation of stem cell spheroids. Stem cell spheroids were generated using concave microwells in the presence of FGF-4 at concentrations of 0, 50, 100 and 200 ng/ml. Cellular viability was qualitatively assessed by a fluorometric live/dead assay using a microscope and quantitatively determined by using Cell Counting Kit-8. Furthermore, alkaline phosphatase activity and calcium deposition were determined to assess osteogenic differentiation. Reverse transcription-quantitative PCR (RT-qPCR) was performed to evaluate the mRNA expression levels of Runt-related transcription factor 2 (RUNX2) and bone γ-carboxyglutamate protein (BGLAP). Spheroidal shapes were achieved in the microwells on day 1 and a significant increase in the spheroid diameter was observed in the 200 ng/ml FGF-4 group compared with the control group on day 1 (P<0.05). The results regarding viability using Cell Counting Kit-8 in the presence of FGF-4 at 50, 100 and 200 ng/ml at day 1 were 98.0±2.5, 106.2±17.6 and 99.5±6.0%, respectively, when normalized to the control group (P>0.05). Furthermore, the alkaline phosphatase activity was significantly elevated in the 200 ng/ml group, when compared with the control group. The RT-qPCR results demonstrated that the mRNA expression levels of RUNX2 and BGLAP were significantly increased at 200 ng/ml. Therefore, the present results suggested that the application of FGF-4 maintained cellular viability while enhancing the osteogenic differentiation of stem cell spheroids, at least partially by regulating RUNX2 and BGLAP expression levels.

Lovastatin increases the proliferation and osteoblastic differentiation of human gingiva-derived stem cells in three-dimensional cultures

Lovastatin is a cholesterol-lowering agent that also has effects of cell proliferation and apoptosis. The present study was performed to evaluate the effects of lovastatin on the proliferation and osteogenic differentiation of three-dimensional cell spheroids formed from human gingiva-derived stem cells (GDSCs) using concave microwells. GDSCs were plated on polydimethylsiloxane-based concave micromolds and grown in the presence of lovastatin at concentrations of 0, 2 and 6 µM. The morphology of the cells was viewed under an inverted microscope, and cell viability was determined with Cell Counting kit-8 on days 2, 7 and 14. Alkaline phosphatase activity assays were performed to evaluate the osteogenic differentiation on days 2 and 8. Alizarin red-S staining was also used to assess the mineralization of the stem cell spheroids at day 14. The results confirmed that GDSCs formed spheroids in concave microwells. No significant changes were noted with longer incubation time, and no significant differences in cell viability were noted between the three lovastatin groups at each time point. Higher osteogenic differentiation was observed in the 2 µM group when compared with the control. Mineralized extracellular deposits were visible after Alizarin red-S staining, and higher mineralization was noted in the 2 and 6 µM lovastatin groups when compared with the 0 µM control. The relative mineralization values of the 0, 2 and 6 µM groups on day 14 were 39.0±9.6, 69.3±6.0 and 60.9±7.5, respectively. This study demonstrated that the application of lovastatin enhanced the osteogenic differentiation of cell spheroids formed from GDSCs. This suggests that combinations of lovastatin and stem cell spheroids may have the potential for use in tissue engineering.

Evaluation of fibroblast growth factor-2 on the proliferation of osteogenic potential and protein expression of stem cell spheroids composed of stem cells derived from bone marrow

Fibroblast growth factor-2 (FGF-2) is reported to have various functions and is considered a key human mesenchymal stem cell mitogen, often supplemented to increase human mesenchymal stem cell growth rates. The purpose of this study was to evaluate the effects of FGF-2 on cellular viability and osteogenic differentiation using three-dimensional cell spheroids of stem cells. Three-dimensional cell spheroids were fabricated using concave silicon elastomer-based microwells in the presence of FGF-2 at concentrations of 0, 30, 60 and 90 ng/ml. Qualitative cellular viability was determined with a confocal microscope, and quantitative cellular viability was evaluated using a Cell Counting Kit-8 assay. Alkaline phosphatase activity and Alizarin Red S staining were used to assess osteogenic differentiation. Spheroids were well formed in silicon elastomer-based concave microwells on Day 1. The average spheroid diameters at Day 1 for FGF-2 at 0, 30, 60 and 90 ng/ml were 202.2±3.0, 206.6±22.6, 208.8±6.8 and 196.6±26.7 µm, respectively (P>0.05). The majority of the cells in the cell spheroids emitted green fluorescence. The relative Cell Counting Kit-8 assay values for FGF-2 at 0, 30, 60 and 90 ng/ml at Day 1 were 100.0±5.5, 101.8±8.8, 99.2±4.8 and 103.4±9.6% (P>0.05). The addition of FGF-2 at 60 ng/ml concentration produced the highest value for alkaline phosphatase activity. Mineralized extracellular deposits were evenly observed in each group, and the highest value was identified for FGF-2 groups at 60 ng/ml concentration for Alizarin Red S staining. Based on these findings, it was concluded that FGF-2 may increase alkaline phosphatase activity or Alizarin Red S staining, and further studies are needed to fully elucidate the mechanisms of FGF-2.

Osteogenic potential of cell spheroids composed of varying ratios of gingiva-derived and bone marrow stem cells using concave microwells

The aim of the current study was to evaluate cell viability and osteogenic differentiation potential in cell spheroids composed of varying ratios of gingiva-derived and bone marrow stem cells cultured in concave microwells. Cell spheroids were established from bone marrow and gingiva-derived stem cells in ratios of 6:0 (Group 1), 2:1 (Group 2), 3:3 (Group 3), 1:2 (Group 4), and 0:6 (Group 5). On days 3 and 5, the viability of the cell spheroids was qualitatively analyzed using a calcein acetoxymethyl ester working solution and an ethidium homodimer-1 live/dead assay. On days 1, 3, 5 and 7, a quantitative cell viability analysis was performed using a Cell Counting Kit-8. Alkaline phosphatase activity assays were performed using a commercially available kit on day 7 to assess osteogenic differentiation. In addition, reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed to evaluate runt-related transcription factor 2 (Runx2) and osteocalcin expression. The ratio of gingiva-derived to bone marrow stem cells did not affect the stem cell spheroid morphology. No significant changes in cell viability were noted among the different groups following incubation for 7 days. A consistent alkaline phosphatase activity was measured in co-cultured gingiva-derived and bone marrow stem cell spheroids of varying compositions. Runx2 and osteocalcin expression was increased when co-cultured compared with pure gingiva-derived or bone marrow stem cells. In conclusion, stem cell spheroids established by co-culturing maintained morphology, viability and a high osteogenic differentiation potential during the experimental period of 7 days. These spheroids containing human gingiva-derived and bone marrow stem cells may enhance the osteogenic differentiation potential. The use of multicell spheroids may be a simple and effective strategy for improving stem cell therapy.

The effects of doxorubicin-loaded liposomes on viability, stem cell surface marker expression and secretion of vascular endothelial growth factor of three-dimensional stem cell spheroids

The aim of the present study was to evaluate the effects of anionic, cationic and neutral liposomes containing doxorubicin on the cellular viability and osteogenic differentiation of three-dimensional stem cell spheroids. Doxorubicin-loaded liposomes were prepared using the traditional thin-lipid-film-hydration method and were characterized using transmission electron microscopy and a zeta potential analyzer. The doxorubicin release profile from these liposomes was also analyzed in vitro. Three-dimensional cell spheroids were fabricated using silicon elastomer-based concave microwells. Qualitative results of cellular viability were observed using a confocal microscope and quantitative cellular viability was evaluated using a Cell-Counting Kit-8 (CCK-8) assay. Furthermore, the secretion of vascular endothelial growth factor was evaluated. Western blot analysis was performed to assess the expression of collagen I and glyceraldehyde 3-phosphate. Results indicated that the spheroids were well formed in silicon elastomer-based concave microwells on day 1. In general, the shapes of the cells in the in the doxorubicin-loaded anionic, cationic and neutral liposome groups were similar to the control group except for the 10 µg/ml groups on days 3, 5, and 7. No significant changes in cellular viability were noted with the addition of doxorubicin at day 1 but significant decreases in cellular viability were noted with application of doxorubicin at day 5. Notably, higher concentrations of doxorubicin reduced the secretion of vascular endothelial growth factor and stem cell marker expression. To conclude, the present study indicated that doxorubicin-loaded anionic liposomes produced the most sustained release profile and cationic liposomes produced the highest uptake of the stem cell spheroids. These findings suggested that higher concentrations of doxorubicin-loaded liposomes affected cellular viability, the secretion of vascular endothelial growth factor and stem cell marker expression.

Enhanced Osteogenic Differentiation Potential of Stem-Cell Spheroids Created From a Coculture of Stem Cells and Endothelial Cells

PURPOSE

This study was performed to fabricate stem-cell spheroids formed with human gingiva-derived stem cells and endothelial cells and to evaluate their viability and osteogenic differentiation potential.

MATERIALS AND METHODS

Gingiva-derived stem cells were isolated, and stem cells and endothelial cells with a total of 6 × 10 cells were seeded into concave micromolds with different ratios of 6:0 (group 1), 4:2 (group 2), 3:3 (group 3), and 2:4 (group 4).

RESULTS

Gingiva-derived stem cells and/or endothelia cells formed spheroids in concave microwells. There was a decreasing trend in the diameter of spheroids with increasing amounts of endothelial cells, but there were no statistically significant differences between the groups. The secretion of vascular endothelial growth factor from the spheroids was noted. The results of the alkaline phosphatase activity assays showed significantly higher values for groups 2, 3, and 4 when compared with the value of group 1.

CONCLUSIONS

Conclusively, stem-cell spheroids formed with human gingiva-derived stem cells and endothelial cells using concave microwells enhanced osteogenic differentiation potential, and multicell spheroid-based cell delivery could be a simple and effective strategy for improving stem-cell therapy.