Cobalt Chloride as a Hypoxia Mimicking Agent Induced HIF-1α and mTOR Expressions of Human Umbilical Cord Mesenchymal Stem Cells

ABSTRACT Objective: To assess the effects of cobalt chloride (CoCl2) as a hypoxia mimicking agent on human umbilical cord mesenchymal stem cells (hUCMSCs) expression of HIF-1α and mTOR for use in regenerative dentistry. Material and Methods: Human umbilical cord mesenchymal stem cells were isolated and then cultured. The characteristics of stemness were screened and confirmed by flow cytometry. The experiment was conducted on hypoxia (H) and normoxia (N) groups. Each group was divided and incubated into 24-, 48-, and 72-hours observations. Hypoxic treatment was performed using 100 µM CoCl2 on 5th passage cells in a conventional incubator (37°C; 5CO2). Then, immunofluorescence of HIF-1α and mTOR was done. Data was analyzed statistically using One-way ANOVA and Tukey's HSD. Results: Significant differences were found between normoxic and hypoxic groups on HIF-1α (p=0.015) and mTOR (p=0.000) expressions. The highest HIF-1α expression was found at 48 hours in the hypoxia group, while for mTOR at 24 hours in the hypoxia group. Conclusion: Hypoxia using cobalt chloride was able to increase human umbilical cord mesenchymal stem cells expression of HIF-1α and mTOR.

Lipopolysaccharides' Cytotoxicity on Human Umbilical Cord Mesenchymal Stem Cells

Abstract Objective: To show the cytotoxicity of Porphyromonas gingivalis lipopolysaccharide (LPS) on human umbilical cord mesenchymal stem cells (HUCMSCs) to better understand the characteristics for its application in regenerative procedures under periodontopathogen LPS influence. Material and Methods: Ultrapure Porphyromonas gingivalis LPS was used in this study. This research used a frozen stock HUCMSCs, previously confirmed by flow cytometry. The biological characteristics, such as cell morphology, proliferation, and protein expression, were screened. To check the cytotoxicity, HUCMSCs were cultured and divided into two groups, the control group and LPS group with various concentrations from 25 to 0.39 µg/mL. MTT assay was done and the cells were observed and counted. The significance level was set at 5%. Results: The percentage of living HUCMSCs on LPS group were not significantly different among concentrations (p>0.05) from 25 to 0.39 µg/mL, even though there were slight mean decrease between groups, but they were not significant. The duration of 24 hours of exposure of LPS does not significantly lower HUCMSCs viability. Conclusion: LPS does not affect the viability of HUCMSCs. The lower the concentration of LPS, the higher the viability of HUCMSCs.

Regeneration of Salivary Gland Defects of Diabetic Wistar Rats Post Human Dental Pulp Stem Cells Intraglandular Transplantation on Acinar Cell Vacuolization and Interleukin-10 Serum Level

Abstract Objective: To investigate the regeneration of rat's salivary gland diabetic defect after intraglandular transplantation of Human Dental Pulp Stem Cells (HDPSCs) on acinar cell vacuolization and Interleukin-10 (IL-10). Material and Methods: HDPSCs isolated from the dental pulp of first premolars #34. HDPSCs from the 3rd passage was characterized by immunocytochemistry of CD73, CD90, CD105 and CD45. Twenty-four male Wistar rats, 3-month-old, 250-300 grams induced with Streptozotocin 30 mg/kg body weight to create diabetes mellitus (DM) divided into 4 groups (n=6); positive control group on Day-7; positive control group on Day-14; treatment group Day-7 (DM+5.105HDPSCs); treatment group on Day-14. On Day-7 and Day-14, rats were sacrificed. Histopathological examination performed to analyze acinar cells vacuolization while Enzyme-linked Immunoabsorbent Assay to measure IL-10 serum level. Data obtained were analyzed statistically using multiple comparisons Bonferroni test, Kruskal Wallis, Shapiro-Wilk and Levene's test result Results: The highest acinar cell vacuolization found in control group Day 14 (0.239 ± 0.132), meanwhile the lowest acinar cell vacuolization found in treatment group Day 7 (0.019 ± 0.035) with significant difference (p=0.003). The highest IL-10 serum level found in treatment group Day 14 (175.583 ± 120.075) with significant difference (p=0.001) Conclusion: Transplantation of HDPSC was able to regenerate submandibular salivary gland defects in diabetic rats by decreasing acinar cell vacuolization and slightly increase IL-10 serum level.