Induction of Migration and Collagen Synthesis in Human Gingival Fibroblasts Using Periodontal Ligament Stem Cell Conditioned Medium

OBJECTIVE

 This study aimed to examine the effect of periodontal ligament stem cell conditioned medium (PDLSC-CM) on human gingival fibroblast (HGF) migration and collagen synthesis.

MATERIALS AND METHODS

 To assess cell viability, we extracted PDLSC-CM, and the total derived protein concentration was adjusted to 12.5 to 200 µg/mL, followed by treatment with HGFs. The viability of HGFs was observed for 24 hours using the MTT assay. Cell migration was monitored for 24 to 48 hours by wound healing and Boyden chamber assays. Collagen synthesis from HGFs was examined by picrosirius red dye and real-time polymerase chain reaction (PCR) to measure collagen type I and III gene expression for 7 to 10 days. A comparison among the groups was assessed using a one-way analysis of variance (ANOVA) and Bonferroni post hoc test, with the exception of the cell viability assay, which was subjected to Welch's test and Dunnett's T3 post hoc test.

RESULTS

 HGF viability was significantly enhanced by 12.5, 25, and 50 µg/mL PDLSC-CM. The HGFs treated with 50 µg/mL PDLSC-CM promoted cell migration as shown by wound healing and Boyden chamber assays. At this concentration, collagen synthesis increased at 10 days. Collagen type I gene expression increased by 1.6-fold (p < 0.001) and 4.96-fold (p < 0.001) at 7 and 10 days, respectively. Collagen type III gene expression showed an increase of 1.76-fold (p < 0.001) and 6.67-fold (p < 0.001) at the same time points.

CONCLUSION

 Our study suggested that a low concentration of PDLSC-CM at 50 µg/mL has given an amelioration of HGFs providing for periodontal wound healing and periodontal regeneration, particularly migration and collagen synthesis.

Cytotoxicity of Propolis Extracts obtained using Dichloromethane and Hexane Solvent on Human Salivary Gland Tumor Cell Line

AIM

This in vitro study aimed to investigate the effect of propolis extracts from two different solvents on human submandibular salivary gland (HSG) tumor cell line.

MATERIALS AND METHODS

Propolis was extracted by dichloromethane (DCM) and hexane (HEX). Crude extracts were prepared from 6.25 to 200 µg/mL in Dulbecco's modified eagle medium without serum. Flavonoid and total phenolic contents of crude extracts were measured using a modified colorimetric method. The cytotoxicity was evaluated by 3-[4, 5-dimethylthiazol-2-yl]-2,5 diphenyl-tetrazolium (MTT) assay and lactate dehydrogenase (LDH) release assay. The statistics were analyzed by independent sample t-test.

RESULTS

Propolis extracts obtained using DCM and HEX exhibited comparable % yield (38.58 and 38.25) and physical characteristics and different amounts of flavonoid (0.439 ± 0.02 and 0.250 ± 0.01 mg catechin/g sample) and total phenolic compounds (3.759 ± 0.03 and 1.618 ± 0.03 mg gallic acid equivalents/g sample). The DCM group at 25, 50, 100, and 200 µg/mL as well as the HEX group at 50, 100, and 200 µg/mL significantly displayed a decrease in % cell viability and an increase in % cytotoxicity, compared with the untreated control group (P < 0.05). The DCM group showed the half-maximal inhibitory concentration (IC50) of MTT (42.93 ± 2.70) and LDH (34.94 ± 0.22). The HEX group showed the IC50 of MTT (61.30 ± 5.39) and LDH (42.32 ± 1.00). Propolis extracts obtained using both DCM and HEX are effective to inhibit HSG viability.

CONCLUSION

Regarding to the cell morphological observation, MTT and LDH assays, propolis extracts obtained using DCM and HEX exhibited the cytotoxic effect on HSG tumor cell line. Based on our knowledge, this research demonstrates the first preliminary result suggesting propolis as a natural product of choice for salivary gland cancer prevention and therapy.

Expression of a secretory α-glucosidase II from Apis cerana indica in Pichia pastoris and its characterization

Background

α–glucosidase (HBGase) plays a key role in hydrolyzing α-glucosidic linkages. In Apis mellifera, three isoforms of HBGase (I, II and III) have been reported, which differ in their nucleotide composition, encoding amino acid sequences and enzyme kinetics. Recombinant (r)HBGase II from A. cerana indica (rAciHBGase II) was focused upon here due to the fact it is a native and economic honeybee species in Thailand. The data is compared to the two other isoforms, AciHBGase I and III from the same bee species and to the three isoforms (HBGase I, II and III) in different bee species where available.

Results

The highest transcript expression level of AciHBGase II was found in larvae and pupae, with lower levels in the eggs of A. cerana indica but it was not found in foragers. The full-length AciHBGase II cDNA, and the predicted amino acid sequence it encodes were 1,740 bp and 579 residues, respectively. The cDNA sequence was 90% identical to that from the HBGase II from the closely related A. cerana japonica (GenBank accession # NM_FJ752630.1). The full length cDNA was directionally cloned into the pPICZαA expression vector in frame with a (His)₆ encoding C terminal tag using EcoRI and KpnI compatible ends, and transformed into Pichia pastoris. Maximal expression of the rAciHBGase II–(His)₆ protein was induced by 0.5% (v/v) methanol for 96 h and secreted into the culture media. The partially purified enzyme was found to have optimal α-glucosidase activity at pH 3.5 and 45°C, with > 80% activity between pH 3.5–5.0 and 40–55°C, and was stabile (> 80% activity) at pH 4–8 and at < 25–65°C. The optimal substrate was sucrose.

Conclusions

Like in A. mellifera, there are three isoforms of AciHBGase (I, II and III) that differ in their transcript expression pattern, nucleotide sequences and optimal enzyme conditions and kinetics.