This study aimed to investigate effects of dental pulp stem cells (DPSCs) on regeneration of a defect experimentally created in the periodontium of a canine model. Surgically created mesial 3-walled periodontal defects with ligature-induced periodontitis were produced bilaterally in the first lower premolar teeth of 10 mongrel dogs. Simultaneously, DPSCs were derived from the maxillary premolar teeth of the same dogs. Four weeks after creation of the periodontitis model, autologous passaged-3 DPSCs combined with Bio-Oss were implanted on one side as the test group. On the other side, only Bio-Oss was implanted as a control. Eight weeks after surgery, regeneration of the periodontal defects was evaluated histologically and histomorphometrically in terms of bone, periodontal ligament (PDL), and cement formation. Histologically, in all test specimens (10 defects), regeneration of cementum, bone, and PDL was observed. In the control groups, although we observed the regeneration of bone in all defects, the formation of cementum was seen in 9 defects and PDL was seen in 8 defects. Histomorphometric analyses showed that the amount of regenerated cementum and PDL in the test groups (3.83 ± 1.32 mm and 3.30 ± 1.12 mm, respectively) was significantly higher than that of the control groups (2.42 ± 1.40 mm and 1.77 ± 1.27 mm, respectively; P< .05). A biocomplex consisting of DPSCs and Bio-Oss would be promising in regeneration of periodontal tissues.

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The combination of bioceramics and stem cells has attracted the interest of research community for bone tissue engineering applications. In the present study, a combination of Bio-Oss(®) and type 1 collagen gel as scaffold were loaded with human adipose-tissue derived mesenchymal stem cells (AT-MSCs) after isolation and characterization, and the capacity of them for bone regeneration was investigated in rat critical size defects using digital mammography, multi-slice spiral computed tomography imaging and histological analysis. 8 weeks after implantation, no mortality or sign of inflammation was observed in the site of defect. According to the results of imaging analysis, a higher level of bone regeneration was observed in the rats receiving Bio-Oss(®)-Gel compared to untreated group. In addition, MSC-seeded Bio-Oss-Gel induced the highest bone reconstruction among all groups. Histological staining confirmed these findings and impressive osseointegration was observed in MSC-seeded Bio-Oss-Gel compared with Bio-Oss-Gel. On the whole, it was demonstrated that combination of AT-MSCs, Bio-Oss and Gel synergistically enhanced bone regeneration and reconstruction and also could serve as an appropriate structure to bone regenerative medicine and tissue engineering application.

Strontium is known to reduce bone resorption and stimulate bone formation. Incorporation of strontium into calcium phosphate bioceramics has been widely reported. In this work, calcium and calcium/strontium silicophosphate glasses were synthesized from the sol-gel process and their rheological, thermal, and in vitro biological properties were studied and compared to each other. The results showed that the gel viscosity and thus the rate of gel formation increased by using strontium in glass composition and by increasing aging temperature. In strontium-containing glass, the crystallization temperature increased and the type of the crystallized phase was different to that of strontium-free glass. Both glasses favored precipitation of calcium phosphate layer when they were soaked in simulated body fluid; however strontium seemed to retard the rate of precipitation slightly. The in vitro biodegradation rate of the strontium/calcium silicophosphate glass was higher than that of strontium-free one. The cell culture experiments carried out using rat calvaria osteoblasts showed that the incorporation of strontium into the glass composition stimulated proliferation of the cells and enhanced their alkaline phosphatase activity, depending on cell culture period.

In polycystic ovary syndrome (PCOS), substantial genetic and environmental alterations, along with hyperandrogenism, affect the quality of oocytes and decrease ovulation rates. To determine the mechanisms underlying these alterations caused specifically by an increase in plasma androgens, the present study was performed in experimentally-induced PCOS mice. As the study model, female B6D2F1 mice were treated with dehydroepiandrosterone (DHEA, 6mg per 100g bodyweight). After 20 days, oocytes at the germinal vesicle and metaphase II stages were retrieved from isolated ovaries and subsequent analyses of oocyte quality were performed for each mouse. DHEA treatment resulted in excessive abnormal morphology and decreased polar body extrusion rates in oocytes, and was associated with an increase in oxidative stress. Analysis of fluorescence intensity revealed a significant reduction of DNA methylation and dimethylation of histone H3 at lysine 9 (H3K9) in DHEA-treated oocytes, which was associated with increased acetylation of H4K12. Similarly, mRNA expression of DNA methyltransferase-1 and histone deacetylase-1 was significantly decreased in DHEA-treated mice. There was a significant correlation between excessive reactive oxygen species (ROS) production and increased histone acetylation, which is a novel finding and may provide new insights into the mechanism causing PCOS. The results of the present study indicate that epigenetic modifications of oocytes possibly affect the quality of maturation and ovulation rates in PCOS, and that the likely mechanism may be augmentation of intracytoplasmic ROS.

Hydroxyapatite with different characteristics in terms of morphology and chemistry were prepared via conventional sintering and low temperature biomimetic mineralization methods. The biomineralization route introduced nanocrystalline carbonate-substituted hydroxyapatite (n-CHA) with needle-like crystals ranging 20-30 nm whereas sintered HA (S-HA) comprised of polygonal grains ranging 2-5 μm. The response of fibroblastic cells was investigated using the extract of the samples whereas Wistar rat-derived mesenchymal stem cells (MSCs) were evaluated on top of each sample while maintaining in an osteogenic-free medium. The proliferation, activity, and morphology of adherent MSCs were determined at different culturing periods. The osteogenic differentiation of MSCs was also assayed by determining expression of runx2, osteonectin, osteopontin, and osteocalcin genes using real time-PCR analysis. The fibroblastic cells exhibited better proliferation rate at the presence of n-CHA compared to S-HA. Furthermore, the MSCs attached and spread well on both n-CHA and S-HA with better proliferation rate and alkaline phosphatase activity on n-CHA. Interestingly, the osteogenic differentiation of MSCs on n-CHA was confirmed by the expression of bone specific proteins whereas poor expression of these proteins was detected for the cells on S-HA. The results showed that the role of morphology, crystallinity, and chemistry of hydroxyapatite is crucial for osteogenesis differentiation of MSCs. The results predict osteoinductivity of n-CHA, because MSCs differentiation occurred at the absence of osteogenic medium. However, in vivo data are also required to support this suggestion.