The Experimental Study of the Performance of Nano-Thin Polyelectrolyte Shell for Dental Pulp Stem Cells Immobilization

Carious is the most frequent disease of mineralized dental tissues which might result in dental pulp inflammation and mortality. In such cases an endodontic treatment is the only option to prolong tooth functioning in the oral cavity; however, in the cases of severe pulpitis, especially when complicated with periodontal tissue inflammation, the endodontic treatment might not be enough to protect against tooth loss. Thus, keeping the dental pulp viable and/or possibility of the reconstruction of a viable dental pulp complex, appears to become a critical factor for carious and/or pulp inflammation treatment. The nowadays technologies, which allow handling dental pulp stem cells (DPSC), seem to bring us closer to the usage of dental stem cells for tooth tissues reconstruction. Thus, DPSC immobilized within nano-thin polymeric shells, allowing for a diffusion of produced factors and separation from bacteria, may be considered as a cover system supporting technology of dental pulp reconstruction. The DPSC were immobilized using a layer-by-layer technique within nano-thin polymeric shells constructed and modified by nanostructure involvement to ensure the layers stability and integrity as well as separation from bacterial cells. The cytotoxity of the material used for membrane production was assessed on the model of adherent cells. The performance of DPSC nano-coating was assessed in vitro. Membrane coatings showed no cytotoxicity on the immobilized cells. The presence of coating shell was confirmed with flow cytometry, atomic force microscopy and visualized with fluorescent microscopy. The transfer of immobilized DPSC within the membrane system ensuring cells integrity, viability and protection from bacteria should be considered as an alternative method for dental tissues transportation and regeneration.

Id1 Expression Level Determines the Differentiation of Human Dental Pulp Stem Cells

TWIST1 plays a crucial role in dentinogenesis, and its activity depends on both a dimerization partner selection and phosphorylation. Other factors, like Id proteins, can affect the availability of dimerization partners for TWIST1, subsequently leading to diverse biological outcomes. The purpose of this study was to evaluate an impact of Id1 expression on differentiation of dental pulp stem cells (DPSCs). The altered expression of Id1 was achieved by transfection of human DPSCs with lentiviral vectors either driving an entire sequence of Id1, hence leading to Id1 overexpression, or carrying the Id1 silencing sequence. We observed that both overexpression and silencing of Id1 modulated human DPSC differentiation. Id1 overexpression resulted in a prevailing formation of TWIST1 homodimer and increased expression of genes encoding dentin sialophosphoprotein and dentin matrix protein 1, which confirm an enhanced odontogenic differentiation of DPSCs. Concurrently, Id1 silencing produced an opposite effect, slowing DPSC differentiation. These results highlight Id1 as an important modulator of molecular events during DPSC commitment and differentiation, which should be considered in dental research on tissue engineering. Moreover, we assume that the balance between TWIST1 dimerization forms in DPSCs might function in a cell-type-specific manner.

Impact of adenosine receptors on immunoglobulin production by human peripheral blood B lymphocytes

Adenosine is an endogenous compound that regulates function of several immune cells including lymphocytes by activating adenosine receptors (ARs). Several reports indicate that stimulation of ARs on lymphocytes affects lymphocyte activation, proliferation and lymphocyte-mediated cytolysis. Unfortunately, most studies focused on T lymphocytes and little information exists on involvement of ARs in B cells regulation. In this study we elucidated the impact of ARs activation on immunoglobulin M (IgM) production by purified human peripheral blood B lymphocytes stimulated in vitro with Staphyloccocus aureus Covan I (SAC) plus IL-2. Performed experiments showed that endogenous adenosine that is released/produced by human B lymphocytes is able to induce cAMP accumulation in the cell through activation of A2A-AR however, this takes place only when other ARs are inhibited by selective antagonists. We observed that accumulated intracellular cAMP suppressed IgM production by B cells stimulated with SAC plus IL-2. Our experiments showed that human B cells cultured at 25 mM glucose produced significantly less IgM in response to stimulation with SAC comparing to cells maintained in media containing 5 mM glucose. However, the high glucose effect on IgM production by B cells stimulated with SAC depended on other factor/s than ARs.

TWIST1 promotes the odontoblast-like differentiation of dental stem cells

Stem cells derived from the dental pulp of extracted human third molars (DPSCs) have the potential to differentiate into odontoblasts, osteoblasts, adipocytes, and neural cells when provided with the appropriate conditions. To advance the use of DPSCs for dentin regeneration, it is important to replicate the permissive signals that drive terminal events in odontoblast differentiation during tooth development. Such a strategy is likely to restore a dentin matrix that more resembles the tubular nature of primary dentin. Due to the limitations of culture conditions, the use of ex vivo gene therapy to drive the terminal differentiation of mineralizing cells holds considerable promise. In these studies, we asked whether the forced expression of TWIST1 in DPSCs could alter the potential of these cells to differentiate into odontoblast-like cells. Since the partnership between Runx2 and Twist1 proteins is known to control the onset of osteoblast terminal differentiation, we hypothesized that these genes act to control lineage determination of DPSCs. For the first time, our results showed that Twist1 overexpression in DPSCs enhanced the expression of DSPP, a gene that marks odontoblast terminal differentiation. Furthermore, co-transfection assays showed that Twist1 stimulates Dspp promoter activity by antagonizing Runx2 function in 293FT cells. Analysis of our in vitro data, taken together, suggests that lineage specification of DPSCs can be modulated through ex vivo gene modifications.

Fluoride alters type I collagen expression in the early stages of odontogenesis

Fluoride alters the expression and post-translational modifications of extracellular matrix proteins in dentin. The aim of our study was to determine the effects of fluoride on type I collagen expression during the early stages of tooth germ development in rats. Pregnant dams were divided into three groups and fed a standard diet. From the fifth day of pregnancy the three groups received tap water with, respectively, trace amounts of fluoride (C), a low fluoride concentration (FL) or and a high fluoride concentration (FH). Changes in type I collagen expression and distribution were evaluated. The expression of type I collagen was restricted to the extracellular spaces of cells of mesenchymal origin. In the youngest animals the most intense immunoreactivity for type I collagen was detected in predentin of the FL group. Although the intensity of immunostaining increased in proportion to the age of the animals, the largest increase in the groups investigated was detected in the FL group. We concluded that a low concentration of fluoride can act as a stimulator of type I collagen deposition in the extracellular matrix of dentin, while high concentrations of fluoride have an opposite effect, acting as an inhibitor of type I collagen formation in dentin.

Influence of low and high doses of fluoride on tooth germ development in rats

The influence of fluoride on tooth germ development, especially mineralised tissue, is well documented in numerous dental publications, but there are few reports concerning the influence of fluoride on enamel organ and dental papilla cells. The aim of the study was to assess histologically the development of tooth germs of 20-day-old rat foetuses whose mothers drank water without fluoride or with low (10 mg) and high (110 mg) contents of natrium fluoride, starting from the 12th day of the pregnancy. The fluoride contained in drinking water in low as well as high concentration accelerated the development of enamel organ and dental papilla structures in rat foetuses. The acceleration was proportional to the content of fluoride in drinking water. No disturbances caused by high concentration of natrium fluoride were observed.

Influence of diet and fluoride on dentin and enamel deposition and maturation in rats

Diet and fluoride can modify tooth-germ development. In many morphological and biochemical studies malnutrition was shown to impair odontogenesis. However, quantitative observations of the morphological changes implemented by underfeeding and fluoride are still scanty. The aim of the study was to assess stereologically the enamel and dentin deposition in tooth-germ of 14-day-old rat pups derived from dams fed with deficient diet and given water without or with low (10 mg/l) and high (110 mg/l) doses of natrium fluoride, starting from the 13th day of pregnancy. The volume fractions of ameloblasts, enamel, dentin and odontoblasts in histological sections were estimated by the point counting method. The lack of fluoride in drinking water in rats maintained on low-protein diet changed the proportions of the deposited dental mineralised tissues as compared to the control animals: it substantially increased deposition of enamel (by 48%), and significantly decreased dentin production (by 28%). The supplementation of drinking water with fluoride in rats fed with deficient diet partially reversed these effects towards values found in the control rats maintained on standard diet that drank water with trace amount of fluoride. The possible toxic activity of high doses of fluoride can only be conferred to the decreased volume fraction of ameloblasts. Our findings suggests an important role of the fluoride ion in the maintenance of the proper enamel and dentin relation in the developing teeth of rats fed with low-protein, low-fat, high-carbohydrate diet.

Effects of diet and fluoride on early phases of odontogenesis in rats

The influence of diet and fluoride on odontogenesis in rats was investigated. 20 foetuses, 20 days old, were divided into four groups. The control group was fed with the standard diet and drank water with 0.16 mg F/l. The second, third and fourth groups were fed with the deficit, experimental diet and drank distilled water with 10 and 110 mg of natrium fluoride per litre or without fluoride. In each group, the observed tooth-bud development assumed different stages. The less advanced cap stage assumed the tooth-bud in the group fed with the deficit diet and given distilled water without fluoride. In the remaining groups, the development of observed first molars in mandible assumed the different level of its advancement in the same stage of odontogenesis--bell stage.

[Results of treatment of severe craniocerebral injuries in an interdisciplinary intensive therapy unit]

Early results of treatment of severe craniocerebral injury were analysed in the Department of Anaesthesiology and Intensive Therapy, Province Hospital in Bielsko Biała. The preliminary scoring below 15 points of Glasgow scale was obtained. During five years of observation 63 out of 78 patients (80.7%) died. Full recovery was obtained in two cases (2.56%). The results of treatment were analysed in relation to clinical diagnosis, associated injuries, age of patients and treatment results. Pulmonary complications were significantly more frequent: adult respiratory distress syndrome and acute posttraumatic pulmonary oedema (over 60% of cases). The treatment methods and their modifications are surveyed.