Gingival Mesenchymal Stem Cell (GMSC) Delivery System Based on RGD-Coupled Alginate Hydrogel with Antimicrobial Properties: A Novel Treatment Modality for Peri-Implantitis

Purpose Peri-implantitis is one of the most common inflammatory complications in dental implantology. Similar to periodontitis, in peri-implantitis, destructive inflammatory changes take place in the tissues surrounding a dental implant. Bacterial flora at the failing implant sites resemble the pathogens in periodontal disease and consist of Gram-negative anaerobic bacteria including Aggregatibacter actinomycetemcomitans (Aa). Here we demonstrate the effectiveness of a silver lactate (SL)-containing RGD-coupled alginate hydrogel scaffold as a promising stem cell delivery vehicle with antimicrobial properties. Materials and Methods Gingival mesenchymal stem cells (GMSCs) or human bone marrow mesenchymal stem cells (hBMMSCs) were encapsulated in SL-loaded alginate hydrogel microspheres. Stem cell viability, proliferation, and osteo-differentiation capacity were analyzed. Results Our results showed that SL exhibited antimicrobial properties against Aa in a dose-dependent manner, with 0.50 mg/ml showing the greatest antimicrobial properties while still maintaining cell viability. At this concentration, SL-containing alginate hydrogel was able to inhibit Aa on the surface of Ti discs and significantly reduce the bacterial load in Aa suspensions. Silver ions were effectively released from the SL-loaded alginate microspheres for up to 2 weeks. Osteogenic differentiation of GMSCs and hBMMSCs encapsulated in the SL-loaded alginate microspheres were confirmed by the intense mineral matrix deposition and high expression of osteogenesis-related genes. Conclusion Taken together, our findings confirm that GMSCs encapsulated in RGD-modified alginate hydrogel containing SL show promise for bone tissue engineering with antimicrobial properties against Aa bacteria in vitro

Pluronic F-127 hydrogel as a promising scaffold for encapsulation of dental-derived mesenchymal stem cells

Dental-derived mesenchymal stem cells (MSCs) provide an advantageous therapeutic option for tissue engineering due to their high accessibility and bioavailability. However, delivering MSCs to defect sites while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated tissue regeneration. Here, we tested the osteogenic and adipogenic differentiation capacity of dental pulp stem cells (DPSCs) in a thermoreversible Pluronic F127 hydrogel scaffold encapsulation system in vitro. DPSCs were encapsulated in Pluronic(®) F-127 hydrogel and stem cell viability, proliferation and differentiation into adipogenic and osteogenic tissues were evaluated. The degradation profile and swelling kinetics of the hydrogel were also analyzed. Our results confirmed that Pluronic F-127 is a promising and non-toxic scaffold for encapsulation of DPSCs as well as control human bone marrow MSCs (hBMMSCs), yielding high stem cell viability and proliferation. Moreover, after 2 weeks of differentiation in vitro, DPSCs as well as hBMMSCs exhibited high levels of mRNA expression for osteogenic and adipogenic gene markers via PCR analysis. Our histochemical staining further confirmed the ability of Pluronic F-127 to direct the differentiation of these stem cells into osteogenic and adipogenic tissues. Furthermore, our results revealed that Pluronic F-127 has a dense tubular and reticular network morphology, which contributes to its high permeability and solubility, consistent with its high degradability in the tested conditions. Altogether, our findings demonstrate that Pluronic F-127 is a promising scaffold for encapsulation of DPSCs and can be considered for cell delivery purposes in tissue engineering

Evaluation of the phagocitary capacity of the mononuclear system in an experimental model of obstructive jaundice employing Tc- 99m Escherichia coli

Infections and endotoxemia continue to be the principal causes of morbidity and mortality of patients with obstructions of the bile duct. The objective of the present work was the investigation of the phagocitary capacity of the mononuclear system in an experimental model of obstructive jaundice utilizing Tc-99m E.coli. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were significantly higher in jaundiced rats than in the control animals (p < 0.001). The liver of the jaundiced animals presented a significant reduction in Tc-99m E.coli uptake when compared to the controls (p < 0.001). The data also showed that there was a significant increase in the uptake of Tc-99m E.coli by the lungs of jaundiced rats (p < 0.01). The histological analyses of the liver of jaundiced rats showed an intense and diffuse proliferation of the bile ducts and an intensified polyploidy of the hepatocytes (mean volume = 843 µm³), but no significant alterations were observed in the lungs of either group. This dates could contribute to a better understanding of the mechanisms involved in cases of bacteremia, renal failure and pulmonary dysfunction observed in clinical analyses of obstructive jaundice.<br>Nos pacientes com obstrução do ducto biliar, as infecções e a endotoxemia continuam sendo uma das principais causas de morbidade e mortalidade. O objetivo desse trabalho foi investigar a capacidade fagocitária do sistema mononuclear, em um modelo experimental de icterícia obstrutiva, utilizando Tc-99m E.coli. Os níveis de aspartato aminotransferase (AST), alanina aminotransferase (ALT) e fosfatase alcalina (PAL) nos ratos com ligadura do ducto biliar comum (CBD) encontram-se significativamente mais elevados do que nos ratos sham. (p < 0.001). O fígado dos animais ictéricos apresentou uma significativa redução na captação da Tc-99m E.coli quando comparado com o controle. Os dados mostraram também, que houve um aumento significativo na captação da Tc-99m E.coli pelo pulmão dos ratos ictéricos (p < 0.01). O exame histológico dos cortes de fígado dos animais ictéricos apresentou proliferação intensa e difusa dos ductos biliares e uma acentuada poliploidia dos hepatócitos (volume médio: 843 µm³), Não foram observadas alterações significativas nos pulmões de nenhum grupo