Background Over the past ten years, regenerative medicine has focused on the regeneration and the reconstruction of damaged, diseased, or lost tissues and organs. Skin, being the largest organ in the human body, had attained a good attraction in this field. Delayed wound healing is one of the most challenging clinical medicine complications. This study aimed to evaluate the collagen chitosan scaffold’s effect alone, or enriched with either bone marrow-derived mesenchymal stem cells (BM-MSCs) or their secreted extracellular vesicles (EVs) on the duration and quality of skin wound healing. Methods A full-thickness skin wound was induced on the back of 32 adult male Sprague-Dawley rats. The wounds were either covered with collagen chitosan scaffolds alone, scaffolds enriched with stem cells, or extracellular vesicles. Unprotected wounds were used as control. Healing duration, collagen deposition and alignment, CD 68+ macrophage count, and functional tensile strength of healed skin were assessed (α = 0.05, n = 8). Results The rate of skin healing was significantly accelerated in all treated groups compared to the control. Immuno-histochemical assessment of CD68+ macrophages showed enhanced macrophages count, in addition to higher collagen deposition and better collagen alignment in EVs and BM-MSCs treated groups compared to the control group. Higher tensile strength values reflected the better collagen deposition and alignment for these groups. EVs showed higher amounts of collagen deposition and better alignment compared to MSCs treated group. Conclusion The collagen chitosan scaffolds enriched with MSCs or their EVs improved wound healing and improved the quantity and remodeling of collagen with a better assignment to EVs.
Background In recent years, treated dentin matrix (TDM) has been introduced as a bioactive hydrogel for dentin regeneration in DPC. However, no study has introduced TDM as a photocrosslinkable hydrogel with a natural photoinitiating system. Therefore, the present study aimed to explore the synthesis, characterizations and grafting optimization of injectable gelatin- glycidyl methacrylate (GMA)/TDM hydrogels as a novel photocrosslinkable pulp capping agent for dentin regeneration. Methods G-GMA/TDM hydrogel was photocrosslinked using a new two-component photoinitiating system composed of riboflavin as a photoinitiator under visible light and glycine as a first time coinitiator with riboflavin. The grafting reaction conditions of G-GMA/TDM e.g. GMA concentration and reaction time were optimized. The kinetic parameters e.g. grafting efficiency (GE) and grafting percentage (GP%) were calculated to optimize the grafting reaction, while yield (%) was determined to monitor the formation of the hydrogel. Moreover, G-GMA/TDM hydrogels were characterized by swelling ratio, degradation degree, and cytotoxicity. The instrumental characterizations e.g. FTIR, 1H-NMR, SEM and TGA, were investigated for verifying the grafting reaction. Statistical analysis was performed using F test (ANOVA) and Post Hoc Test (P = 0.05). Results The grafting reaction dramatically increased with an increase of both GMA concentration and reaction time. It was realized that the swelling degree and degradation rate of G-GMA/TDM hydrogels were significantly reduced by increasing the GMA concentration and prolonging the reaction time. When compared to the safe low and moderate GMA content hydrogels (0.048, 0.097 M) and shorter reaction times (6, 12, 24 h), G-GMA/TDM with high GMA contents (0.195, 0.391 M) and a prolonged reaction time (48 h) demonstrated cytotoxic effects against cells using the MTT assay. Also, the morphological surface of G-GMA/TDM freeze-dried gels was found more compacted, smooth and uniform due to the grafting process. Significant thermal stability was noticed due to the grafting reaction of G-GMA/TDM throughout the TGA results. Conclusions G-GMA/TDM composite hydrogel formed by the riboflavin/glycine photoinitiating system is a potential bioactive and biocompatible system for in-situ crosslinking the activated-light pulp capping agent for dentin regeneration.
BACKGROUND: Over the past ten years, an alternative for maxillofacial reconstruction was offered through regenerative medicine. It provided a new scope for improving the reconstruction of the oral and maxillofacial structures whether they are hard tissues which include the teeth and bone or the soft tissues like the oral mucosa, skin, nerves and blood vessels. OBJECTIVES: The aim of this study is to evaluate the effect of the collagen chitosan scaffolds on the duration and quality of skin surface healing. MATERIALS AND METHODS: An experimental in vivo comparative study was conducted, on twelve adult male Sprague-Dawley rats, where an induced skin wound was made on the backs of rats and then classified into two groups; 1-control group and 2-scaffold group. The effect of the collagen-chitosan scaffolds on the duration and quality of skin surface healing were assessed using Masson's trichrome staining for collagen fibers and the imageJ software to calculate % area after wound healing also the number of CD 68 macrophages was counted using histological sections then the two groups were compared using student t-test (p<0.05). RESULTS: The scaffold group showed accelerated wound healing in comparison to the control group and with a significant result. Quality of healed skin was significantly better in the scaffold treated group, which is attributed to the better collagen alignment and deposition in the stained histological sections indicated by the % area after wound healing. The number of CD 68 macrophages was higher in the scaffold group compared to the control group. CONCLUSION: The collagen chitosan scaffolds can be considered as a treatment regimen for treating skin wounds.
INTRODUCTION:Recently, Nanosilver fluoride (NSF) has been raised in the research field of caries prevention. Pit-and-fissure sealants could have an additional antibacterial and remineralizing benefit through enamel pretreatment by NSF. OBJECTIVES:The aim of the study was to evaluate in-vitro the effect of NSF pretreatment on shear bond strength, marginal seal, and quantity of color change of pit and fissure sealant in comparison to sealant only in permanent teeth. MATERIALS AND METHODS: Fifty-four freshly extracted permanent teeth were collected and randomly allocated into two groups: Group I: (n=27) NSF was applied to the enamel prior to sealant application. Group II: (n= 27) enamel was etched and sealed. Each group was further divided into three subgroups according to the test applied. (n= 9 teeth each). Subgroup A: Shear bond strength was measured using a Universal Test Machine. The deboned area was then examined under a stereomicroscope to assess the mode of failure. Subgroup B: Microleakage samples were examined under a stereomicroscope to assess the degree of microleakage. Subgroup C: Color Assessment: After a sealant application, any change in sealant color was evaluated using a spectrophotometer. RESULTS: There was no statistically significant difference between both subgroups neither in shear bond strength nor microleakage. The comparison of the final color of sealants in both subgroups showed a higher color change in subgroup Ic with a significant difference (P-value =0.001). CONCLUSION: Pretreatment with nanosilver fluoride prior to pit-and-fissure sealant application did not affect neither its shear bond strength nor its sealing ability. However, it altered the sealant color to an extent that exceeded the clinical acceptance levels.
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