Regeneration of dentin-pulp complex by using dental pulp stem cells in dog.

INTRODUCTION: Although missing tooth is not life-threatening, it affects the quality of daily life. Stem cells have emerged as an important player in the generation and maintenance of many tissues. The role of scaffolds has changed from a passive carrier to a bioactive matrix, which can be used to induce cellular behavior. The aim of this study was to determine the possibility of regeneration of dentin-pulp complex with dental pulp stem cells (DPSCs) in an animal model. MATERIALS AND METHODS: In this animal study after extraction of DPSCs and cultivation, 10 types of scaffolds were made by using platelet-rich plasma (PRP), cancellous bone, and collagen pad. They were inserted in different parts of the dog's mouth. After the 4th month, the area was operated, and the scaffolds were removed. RESULTS: Microscopic examination revealed no sign of cell differentiation and formation of new structures in those models which used collagen scaffolds. However, the dentin-pulp complex emerged in models that the combination of bone scaffolds and PRP or stem cells was used. CONCLUSION: Using bone scaffolds in combination with PRP or DPSCs to regenerate dentin-pulp complex in dog helped odontoblastic and pulpal differentiation as well as the formation of predentin and tubular dentin.

Efficacy of silver nanoparticle gel on healing of traumatic oral ulcers compared with triamcinolone oral paste: An experimental study on rats.

BACKGROUND: There are many treatment protocols for relieving pain and accelerating oral ulcer healing. The purpose was to evaluate the anti-inflammatory and antimicrobial effect of silver nanoparticle (AgNP) gel on oral ulcers compared with the traditional treatment in animal model. MATERIALS AND METHODS: In this experimental study, 72 adult male rats were randomly allocated into four groups, after ulcer induction: control (receive no treatment), placebo (placebo gel was applied on ulcers once daily), triamcinolone (ulcers were treated with triamcinolone paste once daily), and AgNPs (ulcers were treated with AgNP gel once daily). The animals were sacrificed at three successive periods of 3, 7, and 14 days after ulcer induction. Histopathological scores of re-epithelialization and degree of inflammation were assessed. The wound size was measured clinically. For parametric data, the analysis of variance, and for ordinal histopathological data, the Kruskal-Wallis test using SPSS was done. A P < 0.05 was considered statically significant. RESULTS: Control and placebo groups had no case of complete healing. Improvement of wound size by triamcinolone paste was not significant in different days but showed significant differences in degree of inflammation (P < 0.001) and re-epithelialization (P = 0.012). Reduction of wound size by AgNPs gel had significant difference at 14th day (P < 0.001); further, by this gel, significant differences in degree of inflammation and re-epithelialization were seen in long-term medication. CONCLUSION: AgNP gel could be effective in oral ulcer healing clinically and histopathologically. Although this gel showed delayed effect, it had better healing effect according to the cases with complete healing. Hence, the application of AgNP oral gel can be considered as an alternative approach for oral ulcers.

Bilayer Scaffolds for Interface Tissue Engineering and Regenerative Medicine: A Systematic Reviews.

PURPOSE: This systematic review focus on the application of bilayer scaffolds as an engaging structure for the engineering of multilayered tissues, including vascular and osteochondral tissues, skin, nerve, and urinary bladder. This article provides a concise literature review of different types of bilayer scaffolds to understand their efficacy in targeted tissue engineering. METHODS: To this aim, electronic search in the English language was performed in PMC, NBCI, and PubMed from April 2008 to December 2019 based on the PRISMA guidelines. Animal studies, including the "bilayer scaffold" and at least one of the following items were examined: osteochondral tissue, bone, skin, neural tissue, urinary bladder, vascular system. The articles which didn't include "tissue engineering" and just in vitro studies were excluded. RESULTS: Totally, 600 articles were evaluated; related articles were 145, and 35 full-text English articles met all the criteria. Fifteen articles in soft tissue engineering and twenty items in hard tissue engineering were the results of this exploration. Based on selected papers, it was revealed that the bilayer scaffolds were used in the regeneration of the multilayered tissues. The highest multilayered tissue regeneration has been achieved when bilayer scaffolds were used with mesenchymal stem cells and differentiation medium before implanting. Among the studies being reported in this review, bone marrow mesenchymal stem cells are the most studied mesenchymal stem cells. Among different kinds of multilayer tissue, the bilayer scaffold has been most used in osteochondral tissue engineering in which collagen and PLGA have been the most frequently used biomaterials. After osteochondral tissue engineering, bilayer scaffolds were widely used in skin tissue engineering. CONCLUSION: The current review aimed to manifest the researcher and surgeons to use a more sophisticated bilayer scaffold in combinations of appropriate stem cells, and different can improve multilayer tissue regeneration. This systematic review can pave a way to design a suitable bilayer scaffold for a specific target tissue and conjunction with proper stem cells.

Regenerative effect of mesenteric fat stem cells on ccl4-induced liver cirrhosis, an experimental study.

BACKGROUND: Liver cirrhosis is a chronic disease in which normal liver tissue is replaced by fibrous tissue, leads to liver malfunction. Although transplantation is the most certain cure, stem cell therapies are shedding light on efforts to regenerate cirrhotic liver. The purpose of this study was to evaluate the regenerative potential of mesenteric fat stem cells in CCL4-induced liver cirrhosis in an animal model. METHODS: Thirty rats were treated with the mixture of CCL4 and olive oil intraperitoneally by a dose of 0.2 ml (0.1 ml CCL4 and 0.1 ml olive oil) every other day for 16 weeks till cirrhosis signs appeared. Fifteen rats were randomly selected as control group. Others treated by mesenteric fat derived mesenchymal stem cells transferred into the liver parenchyma. RESULTS: After 5 weeks, rats received stem cells had improved clinically by increased movements, appetite, improvement in overall behavior and decreased abdomen size. Histopathologically, liver cells showed state of regeneration and forming new colonies. CONCLUSION: Liver cirrhosis was induced. The mesenchymal stem cells derived from mesenteric adipose tissue could improve hepatic status of the rats, as cirrhotic livers were regenerated back into normal appearing parenchyma. Rats' clinical behavior also reached healthy status.

Effectiveness of Methylene Blue in the Prevention of Stifle Joint Arthrofibrosis in Rabbit Models.

BACKGROUND: One of the major challenges in orthopedic surgery is the prevention of arthrofibrosis, which can be successfully alleviated in its early stages. Many studies suggest the administration of methylene blue (MB) as an accessible and effective agent for the prevention of post-operation adhesions. The purpose of this study was to evaluate the efficacy of MB in the prevention of arthrofibrosis. METHODS: This study was conducted on 18 New Zealand white female mature rabbits. The anterior cruciate ligament of the left stifle joint of each animal was cut during aseptic surgery. In the next step, the rabbits were divided into three groups based on their treatments. The rabbits in the first, second, and third groups were subjected to the injection of normal saline, 1% MB solution, and 2% MB solution into their synovial space, respectively. The postoperative stifle range of motion was measured every week. After 4 weeks, the animals were euthanized and all joints were dissected for histopathology. RESULTS: The histopathological evaluation of tissues indicated the presence of fibrotic connective tissue as a sign of fibrosis in all groups. The fibrosis rate, inflammatory rate, tissue disarrangement, fibroblastic cellularity, and granulation tissue formation were at their highest levels in the 1% MB group. The integrity of articular cartilage in the 2% MB group was lower than the other groups. The level of bone degeneration was similar in both MB groups; however, it was more than the control saline group. The range of motion was reduced during the first week, then increased in the second and third weeks, and finally decreased in the fourth week. CONCLUSION: The MB was not an effective method regarding the prevention or treatment of arthofibrosis and the subsequent osteoarthritis. In contrast with previous studies, fibrosis was lower in the high dose MB group, compared to the low dose MB group. The alterations in the range of motion were related to the reduced movement caused by the pain and stiffness of the operated joints. The current study can be considered as the first report addressing the adverse effect of MB on synovial components. LEVEL OF EVIDENCE: I.