Efectos funcionales e histológicos posteriores al implante de células madre pluripotentes en un modelo murino con esfinterotomía

Introduction and aimsFecal incontinence is a disabling condition with devastating consequences for the patients. Medical and surgical options are not very satisfactory, reason by which regenerative medicine has been considered in this field. In the present research, we analyzed functional and histologic effects after implanting pluripotent stem cells (PSCs) in a murine model with sphincterotomy.Materials and methodsFemale Wistar rats were subjected to sphincterotomy and divided into three groups. Group 1 (control group) was treated with 300 μL of balanced saline solution and group 2 (late treatment) and group 3 (early treatment) received 50,000 PSCs resuspended in 300 μL of balanced saline solution. All animals were evaluated through high-resolution anorectal manometry 24 hours before and after sphincterotomy and every month for three months. Finally, the rats were euthanized and histopathologic sections from the anal canal were obtained.ResultsAll groups showed a decrease in resting anal pressure and squeeze anal pressure 24 hours after sphincterotomy. At the third month, higher anal pressures in the groups treated with PSCs were detected. Regarding the histologic effects, the microscopic architecture was restored and there was a significant decrease in the inflammatory response in the groups treated with PSCs.ConclusionPSCs implantation improves anal tone, as well as histologic structure, presenting better regenerative results when implanted as early treatment.     

Effect of leukocyte and platelet rich fibrin (L-PRF) on stability of dental implants. A systematic review and meta-analysis

The aim of this study was to assess the impact, if any, of L-PRF application in an implant bed prior to implant placement, focusing on stability by means of implant stability quotient (ISQ) values. The literature was searched in a systematic way by means of the main databases and hand searching of the most relevant journals. The inclusion and exclusion criteria were used to determine the eligible studies included in this review. Only randomised controlled trials (RCT) and controlled clinical trials (CCT) were included. A total of four RCTs were included for data extraction. The risk of bias was deemed moderate to unclear. Meta-analysis was performed to assess the effect of L-PRF, on implant stability, immediately post-insertion in three studies, after one week from the implant placement in three studies and after four weeks for all the included studies. The fixed effects model has shown Hedges g statistic for the one week varying from 0.380 to 1.401 with a pooled figure of 0.764 (95% CI 0.443 to 1.085) and for four weeks varying between 0.74 and 1.1 with a combined effect of 0.888 (95% CI 0.598 to 1.177). The results for both intervals were in favour of the use of L-PRF while the statistical difference immediately post-insertion was not statistically significant. The present systematic review, though acknowledging its limitations, suggests that L-PRF has a positive effect on secondary implant stability and that needs to be correlated to the clinical practice to measure the actual clinical effect by means of reducing treatment times.     

Dental regeneration and materials—a partnership

Considerable focus on the biocompatibility of dental materials over the last three decades has provided a platform for a wealth of studies on the cellular and molecular responses of the cells of the pulp to injury, both from the disease process and from subsequent restorative intervention. These studies have been fundamental to understanding not only how we can achieve a biocompatible response during restoration of dental disease but also how we can exploit the pulpal cellular responses to achieve wound healing and tissue regeneration in the dentine–pulp complex. This article examines the responses of the pulp to injury and the events leading to tissue regeneration. As new biologically based regenerative therapies emerge for the dental tissues, it is important that these develop in partnership with more traditional approaches using dental materials.     

Critical features of periodontal flaps with regard to blood clot stability: A review

BackgroundWound healing is a multifactorial procedure involving different cell types and biological mediators. The principles of wound healing are also applicable to periodontal tissues. The formation and stability of blood clots play a vital role in successful healing of wounds in periodontal tissues. The aim of the present review was to highlight the vital factors of periodontal flaps associated with blood clot stability.HighlightThe data on periodontal regeneration and wound healing have evolved greatly in light of several factors, including space for blood clots and blood clot stabilization. In periodontal osseous defects, the stability of blood clots seems critical to wound healing. If mechanical forces can be managed by wound stabilization, the gingival flap-tooth root interface may show connective tissue repair. However, compromised adhesion is susceptible to mechanical forces and can cause wound breakage and epithelialization.ConclusionThe presence of a thick blood clot may hinder the plasmatic circulation between the recipient bed and graft during the initial stage of healing, which is critical in cases of mucogingival surgery. Root conditioning can also determine the healing consequence by enhancing blood clot adhesion.     

The eternal tooth germ is formed at the apical end of continuously growing teeth

Rodent incisors are known to be continuously growing teeth that are maintained by both the cell-proliferation at the apical end and the attrition of the incisal edge. This type of tooth had a special epithelial structure for the maintenance of stem cells, showing the bulbous epithelial protrusion at the apical end. The morphological transition of the epithelial-mesenchymal compartment by serial transverse sections of the apical end toward the incisal direction is likely to reflect the development of the tooth germ in the prenatal stage. Based on the present histological and previous molecular biological studies, the special structure at the apical end is obviously different from the cervical loop giving rise to Hertwig's epithelial root sheath (HERS), in human, mouse and rat molar tooth germs. Hence, we propose a new concept that the eternal tooth bud producing various dental progeny is formed at the apical end of continuously growing teeth, and a new term "apical bud" for indicating this specialized epithelial structure. Furthermore, BrdU labelling analysis suggested that the guinea-pig molars, which were continuously growing teeth, also possessed plural specific proliferative regions and "apical bud" at the apical end.     

Assessment of bone marrow-derived mesenchymal stem cells capacity for odontogenic differentiation and dentin regeneration in methimazole-treated albino rats (Light microscopic Study)

BackgroundMethimazole is an antithyroid drug. It has side effects on many tissues. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are promising in the field of tissue regeneration.ObjectiveTo investigate the capacity of BM-MSCs on odontogenic differentiation and dentin regeneration at different time intervals in methimazole treated rats.MethodsTwenty-eight male albino rats were classified as: Group I: got distilled water. Group II: obtained therapeutic dosage of methimazole as pro-drug “Neo-Mercazole®”. Group III: received methimazole then solitary injection of BM-MSCs at day 21. Group IV: obtained methimazole and single injection of BM-MSCs at the beginning of the experiment. Light microscope was used to examine specimens. Recently formed collagen and β-catenin-immunoreactivity area% were appraised histomorphometrically and statistically.ResultsHistological examination of odontoblasts and dentin illustrated normal structure in Group I and nearly normal features in Group IV. Group II demonstrated discontinuation of odontoblastic layer and areas of different stainability in dentin. Group III showed an evidently wide layer of odontoblast-like cells and distinct dentinal tubules. Masson's trichrome results of dentin in Groups I &IV showed apparently equal areas of new and old collagen. Group II illustrated old collagen mainly. Group III explored new collagen only. β-catenin-immunoreactivity was strong in Groups I & IV, mild in Group II and moderate in Group III. Statistical results revealed that the highest mean of newly formed collagen area% was in Group III, followed by Group I, Group IV then Group II respectively. Regarding β-catenin-immunoreactivity area%, the highest mean was recorded in Group I, subsequently Group IV, next Group III then Group II.ConclusionsMethimazole has destructive consequences. BM-MSCs have a time-based increased capacity for odontogenic differentiation and regeneration of dentin.     

舌神经切断吻合后菌状乳头味蕾再生的实验研究

目的：了解舌神经损伤后味蕾的变化，以及切断的舌神经用神经外膜吻合修复后舌菌状乳头和味蕾的再生能力。方法：模拟临床将SD大鼠一侧舌神经钳夹或切断损伤，即刻用神经外膜吻合的方法修复切断的舌神经．分别于术后20d和100d时用体视显微镜、组织显微镜、扫描电镜观察鼠舌菌状乳头和味蕾的形态和数目。结果：术后20d时，无论钳夹损伤或切断舌神经，切断的舌神经无论是否用神经吻合修复，舌神经损伤侧的菌状乳头和味蕾均萎缩、退化，数目明显减少；术后100d时，舌神经钳夹损伤和舌神经切断后即刻吻合修复的动物，退化、萎缩的菌状乳头和味蕾已完全再生，形态和数目恢复正常。而舌神经切断后未吻合的动物，萎缩、退化的菌状乳头和味蕾无明显再生恢复。结论：钳夹损伤舌神经，萎缩、退化的菌状乳头和味蕾可以自行再生恢复；切断舌神经，萎缩、退化的菌状乳头和味蕾不能自行再生恢复；用神经外膜吻合修复后，萎缩、退化的菌状乳头和味蕾可以再生恢复。舌菌状乳头和味蕾形态、数目的再生恢复，可以作为舌神经修复成功的客观指标。     

膜引导组织再生术与自体静脉桥接法修复面神经缺损的实验研究

目的观察并比较膜引导组织再生术和静脉桥接法修复面神经的作用和效果。方法分别采用膜引导组织再生术和自体静脉桥接法对家兔进行面神经缺损修复,以自体神经移植为对照,通过电生理学和组织学方法,观察和比较两种修复方法的效果。结果两种方法都具有修复面神经缺损的作用,但效果存在一定差别。膜引导组织再生组,术后3个月时两侧面神经干传导速度之差值为(2.10±1.2)m/s,而静脉桥接组为(6.80±1.4)m/s,神经移植组为(2.16±1.6)m/s。组织学上,膜引导组织再生组,术后3个月神经纤维排列整齐,延续连贯;静脉桥接组,神经纤维排列不整齐,结缔组织增生明显。结论膜引导组织再生术和自体静脉桥接法均可用于面神经缺损的修复,膜引导组织再生术的修复效果优于自体静脉桥接法。     

Application of hiPSCs in tooth regeneration via cellular modulation

BackgroundInduced pluripotent stem cell (iPSC)-based technology provides limitless resources for customized development of organs without any ethical concerns. In theory, iPSCs generated from terminally differentiated cells can be induced to further differentiate into all types of organs that are derived from the embryonic germ layers. Since iPSC reprogramming technology is relatively new, extensive efforts by the researchers have been put together to optimize the protocols to establish in vitro differentiation of human iPSCs (hiPSCs) into various desirable cell types/organs.HighlightsIn the present study, we review the potential application of iPSCs as an efficient alternative to primary cells for modulating signal molecules. Furthermore, an efficient culture system that promotes the differentiation of cell lineages and tissue formation has been reviewed. We also summarize the recent studies wherein tissue engineering of the three germ layers has been explored. Particularly, we focus on the current research strategies for iPSC-based tooth regeneration via molecular modulation.ConclusionIn recent decades, robust knowledge regarding the hiPSC-based regenerative therapy has been accumulated, especially focusing on cellular modulation. This review provides the optimization of the procedures designed to regenerate specific organs.