Descelularización y regeneración de tráquea porcina: un acercamiento a la ingeniería tisular / Decellularization and Regeneration of Porcine Trachea: an Approach to Tissue Engineering

Resumen Antecedentes: la ingeniería tisular permite obtener órganos como injertos a partir de tejidos descelularizados, regenerados con células autólogas. Objetivo: descelularizar y regenerar tráqueas porcinas. Material y métodos: se descelularizaron tráqueas porcinas colocándolas cada una en el epiplón de cuatro cerdos Yorkshire para su regeneración in vivo. Una tráquea desce-lularizada con tritón (DT), descelularizada con desoxicolato (DD), descelularizada con desoxicolato y reforzada con un polímero y células epiteliales (DDR), y una nativa crio-preservada (NC). Después de 8 días se obtuvieron la DD, NC y DDR; y al día 15, la DT. Se las evaluó mecánica e histológicamente, se realizó el análisis casuístico. Resultados: las tráqueas descelularizadas conservaron la integridad del cartílago, sin diferencias mecánicas, excepto la DDR con mayor rigidez. Las tráqueas regeneradas presentaron menor rigidez, excepto la DDR que además perdió el epitelio y la vascula-ridad. Las DT, DD mostraron epitelio no respiratorio, fibrosis y vasculogénesis con in-flamación. Conclusiones: las matrices conservaron sus características mecánicas. La regenera-ción in vivo ofrece ventajas como la esterilidad, interacción celular, nutrientes; es senci-llo, factible y económico, pero no hay control del crecimiento celular y vascularización, y los tejidos presentaron alteraciones mecánicas e histológicas. El polímero impidió la re-epitelialización y revascularización. Este estudio abre la posibilidad de mejorar las me-todologías de ingeniería tisular aplicadas al tejido traqueal.

Abstract Introduction: tissue engineering makes it possible to obtain organs as grafts from de-cellularized tissues, regenerated with autologous cells.Objective: decellularize and regenerate porcine tracheas.ARTÍCULO ORIGINAL | Respirar, 2023; 15(3): 188-199 | ISSN 2953-3414 | https://doi.org/10.55720/respirar.15.3.5RECIBIDO: 9 agosto 2023ACEP TADO: 31 agosto 2023 Elisa Barrera-Ramírezhttps://orcid.org/0000-0002-2778-0882Rubén Efraín Garrido-Cardonahttps://orcid.org/0000-0001-6083-5403Alejandro Martínez-Martínezhttps://orcid.org/0000-0003-3448-910XLuis Fernando Plenge-Tellecheahttps://orcid.org/0000-0002-1619-5004Edna Rico-Escobarhttps://orcid.org/0000-0002-0933-0220Esta revista está bajo una licencia de Creative Commons Reconocimiento 4.0 Internacional. Respirar 2023; 15 (3): 189ARTÍCULO ORIGINAL / E. Barrera-Ramírez, R.E. Garrido-Cardona, A. Martínez-Martínez, L.F. Plenge-Tellechea, E. Rico-EscobarDescelularización y regeneración de tráqueaISSN 2953-3414Materials and Methods: Porcine tracheas were decellularized by placing each one in the omentum of four Yorkshire pigs for regeneration in vivo. A trachea decellularized with triton (DT), decellularized with deoxycholate (DD), decellularized with deoxycho-late and reinforced with a polymer, and epithelial cells (DDR), and a cryopreserved na-tive (NC). After 8 days, the DD, NC and DDR were obtained; and on day 15, the DT. The evaluation was mechanically and histologically, performing the case analysis.Results: the decellularized tracheas preserved the integrity of the cartilage, with no me-chanical differences, except for the DDR with greater rigidity. The regenerated trache-as presented less rigidity, except the DDR, which also lost the epithelium and vascular-ity. The DT, DD showed non-respiratory epithelium, fibrosis and vasculogenesis with inflammation.Conclusions: the matrices retained their mechanical characteristics, in vivo regenera-tion offers advantages such as sterility, cell interaction, nutrients; it is simple, feasible and economical, but there is no control of cell growth and vascularization, and the tis-sues presented mechanical and histological alterations. The polymer prevented re-epi-thelialization and revascularization. This study opens the possibility of improving tissue engineering methodologies applied to tracheal tissue.

Células madre en odontología: nuevas perspectivas / Stem cells in dentistry: new perspectives

En el campo de la odontología, prevalecen actualmente alternativas terapéuticas con una filosofía conservadora. Sin embargo, con el advenimiento de los tratamientos con células madre (CM), se amplían las posibilidades terapéuticas, que buscan la combinación y el equilibrio entre la intervención tradicional y las posibilidades de reposición de estructuras anatómicas dañadas, a través de la regeneración de tejidos utilizando células madre o sus derivados (AU)

In the dentistry field, therapeutic alternatives with a conservative philosophy currently prevail. However, with the advent of stem cell (SC) treatments, therapeutic possibilities are expanding, seeking a combination and balance between traditional intervention and the pos- sibility of replacing damaged anatomical structures through tissue regeneration, using stem cells or their derivatives (AU)

Research advances on the application of stem cells in sweat gland regeneration / 中华烧伤杂志

Sweat gland is one of the important appendage organs of the skin, which plays an important role in thermoregulation and homeostasis maintenance. Sweat glands are damaged and unable to self-repair after burns, resulting in perspiration disorders eventually. However, current clinical strategies cannot restore the function of the damaged sweat glands effectively. Therefore, it is urgent to seek treatments that can promote the regeneration of sweat glands and restore their normal functions. Stem cells have extensive sources, low immunogenicity, high proliferation capacity, and multi-directional differentiation potential, which have become a focus in the field of regenerative medicine. In recent years, a variety of stem cells have been induced to differentiate into sweat gland-like tissue with certain secretory function, which provides treatment direction for sweat gland regeneration after burns in clinic. This article reviews the recent research advances on the application of stem cells in sweat gland regeneration from the perspectives of the manner by which stem cells transform into sweat gland cells in different environments and their influencing factors.

A double fluorescence chimeric limb regeneration model reveals muscle fiber reconnection during axolotl limb regeneration / Modelo de regeneración quimérica de doble fluorescencia del miembro revela la reconexión de la fibra muscular durante la regeneración del miembro axolotl

SUMMARY: Axolotl limb regeneration is a fascinating characteristic that has attracted attention for several decades. Our previous studies on axolotl limb regeneration indicated that the satellite cells in the remnant muscles move distally into the blastema to regenerate new muscles that are separated by a gap from remnant muscles. Thereafter, the regenerative muscle fibers start to reconnect with remnant ones. In this study, the reconnection at the individual muscle fiber level was elucidated to test the hypothesis that this reconnection happens synchronously among involved muscles. Three pairs of EGFP+ mid-bud stage blastemas were transplanted onto freshly amputated stumps of RFP+ axolotls at the same thigh position to generate double fluorescence chimeric regenerative hindlimbs. These regenerative limbs were harvested very late far beyond they had reached the late differentiation stage. Fluorescence imaging of these limbs in cross sections revealed that in the proximal remnant part of the muscle fiber, reconnection occurred at a different pace among the muscles. In the major thigh muscle gracilis, the reconnection started from the periphery before it was completed. Furthermore, RFP+ muscle fibers contributed to muscle regeneration in the distal regenerative parts. Intriguingly, this red cell contribution was limited to ventral superficial muscles of the calf. This kind of double fluorescence chimeric limb regeneration model may help increase the understanding of the patterning of axolotl limb regeneration in late stages.

RESUMEN: La regeneración del miembro de Axolotl es una característica fascinante que ha llamado la atención durante varias décadas. Nuestros estudios previos sobre la regeneración del miembro del Axolotl indicaron que las células satélite en los músculos remanentes se mueven distalmente hacia el blastema para regenerar nuevos músculos que están separados por una brecha de músculos remanentes. A partir de entonces, las fibras musculares regenerativas comienzan a reconectarse con las restantes. En este estudio, se aclaró la reconexión a nivel de fibra muscular individual para probar la hipótesis de que esta reconexión ocurre sincrónicamente entre los músculos involucrados. Se trasplantaron tres pares de blastemas EGFP+ en la etapa de yema media en tocones recién amputados de axolotls RFP+ en la misma posición del muslo para generar miembros posteriores regenerativos quiméricos de fluorescencia doble. Estos miembros regenerativos se cosecharon muy tarde mucho más allá de haber alcanzado la etapa de diferenciación tardía. Las imágenes de fluorescencia de estos miembros en secciones transversales revelaron que en la parte remanente proximal de la fibra muscular, la reconexión se produjo a un ritmo diferente entre los músculos. En el músculo grácil, la reconexión comenzó desde la periferia antes de completarse. Además, las fibras musculares RFP+ contribuyeron a la regeneración muscular en las partes regenerativas distales. Curiosamente, esta contribución de glóbulos rojos se limitó a los músculos superficiales ventrales de la pantorrilla. Este tipo de modelo de regeneración quimérica de doble fluorescencia del miembro puede ayudar a aumentar la comprensión del patrón de la regeneración del miembro del Axolotl en etapas tardías.

Evolución de una lesión apicoperirradicular tratada in situ con un material de tercera generación / Evolution of a periradicular apical lesion treated in situ with a third generation material

En la actualidad existe un nuevo paradigma en el tratamiento de piezas dentales con grandes lesiones periapicales. Ello tiene como principal propósito la conservación de dichas piezas, la regeneración de su sistema de inserción y hueso alveolar. Todo esto es posible gracias a la innovación científico-tecnológica que plantea como alternativa, la utilización de una terapéutica dinámica, mínimamente invasiva intralesional, destinada a erradicar los microorganismos que conforman el biofilm periapical e inducir la capacidad autorreparativa del sistema inmune mediante el uso de un biomaterial de tercera generación (Licon-D) (AU)

Currently there is a new paradigm in the treatment of dental pieces with large periapical lesions. The main purpose is the conservation of these pieces, the regeneration of their insertion system and alveolar bone. All this is possible thanks to the scientific and technological innovation that poses as an alternative, the use of a dynamic, minimally invasive intralesional therapy, designed to eradicate the microorganisms that make up the periapical biofilm and induce the autoreparative capacity of the immune system through the use of a third generation biomaterial (Licon-D) (AU)

Muscle regeneration through therapy with estromal stem cells in injury of infraespinhosus muscle of sheep

Abstract Purpose: To evaluate the effects of rotator cuff muscle regeneration in sheep and establish an experimental model for the use of autologous stem cells as a treatment option for tendon injuries. Methods: Infrared muscle tenotomies and Penrose drain implantation were performed on 12 shoulders of six clinically healthy adult sheep. After 60 days, the tendons were submitted to tissue repair, drainage removal, and divided into two groups according to the use of autologous stromal stem cells for treatment. Muscle regeneration was performed by biopsy on days 14 and 34 after repair. Results: The treatment group with cell therapy showed neovascularization and expressive regeneration. Complete regeneration of the muscle pattern did not occur in any sample although some muscle gain was obtained in the group 1 samples at 34 days after repair and introduction of stem cells. Fatty infiltration of these samples from group 1 at 34 days was less intense than that in samples from group 2 at 34 days after repair without the introduction of autologous precursor cells. Conclusion: The sheep proved to be a good experimental model to assist in the development of research on muscle regeneration and the autologous manipulation of stem cells as a therapeutic option.

Proposal for a new histological scoring system for cartilage repair

OBJECTIVE: This study aimed to develop a new histological scoring system for use in a partial-thickness cartilage repair animal model. Although previous papers have investigated the regeneration of articular cartilage, the good results achieved in small animals have not been replicated in large animal models or humans, possibly because of the frequent use of models with perforation of the subchondral bone plates. Partial-thickness lesions spare the subchondral bone, and this pattern is the most frequent in humans; therefore, new therapies should be tested using this model. However, no specific histological score exists to evaluate partial-thickness model results. METHODS: Histological sections from 30 ovine knees were reviewed to develop a new scoring system. The sections were subjected to H&E, Safranin O, and Masson's trichrome staining. RESULTS: This paper describes a new scoring tool that is divided into sections in detail: repair of tissue inside the lesion, cartilage around the lesion and degenerative changes at the base of the lesion. Scores range from 0 to 21; a higher score indicates better cartilage repair. DISCUSSION: Unlike existing tools, this new scale does not assign points for the positioning of a tidemark; we propose evaluation of the degenerative changes to the subchondral bone and calcified cartilage layer. It is necessary to remove the whole joint to access and study the evolution of the lesion as well as the surrounding tissue. CONCLUSION: This article emphasizes the importance of a partial-thickness animal model of cartilage repair and presents a new histological scoring system.

Evaluation of skeletal muscle regeneration in experimental model after malnutrition / Avaliação da regeneração do músculo esquelético em modelo experimental após desnutrição

Abstract The aim of this study was to analyze muscle regeneration after cryoinjury in the tibialis anterior muscle of young rats that were malnourished and then recovered. Forty Wistar rats were divided into a nourished group that received a normal protein diet (14% casein) for 90 days and a malnourished and recovered rats group (MR) that was submitted to 45 days of malnutrition with a hypoproteic diet (6% casein) followed by 45 days of a normal protein diet (14% casein). After the recovery period, all of the animals underwent cryoinjury in the right tibialis anterior muscle and euthanasia after 7, 14 and 21 days. The amount of connective tissue and the inflammation area was higher in the malnutrition recovered injury MR group (MRI) at 14 days post-injury (p < 0.05). Additionally, the cross-sectional area (CSA) of the regenerated fibers was decreased in the MRI (p < 0.05). The MyoD and myogenin protein levels were higher in the nourished injury group. Similar levels of TGF-β1 were found between groups. The proposed malnutrition protocol was effective in showing delayed changes in the regeneration process of the tibialis anterior muscle of young rats. Furthermore, we observed a delay in muscle repair even after nutritional recovery.

Resumo O objetivo do presente estudo foi analisar a regeneração muscular após criolesão no músculo tibial anterior de ratos jovens desnutridos e recuperados. Foram utilizados 40 ratos da linhagem Wistar, divididos em 2 grupos: ratos nutridos receberam dieta normoproteica (14% de caseína) por 90 dias; e ratos desnutridos e recuperado submetidos a duas fases nutricionais pós-desmame, correspondendo a 45 dias de desnutrição com dieta hipoproteica (6% caseína), seguida por 45 dias de dieta normoproteica (14% caseína). Ao completar a fase de recuperação, todos os animais foram submetidos à criolesão no músculo tibial anterior direito e a eutanasia ocorreu 7, 14 e 21 dias após a lesão. A quantidade de tecido conjuntivo e a área de inflamação 14 dias pós-lesão foi maior no grupo desnutrido, recuperado e lesado (MRI – malnourished, recovered and injured group) (p < 0,05). A área de secção transversa (AST) das fibras regeneradas do grupo MRI foi menor (p < 0,05). O conteúdo das proteínas MyoD e Miogenina foi maior no grupo nutridos e lesados. A citocina TGF-β1 não apresentou diferença entre os grupos. O protocolo proposto foi eficaz para demonstrar alterações no processo de regeneração do músculo tibial anterior de ratos jovens, atrasando o reparo muscular mesmo após a recuperação nutricional.

Regulation of muscle plasticity and trophism by fatty acids: A short review / Regulação da plasticidade e do trofismo muscular pelos ácidos graxos: uma breve revisão

Summary The skeletal muscle tissue has a remarkable ability to alter its plastic structural and functional properties after a harmful stimulus, regulating the expression of proteins in complex events such as muscle regeneration. In this context, considering that potential therapeutic agents have been widely studied, nutritional strategies have been investigated in order to improve the regenerative capacity of skeletal muscle. There is evidence of the modulatory action of fatty acids, such that oleic and linoleic acids, that are abundant in Western diets, on muscle function and trophism. Thus, fatty acids appear to be potential candidates to promote or impair the recovery of muscle mass and function during regeneration, since they modulate intracellular pathways that regulate myogenesis. This study is the first to describe and discuss the effect of fatty acids on muscle plasticity and trophism, with emphasis on skeletal muscle regeneration and in vitro differentiation of muscle cells.

Resumo O tecido muscular esquelético possui a notável capacidade plástica de alterar suas propriedades estruturais e funcionais após um estímulo lesivo, regulando a expressão de proteínas durante eventos complexos como a regeneração muscular. Nesse contexto, considerando que possíveis agentes terapêuticos vêm sendo amplamente estudados, estratégias nutricionais têm sido investigadas na perspectiva de melhorar a capacidade regenerativa do músculo esquelético. Há evidências da ação modulatória dos ácidos graxos, como os ácidos oleico e linoleico, que são abundantes nas dietas ocidentais, sobre a função muscular e o trofismo. Nesse sentido, os ácidos graxos parecem ser potenciais candidatos para promover ou prejudicar a recuperação da massa e a função muscular durante a regeneração, uma vez que modulam vias intracelulares reguladoras da miogênese. Este trabalho é o primeiro a descrever e discutir o efeito dos ácidos graxos sobre a plasticidade e o trofismo muscular, com ênfase na regeneração do músculo esquelético e na diferenciação de células musculares in vitro.

Local inhibition of nitrergic activity in tenotomized rats accelerates muscle regeneration by increasing fiber area and decreasing central core lesions

Muscular atrophy is a progressive degeneration characterized by muscular proteolysis, loss of mass and decrease in fiber area. Tendon rupture induces muscular atrophy due to an intrinsic functional connection. Local inhibition of nitric oxide synthase (NOS) by Nω-nitro-L-arginine methyl ester (L-NAME) accelerates tendon histological recovery and induces functional improvement. Here we evaluate the effects of such local nitrergic inhibition on the pattern of soleus muscle regeneration after tenotomy. Adult male Wistar rats (240 to 280 g) were divided into four experimental groups: control (n=4), tenotomized (n=6), vehicle (n=6), and L-NAME (n=6). Muscular atrophy was induced by calcaneal tendon rupture in rats. Changes in muscle wet weight and total protein levels were determined by the Bradford method, and muscle fiber area and central core lesion (CCL) occurrence were evaluated by histochemical assays. Compared to tenotomized (69.3±22%) and vehicle groups (68.1%±17%), L-NAME treatment induced an increase in total protein level (108.3±21%) after 21 days post-injury. A reduction in fiber areas was observed in tenotomized (56.3±1.3%) and vehicle groups (53.9±3.9%). However, L-NAME treatment caused an increase in this parameter (69.3±1.6%). Such events were preceded by a remarkable reduction in the number of fibers with CCL in L-NAME-treated animals (12±2%), but not in tenotomized (21±2.5%) and vehicle groups (19.6±2.8%). Altogether, our data reveal that inhibition of tendon NOS contributed to the attenuation of atrophy and acceleration of muscle regeneration.

Cardiac Regeneration using Growth Factors: Advances and Challenges / Regeneração Cardíaca com Fatores de Crescimento: Avanços e Desafios

Abstract Myocardial infarction is the most significant manifestation of ischemic heart disease and is associated with high morbidity and mortality. Novel strategies targeting at regenerating the injured myocardium have been investigated, including gene therapy, cell therapy, and the use of growth factors. Growth factor therapy has aroused interest in cardiovascular medicine because of the regeneration mechanisms induced by these biomolecules, including angiogenesis, extracellular matrix remodeling, cardiomyocyte proliferation, stem-cell recruitment, and others. Together, these mechanisms promote myocardial repair and improvement of the cardiac function. This review aims to address the strategic role of growth factor therapy in cardiac regeneration, considering its innovative and multifactorial character in myocardial repair after ischemic injury. Different issues will be discussed, with emphasis on the regeneration mechanisms as a potential therapeutic resource mediated by growth factors, and the challenges to make these proteins therapeutically viable in the field of cardiology and regenerative medicine.

Resumo O infarto do miocárdio representa a manifestação mais significativa da cardiopatia isquêmica e está associado a elevada morbimortalidade. Novas estratégias vêm sendo investigadas com o intuito de regenerar o miocárdio lesionado, incluindo a terapia gênica, a terapia celular e a utilização de fatores de crescimento. A terapia com fatores de crescimento despertou interesse em medicina cardiovascular, devido aos mecanismos de regeneração induzidos por essas biomoléculas, incluindo angiogênese, remodelamento da matriz extracelular, proliferação de cardiomiócitos e recrutamento de células-tronco, dentre outros. Em conjunto, tais mecanismos promovem a reparação do miocárdio e a melhora da função cardíaca. Esta revisão pretende abordar o papel estratégico da terapia, com fatores de crescimento, para a regeneração cardíaca, considerando seu caráter inovador e multifatorial sobre o reparo do miocárdio após dano isquêmico. Diferentes questões serão discutidas, destacando-se os mecanismos de regeneração como recurso terapêutico potencial mediado por fatores de crescimento e os desafios para tornar essas proteínas terapeuticamente viáveis no âmbito da cardiologia e da medicina regenerativa.

The use of a biocompatible cement in endodontic surgery. A randomized clinical trial 1

ABSTRACT PURPOSE: To evaluate the clinical applicability of Pozzolana Biologic Silva cement (PBS(r)) in endodontic surgery. METHODS: Persistent apical periodontitis was diagnosed in 30 teeth of 12 patients by cone-beam computed tomography (CT). All patients had 2 or 4 affected teeth and underwent endodontic surgery with root-end filling. Patients with 2 affected teeth had one tooth (control) treated with mineral trioxide aggregate (MTA-Angelus(r)) as a root-end filling material, and the other tooth treated with PBS (experiment). When the patient had four affected teeth, two of them were treated with MTA and two with PBS. Six months after surgery, all patients were assessed by CT scan. Between-group comparisons of measurements were performed using the Wilcoxon test. RESULTS: Periradicular tissue regeneration was observed in all cases. Significant within-group differences in long axes of the lesion were found in the bucco-palatal direction (PBS group, p=0.0012; MTA group, p=0.024) and coronal-apical direction (PBS group, p=0.0007; MTA group, p=0.0015) between pre- and postoperative measurements. CONCLUSIONS: Pozzolana Biologic Silva cement can be used in the treatment of persistent periradicular lesions. The clinical use of PBS as a root-end filling material may be an alternative to MTA. PBS has additives, which provide enhanced strength.

Ultrasound biomicroscopy and claudication test for in vivo follow-up of muscle repair enhancement based on platelet-rich plasma therapy in a rat model of gastrocnemius laceration

PURPOSE: To track the regeneration process of lateral gastrocnemius due to a muscle laceration in rats, and to treatment with plateletrich plasma (PRP). METHODS: Ultrasound (40 MHz) images were used for measuring pennation angle (PA), muscle thickness (MT) and mean pixel intensity, along with claudication scores, of treated (PRPG) and non-treated (NTG) groups of rats. RESULTS: NTG showed a PA increase for the non-injured leg (p<0.05) and a tendency of MT to increase, whereas for PRPG there were no differences. There was a progressive reduction of the claudication score for the PRPG group throughout the entire period, with an immediate difference after seven days (p<0.05), whereas the NTG had a significant reduction only at day 28 (p<0.05). CONCLUSION: It was observed a compensatory hypertrophic response due to the overload condition imposed to healthy leg for NTG that did not occur in PRPG, suggesting an accelerated repair process of the injured leg due to treatment, anticipating its use.

Actualización sobre la evidencia histológica de los tejidos formados mediante terapia de regeneración pulpar guiada / Update on histological evidence of tissue formed by guided pulp tissue regeneration

La finalidad de la endodoncia regenerativa es restablecer la función de la pulpa normal endientes traumatizados, necróticos o infectados, convirtiendo a un diente no vital en uno vital nuevamente. Sin embargo, aún los resultados son imprevisibles. El objetivo de esta revisión fue recopilar y sintetizar la información disponible sobre la evidencia histológicas de los tejidos del complejo pulpo dentinario formados a través de la terapia de regeneración de tejido guiada. Se realizó una investigación basada en la búsqueda en MEDLINE utilizando filtros de tiempo (2011-2016) y palabras clave "Pulp", "Dentin", "Regeneration", "Tissue" and"Histologic". La búsqueda arrojó alrededor de 140 artículos; los de interés fueron seleccionados y descargados a texto completo. Los estudios más alentadores respecto a la regeneración de tejido guiada han sido descritos en reportes de caso de dientes inmaduros con diagnóstico de pulpitis irreversible en el cual al estudio histológico se observaron células tipo odontoblastos. Sin embargo, no existen estudios con seguimiento a largo plazo sobre este tipo de terapia. Algunos protocolos de tratamiento pueden dar lugar a resultados no deseados e impredecibles. Se requieren esfuerzos para mejorar y actualizar las estrategias de endodoncia regenerativa para que sea aplicada de un modo biológicamente eficaz y seguro para salvar los dientes.

The goal of regenerative endodontics is to reinstate normal pulp function in traumatized, necrotic and infected teeth that would result in reestablishment of their functions, but still fail to re-establish real pulp tissue and give unpredictable results. The aim of this review was to compile and synthesize available information on the histological evidence of tissue pulp-dentinal complex formed through guided tissue regeneration. A web-based research on MEDLINE was done using filter terms Review, published in the last 10 years and Dental journals. Keywords used for research were “Pulp", "Dentin", "Regeneratión", "Tissue” and "Histologic". The search yielded about 140 articles; the interest were selected and downloaded in full text. The most encouraging studies regarding guided tissue regeneration have been described in case reports of immature teeth diagnosed with irreversible pulpitis in which the histology odontoblasts type cells were observed. However, there are no studies with long-term follow up on this type of therapy. Some treatment protocols might result in undesired and unpredictable outcomes. Efforts are required to improve and update existing regenerative endodontic strategies to make it an effective, safe, and biological mode to save teeth.

Effect of low-level laser therapy (808 nm) on skeletal muscle after endurance exercise training in rats

BACKGROUND: Low-level laser therapy (LLLT) has been demonstrated to be effective in optimizing skeletal muscle performance in animal experiments and in clinical trials. However, little is known about the effects of LLLT on muscle recovery after endurance training. OBJECTIVE: This study evaluates the effects of low-level laser therapy (LLLT) applied after an endurance training protocol on biochemical markers and morphology of skeletal muscle in rats. METHOD: Wistar rats were divided into control group (CG), trained group (TG), and trained and laser irradiated group (TLG). The endurance training was performed on a treadmill, 1 h/day, 5 days/wk, for 8 wk at 60% of the maximal speed reached during the maximal effort test (Tmax) and laser irradiation was applied after training. RESULTS: Both trained groups showed significant increase in speed compared to the CG. The TLG demonstrated a significantly reduced lactate level, increased tibialis anterior (TA) fiber cross-section area, and decreased TA fiber density. Myogenin expression was higher in soleus and TA muscles in both trained groups. In addition, LLLT produced myogenin downregulation in the TA muscle of trained animals. CONCLUSION: These results suggest that LLLT could be an effective therapeutic approach for stimulating recovery during an endurance exercise protocol.

Stem Cell Therapy in Dentistry: An Overview.

Cells with a unique capacity for self-renewal and potency are called stem cells. With appropriate biochemical signals stem, cells can be transformed into desirable cells. Regeneration of oral and maxillofacial structures is earned out by using stem cell therapy, and this has gained momentum in recent days. Future tissues like tissue engineered bone grafts, engineered joints and cranial sutures can be developed with stem cell therapy. We have described the properties, types and advantages of dental stem cells. Emphasis is been given to the possibilities of stem cell therapy in the oral and maxillofacial region including regeneration of tooth and craniofacial defects.

Analysis of the rate of maturogenesis of a traumatized Cvek’s stage 3 anterior tooth treated with platelet‑rich fibrinas a regenerative tool using three‑dimensional cone‑beam computed tomography: An original case report.

Regenerative endodontic procedures are biologically based procedures which deal with the regeneration of pulp‑like tissue, more idealistically the pulp‑dentin complex. The regeneration of this pulp‑dentin complex in an infected necrotic tooth with an open apex is possible only when the canal is effectively disinfected. Though there are various procedures for treating open apex ranging from Ca(OH) 2 apexification, mineral trioxide aggregate apexification and surgical approach, regeneration of tissues has always taken superior hand over the repair of tissues. The mechanics behind the regenerative endodontic procedures is that despite the tooth being necrotic, some pulp tissue can survive apically which under favorable conditions proliferate to aid in the process of regeneration. In the past 2 decades, an increased understanding of the physiological roles of platelets in wound healing and after tissue injury has led to the idea of using platelets as therapeutic tools in the field regenerative endodontics. In the present case report with an open apex, high sterilization protocol is followed using triple antibiotic paste as intra‑canal medicament, followed which platelet rich fibrin is used as the regenerative material of choice. Over an 18‑month follow‑up period, clinically patient is asymptomatic and radiographically there is complete regression of the periapical lesion and initiation of the root end closure.

Laceration in rat gastrocnemius. Following-up muscle repairing by ultrasound biomicroscopy (in vivo), contractility test (ex vivo) and histopathology

PURPOSE: Implement a laceration protocol of the rat lateral gastrocnemius (LG) and following-up its repair with ultrasound biomicroscopy (UBM), contractility tests and histology. METHODS: Sixty-three male Wistar rats were distributed into two groups. One, with sub-groups GI, GII and GIII (n=12), each containing right LG lacerated (n=6), control and sham (n=3) animals. LG muscles in GI, GII and GIII were inspected by UBM (40 MHz) immediately after, 14 and 28 days post-surgery and thereafter excised with four (GI), 14 (GII) and 28 (GIII) days post-surgery for histology. Animals in second group were distributed into right LG lacerated and control sub-groups. LG muscles in lacerated sub-group were submitted to contractility tests at four (n=8), 14 (n=8) and 28 (n=8) days post-surgery, while in the control sub-group (n=5) were submitted to contractility tests along the course of the experiments. RESULTS: Descriptive findings agreed between the lesion model, muscle repair, UBM images and histology. Contractility results for right LG were different (p<0.05) between control and injured muscle with four and 14 days post-surgery, at tetanic stimulating frequencies (50 and 70 Hz). CONCLUSION: A laceration protocol of the lateral gastrocnemius was implemented and ultrasound biomicroscopy, contractility and histology findings agreed regarding the following-up of injured muscle repair. .

Mannitol-induced drought stress on calli of Trigonella foenum-graecum L. Var. RMt-303.

Different explants of fenugreek, T. foenum-graecum L. (Var. RMt-303), were compared for their callus induction and subsequent shoot regeneration capabilities on Murashige and Skoog media supplemented with different phytohormones in varying concentration. The highest percentage of callus induction frequency was observed in 1ppm benzylaminopurine (BAP). Maximum shoots were induced on media supplemented with 0.5ppm BAP using leaf and stem tissues as explants. However, root tissues showed only callusing with no subsequent shooting. Cotyledonary node responded better than hypocotyls in terms of shoot induction on media supplemented with thidiazuron (0.1ppm). The callus was subjected to drought stress as simulated by reduced water potential of growth media due to addition of mannitol. Calli could withstand -2 MPa water potential till 30 days indicating that the drought stress tolerance mechanisms are functional in this variety. Chlorophyll a and b and total chlorophyll, proline and total phenolic contents, total peroxidase and catalase activities increased under stress conditions suggesting the tolerance of callus to drought stress. However, ascorbate peroxidase, guaiacol peroxidase activities were found to decrease slightly. Malondialdehyde and H2O2 contents were found to decrease while only a slight disturbance was found in membrane stability index. These results underline the mechanisms that are crucial for drought stress tolerance in fenugreek.