Importancia de la angiogénesis en el diseño de scaffolds para ingeniería de tejido óseo / Importance of angiogenesis in the design of scaffolds for bone tissue engineering

Hematoma, inflamación, angiogénesis y osteogénesis son distintas etapas que se superponen durante el proceso de reparación de una fractura ósea. Durante las primeras etapas se liberan distintos factores de crecimiento quimioatractantes que producen el reclutamiento de diversas células para generar la formación de un hueso funcional con su respectiva vasculatura. Debido a la importancia que posee la angiogénesis en el desarrollo de una adecuada red vascular, tanto para la formación ósea como en su reparación, en los últimos años los especialistas en ingeniería de tejido óseo han estudiado la manera de fomentar tanto la osteogénesis como la angiogénesis durante la reparación ósea. En este trabajo de revisión, se recopilan y discuten los principales conceptos sobre distintas estrategias a fin de lograr un implante sintético con funcionalidad dual promoviendo los procesos que garanticen la angiogénesis y la osteogénesis en forma acoplada utilizando distintos tipos de scaffolds y sistemas de liberación de drogas osteoinductoras y angioinductoras. La liberación dual de factores osteoinductores y angioinductores debe producirse en forma témporo-espacial controlada para garantizar los efectos deseados sin producir efectos adversos como tumores o hueso ectópico. Se deben tener en cuenta varios factores como el tipo y la arquitectura de hueso, tipo de daño, edad, sexo y condiciones patológicas del paciente. En cuanto a los materiales se debe considerar el tipo de material para usar como scaffold, los factores inductores seleccionados, su combinación y sistemas de liberación. El avance en estos estudios hará que la Ingeniería de Tejido Óseo sea una alternativa terapéutica en el futuro. (AU)

Hematoma, inflammation, angiogenesis, and osteogenesis are different stages that overlap during the healing process of a bone fracture. During the first stages, different chemoattractant growth factors are released which produce the recruitment of various cells that will induce the formation of a functional bone with its respective vasculature. Due to the importance of angiogenesis for the development of an adequate vascular network in both bone formation and repair, in recent years specialists in bone tissue engineering have studied how to promote both osteogenesis and angiogenesis during bone repair. In this review, the main concepts on different strategies developed to achieve a synthetic implant with dual functionality, promoting processes that guarantee angiogenesis and osteogenesis in a coupled way using different types of scaffolds and osteo-drug delivery systems and angioinductors, are collected and discussed. The dual release for osteoinductive and angioinductive factors must ensure the release of them in a controlled time-space manner to guarantee the desired effects without producing adverse effects such as tumors or ectopic bone. Several factors must be taken into account, such as bone type and architecture, type of damage to be repaired, age, sex, and pathological conditions of the patient. Regarding the materials, the type of material to be used as scaffolds, selected inducing factors and drug release system must be considered. Advances in these studies will make Bone Tissue Engineering a therapeutic alternative in the future. (AU)

Estudo da gelificação do produto de digestão de ECM descelularizada para uso em engenharia de tecidos / Gelation study of extracellular matrix digestion products for tissue engineering

Os implantes utilizados para regeneração tecidual ainda falham na tentativa de mimetizar as propriedades da matriz extracelular (ECM), o que compromete a viabilidade e aplicabilidade do material. Além disso, permanece o desafio de desenvolver um método de aplicação minimamente invasivo para evitar danos teciduais adicionais (Badylak et al., 2015; Crapo et al., 2011; Xing et al., 2014). Assim, o objetivo do projeto é desenvolver um hidrogel injetável composto de ECM de pericárdio, tendão e osso bovino enzimaticamente digerida e reticulada com glutaraldeído, ésteres ativados de NHS e derivados de polietilenoglicol (PEG). O protocolo de digestão foi modificado de Willians (Williams et al., 2015), utilizando tripsina, pepsina e colagenase. A quantificação de GAGs e peptídeos mostrou que, independentemente do substrato e enzima utilizados, o processo em etapas gerou uma maior concentração de estruturas em relação ao processo contínuo. Adicionalmente, a análise de dicroísmo circular mostrou que o processo em etapas preservou mais estruturas secundárias. O perfil proteico das ECMs foi analisado como descrito em Flores (Flores et al., 2016), e foi verificado que ele é altamente diverso e tecido - específico. A ECM do pericárdio possui 94 tipos diferentes de proteínas, seguidas pela ECM do tendão (48) e pela ECM óssea (35), sendo o colágeno α1 (1) e o colágeno α2 (1) presentes em todas elas. Além disso, os produtos digeridos ECMp aumentaram a proliferação e diferenciação de células-tronco mesenquimais da medula óssea a osteoblastos maduros. A cinética do processo de gelificação, bem como as propriedades mecânicas do gel são dependentes do tipo de agente reticulante, assim como da concentração da gelatina. Este novo material é altamente personalizável e adaptável à aplicação biológica desejada

The implants used for tissue regeneration still fail to mimic properties of extracellular matrix. It compromises the material viability and applicability. Furthermore, the challenge to manufacture a minimally invasive delivery system for it to avoid extra tissue damage still remains (Badylak et al., 2015; Crapo et al., 2011; Xing et al., 2014). Thus, the project goal is to develop an injectable hydrogel composed of pericardium, tendon and bovine bone ECM enzymatically digested and crosslinked with glutaraldehye, activated esters of NHS and polyethylene glycol (PEG) derivatives. The digestion protocol was modified from Willians (Williams et al., 2015), using trypsin, pepsin and collagenase as lytic enzymes. GAGs and peptides quantification showed that regardless of the substrate and enzyme, the stepwise process yields a higher amount of GAGs and peptides in comparison with the continuous process. In addition, circular dicroism analysis showed that the stepwise process preserves more secondary structures of proteins. ECMs protein profile was analyzed as in Flores (Flores et al., 2016) and verified that it is the highly diverse and tissue-specific. Pericardium ECM has 94 different types of proteins, followed by tendon ECM (48) and bones ECM (35), being collagen α1(1) and collagen α2(1) present in all of them. Furthermore, the ECMp digested products enhanced bone marrow mesenchymal stem cells proliferation and differentiation in mature osteoblast. The kinetics of the gelification process, as well as mechanical properties of the gel is dependent of the type of crosslinker and concentration of gelatin. This new material is highly customizable and adaptable to the biological application

Cardiac tissue engineering: current state-of-the-art materials, cells and tissue formation / Engenharia de tecidos cardíacos: atual estado da arte a respeito de materiais, células e formação tecidual

ABSTRACT Cardiovascular diseases are the major cause of death worldwide. The heart has limited capacity of regeneration, therefore, transplantation is the only solution in some cases despite presenting many disadvantages. Tissue engineering has been considered the ideal strategy for regenerative medicine in cardiology. It is an interdisciplinary field combining many techniques that aim to maintain, regenerate or replace a tissue or organ. The main approach of cardiac tissue engineering is to create cardiac grafts, either whole heart substitutes or tissues that can be efficiently implanted in the organism, regenerating the tissue and giving rise to a fully functional heart, without causing side effects, such as immunogenicity. In this review, we systematically present and compare the techniques that have drawn the most attention in this field and that generally have focused on four important issues: the scaffold material selection, the scaffold material production, cellular selection and in vitro cell culture. Many studies used several techniques that are herein presented, including biopolymers, decellularization and bioreactors, and made significant advances, either seeking a graft or an entire bioartificial heart. However, much work remains to better understand and improve existing techniques, to develop robust, efficient and efficacious methods.

RESUMO Doenças cardiovasculares são responsáveis pelo maior número de mortes no mundo. O coração possui capacidade de regeneração limitada, e o transplante, por consequência, representa a única solução em alguns casos, apresentando várias desvantagens. A engenharia de tecidos tem sido considerada a estratégia ideal para a medicina cardíaca regenerativa. Trata-se de uma área interdisciplinar, que combina muitas técnicas as quais buscam manter, regenerar ou substituir um tecido ou órgão. A abordagem principal da engenharia de tecidos cardíacos é criar enxertos cardíacos, sejam substitutos do coração inteiro ou de tecidos que podem ser implantados de forma eficiente no organismo, regenerando o tecido e dando origem a um coração completamente funcional, sem desencadear efeitos colaterais, como imunogenicidade. Nesta revisão, apresentase e compara-se sistematicamente as técnicas que ganharam mais atenção nesta área e que geralmente focam em quatro assuntos importantes: seleção do material a ser utilizado como enxerto, produção do material, seleção das células e cultura de células in vitro. Muitos estudos, fazendo uso de várias das técnicas aqui apresentadas, incluindo biopolímeros, descelularização e biorreatores, têm apresentado avanços significativos, seja para obter um enxerto ou um coração bioartifical inteiro. No entanto, ainda resta um grande esforço para entender e melhorar as técnicas existentes, para desenvolver métodos robustos, eficientes e eficazes.

Regulation of Tissue Engineered Devices in some Latin American Countries: Development and External Influences / Reglamentación de dispositivos de ingeniería tisular en algunos países Latinoamericanos: desarrollo e influencias externas

Antecedentes: El surgimiento de estrategias de ingeniería tisular para tratar enfermedades está cambiando la definición tradicional de dispositivos médicos. Los productos de ingeniería tisular, fabricados a partir de la combinación de biomateriales, células y factores bioactivos, remplazan temporalmente un órgano o tejido e inducen la producción de nuevo tejido. Los mecanismos de reglamentación de productos de ingeniería tisular necesitan agrupar las políticas que controlan cada uno de sus componentes: materiales, células humanas y moléculas activas. Objetivo: Revisar las políticas de reglamentación actuales para dispositivos médicos (y entre estos, los productos de ingeniería tisular), en un grupo de países latinoamericanos, y evaluar la influencia que organizaciones internacionales y países con poder tecnológico mundial ejercen en las políticas locales. Métodos: Se utilizaron modelos de difusión top-down y horizontal para identificar cómo las políticas de reglamentación han llegado a Brasil, Colombia, Ecuador, México y Perú. Resultados: La apropiación tecnológica empleada para clasificar los dispositivos médicos de manera integral difiere entre los países. Ninguno define el concepto productos de ingeniería tisular. Se encontró un patrón de difusión top-down asociado a las reglamentaciones empleadas. Se está aplicando una difusión horizontal como esfuerzo regional para facilitar la comercialización de productos médicos. Conclusión: El concepto de producto de ingeniería tisular está llegando lentamente a los países latinoamericanos. Cada país tiene el potencial de aprovechar las instituciones locales y las coaliciones regionales e interregionales para mejorar la regulación actual y preparar al sistema de salud para la llegada de productos de ingeniería tisular.

Background: Emergence of new technologies and advances in tissue engineering strategies to treat diseases are shifting the conventional conception of medical devices. Tissue engineered products, manufactured as a combination of biomaterials, cells, and/or bioactive factors, are intended to temporarily restore an organ or tissue function, and induce the generation of newly site-appropriate functional tissue. Regulatory pathways for tissue engineered products require grouping policies controlling each of the components: materials, human cells, and active molecules. Purpose: To review current regulatory policies for medical devices (and within this, tissue engineered products), in a subset of Latin American countries, and to analyze the influence of international organizations and technological world power countries on policies of that subset. Methods: Top-down and horizontal diffusion models were employed to identify how regulatory policies have moved to Brazil, Colombia, Ecuador, Mexico, and Peru. Results: There are differences in technological appropriation to comprehensively define and classify medical devices. None of the countries have a definition of tissue engineered products. A top-down diffusion pattern was found to be associated with the current regulations. A horizontal diffusion is being applied as a regional effort to facilitate commercialization of medical products within Latin America. Conclusion: The concept of tissue engineered products is slowly arriving into the evaluated Latin American countries. Each country has the potential to take advantage of local institutions and regional and inter-regional coalitions to improve current guidelines and prepare the health system to the introduction of tissue engineered products.

Matrices de tercera generación en la ingeniería de tejidos ósea / Third-generation matrices in bone tissue engineering

Existen numerosas patologías que generan situaciones invalidantes debido a problemas asociados a nivel de defectos óseos. Esto genera, en muchas oportunidades, cuestiones sanitarias de alto impacto. La ingeniería de tejidos óseos pretende generar propuestas novedosas para reparar pérdidas o fracturas óseas, promoviendo regenerar el tejido mediante el implante de matrices biodegradables que puedan actuar como estructuras para la adhesión celular, favoreciendo el crecimiento y la diferenciación hasta formar hueso de novo. El incremento notable de los conocimientos en las áreas biotecnológicas, de síntesis química, así como de biomedicina, permiten el desarrollo de numerosos tipos de matrices de tercera generación, biodegradables y no tóxicas, con características que proponen sean consideradas en la regeneración tisular ósea. Este trabajo intenta resumir los tipos de matrices que mayor impacto han tenido hasta el momento en la medicina regenerativa ósea, mostrando los casos más relevantes de resultados experimentales y clínicos, y propone algunas perspectivas que se deberían considerar para poder aplicarlas a la práctica clínica. Esta es un área que invita a los investigadores a posicionarse en un pensamiento complejo desde el punto de vista científico-filosófico. (AU)

There are several pathologies that generate disability due to complications associated with bone defects. This often generates high impact health troubles. Bone tissue engineering aims to generate novel means to repair bone loss or bone fractures, promoting tissue regeneration through the implantation biodegradables scaffolds, which can act as structures for cell adhesion, that promts cell growth and differentiation for the novo bone formation. The remarkable for the novo bone formation in biotechnology, chemical synthesis, and biomedical knowledge allows the development of numerous types of third generation scaffolds, applied to promote bone tissue regeneration. This brief report aims to review the scaffolds that have had more impact in bone regenerative medicine so far, describing the most relevant experimental and clinical results. This is an area that invites researchers to situate themselves in a complex thought of scientific-philosophical point of view. (AU)

Hard tissue regeneration using bone substitutes: an update on innovations in materials

Bone is a unique organ composed of mineralized hard tissue, unlike any other body part. The unique manner in which bone can constantly undergo self-remodeling has created interesting clinical approaches to the healing of damaged bone. Healing of large bone defects is achieved using implant materials that gradually integrate with the body after healing is completed. Such strategies require a multidisciplinary approach by material scientists, biological scientists, and clinicians. Development of materials for bone healing and exploration of the interactions thereof with the body are active research areas. In this review, we explore ongoing developments in the creation of materials for regenerating hard tissues.

Ingeniería tisular como puntal de la medicina regenerativa en estomatología / Tissue engineering as a pillar of regenerative medicine in dentistry

El deseo de crear alternativas más biológicas para la implantación permanente de materiales sintéticos ha inspirado el campo de la ingeniería de tejidos, que como uno de los pilares de la medicina regenerativa amplía las posibilidades de investigación y aplicación clínica en la rama estomatológica. Objetivo: realizar una revisión bibliográfica sobre la ingeniería tisular como puntal de la medicina regenerativa en estomatología. Métodos: se realizó una revisión en el período comprendido entre mayo y junio de 2013. Se evaluaron revistas de impacto de Web of Sciencies (43 revistas) y dos revistas cubanas. Se consultaron las bases de datos de sistemas referativos, como MEDLINE, PubMed y Scielo con la utilización de descriptores como tissue engineering AND dentistry, regenerative medicine, biomaterials, scaffolds, nanotechnology y sus contrapartes en español. Se incluyeron artículos en idioma inglés y español y publicaciones de los últimos cinco años. Se obtuvieron 127 artículos, circunscribiéndose el estudio a 55 que enfocaron estas temáticas de manera más integral. Se revisó un libro. Resultados: al analizar el comportamiento de los artículos respecto a su representatividad en las diferentes revistas científicas donde fueron publicados 5,45 por ciento de ellos correspondieron, a la revista International Journal of Nanomedicine y Biomatter. Los demás artículos estuvieron distribuidos de manera uniforme entre las otras revistas. Conclusiones: múltiples son las publicaciones que abordan la temática de la ingeniería tisular en las ramas biomédicas y particularmente en Estomatología y todas coinciden en términos generales en que la investigación de la biología de células madre y biomateriales modernos ha creado interesantes oportunidades para la regeneración y la terapia basada en la ingeniería de tejidos. El correcto manejo de los elementos que conforman la ingeniería tisular, con el sistema de señalización tisular, nanomateriales, sistemas de administración, células madre y biomateriales amplía las posibilidades de aplicación en la estomatología moderna y futura(AU)

The wish to create more biological alternatives for the permanent implantation of synthetic materials has fostered the development of tissue engineering. As one of the pillars of regenerative medicine, tissue engineering broadens the range of research and clinical application possibilities in dentistry. Objective: carry out a bibliographic review about tissue engineering as a pillar of regenerative medicine in dentistry. Methods: the review covered the period May-June 2013. An evaluation was conducted of high impact journals from the Web of Sciences (43 journals) and 2 Cuban journals. Databases from reference systems, such as MEDLINE, PubMed and Scielo, were consulted with the aid of search terms like tissue engineering AND dentistry, regenerative medicine, biomaterials, scaffolds, nanotechnology, and their Spanish counterparts. The review included papers in English and Spanish, and publications from the last five years. Of the 127 papers obtained, the reviewers selected the 55 which approached the study topic in a more comprehensive manner. One book was reviewed. Results: an analysis of the representativeness of papers in the scientific journals where they were published showed that 5.45 percent corresponded to the International Journal of Nanomedicine and Biomater. The remaining papers were evenly distributed among the other journals. Conclusions: many are the publications dealing with the subject of tissue engineering in biomedicine and particularly in dentistry. In general terms, all of them agree that research into stem cells biology and modern biomaterials has created interesting opportunities for regeneration and therapy based on tissue engineering. Appropriate management of the elements making up tissue engineering, alongside the tissue signaling system, nanomaterials, management systems, stem cells and biomaterials, broaden the possibilities of application in contemporary and future dentistry(AU)

La curación de las heridas de gran superficie y la medicina regenerativa / Wound healing of large surface and regenerative medicine

La medicina regenerativa, con los conocimientos de la biología celular y molecular, llegó a las especialidades quirúrgicas y así a la atención del paciente. Se describen los fundamentos teóricos de un nuevo concepto de curación de las superficies cruentas. Se explica un nuevo procedimiento de curación de las heridas no infectadas a través del uso de un epitelio transitorio que al evitar la evaporación protege a las señales electromagnéticas de información entre célula y célula, así como la regeneración de un nuevo tejido mediante el uso de ADM. Se presentan cinco pacientes críticos, cuatro de ellos con indicación de amputación por la gravedad del traumatismo.

Regenerative medicine with knowledge of cell and molecular biology, reached the surgical specialities and thereby patient care. It describes the theoretical basis of a new concept of wound healing and a new procedure for healing of uninfected wounds through the use of a transitional epithelium to prevent evaporation that protects information of the electromagnetic signals between the cells, and regeneration of a new tissue using ADM. We present five critical patients, four of them with an indication of amputation due to the severity of the injury.

Bioingeniería dental, ¿el futuro de la terapia odontológica? / Dental bioengineering: is this the future of dental treatment?

Desde las primeras épocas de la historia, el hombre ha intentado restituir la función de los órganos dentarios perdidos. El sueño de la odontología es sustituir los materiales que se usan hoy en día por otros de origen biológico, basados en células que tengan las mismas características o semejantes a las naturales para poder así regenerar o reparar los tejidos perdidos. Las publicaciones recientes enfatizan el uso de las células troncales inducidas a pluripotencia (iPSC por sus siglas en inglés), como la posible solución al controvertido uso de células madre y la obtención de ellas; ésta es sólo una de las muchas posibilidades que se plantean para las futuras investigaciones; sin embargo, debido a que es la más acertada, la aplicación de estas técnicas en el ámbito odontológico es la forma más cercana de poder llegar a restituir los tejidos perdidos. Es así como la bioingeniería dental se abre a nuevos horizontes, esperando obtener mejores alcances en beneficio de la salud de nuestra población.

Tooth regeneration: Current status.

Regeneration of a functional tooth has the potential to be a promising therapeutic strategy. Experiments have shown that with the use of principles of bioengineering along with adult stem cells, scaffold material, and signaling molecules, tooth regeneration is possible. Research work is in progress on creating a viable bioroot with all its support. A new culture needs to be created that can possibly provide all the nutrients to the stem cells. With the ongoing research, tissue engineering is likely to revolutionize dental health and well-being of people by regenerating teeth over the next decade.