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: BACKGROUND: Patients suffering from diseased and injured organs may be treated with transplanted organs. However, there is a severe shortage of donor organs which is worsening yearly due to the aging population. Scientists in the field of tissue engineering apply the principles of cell transplantation, materials science, and bioengineering to con...
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... Também podem decorrer em alguns vertebrados, como as cobras, pássaros e anfíbios. Em mamíferos, só é possível verificá-la em estágios iniciais do desenvolvimento embrionário, por meio de alguns estímulos in vitro no oócito de ratas, cabras, vacas, macacas e humanas (Hipp & Atala, 2004;Kharche & Birade, 2013). ...
A produção in vitro de embriões (PIV) é uma biotécnica utilizada, alternativamente, para acelerar a produção de animais geneticamente superiores, com diferentes etapas: colheita e maturação in vitro (MIV) de oócitos, fecundação in vitro (FIV), cultivo in vitro (CIV) de zigotos até ao estádio de blastocisto. A PIV, em conjunto com a criopreservação de oócitos e embriões, pode permitir a comercialização de embriões em larga escala, o transporte de embriões livres de patógenos e transações comerciais de germoplasma mais fáceis e baixos custos. Porém, não é efetivo devido a vários fatores relacionados a evolução no processo. Estudos visam facilitar o uso de oócitos por razões biológicas, comerciais e melhor aproveitamento celular. Foi realizada uma revisão narrativa da literatura, por meio de artigos científicos, dissertações, teses e livros publicados nas bases de dados: Scopus, PubMed, Scielo e Google acadêmico, com o objetivo de fornecer uma perspectiva geral dessa biotécnica em caprinos com ênfase na descrição enfatizando as principais metodologias atualmente utilizadas para colheita de oócitos, MIV, FIV e CIV de embriões.
... However, drawbacks including ethical issues, immunological rejection, costs, and low quantity of cells harvested, still need to be overcome in order to apply MSCs' transplantation as a therapy [20,65]. It is also reported that MSCs can cause serious secondary effects. ...
Tissue regeneration is a hot topic in health sciences, particularly because effective therapies promoting the healing of several cell types are lacking, specifically those of the musculoskeletal system. Mesenchymal Stem/Stromal Cells (MSCs) have been identified as crucial players in bone homeostasis, and are considered a promising therapy for diseases such as osteoarthritis (OA) and Rheumatoid Arthritis (RA). However, some known drawbacks limit their use, particularly ethical issues and immunological rejections. Thus, MSCs byproducts, namely Extracellular Vesicles (EVs), are emerging as potential solutions to overcome some of the issues of the original cells. EVs can be modulated by either cellular preconditioning or vesicle engineering, and thus represent a plastic tool to be implemented in regenerative medicine. Further, the use of biomaterials is important to improve EV delivery and indirectly to modulate their content and secretion. This review aims to connect the dots among MSCs, EVs, and biomaterials, in the context of musculoskeletal diseases.
... In addition, MPF plays an important role in oocyte activation (23,24). When oocytes are fertilized or parthenogenetically activated, the Ca 2+ concentration increases instantaneously and cytostatic factor (CSF) expression decreases, resulting in the decrease or even disappearance of MPF activity and chromosome segregation, prompting oocytes to enter meiotic anaphase II (25). ...
Oocytes reconstructed by spindle transfer (ST) are prone to chromosome abnormality, which is speculated to be caused by mechanical interference or premature activation, the mechanism is controversial. In this study, C57BL/6N oocytes were used as the model, and electrofusion ST was performed under normal conditions, Ca2+ free, and at room temperature, respectively. The effect of enucleation and electrofusion stimulation on MPF activity, spindle morphology, γ-tubulin localization and chromosome arrangement was compared. We found that electrofusion stimulation could induce premature chromosome separation and abnormal spindle morphology and assembly by decreasing the MPF activity, leading to premature activation, and thus resulting in chromosome abnormality in oocytes reconstructed via ST. Electrofusion stimulation was an independent factor of chromosome abnormality in oocytes reconstructed via ST, and was not related to enucleation, fusion status, temperature, or Ca2+. The electrofusion stimulation number should be minimized, with no more than 2 times being appropriate. As the electrofusion stimulation number increased, several typical abnormalities in chromosome arrangement and spindle assembly occurred. Although blastocyst culture could eliminate embryos with chromosomal abnormalities, it would significantly decrease the number of normal embryos and reduce the availability of embryos. The optimum operating condition for electrofusion ST was the 37°C group without Ca2+.
... 2. Explain the process of therapeutic cloning. 3. Provide an example of therapeutic cloning applications. ...
... Dentro dessa ótica inovadora, com o advento da medicina regenerativa, vários estudos demonstraram, que as células-tronco tem grande capacidade de autogeração, proliferação, expansão e diferenciação, podendo inclusive reconstituir tecidos lesados e até formar um novo órgão. (11)(12)(13) A capacidade de imunomodulação, aliada a falta de expressão dos antígenos de histocompatibilidade, faz com que as células mesenquimais (MSC) dentre as demais linhagens de células tronco, sejam provavelmente as ideais para uso nas técnicas de medicina regenerativa. (14,15) A principal fonte de obtenção das células-tronco é a medula óssea, mas elas podem ser adquiridas de outros tecidos como sangue de cordão, fígado fetal, líquido amniótico, de polpa dentária e tecido adiposo. ...
Obtective: To verify the presence of mesenchymal stem cells (MSC) in the area close to the optic nerve of previously injured with absolute alcohol. Methods: Twelve New Zealand breed rabbits were divided into two groups, and after sedation, each eye of the animal received a retrobulbar injection of 1 ml of absolute ethanol in one eye, and 1 ml of physiological solution 0.9 % (PS) in the contralateral eye. After 15 days all eyes of animals belonging to group A, received via retrobulbar a solution containing MSCs from human adipose tissue (AT) and previously marked with Qdots, while all eyes of animals from group B received solution containing PBS. Results: The presence of MSC was observed in 100% of the eyes of the animals of group A and the more central areas near and into the optic nerve. Conclusion: The results suggest that the appointment of MSC with Qdots allowed their follow-up applied in the region and in the inner areas of the optic nerve. The MSC permanence after 15 days of application around the optic nerve suggests the feasibility and possible involvement of the same during the damaged tissue regeneration process. Under the conditions of this study, the route of retrobulbar application and the presence of the stem cells to the central areas of the optic nerves in animals of group A, suggests that this might be an effective approach for MSCs in regeneration process of optic neuropathies.
... The current results showed that autologous cell transplantation was more effective in comparison with nonautologous transplantation, which could explain why autologous cell transplantation had a lower risk of rejection and transplanted cells appeared easily in damaged tissue (REF) (46). ...
Background: Mesenchymal stem cells are one type of adult stem cells, which are able to give rise to mesodermal origin tissues. The application of mesenchymal stem cells for tissue and organ regeneration o er advantages because of the relative ease of collection and their potential to di erentiate to 3 cell lineages. Objectives: This research was designed to study and evaluate the e ect of mesenchymal stem cells on the repair of bone defects in Wistar rat models and to compare autologous and non-autologous cell transplantation in repairing bone defects. Methods: The mesenchymal stem cells were cultured and expanded in MEM medium supplemented with 10% fetal bovine serum (FBS) and 2% penicillin/streptomycin by incubation at 37 C in 5% CO2. Immunocytochemistry analysis was performed using CD44 and fibronectin markers to detect the mesenchymal stem cells. A transcortical defect was created within the distal epiphyses of the femur bone. After 3 days of injury, Brdu-labeled cells were injected at the site of injury. The animals were sacrificed after 4 weeks of transplantation and the femurs with the recipient area were removed and the length, weight, area, density, and biomechanical parameters were evaluated. Results: The obtained results showed that although neither non-autologous nor autologous cell transplantation significantly improved the e ect on length and area of the defective femur bone, the mass and bone density of the cell-injected transplanted groups had a significant increase in comparison with the control and sham groups. Conclusion: It seems that cell transplantation could improve these parameters, improving the mean mass, length, area, and density of parameters during the the regeneration process.
... While experimental and some clinical studies have shown beneficial effects of MSCs on bone healing, the exact mechanisms by which these cells improve bone regeneration remain unclear. Clinical applications of stem cells have been restricted by numerous factors, including: (1) ethical concerns; (2) the immunological rejection of cells from heterologous origins; (3) the limited amount of available stem cells for implantation at the injured site, requiring ex vivo expansion; (4) donor-related differences; (5) cost; (6) feasibility; (7) expertise; (8) aging; (9) translational difficulties; and (10) other factors [Hipp and Atala, 2004]. Moreover, the safety of these procedures has to be evaluated before clinical application. ...
Healing and regeneration of bone injuries, particularly those that are associated with large bone defects, are a complicated process. There is growing interest in the application of osteoinductive and osteogenic growth factors and mesenchymal stem cells (MSCs) in order to significantly improve bone repair and regeneration. MSCs are multipotent stromal stem cells that can be harvested from many different sources and differentiated into a variety of cell types, such as preosteogenic chondroblasts and osteoblasts. The effectiveness of MSC therapy is dependent on several factors, including the differentiating state of the MSCs at the time of application, the method of their delivery, the concentration of MSCs per injection, the vehicle used, and the nature and extent of injury, for example. Tissue engineering and regenerative medicine, together with genetic engineering and gene therapy, are advanced options that may have the potential to improve the outcome of cell therapy. Although several in vitro and in vivo investigations have suggested the potential roles of MSCs in bone repair and regeneration, the mechanism of MSC therapy in bone repair has not been fully elucidated, the efficacy of MSC therapy has not been strongly proven in clinical trials, and several controversies exist, making it difficult to draw conclusions from the results. In this review, we update the recent advances in the mechanisms of MSC action and the delivery approaches in bone regenerative medicine. We will also review the most recent clinical trials to find out how MSCs may be beneficial for treating bone defects.
... Since the main question arises from the use of hESCs, many works had suggested alternate sources of stem cells including bone marrow derived stem cells [35][36][37][38][39], stem cells derived from amniotic fluid [33,40,41], placenta [33,[42][43][44], umbilical cord blood stem cells [45][46][47][48][49][50][51], collectively or commonly referred to as mesenchymal stem cells (MSCs). Other important alternative sources suggested are the stem cells that are derived by reprograming differentiated somatic cells [52][53][54][55] and finally novel techniques to acquire hESCs without destroying viable embryos [56][57][58][59][60][61]. ...
3D printing is one of the most innovative technologies in the current era, while 3D bioprinting is revolutionizing the medical technology industry. Bioprinting technology could help overcome the limitations of the current tissue engineering methods, including the problem of longer waiting times for treatment (especially with organ transplants). While fighting infectious diseases had been the main focus of medicine in the past, dealing with the consequences of a predominantly ageing population will be the priority in the future and bioprinting is a promising technology to tackle this challenge effectively. Bioprinting will not only cater the needs of ageing population but also in the field of paediatrics, where the bioprinted tissue or organ should possess the capability to grow with the patient. As researchers around the world are working on 3D bioprinting of tissues and organs, companies are burgeoning all over, making and marketing new bioprinters. While the research and commercialisation are moving at such a rapid pace, the issues surrounding the technology, in terms of ethics, policies, regulations and social acceptance, are not addressed in commensurate. Identifying the ELSA (Ethical Legal and Social Aspects) concerns of this technology at an early stage is not only part of our social responsibility but also in the interest of the future of the technology itself. This paper reviews and foresees these challenges with pragmatism, thereby creating awareness to the researchers and policy makers and to urge a positive course of action in the foreseeable future. The significance of this work will be to address a broad audience, associated with this technology, from scientists to businessmen, engineers to clinicians, laymen to lawmakers. A ‘complete’ policy approach for this technology is recommended rather than a ‘piecemeal’ approach of the various constituents of this technology. An effective course of action will be to setup a multi-disciplinary international panel to work on the policy framework, which will look in to both ‘hard’ and ‘soft’ impacts of 3D bioprinting, the associated ethical challenges, legal measures including patenting and effective controls to prevent the misuse, as well as the social aspects encompassing the cultural and religious differences which accounts for the success of this technology. Setting up national level panels to assess the risk-benefit analysis, taking into consideration the cultural and religious view of its population and other legal and social aspects, might be a good starting point.
... However mammalian mature oocytes can be activated in vitro, leading to the generation of parthenotes that will form blastocysts morphologically indistinguishable from those derived from fertilized eggs. Despite this similarity, many studies reported fundamental alterations, which are surprisingly compatible with the survival of cells and do not affect the formation of fetuses that can develop to different stages after activation, depending on the species (Hipp and Atala, 2004). ...
... Parthenogenetic cells display fundamental alterations, which are surprisingly compatible with their survival and do not affect the formation of embryos that can develop to different stages after activation, depending on the species (Hipp and Atala, 2004). We hypothesized that one possible mechanism that may enable these severely aneuploid cells to proliferate and differentiate is the formation of intercellular bridges since these structures allow the passage of organelles and other cytoplasmic constituents between daughter cells (Morales et al., 2002;Ventela et al., 2003). ...
Parthenogenetic cells, obtained from in vitro activated mammalian oocytes, display multipolar spindles, chromosome malsegregation and a high incidence of aneuploidy, probably due to the lack of paternal contribution. Despite this, parthenogenetic cells do not show high rates of apoptosis and are able to proliferate in a way comparable to their biparental counterpart. We hypothesize that a series of adaptive mechanisms are present in parthenogenetic cells, allowing a continuous proliferation and ordinate cell differentiation both in vitro and in vivo. Here we identify the presence of intercellular bridges that contribute to the establishment of a wide communication network among human parthenogenetic cells, providing a mutual exchange of missing products. Silencing of two molecules essential for intercellular bridge formation and maintenance, demonstrates the key function played by these cytoplasmic passageways that ensure normal cell functions and survival, alleviating the unbalance in cellular component composition.
Copyright © 2015. Published by Elsevier Ireland Ltd.
... In scaffold-based tissue engineering, there are a number of important factors to consider: route of delivery, pre-conditioning using different growth factors or cytokines, immunological function, and accessibility and availability of cell sources. Cells may be allogeneic (same species, different individual) or autologous (same individual) [28]. Although autologous cells are preferred because an immunologic response is not evoked, there might be problems with achieving an adequate cell yield for expansion and transplantation, especially in patients with end-stage organ disease. ...
Stem cells possess the unique properties of unlimited self-renewal capability and a broad differentiation spectrum to produce multiple different cell types. This provides many platforms to explore novel multidisciplinary approaches to create and/or restore functional three-dimensional tissues or organs for the treatment of a range of diseases. In this chapter, in the context of respiratory diseases, we review the unique properties of stem cells, and how they have been studied for their therapeutic potential in cell therapy and tissue engineering. In addition, we give a brief overview of the current clinical studies on the use of stem cells for both acute and chronic respiratory diseases.
