RESUMO
Stem cells have drawn extraordinary attention from scientists and the general public due to their potential to generate effective therapies for incurable diseases. At the same time, the production of embryonic stem cells involves a serious ethical issue concerning the destruction of human embryos. Although adult stem cells and induced pluripotential cells do not pose this ethical objection, there are other bioethical challenges common to all types of stem cells related particularly to the clinical use of stem cells. Their clinical use should be based on clinical trials, and in special situations, medical innovation, both of which have particular ethical dimensions. The media has raised unfounded expectations in patients and the public about the real clinical benefits of stem cells. At the same time, the number of unregulated clinics is increasing around the world, making direct offers through Internet of unproven stem cell therapies that attract desperate patients that have not found solutions in standard medicine. This is what is called stem cells tourism. This article reviews this situation, its consequences and the need for international cooperation to establish effective regulations to prevent the exploitation of patients and to endanger the prestige of legitimate stem cell research.
Assuntos
Humanos , Turismo Médico , Pesquisa com Células-Tronco , Células-Tronco , Chile , Destinação do Embrião , Destinação do Embrião/legislação & jurisprudência , Turismo Médico/legislação & jurisprudência , Educação de Pacientes como Assunto , Autonomia PessoalRESUMO
Stem cells have drawn extraordinary attention from scientists and the general public due to their potential to generate effective therapies for incurable diseases. At the same time, the production of embryonic stem cells involves a serious ethical issue concerning the destruction of human embryos. Although adult stem cells and induced pluripotential cells do not pose this ethical objection, there are other bioethical challenges common to all types of stem cells related particularly to the clinical use of stem cells. Their clinical use should be based on clinical trials, and in special situations, medical innovation, both of which have particular ethical dimensions. The media has raised unfounded expectations in patients and the public about the real clinical benefits of stem cells. At the same time, the number of unregulated clinics is increasing around the world, making direct offers through Internet of unproven stem cell therapies that attract desperate patients that have not found solutions in standard medicine. This is what is called stem cells tourism. This article reviews this situation, its consequences and the need for international cooperation to establish effective regulations to prevent the exploitation of patients and to endanger the prestige of legitimate stem cell research.
Assuntos
Turismo Médico/ética , Pesquisa com Células-Tronco/ética , Células-Tronco , Chile , Destinação do Embrião/ética , Destinação do Embrião/legislação & jurisprudência , Humanos , Turismo Médico/legislação & jurisprudência , Educação de Pacientes como Assunto , Autonomia PessoalRESUMO
The ischemia-induced death of cardiomyocytes results in scar formation and reduced contractility of the ventricle. Several preclinical and clinical studies have supported the notion that cell therapy may be used for cardiac regeneration. Most attempts for cardiomyoplasty have considered the bone marrow as the source of the "repair stem cell(s)," assuming that the hematopoietic stem cell can do the work. However, bone marrow is also the residence of other progenitor cells, including mesenchymal stem cells (MSCs). Since 1995 it has been known that under in vitro conditions, MSCs differentiate into cells exhibiting features of cardiomyocytes. This pioneer work was followed by many preclinical studies that revealed that ex vivo expanded, bone marrow-derived MSCs may represent another option for cardiac regeneration. In this work, we review evidence and new prospects that support the use of MSCs in cardiomyoplasty.
Assuntos
Cardiomioplastia/métodos , Cardiopatias/terapia , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/fisiologia , Animais , Transplante de Medula Óssea/métodos , Cardiopatias/patologia , Humanos , Infarto do Miocárdio/patologia , Infarto do Miocárdio/terapia , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/transplante , RegeneraçãoRESUMO
Ex vivo cultures of human bone marrow-derived mesenchymal stem cells (MSCs) contain subsets of progenitors exhibiting dissimilar properties. One of these subsets comprises uncommitted progenitors displaying distinctive features, such as morphology, a quiescent condition, growth factor production, and restricted tissue biodistribution after transplantation. In this study, we assessed the competence of these cells to express, in the absence of differentiation stimuli, markers of mesoderm and ectodermic (neural) cell lineages. Fluorescence microscopy analysis showed a unique pattern of expression of osteogenic, chondrogenic, muscle, and neural markers. The depicted "molecular signature" of these early uncommitted progenitors, in the absence of differentiation stimuli, is consistent with their multipotentiality and plasticity as suggested by several in vitro and in vivo studies.
Assuntos
Células-Tronco Mesenquimais/citologia , Células da Medula Óssea/citologia , Ciclo Celular , Diferenciação Celular , Linhagem da Célula , Proliferação de Células , Citometria de Fluxo , Humanos , Técnicas In Vitro , Luz , Mesoderma/metabolismo , Microscopia de Fluorescência , Espalhamento de Radiação , Células-Tronco/citologia , Fatores de TempoRESUMO
Bone marrow is the residence site of mesenchymal stem cells (MSC), which upon commitment and maturation develop into several mesenchymal phenotypes. Recently, we have described the presence of MSC in human cord blood (cbMSC) and informed that their properties are the same as those for MSC obtained from adult bone marrow. In this study we have investigated the capability of transplanted cbMSC to home and survive in the marrow of unconditioned nude mice. cbMSC utilized for transplantation studies were characterized by morphology, differentiation potential, and immunophenotype. After transplantation by systemic infusion, human DNA (as detected by PCR amplification of human-specific beta-globin gene) was detected in the marrow of recipients as well as in ex vivo-expanded stromal cells prepared from the marrow of transplanted animals. These results demonstrate homing and survival of cbMSC into the recipient marrow and also suggest a mesenchymal-orientated fate of engrafted cells, because human DNA was also detected in cells of other recipient tissues, like cardiac muscle, teeth, and spleen.
Assuntos
Medula Óssea/cirurgia , Transplante de Células-Tronco de Sangue do Cordão Umbilical/métodos , Sangue Fetal/citologia , Sobrevivência de Enxerto/imunologia , Síndromes de Imunodeficiência/terapia , Transplante de Células-Tronco Mesenquimais/métodos , Animais , Medula Óssea/imunologia , Diferenciação Celular/imunologia , Linhagem da Célula/imunologia , Tamanho Celular/imunologia , Quimiotaxia/imunologia , Transplante de Células-Tronco de Sangue do Cordão Umbilical/tendências , DNA/metabolismo , Modelos Animais de Doenças , Feminino , Globinas/genética , Humanos , Síndromes de Imunodeficiência/imunologia , Imunofenotipagem , Recém-Nascido , Transplante de Células-Tronco Mesenquimais/tendências , Camundongos , Camundongos Nus , Células Estromais/citologia , Células Estromais/imunologia , Transplante HeterólogoRESUMO
Interleukin-6 (IL-6) promotes osteodifferentiation in bone-located progenitors; however, it is not known whether this cytokine affects the differentiation of bone marrow-located osteoprogenitors. To address this issue, we prepared human bone marrow-derived mesenchymal stem cells (MSCs), which were characterized by a cell surface phenotype and multipotential nature. It was observed that in the presence of IL-6, MSCs were not differentiated into the osteogenic lineage, as evidenced by a failure to induce alkaline phosphatase activity, an earlier marker of osteodifferentiation. The lack of effect of IL-6 correlates with the observation that MSCs do not express a membrane-bound or soluble IL-6 receptor (sIL-6R). The incompetence of IL-6 was not reversed by the addition of sIL-6R alone or the sIL-6R/IL-6 complex, as it occurs in other IL-6R-negative cells. However, after MSC osteocommittment by dexamethasone, sIL-6R or the sIL-6R/IL-6 complex enhanced alkaline phosphatase activity. The effect of sIL-6R or sIL-6R/IL-6 proved to be dependent on gp130 availability, which is expressed by MSCs, and involves stat-3 phosphorylation. These data suggest that IL-6R deficiency may represent for bone marrow-located mesenchymal progenitors a sort of protective mechanism to escape the osteogenic effect of IL-6, which is produced by the MSC itself as well as by other marrow stromal cells.