Cómo funciona JustAnswer:

  • Preguntar a un Experto
    Los expertos tiene muchos conocimientos valiosos y están dispuestos a ayudar en cualquier pregunta. Credenciales confirmadas por una empresa de verificación perteneciente a Fortune 500.
  • Obtener una respuesta profesional
    Por correo electrónico, mensaje de texto o notificación mientras espera en su sitio.
    Haga preguntas de seguimiento si lo necesita.
  • Garantía de satisfacción plena
    Garantizamos tu satisfacción.

Formule su propia pregunta a Pablo Rodríguez

Pablo Rodríguez
Pablo Rodríguez, Licenciatura
Categoría: Medicina
Clientes satisfechos: 15716
Experiencia:  Médico adjunto de Servicio de Urgencias Hospitalarias. Consulta de Medicina Familiar y Comunitaria
59774832
Escriba su pregunta sobre Medicina aquí...
Pablo Rodríguez está en línea ahora

etimado doctor. he tenido un desprendimiento de retina natural,

Pregunta del cliente

etimado doctor. he tenido un desprendimiento de retina natural, no soy7 diabetico, no he tenido accidente a se debria , no es todo se complico he tenido alta presion termine con cirugiA OPTICA DE CATARATAS, ESTOY SIN EL CRISTALINO NO ES TODO AHORA ME DICEN QUE NO ME PUEDE COLOCAR LA LENTE, PORQUE EL NERVIO OPTICO ESTA PALIDO QUE SIGNIFICA ESO TIENE SOLUCION, HA TENGO 544 ANOS Y HASTA ENTONCES MI VISION FUE PERFECTA NO USABA ANTEOJOIS GRACIAS XXXXX ARGENTINA
Enviada: hace 4 año.
Categoría: Medicina
Experto:  Dr. Navas Benavides escribió hace 4 año.
Hola, será un placer poder ayudarle con mis respuestas. Esperando que su salud sea la mejor, permítame ser parte de la solución a su problema.

El tipo más común de desprendimientos de retina con frecuencia se debe a un desgarro o perforación en dicha retina, a través del cual se pueden filtrar los líquidos del ojo. Esto causa la separación de la retina de los tejidos subyacentes, muy parecido a una burbuja debajo de un papel decorativo. No se puede predecir a menos que haya tenido antes por lo menos un examen de fondo de ojo cada año o cada 6 mses por el mismo examinador.

Otro tipo de desprendimiento de retina se llama desprendimiento por tracción y se observa en personas con diabetes no controlada, cirugía previa de la retina o que tienen inflamación crónica.

En cuanto a la frase "NERVIO OPTICO ESTA PALIDO" significa que aparentemente no tiene la irrigación adecuada, y hay algún grado de lesión del nervio por baja de oxígeno, y se traduce en ceguera parcial o permanente.

Por el momento no se pude hacer nada más que esperar, y que su oftalmólogo evalúe el daño que quede, y si pudiera evaluarle un retinólogo, que es el oftalmólogo especializado sólo en retina, para ver qué opinión le da, sería lo ideal.

Saludos, XXXXX XXXXXún puedo ayudarle con alguna otra duda o pregunta, escríbala abajo de esta respuesta. Hasta pronto.
Cliente: escribió hace 4 año.
estimado doctor- no habia podido tener contacto con ud. probablemente a la diferencia horaria con argentina, tengo la confirmacion que no tengo vision por dano en el nevio optico, lo que quiero saber ya que la medicina tradicional no tiene solucion, donde puedo hacer tratamiento con celulas madres para regenera el nervio optico. atte mario paredes
Cliente: escribió hace 4 año.
Volver a incluir en lista: Respuesta incompleta.
si me pueden contestar mis dudas no he podido dialogar con el profesional y tengo mis dudas
Experto:  Pablo Rodríguez escribió hace 4 año.
Hola Mario, le comento que actualmente no se ha conseguido obtener resultados satisfactorios con la terapia de células madre en la regeneración de retina ni nervio óptico. La terapia con células madre tiene utilidad para el infarto de corazón pero en su problema aún no han conseguido obtener resultados en la fase experimental, lo lamento profundamente.

Si mi respuesta le ha sido de ayuda, por favor, sea tan amable de aceptarla haciendo click en el botón verde "Aceptar Respuesta".

Reciba un cordial saludo.
Pablo Rodríguez, Licenciatura
Categoría: Medicina
Clientes satisfechos: 15716
Experiencia: Médico adjunto de Servicio de Urgencias Hospitalarias. Consulta de Medicina Familiar y Comunitaria
Pablo Rodríguez y otros 2 otros especialistas en Medicina están preparados para ayudarle
Experto:  Pablo Rodríguez escribió hace 4 año.
Hola, le comento que la información que usted ha leído es experimental, por ejemplo este artículo:

http://www.informador.com.mx/tecnologia/2011/283509/6/cientificos-japoneses-reproducen-retina-a-partir-de-celulas-madre.htm

Tenga en cuenta que algo que sale en los medios NO quiere decir que se use en los hospitales o como tratamientos a la población, hasta la fecha la terapia con células madre en retina no se usa como tratamiento establecido, demostrado en eficacia y seguridad; seguramente haya ensayos abiertos de investigación pero al menos en España NO se hace en la población actualmente y es uno de los mejores sistemas sanitarios del mundo.

Aún así, le agradecería de forma muy especial si me puede comentar el origen de la información sobre el hospital que esté aplicando esa técnica en la población, me interesa mucho.

Reciba un cordial saludo. :)
Cliente: escribió hace 4 año.
ESTIMADO DOCTOR- LE DOY LA INFORMACION, EL DE CHINA ES BEIKE BIOTECNOLOGY, META ASI EN EL BUSCADOR Y LE VA A SALIR EN MEXICO, ES PROGENCELL, TAMBIEN BUSQUE ASI, EN MEXICO ES CON CELULAS AUTOLOGAS Y EN CHINA ES DEL CORDON UMBILICAL, SANGRE DE CORDON UMBILICAL Y MEDULAS OSEAS DE TERCEROS, EN MEXICO ES COLOCAN EN EL MISMO OJO Y EN CHINA ES INTRAVENOSAS, Y TENGO PRESUPUESTO DE AMBOS , PERO DESEARIA SABER Y PUDIERA SER VERACES LO QUE DICEN YA QUE NO TENGO CONOCIMEINTOS MEDICOS, AGRADECERIA SU AYUDA , ESPERO SU RESPUESTA UNA VEZ QUE HAYA VISTO ESTAS PAGINAS. ATTE MARIO PAREDES
Experto:  Pablo Rodríguez escribió hace 4 año.
Hola, esos enlaces son una estafa, le dejo un artículo (está en inglés) donde está con rigor científico lo que se sabe hasta ahora de las "stem cell" (células madre), en concreto en la retina es:

Retinal disease — Human ES cell-derived retinal photoreceptors have been used to improve visual functions in blind mice [12]. Following intraocular injection, retinal cells derived from human ES migrated into the appropriate retinal layers and expressed markers of differentiated rod and cone photoreceptor cells. Subretinal transplantation of the cells into the subretinal space of mice modeling Leber's congenital amaurosis restored light responses to the animals.

Los resultados obtenidos son en RATONES (mice), la información proviene de www.uptodate.com ; mi hospital paga una licencia para que los médicos estemos informados, es información médica contrastada y relevante. Lo que ofrecen esas páginas son progenitores hematopoyéticos... son un engaño.

Le dejo el artículo sobre la actualidad en stem cell y sus aplicaciones médicas para su adecuado conocimiento.

All topics are updated as new evidence becomes available and our peer review process is complete.
Literature review current through: Jan 2012. | This topic last updated: Feb 16, 2011.

INTRODUCTION — Stem cells are those cells that have the capability of self-renewal and differentiation. First identified in the hematopoietic system, they are likely to be present in many other tissues. Stem cells have altered the care of individuals with hematologic, oncologic, dermatologic, ophthalmologic, and orthopedic conditions. The range of possible applications of stem cells to medicine extends beyond the conception of stem cells as replacement parts (table 1).

The evolving role of stem cells in clinical medicine is developing along at least three lines:

  • Stem cells as therapy (either to replace cell lines that have been lost or destroyed, or to modify the behavior of other cells)
  • Stem cells as targets of drug therapy
  • Stem cells to generate differentiated tissue for in vitro study of disease models for drug development.

This topic will review the biology of stem cells and present an overview of their use in clinical and research settings, as well as ethical considerations that have generated much controversy.

Hematopoietic stem cells are discussed separately. (See "Overview of hematopoiesis and stem cell function" and "Sources of hematopoietic stem cells".) Hematopoietic stem cell transplantation for specific clinical conditions is discussed in multiple related topics.

TYPES OF STEM CELLS — All stem cells share two cardinal features: they are capable of self-renewal and they can differentiate. Self-renewal is the ability of cells to proliferate without the loss of differentiation potential and without undergoing senescence (biologic aging). Self-renewal does not imply that each cell division results in two exact replicas of the stem cell; daughter cells may be either stem cells or more differentiated cells. Indeed, stem cells are hypothesized to be able to divide symmetrically (in which both daughter cells are either stem cells or differentiated cells) or asymmetrically (yielding both a stem cell and a more differentiated cell) [1,2] (figure 1).

The potency of a stem cell is defined by the types of more differentiated cells that the stem cell can make (table 2). Stem cells can be either totipotent, pluripotent, multipotent, or unipotent.

  • Totipotent cells have the capability to produce all cell types of the developing organism, including both embryonic and extraembryonic (eg, placenta) tissues.
  • Pluripotent cells can only make cells of the embryo proper, but make all cells of the embryo including germ cells and cells from any of the germ layers. Therefore, they can make any cell of the body.
  • Multipotent cells can only make cells within a given germ layer. For example, multipotent stem cells from a mesodermal tissue like the blood can make all the cells of the blood, but cannot make cells of a different germ layer such as neural cells (ectoderm) or liver cells (endoderm).
  • Unipotent cells make cells of a single cell type. An example is a germ cell stem cell that makes the cells that mature to become egg or sperm, but not other cell types.

SOURCES OF STEM CELLS — Classically, the potency of cells has been thought to be tied to the time of embryonic development of the organism. That is, cells that arise from the first few cell divisions following fertilization of the egg are generally the only cells that have totipotency. Pluripotent cells were thought to be limited to cells derived from either the inner cell mass of the blastocyst (a pre-implantation stage of development occurring approximately 7 to 10 days after fertilization in the human) or nascent germ cells in the embryo. Cells cultured and cell lines established from these structures are called embryonic stem (ES) cells and embryonic germ cells respectively. It is now known that pluripotent cells can arise from other cells types as well. (See 'Induced pluripotent stem cells (iPS)' below.)

Once the primitive streak forms in embryonic development (day 10 to 14 post fertilization in the human), it is thought that most stem cells are restricted to be either multipotent or unipotent. These have often been called 'adult' stem cells. If they are derived from tissue other than the germ cells, they may be called 'somatic' stem cells. Such cells would include cells derived from the cord blood, sometimes mistakenly considered equivalent to ES cells in the popular press.

Adult stem cells are thought to be present in most, but not all, tissues and to persist throughout life (figure 2). They are thought to provide the basis for tissue maintenance and response to injury. This is particularly true for tissues where there is high cell turnover, such as the blood, skin, and intestine, where stem cells have been clearly defined experimentally [3-5]. There is also clear evidence for a resident stem cell population for some tissues where the rate of cell turnover is lower (such as muscle and brain) [6,7].

However, for other tissues, including the islet cells of the pancreas, it is not clear whether adult stem cells exist and it is possible that stem cells are a durable source of replacement cells in some tissues but not in others. Division of mature cells may be the basis for the replacement after loss of some cells in other tissues. The implications of this are that mature cells are thought to only have a limited number of cell divisions, as opposed to stem cells. Therefore in settings of extensive injury, a tissue that depends upon residual mature cells to replace the injured cells may be more limited in its regenerative capacity than tissues that can rely on resident stem cells. This is one hypothesis for the failure of repair of pancreatic islet damage in type I diabetes mellitus, whereas extensive cell damage to the blood with cancer chemotherapy can result in complete restoration of tissue function.

Induced pluripotent stem cells (iPS) — The concept of the close relationship between stem cell potential and stage of development dramatically changed in 2006 [8]. In a remarkable set of experiments, Shinya Yamanaka and his colleagues took genes that were expressed in pluripotent ES cells, but not generally in mature cells, and introduced them into mature cells. They did so in a manner such that the genes would now be “ectopically” expressed, ie, expressed in a cell type where the gene is normally not expressed. A small number of the mature cells reverted back to a highly immature cell state that resembled an ES cell. This process, now called reprogramming, induced a pluripotent state in a previously differentiated cell type (figure 3). These cells are therefore called induced pluripotent cells (iPS).

The ability to induce pluripotency has changed the landscape of stem cell biology along several lines.

  • First, it indicates that the state of a given cell (ie, its level of differentiation) can be manipulated, resulting in drastic shifts in cell function. Cells have a plasticity that is far greater than previously recognized and can be programmed by specific manipulations to achieve a different cell state. A keratinocyte derived from the skin can be induced to become a pluripotent stem cell, essentially rewinding the cell’s history of the cells to revert to an embryonic-like state.
  • Second, a cell taken from an individual can be induced to become a cell type capable of forming any other cell type in that individual's body. This means, for example, that a skin or blood sample obtained from a patient with a degenerative brain disorder can be converted into a pluripotent cell. The iPS cell can then become a source for generating the neural cells affected by the disease. Thus, disease models can be generated using human cells for disorders where obtaining primary tissue, or developing reliable animal models, has been difficult.
  • Third, iPS from a given individual represents a highly personalized source of cells. While technologies to generate iPS currently involve genetic manipulation, it is anticipated that other methods will be developed to generate iPS that are genetically identical to the individual. Such cells could be used to assess 'personalized' drug therapies and may represent a source of immunologically identical cells for transplantation.

While under active development, such approaches remain far from clinical application.

CLINICAL APPLICATIONS: CELL REPLACEMENT — The paradigm for stem cells as a means of replacing injured or diseased tissue was first explored in response to the threat of nuclear warfare after World War II. Research on overcoming the effects of radiation injury led to the first demonstration of stem cells, whose existence had been hypothesized since the early twentieth century. In 1963, researchers in Toronto demonstrated that a bone marrow-derived cell could replace all the blood elements and rescue an otherwise lethally-irradiated animal by simple infusion of donor cells into the blood [9].

This demonstration quickly led to clinical testing and application. Over the ensuing twenty years, hematopoietic stem cell transplantation has become a standard means of treating individuals with hematologic malignancies as well as clinical and acquired bone marrow failure states, including radiation injury. In 1975, it was reported that cultured cells from the skin could result in the generation of large numbers of cells sufficient to provide an autologous cutaneous barrier in patients with severe burns [10]. Thus both un-manipulated stem cells from bone marrow and manipulated stem cells from skin have tremendous clinical utility in otherwise fatal settings.

In addition to treatment for hematologic disease and burns, stem cells are now used for bone grafting in orthopedics and corneal generation from limbal stem cells in ophthalmology. The presence of stem cells in other tissue types has led to the preclinical testing of stem cell therapies for other disorders, including those involving muscle and nerve tissue.

Preclinical examples using human ES cells — Human embryonic stem cells have been successfully differentiated in vitro into multiple cell types for therapeutic uses, including oligodendrocytes, pancreatic cells, cardiomyocytes, motor and dopaminergic neurons, and hematopoietic precursor cells [11]. The therapeutic potential for ES cell-derived somatic cells has been demonstrated in animal models of retinal blindness, Parkinson's disease, spinal cord injury, myocardial infarction, and type I diabetes mellitus.

Retinal disease — Human ES cell-derived retinal photoreceptors have been used to improve visual functions in blind mice [12]. Following intraocular injection, retinal cells derived from human ES migrated into the appropriate retinal layers and expressed markers of differentiated rod and cone photoreceptor cells. Subretinal transplantation of the cells into the subretinal space of mice modeling Leber's congenital amaurosis restored light responses to the animals. (See "Retinitis pigmentosa: Treatment", section on 'Retinal cell transplantation'.)

Parkinson disease — A highly enriched population of midbrain neural stem cells was derived from mouse ES cells [13]. The dopamine neurons generated by these stem cells showed electrophysiologic and behavioral properties expected of neurons from the midbrain. These ES-derived neurons survived after being transplanted into rats with symptoms of Parkinson disease, showed appropriate electrophysiological properties, and ameliorated pathologic movements in the animals. Subsequently, functional improvement was seen with use of human ES cell-derived dopaminergic neurons after transplantation in a rat model of Parkinsonism [14].

Spinal cord injury — Transplantation of human ES-derived oligodendrocyte progenitor cells into adult rats, seven days after the induction of a spinal cord injury, was shown to enhance remyelination and promote improved motor function [15]. Transplanted cells survived, redistributed over short distances, and differentiated into oligodendrocytes, demonstrating their therapeutic potential after recent spinal cord injury.

Myocardial infarction — Several studies have demonstrated that transplantation of human ES-derived cardiomyocytes improves contractile function of the infarcted mouse heart. Using a combination of pro-survival factors that limited cardiomyocyte death after transplantation, one group demonstrated decreased rates of heart failure and partial remuscularization (as evidenced by systolic thickening of the infarction wall) for animals treated with human ES-derived cardiomyocytes in comparison to control animals treated with non-cardiac human ES derivatives [16]. Similar results in another study [17] highlight the potential of human ES for myocardial cell therapy strategies. Another report, however, found that the beneficial effects were transient, stressing the importance of long-term follow-up in the assessment of therapeutic benefit in animal models [18]. (See "Genetic and cellular therapy in heart failure and myocardial infarction", section on 'Hematopoietic stem cell therapy' and "New therapies for angina pectoris", section on 'Stem cell therapy'.)

Diabetes mellitus type I — There are currently no reproducible methods for the efficient direct differentiation of human ES cells to insulin-producing beta cells, although the generation of beta cells in vitro by selecting for the expression of beta cell genes or varying growth conditions has been reported [19]. However, the physiologic ability of human ES-derived pancreatic endoderm to differentiate in vivo into glucose-responsive insulin-secreting cells in immunodeficient mice with streptozotocin-induced diabetes, ameliorating hyperglycemia in these mice, has been demonstrated [20,21].

Preclinical studies using iPS cells — The recognition that a cell taken from an individual can be induced to become pluripotent (a cell type capable of forming any other cell type in that individual's body) provides unprecedented opportunities for regenerative medicine. Easily accessible patient cell types, such as skin fibroblasts or blood cells, can be reprogrammed to iPS. These pluripotent cells are envisioned to then be differentiated into mature cells that may be deficient in diseases such as islet cells for type I diabetes, or into tissue-specific adult (stem) cells. The cells can theoretically be used for tissue regeneration in the same patient (figure 4).

In such a way, iPS cell technology could overcome two important obstacles associated with human ES cells: immune rejection after transplantation and ethical concerns regarding the use of human embryos. The approach would be particularly powerful in monogenic diseases, where ‘patient-specific’ iPS can be generated, the diseased gene in those cells potentially corrected, and the gene-corrected cells transplanted to restore organ function. This field is rapidly evolving, although there remains a great deal of research needed to make such a schema viable in the clinical setting.

Many of the studies to evaluate iPS cells as a source of cell replacement are being conducted in rodents. These studies permit testing of basic principles in a physiologic setting and are therefore useful, particularly where murine models of human diseases have been generated. Two such contexts are Parkinson disease [16] and hemophilia A [22]. In both of these settings, iPS cells were generated and used to differentiate cells that could then be transplanted for therapy.

Other technologies developed for gene therapy have also been used to test whether iPS cells can be useful to create gene corrected cells for transplantation. One proof-of-principle study used a mouse model for sickle cell disease where the hemoglobin genes of the mouse contained the mutations known to cause red cell sickling in human sickle cell anemia. Investigators generated iPS cells from skin cells of the mouse and introduced a normal hemoglobin gene allele to replace the sickle hemoglobin gene (this can be done by gene targeting technology used to engineer mouse strains for research) [23]. They then generated blood stem cells from the gene corrected iPS cells. Transplantation of these cells into sickle cell anemic mice improved the disease phenotype. This approach is a model for how iPS may be used as cell therapy in the setting of genetic disorders. If this could be applied to humans, correcting genetic disorders in iPS cells might then yield a cell type for transplantation.

This approach was extended to humans, using fibroblasts from Fanconi anemia patients that were corrected for the diseased Fanconi gene [24]. The normal (non-diseased) Fanconi gene was transferred into the fibroblast cells using a virus specifically engineered for transferring genes into cells. The gene-corrected cells were reprogrammed to pluripotency to generate patient-specific iPS cells. The iPS cells now carrying a normal Fanconi gene were tested for their ability to become blood cells in tissue culture outside the body. The cells with the normal Fanconi gene were able to generate blood cell types in a manner similar to cells from normal volunteers. This study indicated that skin cells from patients with an abnormal gene (as in the setting of Fanconi anemia) can be used to generate gene-corrected iPS cells that might serve as a source of cells for transplantation. Therefore, we are edging closer to demonstrating the feasibility of using iPS cells as therapy.

Challenges in the clinical use of stem cells as replacement — The use of stem cells to replace abnormal or missing cells is conceptually compelling. The successful use of stems cells for bone marrow and skin therapies, and the identification of stem or progenitor populations in a number of tissue types, offers great promise for expanded clinical applications. There is the additional potential that human pluripotent cells may be a source of virtually any cell type. However, several complexities must be addressed before widespread application becomes feasible.

The first issue is how transplanted cells will integrate into surrounding tissue to achieve a physiologically beneficial effect. This is of particular relevance where coordination of complex networks of cells is essential, such as in the heart and brain where aberrant circuits can result in serious adverse events. This challenge will require extensive further testing. One encouraging observation is that some cells appear to have an inherent capacity to incorporate into existing structures. An example is that, in an animal model, human endothelial cells derived from ES cells were able to organize into tubular structures and integrate into the host vasculature when inserted as dispersed cells into a host tissue [25].

A second concern is the potential for transplanted cells to form tumors. This is of particular importance when using pluripotent cells, since these are characterized by the ability to form teratomas (neoplastic tumors containing cells corresponding to all three embryonic layers) in animal models [8,26]. Thus, the differentiation state of transplanted cells will need to be defined with high precision to avoid delivery of residual pluripotent cells that may differentiate aberrantly in vivo. Evidence also suggests that this issue is not restricted to pluripotent cells. In one case, a child was given cultured fetal brain cells intrathecally and subsequently developed multiple CNS tumors of donor origin [27]. The culture process may enable the outgrowth of genetically abnormal cell types that could be of potential danger. The specifics of what types of testing will be required for pluripotent or other cells to assure genetic integrity of transplanted cells is an active area of consideration by the field.

The issue of malignant potential of cells is of greatest concern in iPS cells. The methods of greatest efficiency for reprogramming cells are currently retrovirus or lentivirus-based, and therefore run the risk of mutagenesis by virtue of viral integration into the host genome. In addition, some of the genes used to induce reprogramming have known oncogenic potential (eg, c-Myc) [28]. Progress in reducing the number of gene products needed for reprogramming, and in the use of either non-integrating viruses or small molecules to supplant retrovirus-based reprogramming, is ongoing [29-33]. These developments may mitigate the concerns about insertional mutagenesis, but will not entirely assuage concern for altered growth control of modified cells, particularly those with pluripotency.

A third concern is the ability to direct the differentiation state of the cells to be used. Generating the proper cell type from pluripotent cells remains a significant challenge for some cell types. Protocols have now been devised to create some neural cell types of clear clinical importance [34]. However, for other tissues, such as the blood, the cell types created most closely resemble embryonic blood cells and are not capable of engrafting the bone marrow without further and undesirable genetic manipulation [35].

Achieving the right stage of differentiation is another consideration in development of the stem cell derived cell therapies. It may be most desirable to generate progenitors, rather than fully mature terminally differentiated cells in some tissues so that the replaced cells do not quickly senesce and die.

Finally, the uniformity and consistency of the cell product may be difficult to achieve across different donor sources of cells.

These hurdles are not likely to be prohibitive, but each will require considerable effort and attention.

OTHER CLINICAL APPLICATIONS

Disease modifiers — Beyond use of stem cells for cell replacement, the ability of certain stem cells to alter disease without engrafting has been most extensively explored as a means of modifying cellular response to injury or aberrant immune activity. Such non-engrafting stem cells are hypothesized to provide complex signals, affecting disease outcome without directly replacing injured cells.

The identification of a population of cells in the bone marrow that could form a number of mesenchymal cell populations ex vivo led to the concept of a mesenchymal stem cell [36,37]. This population of cells is defined primarily by its ability to form colonies in tissue culture, and by the ability of single cells derived from the colonies to differentiate into osteoblasts, adipocytes or chondrocytes in vitro. Identification of these cells in the body, and understanding of how they function in vivo, remains controversial.

The potential for these mesenchymal stem cells to form muscle led to exploration of their use in the setting of ischemic injury of the heart. While initial indications suggested that the cells may directly contribute to generating cells in the area of injury, it has subsequently been shown that the cells do not engraft [38]. Rather, it is proposed that they provide complex signals, in a paracrine manner, that may alter the ability of the heart (and other tissues) to respond to ischemic injury [39,40]. This use of a stem cell population remains highly contested despite numerous clinical trials in various settings, in part because the mechanisms by which they work are not clear. The mesenchymal stem cell populations studied are highly variable and have been variably reported to secrete a number of factors including indoleamine 2, 3-dioxygenase, prostaglandins, interleukin-6, hepatocyte growth factor, inducible nitric oxide synthase, and tumor growth factor (TGF)-ß1 [41]. Which of these might participate in particular clinical settings is difficult to discern.

It has been proposed that the mesenchymal stem cell population is capable of altering immune function and may therefore modulate injury responses as in ischemia, or mitigate the effects of immune mediated diseases. As an example, mesenchymal stem cells have been tested in clinical trials in humans in settings of graft versus host disease following allogeneic hematopoietic stem cell transplantation, and in inflammatory bowel disease. For each, there has been controversy regarding the impact of the cells and the mechanism by which the cells may be acting. (See "Treatment of acute graft-versus-host disease: Clinical trials", section on 'Mesenchymal stem cells' and "Investigational therapies in the medical management of Crohn's disease", section on 'Stem cell therapy'.)

While this use of stem cell populations as disease modifying cell platforms is an area of active investigation, the concept should not be considered proven at this time. The prospect that mesenchymal cell populations may have the ability to arrive at sites of injury and provide paracrine signals is an exciting and potentially important application of stem cell biology, but it is not yet a defined therapy.

Drugs targeting endogenous stem cells — In addition to cells being introduced into the patient as therapy, there is emerging recognition that stem cells resident in adult tissues may be targeted pharmacologically. In this context, the therapeutic intervention is drug-based with the goal of altering the function of endogenous stem cells. This approach may be less likely to engender the issues related to tissue integration that are concerns with exogenously applied cells.

Growing understanding of the signaling processes that induce activation of stem cells, or modify their differentiation, makes this approach one of growing interest.

Analogous to the use of erythropoietin to modify the activity of red cell progenitors, agents with similar effects on stem cells might generate reconstitution of a broader number of cells in the case of hematopoietic stem cells, and of other mature cell types in other tissue settings.

Some studies have identified agents capable of altering stem cell activity in settings of injury to the bone marrow or the bone [42,43]. One study has identified an agent (a derivative of prostaglandin E2) that is being tested for the ability to improve stem cell regeneration of hematopoiesis in the treatment of hematologic malignancies [44].

Whether other agents can be identified that can alter the ability of stem cells to regenerate cell lines after tissue injury is to be determined.

Disease models — Stem cells offer the possibility of creating in vitro disease models that may improve molecular understanding of disease and accelerate the development of new therapies. Human cells from affected individuals with diseases affecting the nervous system, for example, have been extremely difficult to obtain for in vitro analysis except through the use of stem cell technologies. With stem cell approaches, it is now possible to generate sufficiently large numbers of cells to be able to investigate molecules involved in the functional deficits associated with the disease and to use the cells to develop high through-put drug discovery strategies.

The development of iPS cells has led to a number of efforts to create in vitro disease models amenable to genetic and small molecule study. A major goal of such efforts is to identify compounds capable of altering the progression of cell events corresponding to disease progression. These efforts depend upon robust cell culture systems that resemble the in vivo context closely enough to be useful for drug evaluation. Fulfillment of this requirement still needs validation.

Two examples depict use of iPS cells of to create a disease model for further study of human disease pathogenesis and treatment.

  • The potential of iPS cell technology to model disease pathogenesis and treatment was demonstrated by creating iPS cell lines from patients with familial dysautonomia (FD), a rare fatal sensory autonomic neuropathy caused by a point mutation in the IKBKAP gene involved in transcriptional elongation [45]. The investigators demonstrated tissue-specific missplicing of IKBKAP in purified FD-iPSC-derived lineages, suggesting a mechanism for disease specificity. Functional studies revealed marked defects in neurogenic differentiation and migration behavior, recapitulating disease characteristics. FD-iPSCs were subsequently used for validating the potency of candidate drugs to reverse aberrant splicing and ameliorate neuronal differentiation and migration. (See "Hereditary sensory autonomic neuropathies", section on 'HSAN3 (Familial dysautonomia)'.)
  • In another study, iPS cells were generated from skin fibroblasts from a child with spinal muscular atrophy [46]. These cells expanded robustly in culture, maintained the disease genotype, and generated motor neurons that showed selective deficits compared to those derived from the child's unaffected mother.

An additional application of stem cell biology to disease modeling is in the setting of cancer. In this context, the stem cell paradigm has been applied to consider cancer through the perspective of a tissue organized as a self-renewing subpopulation that generates diverse more differentiated daughter cells. The model hypothesizes that there is a definable population of malignant cells that can be demonstrated to have the two cardinal features of stem cells (self-renewal and differentiation capacity). These cells, like stem cells in normal tissues, would replace more mature cells whose lifespan is limited. They are therefore hypothesized to be the cells that enable persistence and perhaps metastasis of tumors.

The hypothesis has gained experimental support through the use of immunodeficient mice in whom human cancer cells can be engrafted [47,48]. A subset of tumor cells can be defined in these animals that is capable of engrafting the tumor, while other subsets cannot. Further, the tumor-initiating subset can be sequentially transplanted to initiate new tumors and can yield the full diversity of cells observed in the original malignancy, thereby fulfilling the experimental definition of stem cells. Human acute myelogenous leukemia, breast, colon, ovarian, pancreatic, head and neck cancer, and malignant glioma have been shown to have such a subpopulation of cells [47-53].

Whether all tumors have a stem-like cell is still controversial, and much of the definition depends upon engraftment in a mouse model, which is not necessarily a surrogate for function in humans. However, the model is beginning to have an impact on the way cancer is viewed and how oncologic drugs are developed. Studies are now investigating whether drugs affect the stem-like cells and not just tumor bulk, and whether agents can target distinctive features of the stem-like cells of cancer rather than the mixture of cells comprising a malignancy.

ETHICAL CONSIDERATIONS — The first derivation of human embryonic stem and embryonic germ cells in 1998 sparked enormous interest and controversy regarding pluripotent stem cells. The initial, and still most frequent, techniques used to derive ES cells disrupt the blastocyst from which the cells are derived, raising concern that an early human life form was being destroyed. The source of the blastocyst was generally discarded material from in vitro fertilization clinics. Nonetheless, for many the issue of using the material for research, even if that research was intended to assuage human suffering, was morally unacceptable. These controversies led to policy decisions among some nations that precluded ES cell research or, as in the case of the United States, federal funding to support such research.

The advent of reprogramming to generate iPS has provided an alternative source of pluripotent cells that has satisfied the concerns of many. It should be recognized that iPS have not yet been shown to be fully equivalent to ES cells, and ES cells still represent the best defined pluripotent cell population. However, iPS cells are increasingly the focus of research and appear to engender less ethical concern since they do not involve the use of blastocysts or embryonic tissue. The cells from animals do have the ability to contribute to a developing organism though, so other ethical concerns are not entirely mitigated.

An issue that is relevant for both pluripotent and other stem cells is how to define safety when proceeding to clinical trial. The area of cell therapies has been well explored in hematology, transfusion medicine, and hematopoietic stem cell transplant. Infusion of other cultured cell products has a well-defined safety profile for keratinocyte skin grafts and mesenchymal stem cell transplants. Several features are unique to the use of pluripotent cells, however:

  • Concern regarding the placement of cells in tissues highly intolerant of aberrant growth control such as the central nervous system and heart.
  • Defining the genetic integrity of manipulated cells can be extremely difficult, though may be resolvable through emerging genomic technologies.
  • Whether the cells have tumorigenic potential is hard to define since even established cancers can be difficult to grow with functional in vitro or in vivo assays.
  • Defining the potential to integrate as functional tissue requires in vivo settings, and animal models have only limited ability to predict events in humans.

Therefore, clinical experience will be necessary to define some of the risks in stem cell-based therapeutics, and careful design of clinical trials with a range of parameters specific to the field are in process.

Stem cells have enormous potential that is well recognized by the public, and are a source of hope for those dealing with otherwise untreatable medical problems. However, the field is in its infancy and progress is painstaking; for those desperate to get help, unproven therapies even outside of reputable centers or clinical trial are a highly tempting option. The potential for patient exploitation raises another extremely challenging area. There has been a profusion of centers in many parts of the world, often offering treatment without clear definition of what cells would be used, what the source of cells is, and what the full experience has been. Services are often offered for cash payment and with unclear provisions to monitor safety or respond to adverse events. Patients and providers should ask a range of specific questions about such therapies. The International Society for Stem Cell Research (ISSCR) has provided such suggested questions and other information that may be of use (www.isscr.org).

SUMMARY AND RECOMMENDATIONS

  • Stem cells are those cells that have the capability of self-renewal and differentiation. Stem cells are classified based on the type of differentiated cell they can reproduce. Pluripotent stem cells can make all cells of the embryo, including germ cells and cells derived from ectodermal, mesodermal and endodermal germ cell lines. (See 'Types of stem cells' above.)
  • Embryonic stem cells are typically derived from the preimplantation blastocyst (7 to 10 days before fertilization). Adult stem cells typically derive from tissue formed beyond 10 to 14 days post fertilization, and are called “somatic” stem cells when derived from non-germ cell tissue. It is unclear whether adult stem cells are present in all tissues, such as pancreatic islet cells. (See 'Sources of stem cells' above.)
  • Since 2006, it has been possible to create induced pluripotent stem cells by “reprogramming,” a process that involves gene transplantation into mature cells, with reversion to a pluripotent state. Induced pluripotent stem (iPS) cells provide the potential to create a specific tissue in tissue culture derived from an entirely other somatic cell. The potential for therapeutic use is great, although the need for genetic manipulation in the process limits the transference clinical application at the present time. (See 'Induced pluripotent stem cells (iPS)' above.)
  • Stem cells present current and future opportunities for several different clinical applications. Hematopoietic stem cell replacement is currently a robust intervention for a number of hematologic conditions. Burn therapy, bone grafting and corneal transplant tissues are examples of other current uses of stem cell generated tissue. Tissue replacement treatment for other conditions (retinal disease, Parkinson disease, myocardial infarction) is in development. Concerns about the technology include integrating the transplanted cells into complex cell networks, oncogenesis of the transplant material, and the ability to generate the correct target cell types in the right stage of differentiation. (See 'Clinical applications: cell replacement' above.)
  • Stem cell transplantation may have the ability to modify diseased tissue in a paracrine fashion, without actual engraftment. Drugs directed at endogenous tissue stem cells may modify tissue response to injury. Finally, stem cells may generate tissue to be used as laboratory models for the study of diseases where obtaining live tissue is otherwise difficult or not possible. (See 'Other clinical applications' above.)
  • Ethical concerns have been raised regarding stem cell research. The use of induced pluripotent cells may mitigate concerns about disruption of embryos, but several other concerns remain to be addressed. (See 'Ethical considerations' above.)
Use of UpToDate is subject to the Subscription and License Agreement.
REFERENCES
  1. Morrison SJ, Kimble J. Asymmetric and symmetric stem-cell divisions in development and cancer. Nature 2006; 441:1068.
  2. Tajbakhsh S, Rocheteau P, Le Roux I. Asymmetric cell divisions and asymmetric cell fates. Annu Rev Cell Dev Biol 2009; 25:671.
  3. Gong JK. Endosteal marrow: a rich source of hematopoietic stem cells. Science 1978; 199:1443.
  4. Tumbar T, Guasch G, Greco V, et al. Defining the epithelial stem cell niche in skin. Science 2004; 303:359.
  5. Barker N, van Es JH, Kuipers J, et al. Identification of stem cells in small intestine and colon by marker gene Lgr5. Nature 2007; 449:1003.
  6. Montarras D, Morgan J, Collins C, et al. Direct isolation of satellite cells for skeletal muscle regeneration. Science 2005; 309:2064.
  7. Reynolds BA, Weiss S. Generation of neurons and astrocytes from isolated cells of the adult mammalian central nervous system. Science 1992; 255:1707.
  8. Takahashi K, Yamanaka S. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 2006; 126:663.
  9. BECKER AJ, McCULLOCH EA, TILL JE. Cytological demonstration of the clonal nature of spleen colonies derived from transplanted mouse marrow cells. Nature 1963; 197:452.
  10. Rheinwald JG, Green H. Formation of a keratinizing epithelium in culture by a cloned cell line derived from a teratoma. Cell 1975; 6:317.
  11. Murry CE, Keller G. Differentiation of embryonic stem cells to clinically relevant populations: lessons from embryonic development. Cell 2008; 132:661.
  12. Lamba DA, Gust J, Reh TA. Transplantation of human embryonic stem cell-derived photoreceptors restores some visual function in Crx-deficient mice. Cell Stem Cell 2009; 4:73.
  13. Kim JH, Auerbach JM, Rodríguez-Gómez JA, et al. Dopamine neurons derived from embryonic stem cells function in an animal model of Parkinson's disease. Nature 2002; 418:50.
  14. Yang D, Zhang ZJ, Oldenburg M, et al. Human embryonic stem cell-derived dopaminergic neurons reverse functional deficit in parkinsonian rats. Stem Cells 2008; 26:55.
  15. Keirstead HS, Nistor G, Bernal G, et al. Human embryonic stem cell-derived oligodendrocyte progenitor cell transplants remyelinate and restore locomotion after spinal cord injury. J Neurosci 2005; 25:4694.
  16. Laflamme MA, Chen KY, Naumova AV, et al. Cardiomyocytes derived from human embryonic stem cells in pro-survival factors enhance function of infarcted rat hearts. Nat Biotechnol 2007; 25:1015.
  17. Caspi O, Huber I, Kehat I, et al. Transplantation of human embryonic stem cell-derived cardiomyocytes improves myocardial performance in infarcted rat hearts. J Am Coll Cardiol 2007; 50:1884.
  18. van Laake LW, Passier R, Monshouwer-Kloots J, et al. Human embryonic stem cell-derived cardiomyocytes survive and mature in the mouse heart and transiently improve function after myocardial infarction. Stem Cell Res 2007; 1:9.
  19. Borowiak M, Melton DA. How to make beta cells? Curr Opin Cell Biol 2009; 21:727.
  20. Shim JH, Kim SE, Woo DH, et al. Directed differentiation of human embryonic stem cells towards a pancreatic cell fate. Diabetologia 2007; 50:1228.
  21. Jiang J, Au M, Lu K, et al. Generation of insulin-producing islet-like clusters from human embryonic stem cells. Stem Cells 2007; 25:1940.
  22. Xu D, Alipio Z, Fink LM, et al. Phenotypic correction of murine hemophilia A using an iPS cell-based therapy. Proc Natl Acad Sci U S A 2009; 106:808.
  23. Hanna J, Wernig M, Markoulaki S, et al. Treatment of sickle cell anemia mouse model with iPS cells generated from autologous skin. Science 2007; 318:1920.
  24. Raya A, Rodríguez-Pizà I, Guenechea G, et al. Disease-corrected haematopoietic progenitors from Fanconi anaemia induced pluripotent stem cells. Nature 2009; 460:53.
  25. Wang ZZ, Au P, Chen T, et al. Endothelial cells derived from human embryonic stem cells form durable blood vessels in vivo. Nat Biotechnol 2007; 25:317.
  26. Thomson JA, Itskovitz-Eldor J, Shapiro SS, et al. Embryonic stem cell lines derived from human blastocysts. Science 1998; 282:1145.
  27. Amariglio N, Hirshberg A, Scheithauer BW, et al. Donor-derived brain tumor following neural stem cell transplantation in an ataxia telangiectasia patient. PLoS Med 2009; 6:e1000029.
  28. Okita K, Ichisaka T, Yamanaka S. Generation of germline-competent induced pluripotent stem cells. Nature 2007; 448:313.
  29. Stadtfeld M, Nagaya M, Utikal J, et al. Induced pluripotent stem cells generated without viral integration. Science 2008; 322:945.
  30. Okita K, Nakagawa M, Hyenjong H, et al. Generation of mouse induced pluripotent stem cells without viral vectors. Science 2008; 322:949.
  31. Zhou H, Wu S, Joo JY, et al. Generation of induced pluripotent stem cells using recombinant proteins. Cell Stem Cell 2009; 4:381.
  32. Yu J, Hu K, Smuga-Otto K, et al. Human induced pluripotent stem cells free of vector and transgene sequences. Science 2009; 324:797.
  33. Huangfu D, Osafune K, Maehr R, et al. Induction of pluripotent stem cells from primary human fibroblasts with only Oct4 and Sox2. Nat Biotechnol 2008; 26:1269.
  34. Dimos JT, Rodolfa KT, Niakan KK, et al. Induced pluripotent stem cells generated from patients with ALS can be differentiated into motor neurons. Science 2008; 321:1218.
  35. Kyba M, Perlingeiro RC, Daley GQ. HoxB4 confers definitive lymphoid-myeloid engraftment potential on embryonic stem cell and yolk sac hematopoietic progenitors. Cell 2002; 109:29.
  36. Friedenstein AJ, Petrakova KV, Kurolesova AI, Frolova GP. Heterotopic of bone marrow. Analysis of precursor cells for osteogenic and hematopoietic tissues. Transplantation 1968; 6:230.
  37. Pittenger MF, Mackay AM, Beck SC, et al. Multilineage potential of adult human mesenchymal stem cells. Science 1999; 284:143.
  38. Iso Y, Spees JL, Serrano C, et al. Multipotent human stromal cells improve cardiac function after myocardial infarction in mice without long-term engraftment. Biochem Biophys Res Commun 2007; 354:700.
  39. Uccelli A, Moretta L, Pistoia V. Mesenchymal stem cells in health and disease. Nat Rev Immunol 2008; 8:726.
  40. Burt RK, Loh Y, Pearce W, et al. Clinical applications of blood-derived and marrow-derived stem cells for nonmalignant diseases. JAMA 2008; 299:925.
  41. Phinney DG, Prockop DJ. Concise review: mesenchymal stem/multipotent stromal cells: the state of transdifferentiation and modes of tissue repair--current views. Stem Cells 2007; 25:2896.
  42. Adams GB, Martin RP, Alley IR, et al. Therapeutic targeting of a stem cell niche. Nat Biotechnol 2007; 25:238.
  43. Mukherjee S, Raje N, Schoonmaker JA, et al. Pharmacologic targeting of a stem/progenitor population in vivo is associated with enhanced bone regeneration in mice. J Clin Invest 2008; 118:491.
  44. North TE, Goessling W, Walkley CR, et al. Prostaglandin E2 regulates vertebrate haematopoietic stem cell homeostasis. Nature 2007; 447:1007.
  45. Lee G, Papapetrou EP, Kim H, et al. Modelling pathogenesis and treatment of familial dysautonomia using patient-specific iPSCs. Nature 2009; 461:402.
  46. Ebert AD, Yu J, Rose FF Jr, et al. Induced pluripotent stem cells from a spinal muscular atrophy patient. Nature 2009; 457:277.
  47. Lapidot T, Sirard C, Vormoor J, et al. A cell initiating human acute myeloid leukaemia after transplantation into SCID mice. Nature 1994; 367:645.
  48. Al-Hajj M, Wicha MS, Benito-Hernandez A, et al. Prospective identification of tumorigenic breast cancer cells. Proc Natl Acad Sci U S A 2003; 100:3983.
  49. O'Brien CA, Pollett A, Gallinger S, Dick JE. A human colon cancer cell capable of initiating tumour growth in immunodeficient mice. Nature 2007; 445:106.
  50. Zhang S, Balch C, Chan MW, et al. Identification and characterization of ovarian cancer-initiating cells from primary human tumors. Cancer Res 2008; 68:4311.
  51. Hermann PC, Huber SL, Herrler T, et al. Distinct populations of cancer stem cells determine tumor growth and metastatic activity in human pancreatic cancer. Cell Stem Cell 2007; 1:313.
  52. Prince ME, Sivanandan R, Kaczorowski A, et al. Identific
Cliente: escribió hace 4 año.
ok doctor lo voy hacer traducir, le comento que el de china me pasaron un presupuesto de 18000 dolares y el de mexico 23000 dolares y cuando pueda me da su mail particular asi le paso el presupuesto con la descripcion de los procesos. atte
Experto:  Pablo Rodríguez escribió hace 4 año.
Mi opinión es que es un engaño y que quieren estafarle. Hay empresas que utilizan la desesperación de los pacientes en su beneficio económico.

La veracidad de la información médica es proporcional a las referencias y estudios, yo le he aportado 52 estudios médicos que son ensayos clínicos bien hechos, formales y valorables. En esas páginas hay "opiniones" de algunos individuos.

Lo lamento profundamente pero la terapia con células madre no tiene aplicación en humanos probada en el momento actual para los problemas de retina, está en fase experimental.

Entiendo su situación pero mi obligación es darle información veraz aunque a veces eso me suponga una valoración "neutral" o "negativa" , si ve mi perfil verá que tengo opiniones negativas.. pero es porque le digo a la gente la verdad no "lo que quiere escuchar".

Reciba un cordial saludo y le deseo lo mejor :)

JustAnswer en los medios:

 
 
 
Sitios web de consulta médica: Si tiene una pregunta urgente puede intentar obtener una respuesta de sitios que afirman disponer de distintos especialistas listos para proporcionar respuestas rápidas... Justanswer.com.
JustAnswer.com...ha visto como desde octubre se ha disparado el número de consultas legales de nuestros lectores sobre despidos, desempleo e indemnizaciones por cese.
Los sitios web como justanswer.com/legal
...no dejan nada al azar.
El tráfico en JustAnswer ha aumentado un 14 por ciento...y hemos recibido 400.000 visitas en 30 días...las preguntas relacionadas con el estrés, la presión alta, la bebida y los dolores cardíacos han aumentado un 33 por ciento.
Tory Johnson, colaboradora de GMA sobre temas relacionados con el lugar de trabajo, habla sobre el "teletrabajo", como JustAnswer, en el que expertos verificados responden a las preguntas de las personas.
Le diré que... las pruebas que hay que superar para llegar a ser un experto son muy rigurosas.
 
 
 

Opiniones de nuestros clientes:

 
 
 
  • Muchísimas gracias a sus psicólogos. Me ayudaron mucho con sus respuestas. Yunuen Abshagen Richardson, EEUU
  • Muchísimas gracias a sus psicólogos. Me ayudaron mucho con sus respuestas. Yunuen Abshagen Richardson, EEUU
  • Sus respuestas han generado tranquilidad en mí y en mi familia. Muchas gracias. Robert W. Dempster Villa del Mar, Chile
  • Me siento mucho mejor y he notado una verdadera empatía con mi caso. Doris Garrido Quito, Ecuador
  • Resolvió mi duda y quedé tranquila de que lo que apliqué a mi familiar es lo correcto. Manuel Alegre Madrid, España.
  • Me siento satisfecha y más orientada con estas respuestas, pienso ir al especialista cuanto antes.... Martínez Buenos Aires, Argentina
  • El tiempo de respuesta es excepcional, de menos de 6 minutos. La pregunta se respondió con profesionalidad y con un alto grado de compasión. Inés Santander
  • Quedé muy satisfecho con la rapidez y la calidad de los consejos que recibí. Me gustaría añadir que puse en práctica los consejos y que funcionaron la primera vez y siguen haciéndolo. Luis Málaga
 
 
 

Conozca a los expertos:

 
 
 
  • Dr. Maldonado

    Dr. Maldonado

    Médico

    Clientes satisfechos:

    6210
    Especialista en medicina familiar. Mas de 12 años de experiencia. Tutor de residentes.
  • http://ww2.justanswer.com/uploads/IS/ismaelmd/2011-4-27_175820_lafoto.64x64.JPG Avatar de Dr. Maldonado

    Dr. Maldonado

    Médico

    Clientes satisfechos:

    6210
    Especialista en medicina familiar. Mas de 12 años de experiencia. Tutor de residentes.
  • http://ww2.justanswer.com/uploads/AG/AGUEDA2011/2011-2-26_1305_CongresoSevillaMarzo2008019.64x64.jpg Avatar de AGUEDA2011

    AGUEDA2011

    Médico.

    Clientes satisfechos:

    801
    Licenciada en Medicina y Cirugía con la Especialidad en Ginecología y Obstetricia.
  • http://ww2.justanswer.com/uploads/TU/tuurologo/2011-4-17_212323_Dr.E.A..64x64.jpg Avatar de Enrique Artozqui

    Enrique Artozqui

    Médico

    Clientes satisfechos:

    300
    Licenciado en Medicina y Cirugía.Especialista en Endocrinología y Nutrición.Especialista en Urología.
  • http://ww2.justanswer.com/uploads/DS/dspalma/2012-10-18_23912_facebook14920836141.64x64.jpg Avatar de Dra. Debora Palma

    Dra. Debora Palma

    Postdoctorado

    Clientes satisfechos:

    201
    doctora en medicina con especialidad en cirugia general
  • http://ww2.justanswer.com/uploads/JU/juancarlosvillanueva/2013-3-7_9363_Dr.JCVillanueva.64x64.JPG Avatar de juancarlosvillanueva

    juancarlosvillanueva

    Médico

    Clientes satisfechos:

    56
    Licenciado en Medicina y Cirugía Universidad de Valencia año 1983
  • http://ww2.justanswer.com/uploads/PA/pablo.rdt/2013-3-14_17142_IMG0614.64x64.JPG Avatar de Pablo Rodríguez

    Pablo Rodríguez

    Licenciatura

    Clientes satisfechos:

    11179
    Médico adjunto de Servicio de Urgencias Hospitalarias. Consulta de Medicina Familiar y Comunitaria
  • http://ww2.justanswer.com/uploads/DR/drgamboa/2015-4-8_1861_foto.64x64.jpg Avatar de Dr. Jorge Gamboa

    Dr. Jorge Gamboa

    Especialidad Medicina Integrada

    Clientes satisfechos:

    1106
    Especialista en Enfermedades Crónicas de los Adultos
 
 
 

Preguntas relacionadas con Medicina