Claudio Bordignon

For decades, transplantation of haematopoietic stem cells — either unmodified, or genetically modified to correct genetic disorders — has been used to treat disorders of the blood and immune systems. The present challenge is to reduce the risk of such transplants and increase the number of patients who can safely access this treatment. In developing countries, such 'one-shot' treatments are highly desirable because chronic treatments are difficult to sustain. To make these therapies more accessible and effective it will be important to improve clinical protocols and gene-delivery vectors, and to gain a deeper understanding of stem cells.

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Posted by Arran Frood at 06:28 PM | Permalink | Comments (1) | TrackBacks (0)

Deepak Srivastava and Kathryn N. Ivey

The use of stem cells to generate replacement cells for damaged heart muscle, valves, vessels and conduction cells holds great potential. Recent identification of multipotent progenitor cells in the heart and improved understanding of developmental processes relevant to pluripotent embryonic stem cells may facilitate the generation of specific types of cell that can be used to treat human heart disease. Secreted factors from circulating progenitor cells that localize to sites of damage may also be useful for tissue protection or neovascularization. The exciting discoveries in basic science will require rigorous testing in animal models to determine those most worthy of future clinical trials.

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Posted by Arran Frood at 06:26 PM | Permalink | Comments (2) | TrackBacks (0)

Olle Lindvall and Zaal Kokaia

Many common neurological disorders, such as Parkinson's disease, stroke and multiple sclerosis, are caused by a loss of neurons and glial cells. In recent years, neurons and glia have been generated successfully from stem cells in culture, fuelling efforts to develop stem-cell-based transplantation therapies for human patients. More recently, efforts have been extended to stimulating the formation and preventing the death of neurons and glial cells produced by endogenous stem cells within the adult central nervous system. The next step is to translate these exciting advances from the laboratory into clinically useful therapies.

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Posted by Arran Frood at 06:25 PM | Permalink | Comments (0) | TrackBacks (0)

Alysson R. Muotri and Fred H. Gage

The production of specialized differentiated neurons derived from stem cells has been proposed as a revolutionary technology for regenerative medicine. However, few examples of specific neuronal cell differentiation have been described so far. Although stem-cell tissue replacement might be seemingly straightforward in other cases, the high degree of complexity of the nervous system raises the challenge of tissue replacement substantially. Understanding mechanisms of neuronal diversification will not only be relevant for therapeutic purposes but might also shed light on the differences in cognitive abilities, personality traits and psychiatric conditions observed in humans.

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Thomas A. Rando

Adult stem cells reside in most mammalian tissues, but the extent to which they contribute to normal homeostasis and repair varies widely. There is an overall decline in tissue regenerative potential with age, and the question arises as to whether this is due to the intrinsic ageing of stem cells or, rather, to the impairment of stem-cell function in the aged tissue environment. Unravelling these distinct contributions to the aged phenotype will be critical to the success of any therapeutic application of stem cells in the emerging field of regenerative medicine with respect to tissue injury, degenerative diseases or normal functional declines that accompany ageing.

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Posted by Arran Frood at 06:21 PM | Permalink | Comments (2) | TrackBacks (0)

David T. Scadden

Stem-cell populations are established in 'niches' — specific anatomic locations that regulate how they participate in tissue generation, maintenance and repair. The niche saves stem cells from depletion, while protecting the host from over-exuberant stem-cell proliferation. It constitutes a basic unit of tissue physiology, integrating signals that mediate the balanced response of stem cells to the needs of organisms. Yet the niche may also induce pathologies by imposing aberrant function on stem cells or other targets. The interplay between stem cells and their niche creates the dynamic system necessary for sustaining tissues, and for the ultimate design of stem-cell therapeutics.

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Sean J. Morrison and Judith Kimble

Much has been made of the idea that asymmetric cell division is a defining characteristic of stem cells that enables them to simultaneously perpetuate themselves (self-renew) and generate differentiated progeny. Yet many stem cells can divide symmetrically, particularly when they are expanding in number during development or after injury. Thus, asymmetric division is not necessary for stem-cell identity but rather is a tool that stem cells can use to maintain appropriate numbers of progeny. The facultative use of symmetric or asymmetric divisions by stem cells may be a key adaptation that is crucial for adult regenerative capacity.

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Austin Smith

Stem-cell biology is in a phase of dynamic expansion and is forming connections with a broad range of basic and applied disciplines. The field is simultaneously exposed to public and political scrutiny. A common language in the stem-cell community is an important tool for coherent exposition to these diverse audiences, not least because certain terms in the stem-cell vocabulary are used differently in other fields.

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Natalie DeWitt

More than 30 years ago, neurologist Oliver Sacks wrote of the Parkinson's drug l-dopa: "It is impossible to avoid the feeling that here, over and above all legitimate enthusiasms, there is this special enthusiasm, this mysticism, of a magical sort."

It is striking how aptly these words describe the current enchantment with stem cells. Now, 25 years after scientists first isolated mouse embryonic stem cells, it is possible to isolate and culture stem cells from embryos and adult tissues of many species, including humans.

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Posted by Arran Frood at 06:04 PM | Permalink | Comments (0) | TrackBacks (0)

Konrad Hochedlinger and Rudolf Jaenisch

The cloning of mammals from differentiated donor cells has refuted the old dogma that development is an irreversible process. It has demonstrated that the oocyte can reprogramme an adult nucleus into an embryonic state that can direct development of a new organism. The prospect of deriving patient-specific embryonic stem cells by nuclear transfer underscores the potential use of this technology in regenerative medicine. The future challenge will be to study alternatives to nuclear transfer in order to recapitulate reprogramming in a Petri dish without the use of oocytes.

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