Tendon ageing is a complicated process caused by multifaceted pathways and ageing plays a critical role in the occurrence and severity of tendon injury. The role of tendon stem/progenitor cells (TSPCs) in tendon maintenance and regeneration has received increasing attention in recent years. The decreased capacity of TSPCs in seniors contributes to impaired tendon functions and raises questions as to what extent these cells either affect, or cause ageing, and whether these age-related cellular alterations are caused by intrinsic factors or the cellular environment. In this review, recent discoveries concerning the biological characteristics of TSPCs and age-related changes in TSPCs, including the effects of cellular epigenetic alterations and the mechanisms involved in the ageing process, are analyzed. During the ageing process, TSPCs ageing might occur as a natural part of the tendon ageing, but could also result from decreased levels of growth factor, hormone deficits and changes in other related factors. Here, we discuss methods that might induce the rejuvenation of TSPC functions that are impaired during ageing, including moderate exercise, cell extracellular matrix condition, growth factors and hormones; these methods aim to rejuvenate the features of youthfulness with the ultimate goal of improving human health during ageing.

Stress urinary incontinence (SUI) is an age health-related issue that generates interest due to its considerable public health burden and the controversies surrounding treatment. It is highly prevalent affecting 30-40% of all women during their lifetime. Midurethral slings are the standard of gold standard treatment for female patients with SUI. They have excellent short-term cure rates; however, their efficacy tends to decrease over time and patients often report urinary incontinence recurrence. This paper addresses the applicability of regenerative medicine and tissue engineering for the treatment of SUI in female patients. Cell-based treatment with periurethral injection of autologous adipose or muscle-derived stem cells have been used for SUI; however, the cure rates and SUI recurrence at 1 year were 40% and 70%, respectively. Novel minimally invasive approaches, such as low-intensity extracorporeal shock wave therapies have shown promising results in SUI animal models. In addition, local injection of growth factors, chemokines, and specific antibodies have shown histological evidence of neoangiogenesis, nerve, and sphincter regeneration in rodents and nonhuman primates with SUI. The use of bioactive factors and proteins secreted by cells, which is called secretomes, have been recognized as key regulators of various mechanisms, such as immunomodulation, angiogenesis, inflammation, apoptosis, and tissue repair. Emerging therapies aiming to replace or restore tissues and organ functionality may improve the long-term efficacy and in the near future may represent the standard of care for the treatment of SUI.

In slightly more than a decade of stem cell plasticity research, 24 peer-reviewed articles have demonstrated plasticity across organ and/or embryonic lineage boundaries at the single-cell level, with only 1 article showing negative results. These data, taken together with data about reversibility of gene restrictions that have also accumulated during the same period, indicate that postnatal cells, even "terminally differentiated" ones, have a degree of plasticity not appreciated previously. This review looks back at the four known pathways of cell plasticity and at previously described "plasticity principles" of Genomic Completeness, Cellular Uncertainty, Stochasticity of Cell Origin and Fate, relating these to issues of experimental design and discourse that are key to understanding and evaluating plasticity data. Although the physiologic roles played by such plasticity may still be debated, the manipulations of these phenomena for therapeutic or industrial purposes should finally be considered ripe for exploration. For the future, plasticity, indeed all stem cell biology, must be considered as part of a larger web of cell-to-cell and cell-to-matrix interactions that function fully only at the tissue level; thus, the success of stem cell biology necessarily must involve assembling data from cell and molecular biology research into systems of interactions that might be reasonably called "tissue biology." Interdisciplinary collaborations with complexity and chaos theorists, using mathematical/computer modeling of cell behaviors, will be vital to fully exploring stem cell behaviors in the coming decades.

Stem cells were elected 'Breakthrough of the Year' by Science(1) magazine in 1999, having shown that stem cells from adult tissues retained the ability to differentiate into other tissue types. During the previous year, the first human embryo stem cell lines were established. Since then, the number of scientific papers on stem cells has been increasing exponentially, establishing new paradigms that are rapidly challenged by subsequent experiments. This paper reviews the stem cell research field, divided into two groups: embryo and adult stem cells. While the differentiation potential of the former is well characterized in mice and humans, their use in cell therapy and research has been hampered by histocompatibility, safety and ethical issues. In contrast, adult stem cells do not present these problems. However, the extent of their plasticity is still under investigation. Nevertheless, numerous clinical trials in humans are under way, mainly with stem cells derived from bone marrow. This paper discusses discuss the importance of working with both classes of human stem cells in order to fulfill the promise of stem cell therapies.

Biomaterial research and tissue engineering are rapidly growing scientific fields that need an interdisciplinary approach where clinicians should be included from the onset. Biocompatibility testing in vitro and in vivo comprise the agarose-overlay test, the MTT test, direct cell seeding tests and the chorioallantoic membrane test for angiogenic effects, among others. Molecular biology techniques such as real-time polymerase chain reaction and microarray technology facilitate the investigation of tissue integration into biomaterials on a cellular and molecular level. The physicochemical characterization of biomaterials is conducted using such methods as X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Excellent biocompatibility and biofunctionality were demonstrated for a series of recently developed multifunctional biodegradable, polymeric biomaterials both in vitro and in vivo. Novel, multifunctional polymeric biomaterials offer a highly specific adjustment to the physiological, anatomical and surgical requirements and can thereby facilitate new therapeutic options in head and neck surgery.

The Juvenile Diabetes Research Foundation International (JDRF) was founded in 1970 by parents of children with juvenile diabetes to find a cure for diabetes and its complications through the support of research. The foundation was an early supporter of stem cell research, recognizing the promise of stem cells to quicken the pace of discovery for a cure for juvenile diabetes. The JDRF has committed considerable resources to supporting stem cell research in both the United States and abroad. In the United States, the organization has been an advocate on the state and national level for increased funding and for expansion of current federal policy restricting embryonic stem (ES) cell research.

Anti-aging is a recent medical discipline and discussed rather controversially. Yet it is frequently misunderstood, not only because it is repeatedly misrepresented by the media but also because it is often practiced by laypersons without any profound knowledge about the subject matter. Moreover, most of the time it is practiced without any objective scientific basis; and this is the reason why anti-aging is being discredited. The intention of this review is to clarify and thus de-mystify the subject. Anti-aging medicine is a complex matter, hence my aim is to further understanding of the different factors and their interplay and thus to create greater interest in this exciting medical discipline.

Dermal multipotent cells (DMCs) with the capacity to differentiate to osteocytes, chondrocytes, adipocytes and neurons were isolated from the dermis of newborn Wistar rats by their adherence to culture plastic dishes. After labeling with a fluorescent nuclear marker, 4',6-diamidino-2-phenylindole, neonatal DMCs were implanted into minced skin. The labeled cells were found in the regenerative skin 2 weeks after implantation. Topical transplantation of DMC suspension on full-thickness excision wounds made on the back of female rats enhanced the initial rate of contraction. Wound fluid collected using polyvinyl alcohol sponges from the incisions on the dorsa of adult rats on day 3 postwounding was used in the experiments. A methylthiazolyldiphenyl tetrazolium bromide assay showed that wound fluid with concentrations from 5 to 30% induced an increase in the number of cultured DMCs. The wound model of a monolayer of cells indicated that 10% wound fluid accelerated the migration rate of DMCs to fill in defects made in the layer of cultured cells. A colorimetric analysis also indicated that 10% wound fluid increased the hydroxyproline content in cultured cells. In conclusion, DMCs have been isolated from newborn rat dermis by their adherence to culture plastic dishes, and acute wound environment in the early stage promotes the viability, migration and collagen synthesis of these cells.

Our previous study indicated that dermal multipotent cells with the differentiation capacity to form cells with the phenotypic properties of osteocytes, adipocytes, chondrocytes, and neurons in specific inducing media could be isolated from the enzymatically dissociated dermal cells of newborn rats by their adherence to culture dish plastic. We have also observed that the systemic transplantation of dermal multipotent cells could not repopulate the hematopoietic system in lethally irradiated rats. In this paper, we found that a transplantation of plastic-adherent dermal multipotent cells into sublethally irradiated rats led to a significant increase of white blood cells in peripheral blood, nucleated cells, CFU-GM, and CFU-F colonies in bone marrow. FISH analysis, using a Y-chromosome specific probe, showed that dermal multipotent cells could engraft into bone marrow in recipients. Flow cytometry (FACS) analysis also showed that the proportion of CD2 and CD25 positive lymphocytes in peripheral blood did not change significantly in two weeks after transplantation. By these results, we infer that dermal multipotent cells may represent an alternative origin of mesenchymal stem cells to restore marrow microenvironment and promote the survival, engraftment, and proliferation of hematopoietic cells.

The degree to which these elephants are disruptive to the steady advancement of the adult stem cell field will become clear with time. In some ways they enliven the discourse, but in many ways they interfere with efficient progress. Naming these elephants is a first step toward dealing with them. If we remain aware of these issues when evaluating new research, we are less likely to make careless mistakes, and we are more likely to be able to hold scientists, politicians, journalists, and entrepreneurs accountable for their practices. Although all adult stem cell researchers will spend time profitably riding some of these elephants, we will all inevitably spend more time cleaning up after them. Perhaps open, careful, and unbiased discussions of these elephants will help the cleanup work be less odious and completed sooner, rather than later.

Somatic stem cells are undifferentiated cells with a high capacity for self-renewal that can give rise to one or more specialized cell types with specific functions in the body. Profound characterization of these cells has been difficult due to the fact that their frequency in different tissues of the body is extremely low; furthermore, their identification is not based on their morphology but on immunophenotypic and functional assays. Nevertheless, significant advances in the study of these cells at both cellular and molecular levels have been achieved during the last decade. The majority of what we know concerning somatic stem cell biology has come from work on hematopoietic stem cells. More recently, however, there has been a great amount of information on neural and epithelial stem cells. The importance of stem cell research has gone beyond basic biology and is currently contributing to the development of new medical approaches for treatment of hematologic, neurologic, autoimmune, and metabolic disorders (cellular therapy).

The article compares policymaking in the field of human embryonic stem cell research in the United States and Germany. Although experimental research with human stem cells is controversial in both countries, restrictions on research are much more strict in Germany than in the United States. In order to explain the contrast between the United States and Germany in dealing with human embryonic stem cell research and to predict possible future developments, we need to look carefully at a number of important differences in the interpretations and discourses of embryonic stem cell research and their consequences for the strategies of institutions and actors in the political-regulatory realm.

Recently, concepts for the transplantation of hematopoietic stem cells have changed dramatically. High-dose myeloablative conditioning regimens are in the process of being replaced by immuno-suppressive regimens, ablating host myelopoiesis, and neoplastic cells by the co-transplanted donor lymphocytes. Furthermore, the presence of stem cells in the bone marrow, capable of differentiating into a variety of nonhematopoietic tissues as well as the presence of cells in other organs, capable of differentiating into hematopoietic cells, has led to the novel concept of the plasticity of stem cells derived from different tissues. It is anticipated that these remarkable studies will also lead to novel therapeutic strategies.

The signals that instruct neural stem cells to differentiate into glia have long proved elusive. Surprising new evidence suggests that this role could be fulfilled by Notch signalling, previously thought to be a general inhibitor of stem cell differentiation.

Proposed National Institutes of Health guidelines for stem cell research are too narrowly drawn and do not adequately protect the freedom of choice and health of women who donate embryos. They need to be expanded to cover not only the point of embryo donation, but also that of embryo creation. Guidelines are provided to ensure that donors undergoing hyperstimulation and egg retrieval gave voluntary informed consent to the production of embryos that might later prove in excess. A standard for determining when embryos have been overproduced is presented to address the possibility that additional embryos will be created for stem cell research in violation of the guidelines and at risk to women's health.

This article addresses two questions: 1) how to understand "respect for embryos," and 2) whether the distinction between surplus embryos from in vitro fertilization and embryos created for research purposes has validity. I caution against confusing respect for embryos as a form of human life with the respect that persons, as autonomous agents, deserve. I also argue that there is no moral difference between research that uses spare embryos and research that uses embryos created for that purpose. The value of the research is what determines whether it accords with the principle of respect for embryos, not the source of the embryos.