Mesenchymal stem cells: progress toward promise

Despite having access to embryonic stem cells, many laboratories choose to study adult stem cells, not because of philosophical reasons but because of the practical aspects and day-to-day progress necessary for developing cellular therapeutics. There is certainly the ethical desire and responsibility to provide patients with therapies where few options exist. Multipotential cells have been isolated from adult tissues in many laboratories, characterized and their multipotentiality examined. Mesenchymal stem cells (MSC) can be isolated from several tissues but easily accessible BM seems to be the most common source. These adult stem cells may not be as 'powerful' or diverse as embryonic stem cells may one day become, but at present they offer many advantages for developing cellular therapeutics: ease of isolation, expansion potential, stable phenotype, shippability, and compatibility with different delivery methods and formulations. Their potential use as cellular therapeutics has prompted the investigation of interactions of allogeneic MSC with the immune response. The great importance of cardiovascular medicine has demanded that MSC also be tested in this discipline. We believe MSC continue to provide a substantial scientific and therapeutic opportunity, and have reviewed some of the recent developments in the field.     

Avian transgenesis: progress towards the promise

The hen has long held promise as a low cost, high-yield bioreactor for the production of human biopharmaceuticals in egg whites. A typical egg white contains 3.5-4.0 grams of protein, more than half of which comes from a single gene (ovalbumin). Harnessing the power of the gene to express a recombinant protein could yield up to a gram or more of the protein in the naturally sterile egg. Accordingly, a major effort has been underway for more than a decade to develop robust methods for modification of the chicken genome. This effort intensified in the mid-1990s when several avian transgenic companies entered the scene. Progress has been made in that time but much remains to be done.     

Molecular evolution study in China: progress and future promise

China has a large land area with highly diverse topography, climate and vegetation, and animal resources and is ranked eighth in the world and first in the Northern Hemisphere on richness of biodiversity. Even though little work on molecular evolution had been reported a decade ago, studies on both the evolution of macromolecules and the molecular phylogeny have become active in China in recent years. This review highlights some of the interesting and important developments in molecular evolution study in China. Chinese scientists have made significant contribution on the methods inferring phylogeny and biogeography of animals and plants in East Asia using molecular data. Studies on population and conservation genetics of animals and plants, such as Golden monkey and Chinese sturgeon, provided useful information for conserving the endangered species. East and South Asia has been demonstrated to be one of the centres of domestication. Origin and evolution of genes and gene families have been explored, which shed new insight on the genetic mechanism of adaptation. In the genomic era, Chinese researchers also made a transition from single-gene to a genomic investigation approach. Considering the fact that amazing progress has been made in the past few years, and more and more talented young scientists are entering field, the future of molecular evolution study in China holds much promise.     

Studies of threespine stickleback developmental evolution: progress and promise

A promising route for understanding the origin and diversification of organismal form is through studies at the intersection of evolution and development (evo-devo). While much has been learned over the last two decades concerning macroevolutionary patterns of developmental change, a fundamental gap in the evo-devo synthesis is the integration of mathematical population and quantitative genetics with studies of how genetic variation in natural populations affects developmental processes. This micro-evo-devo synthesis requires model organisms with which to ask empirical questions. Threespine stickleback fish (Gasterosteus aculeatus), long a model for studying behavior, ecology and evolution, is emerging as a prominent model micro-evo-devo system. Research on stickleback over the last decade has begun to address the genetic basis of morphological variation and sex determination, and much of this work has important implications for understanding the genetics of speciation. In this paper we review recent threespine stickleback micro-evo-devo results, and outline the resources that have been developed to make this synthesis possible. The prospects for stickleback research to speed the micro-(and macro-) evo-devo syntheses are great, and this workhorse model system is well situated to continue contributing to our understanding of the generation of diversity in organismal form for many more decades.     

Tomatoes,lycopene, and prostate cancer: progress and promise

Prostate cancer has emerged as a major public health problem in nations that have an affluent culture with an aging population. The search for etiologic risk factors and an emphasis on the development of chemopreventive agents has gained momentum over the last decade. Among the landmark epidemiologic findings during this period has been the association between the consumption of tomato products and a lower risk of prostate cancer. The traditional reductionist scientific approach has led many investigators to propose that lycopene, a carotenoid consumed largely from tomato products, may be the component responsible for lowering the risk of prostate cancer. Thus, many laboratory and clinical studies are now underway with the goal of assessing the ability of pure lycopene to serve as a chemopreventive agent for prostate and other malignancies. The focus on lycopene should continue, and an improved understanding of lycopene absorption, distribution, role in antioxidant reactions, and metabolism is critical in the quest to elucidate mechanisms whereby this compound could possibly reduce prostate cancer risk. In contrast to the pharmacologic approach with pure lycopene, many nutritional scientists direct their attention upon the diverse array of tomato products as a complex mixture of biologically active phytochemicals that together may have anti-prostate cancer benefits beyond those of any single constituent. These contrasting approaches will continue to be explored in clinical, laboratory and epidemiologic studies in the near future, providing hope that the next generation will benefit from this knowledge and experience a lower risk of prostate cancer.     

Cell biology and clinical promise of G-CSF: immunomodulation and neuroprotection

In the light of the enthusiasm to use of recombinant human granulocyte colony-stimulating factor (G-CSF) for immunomodulation and neuroprotection, it should be remembered that the current knowledge is based on a century of laborious research. G-CSF is a pleiotropic cytokine playing a major role as regulator of haematopoiesis. Although the precise mechanisms of G-CSF are not known, there is growing evidence supporting the notion that G-CSF also exerts profound immunoregulatory effect in adaptive immunity and has a neuroprotective role in both cerebral ischemia and neurodegeneration. Here, we describe the immunomodulation and the neuroprotection that can be achieved with G-CSF, and summarize possible mechanisms of G-CSF as a potential therapeutic agent in autoimmune diseases and neurological disorders. Our understanding of these novel sites of action of G-CSF has opened therapeutic avenues for the treatment of autoimmune diseases and neurological disorders, and has translated the beneficial effects of G-CSF from basic experiments to clinical patients.     

A cardiovascular EST repertoire: progress and promise for understanding cardiovascular disease

The application of expressed sequence tag (EST) technology has proven to be an effective tool for gene discovery and the generation of gene expression profiles. The generation of an EST resource for the cardiovascular system has revealed significant insights into the changes in gene expression that guide heart development and disease. Furthermore, an important genetic resource has been developed for cardiovascular biology that is valuable for data mining and disease gene discovery.     

Green tea polyphenol epigallocatechin 3-gallate in arthritis: progress and promise

Green tea's active ingredient, epigallocatechin 3-gallate (EGCG), has gained significant attention among scientists and has been one of the leading plant-derived molecules studied for its potential health benefits. In the present review I summarize the findings from some of the most significant preclinical studies with EGCG in arthritic diseases. The review also addresses the limitations of the dose, pharmacokinetics, and bioavailability of EGCG in experimental animals and findings related to the EGCG-drug interaction. Although these findings provide scientific evidence of the anti-rheumatic activity of EGCG, further preclinical studies are warranted before phase clinical trials could be initiated with confidence for patients with joint diseases.     

Dynamic imaging of the immune system: progress, pitfalls and promise

Both innate and adaptive immunity are dependent on the migratory capacity of myeloid and lymphoid cells. Effector cells of the innate immune system rapidly enter infected tissues, whereas sentinel dendritic cells in these sites mobilize and transit to lymph nodes. In these and other secondary lymphoid tissues, interactions among various cell types promote adaptive humoral and cell-mediated immune responses. Recent advances in light microscopy have allowed direct visualization of these events in living animals and tissue explants, which allows a new appreciation of the dynamics of immune-cell behaviour. In this article, we review the basic techniques and the tools used for in situ imaging, as well as the limitations and potential artefacts of these methods.     

Genetic susceptibility to coronary artery disease: from promise to progress

Family history is an important independent risk factor for coronary artery disease (CAD), and identification of susceptibility genes for this common, complex disease is a vital goal. Although there has been considerable success in identifying genetic variants that influence well-known risk factors, such as cholesterol levels, progress in unearthing novel CAD genes has been slow. However, advances are now being made through the application of large-scale, systematic, genome-wide approaches. Recent findings particularly highlight the link between CAD and inflammation and immunity, and highlight the biological insights to be gained from a genetic understanding of the world's biggest killer.     

Cardiovascular genomics: recent progress, current challenges, future promise

A report from the second Annual Cardiovascular Genomics Meeting, Sponsored by Cambridge Healthtech, Inc., Miami, January 31-February 1, 2000.     

Cell encapsulation using biopolymer gels for regenerative medicine

There has been a consistent increase in the mean life expectancy of the population of the developed world over the past century. Healthy life expectancy, however, has not increased concurrently. As a result we are living a larger proportion of our lives in poor health and there is a growing demand for the replacement of diseased and damaged tissues. While traditionally tissue grafts have functioned well for this purpose, the demand for tissue grafts now exceeds the supply. For this reason, research in regenerative medicine is rapidly expanding to cope with this new demand. There is now a trend towards supplying cells with a material in order to expedite the tissue healing process. Hydrogel encapsulation provides cells with a three dimensional environment similar to that experienced in vivo and therefore may allow the maintenance of normal cellular function in order to produce tissues similar to those found in the body. In this review we discuss biopolymeric gels that have been used for the encapsulation of mammalian cells for tissue engineering applications as well as a brief overview of cell encapsulation for therapeutic protein production. This review focuses on agarose, alginate, collagen, fibrin, hyaluronic acid and gelatin since they are widely used for cell encapsulation. The literature on the regeneration of cartilage, bone, ligament, tendon, skin, blood vessels and neural tissues using these materials has been summarised.     

Cell encapsulation with alginate and alpha-phenoxycinnamylidene-acetylated poly(allylamine)

In general, microcapsules prepared from alginate and polycations lack mechanical strength because the interaction between alginate and polycations is ionic instead of covalent, which represents a much stronger bond. To increase the mechanical strength of the capsule, we prepared photosensitive microcapsules that could form covalent bonds between polymers in the capsular membrane by light irradiation. Two types of photosensitive poly(allylamine), with 5% and 10% of amino groups modified by alpha-phenoxycinnamylidene acetylchloride, were synthesized. Both photopolymers exhibited an absorption maximum at 325 nm and were capable of crosslinking upon light exposure. These photosensitive polymers were used for the preparation of microcapsules. The capsules formed from this photosensitive poly(allylamine) and alginate were strengthened significantly by light irradiation. Only 28% of the microcapsules prepared from the 5%-modified photopolymer fractured after 48 h of shaking at 150 rpm. This fracture percentage is much lower when compared with the 60% of capsules fractured when prepared from the untreated poly(allylamine). By using poly(allylamine) at 10% modification, the mechanical strength was improved only slightly, with 26% of capsules fractured. Analysis of the permeability test indicated that the photo-crosslinked capsular membrane was freely permeable to cytochrome c and myoglobin, but less permeable to serum albumin. The encapsulation method was used to entrap and culture IW32 mouse leukemia cells. The cells proliferated to a density of about 1.1 x 10(7) cells/mL in the capsules after 7 days of cultivation. Concurrently, the concentration of erythropoietin in the microcapsules increased to 800 mU/mL. This new encapsulation technique has great potential in the application of a bioindustrial cell-culturing process.     

Understanding ion channel biology using epitope tags: progress, pitfalls, and promise

Epitope tags have been increasingly used to understand ion channel subunit assembly and interaction, trafficking, subcellular localization, and function in living cells. In particular, epitope tags have proven extremely useful for analyses of closely related, highly homologous channel subunits in endogenous cell contexts in vitro and in vivo, where multiple channel isoforms may be expressed. However, as the variety of epitope tags that have been used has expanded, and the use of tagged channel subunits has become increasingly sophisticated and widespread, there has also been an increase in the number of examples highlighting the potential problems associated with the use of epitope tags for ion channel studies. Described here are some of the epitope tags that have been used to study ion channel subunits, including the HA, FLAG, myc, His6, and green fluorescent protein (GFP) epitopes, as well as some of the applications and avenues of research in which they have proven advantageous. Potential pitfalls and caveats associated with the use of these epitope tags are also discussed, with an emphasis on the need to include careful characterization of epitope-tagged channel subunits as part of their construction. Finally, potential avenues for future investigation and the development of this approach are considered.     

噬菌体赋形剂的种类、配方及包被技术研究进展

噬菌体制剂的研究与应用受到医药领域、畜牧兽医领域及食品生产在内的各行业的重视。然而,噬菌体作为一种具有蛋白质外壳的活微生物,其在防治致病菌污染、感染及储存运输过程中,会遇到一些活性丧失、储存期短、液体状态运输不便等问题。因此,寻找合适的包被赋形剂,以减少噬菌体在使用、储存及运输过程中的活性损失,是噬菌体疗法亟须解决的问题。本文主要综述制备噬菌体制剂时使用的包被赋形剂种类、配方及包被技术等,及其对噬菌体抗逆性和储存稳定性的影响,并探讨了该领域最重要的研究成果,以期为固态噬菌体制剂寻找合适的包被赋形剂、配方和包被技术,为噬菌体的靶向治疗和控制释放奠定基础,有助于噬菌体治疗的更广泛的临床应用。     

Cell encapsulation in sub-mm sized gel modules using replica molding

For many types of cells, behavior in two-dimensional (2D) culture differs from that in three-dimensional (3D) culture. Among biologists, 2D culture on treated plastic surfaces is currently the most popular method for cell culture. In 3D, no analogous standard method--one that is similarly convenient, flexible, and reproducible--exists. This paper describes a soft-lithographic method to encapsulate cells in 3D gel objects (modules) in a variety of simple shapes (cylinders, crosses, rectangular prisms) with lateral dimensions between 40 and 1000 microm, cell densities of 10(5)-10(8) cells/cm(3), and total volumes between 1x10(-7) and 8x10(-4) cm(3). By varying (i) the initial density of cells at seeding, and (ii) the dimensions of the modules, the number of cells per module ranged from 1 to 2500 cells. Modules were formed from a range of standard biopolymers, including collagen, Matrigel, and agarose, without the complex equipment often used in encapsulation. The small dimensions of the modules allowed rapid transport of nutrients by diffusion to cells at any location in the module, and therefore allowed generation of modules with cell densities near to those of dense tissues (10(8)-10(9) cells/cm(3)). This modular method is based on soft lithography and requires little special equipment; the method is therefore accessible, flexible, and well suited to (i) understanding the behavior of cells in 3D environments at high densities of cells, as in dense tissues, and (ii) developing applications in tissue engineering.