Mesenchymal stem cells in regenerative medicine: Opportunities and challenges for articular cartilage and intervertebral disc tissue engineering

Defects of load‐bearing connective tissues such as articular cartilage and intervertebral disc (IVD) can result from trauma, degenerative, endocrine, or age‐related disease. Current surgical and pharmacological options for the treatment of arthritic rheumatic conditions in the joints and spine are ineffective. Cell‐based surgical therapies such as autologous chondrocyte transplantation (ACT) have been in clinical use for cartilage repair for over a decade but this approach has shown mixed results. This review focuses on the potential of mesenchymal stem cells (MSCs) as an alternative to cells derived from patient tissues in autologous transplantation and tissue engineering. Here we discuss the prospects of using MSCs in regenerative medicine and summarize the advantages and disadvantages of these cells in articular cartilage and IVD tissue engineering. We discuss the conceptual and practical difficulties associated with differentiating and pre‐conditioning MSCs for subsequent survival in a physiologically harsh extracellular matrix, an environment that will be highly hypoxic, acidic, and nutrient deprived. Implanted MSCs will be exposed to traumatic physical loads and high levels of locally produced inflammatory mediators and catabolic cytokines. We also explore the potential of culture models of MSCs, fully differentiated cells and co‐cultures as “proof of principle” ethically acceptable “3Rs” models for engineering articular cartilage and IVD in vitro for the purpose of replacing the use of animals in arthritis research. J. Cell. Physiol. 222:23–32, 2010. © 2009 Wiley‐Liss, Inc.     

Thermal limits for behavioural function and resistance-adaptation of goldfish,Carassius auratus L.

Summary Goldfish were trained to perform a conditioned avoidance response in a shuttle tank at acclimation temperatures between 10 °C and 35 °C. A high level of success (85–100%) was maintained over a relatively wide range of test temperatures, although outside this range the response was rapidly and reversibly blocked. The upper and lower thermal limits for the avoidance response were determined in goldfish acclimated to temperatures between 10 °C and 35 °C. The absolute thermal limits for the avoidance response in goldfish were approximately 3 °C to 42 °C, but the range for individuals was considerably more restricted. Increased acclimation temperature resulted in higher upper and lower thermal limits and thus constitutes a reasonable resistance adaptation. Over the lower range of acclimation temperatures the upper thermal limit showed greater mobility, whereas over the upper range of acclimation temperatures the lower thermal limits showed greater mobility. Goldfish acclimated to 5 °C and 38.5 °C exhibited very reduced % success at their respective acclimation temperatures even though they showed high % success when the same individuals were previously acclimated to less stressful temperatures. These extreme acclimation temperatures probably represent the absolute limits for chronic exposure.     

A gonadotropin-releasing hormone (GnRH) antagonist distinguishes three populations of GnRH analog-responsive cells in human and rat pituitary in vitro and produces an acute increase in intracellular Ca2+ concentration without inducing gonadotropin secretion

We have examined the actions of the potent GnRH antagonist [N-acetyl-D beta Na11-D-pCl-Phe2-D-Phe3-D-Arg6,Phe7,Arg8-D-Ala10]NH2GnRH++ + (GnRHa) on basal and GnRH-stimulated LH secretion, inositol phospholipid turnover, and intracellular Ca2+ levels in dispersed rat anterior pituitary tissue. As expected, GnRHa was found to be a pure antagonist of secretion, but was paradoxically equipotent with GnRH in stimulating inositol phospholipid turnover. Examination of intracellular Ca2+ changes at the single cell level using digital video-enhanced fluorescence imaging demonstrated that dispersed rat pituitary cells appeared to contain three GnRH analog-responsive cell populations: those that increased intracellular Ca2+ in response to both GnRH and GnRHa, and those that responded to either GnRH or GnRHa only. These observations were extended to studies of the relatively homogeneous gonadotroph cell populations of endocrinologically inactive pituitary adenomas. Of five adenomas examined, one increased inositol phospholipid turnover in response to GnRHa plus GnRH, but not GnRH alone, three responded to GnRH only, and one responded to both GnRH and GnRHa. Our findings, therefore, suggest that three GnRH analog-responsive cell types are also present in human pituitary and that clonal expansion of any of these cell types may be responsible for tumor formation.     

Reranking candidate gene models with cross-species comparison for improved gene prediction

Background  

Most gene finders score candidate gene models with state-based methods, typically HMMs, by combining local properties (coding potential, splice donor and acceptor patterns, etc). Competing models with similar state-based scores may be distinguishable with additional information. In particular, functional and comparative genomics datasets may help to select among competing models of comparable probability by exploiting features likely to be associated with the correct gene models, such as conserved exon/intron structure or protein sequence features.