Karyotype variation of CHO host cell lines over time in culture characterized by chromosome counting and chromosome painting

Genomic rearrangements are a common phenomenon in rapidly growing cell lines such as Chinese hamster ovary (CHO) cells, a feature that in the context of production of biologics may lead to cell line and product instability. Few methods exist to assess such genome wide instability. Here, we use the population distribution of chromosome numbers per cell as well as chromosome painting to quantify the karyotypic variation in several CHO host cell lines. CHO‐S, CHO‐K1 8 mM glutamine, and CHO‐K1 cells adapted to grow in media containing no glutamine were analyzed over up to 6 months in culture. All three cell lines were clearly distinguishable by their chromosome number distribution and by the specific chromosome rearrangements that were present in each population. Chromosome Painting revealed a predominant karyotype for each cell line at the start of the experiment, completed by a large number of variants present in each population. Over time in culture, the predominant karyotype changed for CHO‐S and CHO‐K1, with the diversity increasing and new variants appearing, while CHO‐K1 0 mM Gln preferred chromosome pattern increased in percent of the population over time. As control, Chinese hamster lung fibroblasts were shown to also contain an increasing number of variants over time in culture.     

Size-spectra as indicators of the effects of fishing on coral reef fish assemblages

The data requirements and resources needed to develop multispecies indicators of fishing impacts are often lacking and this is particularly true for coral reef fisheries. Size-spectra, relationships between abundance and body-size class, regardless of taxonomy, can be calculated from simple sizeabundance data. Both the slope and the mid-point height of the relationship can be compared at different fishing intensities. Here, we develop size-spectra for reef fish assemblages using body size- abundance data collected by underwater visual census in each of ten fishing grounds across a known gradient of fishing intensity in the Kadavu Island group, Fiji. Slopes of the size-spectra became steeper (F_9,69=3.20, p<0.01) and the height declined (F_9,69=15.78, p<0.001) with increasing fishing intensity. Regressions of numbers of individuals per size class across grounds were negative for all size classes, although the slope was almost zero for the smallest size class. Response to exploitation of each size class category was greatest for larger fish. Steepening of the slope with increasing fishing intensity largely resulted from reductions in the relative abundance of large fish and not from the ecological release of small fish following depletion of their predators. The slope and height of the size-spectrum appear to be good indicators of fishing effects on reef fish assemblages.     

Chordin knockdown enhances the osteogenic differentiation of human mesenchymal stem cells

Introduction

Bone morphogenetic proteins (BMPs) are critical growth factors in the osteogenic differentiation of progenitor cells during development in embryos and fracture repair in adults. Although recombinant BMPs are in use clinically, their clinical efficiency needs to be improved. The biological activities of BMPs are naturally regulated by extracellular binding proteins. The specific hypotheses tested in this study were as follows: the BMP inhibitor chordin is produced endogenously during the osteogenic differentiation of human mesenchymal stem cells (MSCs); and blockade of the activity of the BMP inhibitor increases the rate of osteogenic differentiation of human MSCs in vitro.

Methods

Human MSCs were derived from bone marrow from an iliac crest aspirate and from patients undergoing hip hemiarthroplasty. The MSCs were induced down the osteogenic pathway using standard osteogenic differentiation media, and expressions of BMP-2 and chordin were determined by gene expression analysis. During osteogenic differentiation, chordin knockdown was induced using RNA interference. Osteogenic differentiation was assessed by measuring the expression of alkaline phosphatase and calcium deposition. The differences in expression of osteogenic makers between groups were compared by analysis of variance, followed by Gabriel post hoc test.

Results

We demonstrate the expression of BMP-2 and chordin in human MSCs during osteogenic differentiation. Knockdown of chordin by RNA interference in vitro resulted in a significant increase in the expression of the osteogenic marker alkaline phosphatase and the deposition of extracellular mineral, in response to osteogenic stimulation.

Conclusion

We conclude that endogenously produced chordin constrains the osteogenic differentiation of human MSCs. The targeting of BMP inhibitors, such as chordin, may provide a novel strategy for enhancing bone regeneration.     

Intrinsic resistance of neural stem cells to toxic metabolites may make them well suited for cell non-autonomous disorders: evidence from a mouse model of Krabbe leukodystrophy

While transplanted neural stem cells (NSCs) have been shown to hold promise for cell replacement in models of a number of neurological disorders, these examples have typically been under conditions where the host cells become dysfunctional due to a cell autonomous etiology, i.e. a 'sick' cell within a relatively supportive environment. It has long been held that cell replacement in a toxic milieu would not likely be possible; donor cells would succumb in much the same way as endogenous cells had. Many metabolic diseases are characterized by this situation, suggesting that they would be poor targets for cell replacement therapies. On the other hand, models of such diseases could prove ideal for testing the capacity for cell replacement under such challenging conditions. In the twitcher (twi ) mouse -- as in patients with Krabbe or globoid cell leukodystrophy (GLD), for which it serves as an authentic model -- loss of galactocerebrosidase (GalC) activity results in the accumulation of psychosine, a toxic glycolipid. Twi mice, like children with GLD, exhibit inexorable neurological deterioration presumably as a result of dysfunctional and ultimately degenerated oligodendrocytes with loss of myelin. It is believed that GLD pathophysiology is related to a psychosine-filled environment that kills not only host oligodendrocytes but theoretically any new cells placed into that milieu. Through the implantation of NSCs into the brains of both neonatal and juvenile/young adult twi mice, we have determined that widespread oligodendrocyte replacement and remyelination is feasible. NSCs appear to be intrinsically resistant to psychosine -- more so in their undifferentiated state than when directed ex vivo to become oligodendrocytes. This resistance can be enhanced by engineering the NSCs to over-express GalC. Some twi mice grafted with such engineered NSCs had thicker white tracts and lived 2-3 times longer than expected. While their brains had detectable levels of GalC, it was probably more significant that their psychosine levels were lower than in twi mice that died at a younger age. This concept of resistance based on differentiation state extended to human NSCs which could similarly survive within the twi brain. Taken together, these results suggest a number of points regarding cellular therapies against degenerative diseases with a prominent cell non-autonomous component: Cell replacement is possible if cells resistant to the toxic environment are employed. Furthermore, an important aspect of successful treatment will likely be not only cell replacement but also cross-correction of host cells to provide them with enzyme activity and hence resistance. While oligodendrocyte replacement alone was not a sufficient treatment for GLD (even when extensive), the replacement of both cells and molecules -- e.g. with NSCs that could both become oligodendrocytes and 'pumps' for GalC -- emerges as a promising basis for a multidisciplinary strategy. Most neurological disease are complex in this way and will likely require multifaceted approaches, perhaps with NSCs serving as the 'glue'.     

Suspended sediment impairs habitat choice and chemosensory discrimination in two coral reef fishes

Increasing sediment onto coral reefs has been identified as a major source of habitat degradation, and yet little is known about how it affects reef fishes. In this study, we tested the hypothesis that sediment-enriched water impairs the ability of larval damselfish to find suitable settlement sites. At three different experimental concentrations of suspended sediment (45, 90, and 180 mg l⁻¹), pre-settlement individuals of two species (Pomacentrus amboinensis and P. moluccensis) were not able to select their preferred habitat. In a clear water environment (no suspended sediment), both species exhibit a strong preference for live coral over partially dead and dead coral, choosing live coral 70 and 80% of the time, respectively. However, when exposed to suspended sediment, no habitat choice was observed, with individuals of both species settling on live coral, partially dead, and dead coral, at the same frequency. To determine a potential mechanism underlying these results, we tested chemosensory discrimination in sediment-enriched water. We demonstrated that sediment disrupts the ability of this species to respond to chemical cues from different substrata. That is, individuals of P. moluccensis prefer live coral to dead coral in clear water, but in sediment-enriched water, chemical cues from live and dead coral were not distinguished. These results suggest that increasing suspended sediment in coral reef environments may reduce settlement success or survival of coral reef fishes. A sediment-induced disruption of habitat choice may compound the effects of habitat loss on coral reefs.     

Prediction of Cardiovascular Events in Statin-Treated Stable Coronary Patients of the Treating to New Targets Randomized Controlled Trial by Lipid and Non-Lipid Biomarkers

Several plasma non-lipid biomarkers have been shown to predict major cardiovascular events (MCVEs) in population studies. Our objective was to investigate the relationship between lipid and non-lipid biomarkers levels achieved during statin therapy and the incidence of MCVEs in patients with stable coronary heart disease (CHD). We conducted a substudy of the TNT (Treating to New Targets) study, which was a randomized trial that compared the efficacy of high (80 mg) versus low (10 mg) dose atorvastatin for the secondary prevention of CHD. Fasting plasma levels of standard lipids and of 18 non-lipid biomarkers were obtained after an 8-week run-in period on atorvastatin 10 mg in 157 patients who experienced MCVEs during the 4.9 years of study follow-up and in 1349 controls. MCVE was defined as CHD death, nonfatal, non-procedure-related myocardial infarction, resuscitated cardiac arrest, and fatal or nonfatal stroke. After adjusting for age, sex and treatment arm, plasma levels of high-density lipoprotein (HDL) cholesterol, triglycerides, high-sensitivity C-reactive protein (hsCRP), insulin, neopterin, N-terminal pro-brain natriuretic peptide (BNP), lipoprotein(a) [Lp(a)], and the soluble receptor for advanced glycation end products (sRAGE) were predictive of recurrent MCVEs (P≤0.02 for each doubling of plasma concentration). However, no significant association was observed between the risk of recurrent MCVEs and plasma levels of low-density lipoprotein cholesterol, adiponectin, cystatin C, lipoprotein-associated phospholipase A2, monocyte chemotactic protein-1, matrix metalloproteinase-9, myeloperoxidase, osteopontin, soluble CD40 ligand, soluble intercellular adhesion molecule-1, or soluble vascular cell adhesion molecule-1. After further adjustment for diabetes, hypertension, smoking, and BMI, the relationship between hsCRP, insulin and MCVE were no longer significant, while the relationship between Lp(a), neopterin, NT-proBNP and sRAGE and MCVE remained statistically significant. In conclusion, in patients with CHD treated with atorvastatin, plasma levels of Lp(a), neopterin, NT-proBNP, and sRAGE are associated with the risk of recurrent MCVEs.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00327691","term_id":"NCT00327691"}}NCT00327691.