Cellular bioenergetics for better phenotype based drug discovery
The calScreener™ phenotype assay bridges the gap between target discovery and clinical trials. Metabolism-based screening takes you closer to the real-life setting.
Phenotype assays increase the predictive value in drug development
The calScreener provides a direct measurement of the cell activity without any labels or additions of any kind. It is a direct measurement of the energy release, meaning it is not measured via a proxy analysis. The unique upside is that it is not parameter testing.
The calScreener is a true phenotype (functional) assay as compared to most other technologies that use parameter-based (genotype) testing. Most assays are predominantly end-point assays, where samples are gathered at one or a limited number of time points, in contrast to the continuous kinetic measurement of the calScreener.
Direct metabolic readout provided by the calScreener gives you as a scientist access to an unbiased assay where the effects of treatment are studied in a correct biological context resulting in greater predictive value for cost-effective and rapid drug development.
Functional readout of an entire system for increased biorelevance
There are no other label-free and non-destructive technologies available that can be used to study the net effect of all cellular parameters at once and in the correct context, regardless of sample composition and morphology.
The total metabolic response provides a functional readout of an entire system. To better capture clinically relevant biology already in the petri dish that increase the predictive power prior to expensive animal and human studies. Minimize the leap of faith when going from in-vitro to in-vivo with the powerful calScreener phenotypic screening assay.
Thermogenesis in brown adipose cells
The calScreener is used to study the direct heat production as a signature function of brown adipose tissue. Data from an assay on intact adipose tissue samples clearly indicates that stimulation of energy expenditure can be measured as a function of drug stimulation.
This opens up the field of developing drugs for obesity indications directly scored using energy expenditure as the readout and not proxy parameters or indirect measurements.
Unpublished data shows the calScreener is an optimal and highly sensitive method for measuring heat production from UCP1 positive adipocytes.
Metabolic research history
World-wide obesity has triplicated since 1975 with a total amount of 1.9 billion of adults being overweight. Screening for a compound able to help improve this pandemic is performed very actively within the pharmaceutical industry. One approach is to promote brown adipose tissue characteristics on white adipose tissue. Succeeding would mean transferring white fat into brown fat, resulting in weight loss and heat production.
There is no better instrument to measure heat transfer than calScreener™, the first cell biology adapted microcalorimeter
Calorimetry is the gold standard for metabolic rate determination
All body functions, from active cellular transport to macronutrients synthesis or muscular contraction required energy, and also all metabolic processes of the body dissipates energy. Therefore, the energy produced by an organism is directly proportional to metabolic rate. Direct calorimetry is the gold standard of metabolic rate determination, and it has been fundamental in the study of metabolism in health and diseases.
Under the assumption that heat production is proportional to oxygen consumption, metabolic rates have been extensively estimated by indirect calorimetry. However, this assumption is not always correct when it comes to anaerobic metabolism, gluconeogenesis, ketogenesis, or lipogenesis and then subjected to errors.
With CalScreener™ it is possible to measure directly both aerobic and anaerobic metabolism, which it is impossible in other technologies measuring subsets of metabolic parameters and not total energy turnover.
Clark, D.G., Brinkman, M. & Neville, S.D., 1986. Microcalorimetric measurements of heat production in brown adipocytes from control and cafeteria-fed rats. Biochem. J., 235, pp.337–42.
The effects of the sequential addition of glucose, noradrenaline, propranolol and oleic acid on the rates of O2 consumption and heat production by isolated interscapular brown adipocytes from control and cafeteria-fed rats were compared. Although the chemical agents produced very similar changes in oxidative metabolism, the actual rates of O2 uptake and heat output in adipocytes from the cafeteria-fed rats, when expressed per g dry wt. of cells, were approx. 65% less than those obtained with cells from the control rats. However, when the same results were expressed per 10(8) multiloccular brown adipocytes, rather than gravimetrically, rates of O2 consumption and heat production were equivalent. Further interpretation of these data is complicated, because the average volume of multiloccular brown adipocytes from cafeteria-fed rats was 2.5 times that for multiloccular cells from control animals.
Backman, P., 1992. A microcalorimetric buffer suspensions study of human erythrocytes in stirred. Thermochimica Acta, 205, pp.87–97.
The basal heat production rate P of human erythrocytes incubated in stirred buffer suspensions at pH 7.4 and 37.00 ± 0.01°C was found to be 95.8 ± 2.5 mW 1−1 (of packed erythrocytes). A lower P value of 86.5 ± 1.9 mW 1−1 was observed under static conditions. Within experimental errors, the measured Pvalues could be accounted for by the heat production of chemical reactions related to the catabolic metabolism of exogenous glucose via the hexose monophosphate shunt and the glycolytic pathway. The increase in P value with pH was found to be 139 ± 4 mW 1−1 per pH unit in the pH range 7.1–7.5, corresponding to a relative variation of 139% per pH unit. A decrease in heat production rate with cell concentration was also observed (−0.56 ± 0.14 mW 1−1per vol.% of erythrocytes).
Burnett, C.M.L. & Grobe, J.L., 2013. Direct calorimetry identifies deficiencies in respirometry for the determination of resting metabolic rate in C57Bl/6 and FVB mice. American Journal of Physiology - Endocrinology and Metabolism, 305(7), pp.E916–E924.
Substantial research efforts have been aimed at identifying novel targets to increase resting metabolic rate (RMR) as an adjunct approach to the treatment of obesity. Respirometry (one form of “indirect calorimetry”) is unquestionably the dominant technique used in the obesity research field to assess RMR in vivo, although this method relies upon a lengthy list of assumptions that are likely to be violated in pharmacologically or genetically manipulated animals. A “total” calorimeter, including a gradient layer direct calorimeter coupled to a conventional respirometer, was used to test the accuracy of respirometric-based estimations of RMR in laboratory mice (Mus musculus Linnaeus) of the C57Bl/6 and FVB background strains. Using this combined calorimeter, we determined that respirometry underestimates RMR of untreated 9- to 12-wk-old male mice by ∼10–12%. Quantitative and qualitative differences resulted between methods for untreated C57Bl/6 and FVB mice, C57Bl/6 mice treated with ketamine-xylazine anesthesia, and FVB mice with genetic deletion of the angiotensin II type 2 receptor. We conclude that respirometric methods underestimate RMR in mice in a magnitude that is similar to or greater than the desired RMR effects of novel therapeutics. Sole reliance upon respirometry to assess RMR in mice may lead to false quantitative and qualitative conclusions regarding the effects of novel interventions. Increased use of direct calorimetry for the assessment of RMR and confirmation of respirometry results and the reexamination of previously discarded potential obesity therapeutics are warranted.
Kriszt, R. et al., 2017. Optical visualisation of thermogenesis in stimulated single-cell brown adipocytes. Scientific Reports, 7(1), pp.1–14.
The identification of brown adipose deposits in adults has led to significant interest in targeting this metabolically active tissue for treatment of obesity and diabetes. Improved methods for the direct measurement of heat production as the signature function of brown adipocytes (BAs), particularly at the single cell level, would be of substantial benefit to these ongoing efforts. Here, we report the first application of a small molecule-type thermosensitive fluorescent dye, ERthermAC, to monitor thermogenesis in BAs derived from murine brown fat precursors and in human brown fat cells differentiated from human neck brown preadipocytes. ERthermAC accumulated in the endoplasmic reticulum of BAs and displayed a marked change in fluorescence intensity in response to adrenergic stimulation of cells, which corresponded to temperature change. ERthermAC fluorescence intensity profiles were congruent with mitochondrial depolarisation events visualised by the JC-1 probe. Moreover, the averaged fluorescence intensity changes across a population of cells correlated well with dynamic changes such as thermal power, oxygen consumption, and extracellular acidification rates. These findings suggest ERthermAC as a promising new tool for studying thermogenic function in brown adipocytes of both murine and human origins.