Inter-batch Reproducibility Research Articles

Quality assurance of genotyping array for detection and typing of human papillomavirus

The aim of this study was to evaluate the sensitivity, specificity, reliability and reproducibility of the EasyChip ® HPV blot for human papillomavirus (HPV) genotyping. Type-specific sensitivity and specificity for 39 types of HPV (HPV 6, 11, 16, 18, 26, 31, 32, 33, 35, 37, 39, 42, 43, 44, 45, 51, 52, 53, 54, 55, 56, 58, 59, 61, 62, 66, 67, 68, 69, 70, 72, 74, 82, CP8061, CP8304, L1AE5, MM4, MM7 and MM8) were examined. The operating environment, reliability, reproducibility and blot interpretation were assessed by a quality assurance system. Each batch experiment contained samples from 89 cervical specimens and 7 extrinsic controls. Caski, HeLa and Jurkat cells, male human blood cell DNA and sterile water were used to assess reliability. Furthermore, pairs of sibling controls were used to assess reproducibility. The overall sensitivity of HPV detection was 1–50 copies of HPV genome equivalent. There was no cross-reactivity with amplicons of other HPV genotypes. One hundred batch experiments demonstrated that the reliability was excellent. The intra-batch and inter-batch reproducibility was 98 and 97%, respectively. It was concluded that the EasyChip ® HPV blot is a highly sensitive, reliable and reproducible tool for detection and identification of HPV genotypes.

Reconstructed Skin Kits: Reproducibility of Cutaneous Irritancy Testing

The aim of this study was to determine the reproducibility of data obtained from in vitro irritation testing using three industrial reconstructed human epidermis models, EpiDerm^TM, Episkin^TM and SkinEthic^R, and one in-house model developed at Wella/Cosmital. A common protocol was established based on the measurement of cytotoxicity in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and of extracellular release of proinflammatory mediators and cytosolic enzymes after a range of exposure times to sodium lauryl sulfate (SLS). This time course protocol was applied to 6 different batches of each skin model using triplicate tissue cultures per test condition. The parameters analyzed for intra- and inter-batch reproducibility were the cell viability determined as MTT reduction capacity and the ET-50 values in the 6 batches, as well as the release of the cytokine IL-1α and of the cellular enzymes LDH and GOT in 3 batches only. The MTT viability results showed that EpiDerm was the most resistant to the SLS treatment and at the same time the most reproducible model, SkinEthic was the most sensitive to SLS and the least reproducible, and Episkin and the Cosmital model were intermediate. Measurements of IL-1α release showed a relatively high intra- and inter-batch variability in all the skin models. It was not possible to detect the extracellular release of the enzymes LDH and GOT in the Episkin assay medium. With the 3 other models, the release of LDH and GOT varied in about the same range as that of IL-1α. For all the parameters in this study, the inter-batch variability was generally greater than the intra-batch variability. A possible reduction in the number of batches and replicates for future applications in routine irritancy testing is discussed on the basis of the results obtained using 6 batches in triplicate.

Permeation and Skin Absorption: Reproducibility of Various Industrial Reconstructed Human Skin Models

Human reconstructed skin models could be very useful tools to quantify percutaneous permeation and absorption. Before using such models, the reproducibility in the same batch and/or various batches, i.e. the relevance of the results obtained, must be verified. The reproducibility of 3 industrial models – EpiDerm^®, Episkin^® and SkinEthic^® – was tested regarding the permeation and skin absorption of 3 topically applied compounds (with a large range of physicochemical properties): lauric acid, caffeine and mannitol. For all the models, the intrabatch reproducibility was greater than the interbatch reproducibility. According to the batches tested, the larger difference in terms of reproducibility between the 3 models was observed in the case of mannitol, a very poor permeant. In this case, the best reproducibility was observed with EpiDerm and Episkin. Moreover, the rank order of the 3 compounds applied, in terms of permeation and skin absorption, was the same as that expected from ex vivo human skin. Such results revealed human skin models as a promising means to test in vitro permeation and percutaneous absorption of topical products.