ABSTRACT
BACKGROUND: This study aims to evaluate the trueness of the DI-60 Digital Cell Imaging Analyzer on Wright-stained samples with a focus on prevalence-dependent quality indicators for differential blood counts requested from non-hematology wards. METHODS: Two hundred and ninety-nine samples were included into this performance evaluation study at the Department of Laboratory Medicine, Medical University of Vienna. The following aspects were verified: (a) the reliability of automatedly pre-classified differential counts, (b) the concordance of DI-60 counts with manual-microscopic differential counts and (c) the agreement of DI-60 and manual-microscopic results regarding clinically relevant findings. RESULTS: 82.3% of all leukocytes were correctly pre-classified. Cell categories with a low prevalence (eosinophils, basophils, progenitors/precursors) in non-hematological patients presented with a low positive predictive value (PPV), indicating a high frequency of false positives. Comparisons between visually adjusted results of the DI-60 and manual-microscopic differential counts revealed a good concordance for neutrophil and lymphocyte counts. Besides the detection of precursors/progenitors and normoblasts, no relevant systemic errors were detected. However, due to their low prevalence and technical aspects, the detection of basophilia, monocytosis or the presence of precursors/progenitors showed comparably low accuracies (error rates of 7.4%-24.1%). CONCLUSION: The DI-60 system works well for Wright-stained samples collected in the non-hematology ward. Due to the varying prevalence of cell categories found in peripheral blood, a low PPV can be expected with automatic assignment for those cells with low prevalence (e.g., basophils, eosinophils, precursor and progenitor cells, plasma cells). If the pre-test probability of these conditions is increased, manual microscopic processing may be recommended.
Subject(s)
Leukocytes , Quality Indicators, Health Care , Humans , Leukocyte Count , Reproducibility of Results , PrevalenceABSTRACT
BACKGROUND: After deep excision of burn eschar down to the muscle fascia patients have a non-reversible loss of the skin and underlying subcutaneous tissue. These patients would benefit from the development of a sufficient epidermal, dermal, and hypodermal tissue-engineered replacement provided by new technologies of tissue engineering. The aim of the present study was to determine whether keratinocytes and preadipocytes grow simultaneously on a bovine-derived collagen-elastin matrix under in vitro conditions in order to obtain a multi-layer skin substitute. METHODS: Human keratinocytes as well as human preadipocytes were seeded onto a collagen-elastin matrix (Matriderm®). Human preadipocytes were isolated from human subcutaneous adipose tissue and seeded onto the scaffold directly after isolation. Keratinocytes were isolated from fresh human split-thickness skin harvests and seeded onto the surface of the scaffold after 4 days of proliferation. Twenty one days after seeding all scaffolds were histologically evaluated, using hematoxylin eosin, immunohistochemical staining with collagen IV as well as immunofluorescence labeling with anti-Ki67 antibody and DAPI (4',6-diamidino-2-phenylindole). RESULTS: Simultaneous growth of keratinocytes and preadipocytes could be observed on the collagen-elastin matrix. Keratinocytes adhered well to the surface of the matrix and formed a confluent epidermis-like layer. Preadipocytes adhered well and also penetrated into the deeper layers of the matrix. CONCLUSION: In this study, a collagen-elastin matrix served as a suitable scaffold for simultaneous culturing of preadipocytes and keratinocytes. Preadipocytes showed good penetration into deeper layers of the scaffold, whereas keratinocytes attached only to the uppermost surface of the matrix. This approach towards a multi-layered skin substitute might be a useful asset for future reconstructive surgery.
