Biology subjects

Krause, K.-H.

Publications and source records attributed to Krause, K.-H..

4 recordsLinked to original sources

bioRxiv2022

A cellular assay for spike/ACE2 fusion: quantification of fusion-inhibitory antibodies after COVID-19 and vaccination

Not all antibodies against SARS-CoV-2 inhibit viral entry and hence infection. Neutralizing antibodies are more likely to reflect real immunity, however certain of these tests investigate protein/protein interaction rather than the fusion event. Viral and pseudoviral entry assays detect functionally active antibodies, however they are cumbersome and burdened by biosafety and standardization issues. We have developed a Spike/ACE2-dependant cell-to-cell fusion assay, based on a split luciferase. Hela cells stably transduced with Spike and a large fragment of luciferase were co-cultured with Hela cells transduced with ACE2 and the complementary small fragment of luciferase. Within 24h, cell fusion occured allowing the measurement of luminescence. Light emission was abolished in the absence of Spike and reduced in the presence of an inhibitor of Spike-processing proteases. Serum samples from COVID-19-negative, non-vaccinated individuals, or sera from patients at the moment of first symptoms did not lead to a significant reduction of fusion. In contrast, sera from COVID-19-positive patients as well as sera from vaccinated individuals reduced the fusion. In conclusion, we report a new method measuring fusion-inhibitory antibodies in serum, combining the advantage of a functional full Spike/ACE2 interaction with a high degree of standardization, easily allowing automation in a standard bio-safety environment.

microbiology↗

bioRxiv2022

Efficacy and safety of a patch containing adipose-derived stem cells for skin wound healing. Results form a comprehensive pre-clinical evaluation program

Mesenchymal stem cell-based therapies are emerging as innovative approaches to treat chronic wounds. A common administration route used in clinical trials consists of local injections leading to uncontrolled/sub-optimal delivery. This study reports a comprehensive pre-clinical evaluation program on the mechanism of action, efficacy and safety of an easy-to-use patch that concentrates Adipose-derived Stem Cells (ASCs) in a clinical-grade sponge of porcine crosslinked-gelatin. ASCs were prepared from the fat of ischemic patients. Transcriptome and proteome of ASC-patches and ASC monolayers were assessed by microarrays, bio-arrays and mass spectrometry. Tumorigenesis was investigated in immunosuppressed mice according to the European Pharmacopeia. Angiogenesis was assessed in vivo in the chick chorioallantoic membrane model. Efficacy of the ASC-patch was tested in a rat model of ischemic full-thickness skin defect. Cell stability was assessed by luminescence using ASC-patches generated from ASCs stably transduced with firefly luciferase. ASCs from ischemic patients upregulated the transcription of multiple genes involved in skin wound healing when cultured within the ASC-patch formulation. The patch was not only a concentrator, but also a reservoir of both ASC-derived regenerative factors and sponge-derived soluble fragments having healing capacity. The secretome of the ASC-patch promoted dermal fibroblast survival and epidermal epithelialization. No tumor formation was observed in immunodeficient Nude mice subcutaneously transplanted with the ASC-patch. Transplanted patches were early invaded by new vessels in vivo, and a marked angiogenesis was confirmed in two independent animal models. Finally, ASC-patches prepared from syngeneic rats promoted faster healing and re-vascularization of full-thickness skin defects in a rat animal model. Of note, ASCs were viable and locally stable for at least two weeks in vivo. We provide here compelling pre-clinical evidence that patches concentrating ASCs within crosslinked gelatin may represent a convenient and effective tool for the management of chronic wounds.

bioengineering↗

bioRxiv2020

Neurothreads: Cryogel carrier-based differentiation and delivery of mature neurons in the treatment of Parkinson's disease

We present in-vivo transplantation of mature dopaminergic neurons by means of macroporous, injectable carriers, to enhance cell therapy in Parkinsons disease. The carriers are synthesized by crosslinking carboxymethylcellulose at subzero temperatures, resulting in cylindrical, highly resilient porous cryogels, which we term Neurothreads. We develop efficient covalent immobilization of the neural adhesion proteins laminin 111, collagen IV and fibronectin, as well as of the extracellular matrix extract Matrigel to the Neurothreads. We observe the highest neural spreading on laminin 111 and Matrigel. We show compatibility with established dopaminergic differentiation of both HS420 human embryonic stem cells and the LUHMES midbrain model cell line. The porous Neurothread carriers withstand compression during minimally invasive stereotactic injection, and ensure viability of mature neurons including extended neurites. Implanted into the striatum in mice, the Neurothreads enable survival of transplanted mature neurons obtained by directed differentiation of the HS420 human embryonic stem cells, as a dense tissue in situ, including dopaminergic cells. With the successful in-vivo transfer of intact, mature and fully open 3D neural networks, we provide a powerful tool to extend established differentiation protocols to higher maturity and to enhance preconfigured neural network transplantation.

bioengineering↗

bioRxiv2018

Navigating in vitro bioactivity data: investigating available resources using model compounds

Modern medicine and an increasingly complex environment contribute to exposure of humans to a large number of chemical compounds, that can potentially be toxic. Although widely used, compound testing in animals has important limitations. In vitro testing provides a promising alternative. However, because of the relative inaccessibility and fragmentation of available data, the in vitro approach largely underperforms its potential. The aim of this study is to investigate how available public online resources (tools and databases) support accessing and distribution of in vitro compound data. We examined 19 public online resources, mapped their features, and evaluated their usability with a set of four model compounds (aspirin, rosiglitazone, valproic acid, and tamoxifen). By investigating compound names and identifiers, we observed extensive variation and inconsistencies in available resources: the synonyms were different, compounds structural identifiers (InChI, InChIKey, SMILES and IUPAC systematic name) underperformed in omics databases, identification of compound related metadata (e.g. concentrations used in the experiments) from omics experiments was complex and none of the available resources clearly distinguished between in vivo and in vitro data. In addition, we estimated accessibility of selected public resources using computational queries. Only a few public resources provided access to compound-related data using semantic web technology. The general quality of experiment annotations created further difficulties in identifying data of interest. Therefore, we identified several standardized ontologies with potential to provide an increased accuracy for extensive data retrieval of in vitro compound data. Furthermore, using the examples of our model compounds, we provide recommendations on the use of ontologies by suggesting specific ontology terms to annotate in vitro experimental data when being published.

pharmacology and toxicology↗