Publications by authors named "Michael C Hacker"

Innovative hyphenated technologies, such as size exclusion chromatography coupled with capillary-enhanced Raman spectroscopy (SEC-CERS), enable more comprehensive analyses of biopharmaceutical drug products. However, specialized software for processing and analyzing data from these advanced techniques is often lacking. This study introduces the R package StreamFind, which is designed to help users seamlessly process both chromatographic and Raman spectroscopic data within an integrated workflow.

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Due to an aging society and the associated increase in age-related eye diseases of the posterior segment of the eye, an optimized in vitro vitreous model would be beneficial to assess drug release and distribution in preclinical dosage form development. A key component in such a test system is a compartment simulating the vitreous body. Several hydrogels have been proposed for this purpose.

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A platform of two-component cross-linked hydrogel (cGEL) based on gelatinous peptides and anhydride-containing cross-linkers (oPNMA, oPDMA) is extended for use in peripheral nerve regeneration. Hybrid composites with bio-/chemical cues for enhanced biophysical and biochemical properties were fabricated by covalently grafting small molecular, heterobifunctional amines including the nerve growth factor mimetic LM11A-31 to the oligomeric cross-linkers prior to hydrogel formation. The cytocompatibility and growth-supportive conditions within the matrix are confirmed for pristine and modified hydrogels using L929 mouse fibroblasts and human adipose-derived stem cells (hASCs).

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The analysis of serum for biomarkers is a standard method in clinical diagnosis and health assessment. The application of Raman spectroscopy to probe biomarkers in serum is increasingly investigated due to its time- and cost-efficiency. However, time-consuming sample preparation is often required to analyze the serum samples.

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This study presents the effects of treating polystyrene (PS) cell culture plastic with oxidoreductase enzyme laccase and the catechol substrates caffeic acid (CA), L-DOPA, and dopamine on the culturing of normal human epidermal melanocytes (NHEMs) and human embryonal carcinoma cells (NTERA-2). The laccase-substrate treatment improved PS hydrophilicity and roughness, increasing NHEM and NTERA-2 adherence, proliferation, and NHEM melanogenesis to a level comparable with conventional plasma treatment. Cell adherence dynamics and proliferation were evaluated.

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In this study, deep UV resonance Raman spectroscopy (DUV-RRS) was coupled with high performance liquid chromatography (HPLC) to be applied in the field of pharmaceutical analysis. Naproxen, Metformin and Epirubicin were employed as active pharmaceutical ingredients (APIs) covering different areas of the pharmacological spectrum. Raman signals were successfully generated and attributed to the test substances, even in the presence of the dominant solvent bands of the mobile phase.

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Purpose: Hydrogels derived from decellularized tissues are promising biomaterials in tissue engineering, but their rapid biodegradation can hinder in vitro cultivation. This study aimed to retard biodegradation of a hydrogel derived from porcine decellularized lacrimal glands (dLG-HG) by crosslinking with genipin to increase the mechanical stability without affecting the function and viability of lacrimal gland (LG)-associated cells.

Methods: The effect of different genipin concentrations on dLG-HG stiffness was measured rheologically.

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Article Synopsis
  • Sustainable treatment for aqueous deficient dry eye (ADDE) is lacking, necessitating new strategies like tissue-specific hydrogels that mimic the extracellular matrix to support cell function.
  • Researchers developed a decellularized lacrimal gland hydrogel (dLG-HG) that maintains the necessary biochemical properties, showing improved cell proliferation and secretion capabilities compared to standard culture substrates like Matrigel and collagen type-I.
  • While dLG-HG promotes vital cell interactions and functions, its rapid biodegradation poses challenges for long-term cultivation, indicating a need for further research to slow this process.
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The online coupling of size exclusion chromatography (SEC) to capillary enhanced Raman spectroscopy (CERS) based on a liquid core waveguide (LCW) flow cell was applied for the first time to assess the higher-order structure of different proteins. This setup allows recording of Raman spectra of the monomeric protein within complex mixtures, since SEC enables the separation of the monomeric protein from matrix components such as excipients of a biopharmaceutical product and higher molecular weight species (e.g.

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Label-free identification of tumor cells using spectroscopic assays has emerged as a technological innovation with a proven ability for rapid implementation in clinical care. Machine learning facilitates the optimization of processing and interpretation of extensive data, such as various spectroscopy data obtained from surgical samples. The here-described preclinical work investigates the potential of machine learning algorithms combining confocal Raman spectroscopy to distinguish non-differentiated glioblastoma cells and their respective isogenic differentiated phenotype by means of confocal ultra-rapid measurements.

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This study describes the synthesis, radiofluorination and purification of an anionic amphiphilic teroligomer developed as a stabilizer for siRNA-loaded calcium phosphate nanoparticles (CaP-NPs). As the stabilizing amphiphile accumulates on nanoparticle surfaces, the fluorine-18-labeled polymer should enable to track the distribution of the CaP-NPs in brain tumors by positron emission tomography after application by convection-enhanced delivery. At first, an unmodified teroligomer was synthesized with a number average molecular weight of 4550 ± 20 Da by free radical polymerization of a defined composition of methoxy-PEG-monomethacrylate, tetradecyl acrylate and maleic anhydride.

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Article Synopsis
  • The study develops a 3D scaffold that mimics natural cell environments with adjustable properties using a special photo-cross-linkable resin.
  • The resin is composed of various acrylate monomers that help improve cell interaction and control the scaffold’s phase transition temperature.
  • The research demonstrated that temperature changes can stimulate the growth of muscle cells in these printed scaffolds, suggesting potential applications in tissue engineering.
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RNA interference opened new approaches for disease treatment but safe and efficient cell delivery remains a bottleneck. Extracellular vesicles (EVs) are known to naturally shuttle RNA. Due to their potent cell internalization and low-cost scalability, milk-derived EVs in particular are considered promising RNA delivery systems.

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Article Synopsis
  • The study explores how loading siRNA into gelatin microparticles (cGM) can enhance targeted therapies for bone health.
  • The researchers combined these siRNA-loaded cGM with human mesenchymal stem cells (hMSC) to create microtissues, leading to increased alkaline phosphatase activity after silencing chordin, which inhibits bone formation.
  • The microtissues showed improved bone-related activity in a co-culture model with blood cells, suggesting they could potentially promote bone growth and maintain bone health.
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Convection-enhanced delivery (CED) has been introduced as a concept in cancer treatment to generate high local concentrations of anticancer therapeutics and overcome the limited diffusional distribution, e.g., in the brain.

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The aim of this study was the evaluation of cross-linked gelatin microparticles (cGM) as substrates for osteogenic cell culture to assemble 3D microtissues and their use as delivery system for siRNA to cells in these assemblies. In a 2D transwell cultivation system, we found that cGM are capable to accumulate calcium ions from the surrounding medium. Such a separation of cGM and SaOS-2 ​cells consequently led to a suppressed matrix mineral formation in the SaOS-2 culture on the well bottom of the transwell system.

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The present study analyzes the capacity of collagen (coll)/sulfated glycosaminoglycan (sGAG)-based surface coatings containing bioactive glass nanoparticles (BGN) in promoting the osteogenic differentiation of human mesenchymal stroma cells (hMSC). Physicochemical characteristics of these coatings and their effects on proliferation and osteogenic differentiation of hMSC were investigated. BGN were stably incorporated into the artificial extracellular matrices (aECM).

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Macromers, polymeric molecules with at least two functional groups for cross-polymerization, are interesting materials to tailor mechanical, biochemical and degradative bulk and surface properties of implants for tissue regeneration. In this review we focus on macromers with at least one biodegradable building block. Manifold design options, such as choice of polymeric block(s), optional core molecule and reactive groups, as well as cross-co-polymerization with suitable anchor or linker molecules, allow the adaptation of macromer-based biomaterials towards specific application requirements in both hard and soft tissue regeneration.

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Bovine milk-derived extracellular vesicles (EVs) hold promises as oral drug delivery systems. Since EV bioavailability studies are difficult to compare, key factors regarding EV uptake and intestinal permeability remain little understood. This work aims to critically study uptake and transport properties of milk-derived EVs across the intestinal barrier in vitro by standardization approaches.

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The performance of artificial nerve guidance conduits (NGC) in peripheral nerve regeneration can be improved by providing structures with multiple small channels instead of a single wide lumen. 3D-printing is a strategy to access such multi-channeled structures in a defined and reproducible way. This study explores extrusion-based 3D-printing of two-component hydrogels from a single cartridge printhead into multi-channeled structures under aseptic conditions.

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Injectable gelatine-based hydrogels are valuable tools for drug and cell delivery due to their extracellular matrix-like properties that can be adjusted by the degree of cross-linking. We have established anhydride-containing oligomers for the cross-linking of gelatine via anhydride-amine-conjugation. So far, this conversion required conditions not compatible with cell encapsulation or in vivo injection.

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Article Synopsis
  • The study focused on developing hybrid glass scaffolds that release calcium to enhance integration into bone tissue while maintaining mechanical strength.
  • Various calcium sources, including CaCl and bioactive glass microparticles, were tested for their release profiles; lower CaCl concentrations showed more controlled release, while BG-MP provided a linear release over 12 weeks.
  • In cell culture tests with osteoblast-like cells, the integration of these calcium sources did not significantly improve osteogenic differentiation, possibly due to the consumption of released calcium ions by formed mineral layers.
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High serum levels of Wnt antagonists are known to be involved in delayed bone defect healing. Pharmaceutically active implant materials that can modulate the micromilieu of bone defects with regard to Wnt antagonists are therefore considered promising to support defect regeneration. In this study, we show the versatility of a macromer based biomaterial platform to systematically optimize covalent surface decoration with high-sulfated glycosaminoglycans (sHA3) for efficient scavenging of Wnt antagonist sclerostin.

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Background: Delayed bone regeneration of fractures in osteoporosis patients or of critical-size bone defects after tumor resection are a major medical and socio-economic challenge. Therefore, the development of more effective and osteoinductive biomaterials is crucial.

Methods: We examined the osteogenic potential of macroporous scaffolds with varying pore sizes after biofunctionalization with a collagen/high-sulfated hyaluronan (sHA3) coating in vitro The three-dimensional scaffolds were made up from a biodegradable three-armed lactic acid-based macromer (TriLA) by cross-polymerization.

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Pericardium-based tissue transplantation is a lifesaving treatment. Commercial glutaraldehyde-treated pericardial tissue exhibits cytotoxicity, which is associated with the accelerated graft failure. Replacement of glutaraldehyde has been suggested to overcome those drawbacks.

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