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Gangliosides are an indispensable glycolipid class concentrated on cell surfaces with a critical role in stem cell differentiation. Nonetheless, owing to the lack of suitable methods for scalable analysis covering the full scope of ganglioside molecular diversity, their mechanistic properties in signaling and differentiation remain undiscovered to a large extent. This work introduces a sensitive and comprehensive ganglioside assay based on liquid chromatography, high-resolution mass spectrometry, and multistage fragmentation. Complemented by an open-source data evaluation workflow, we provide automated in-depth lipid species-level and molecular species-level annotation based on decision rule sets for all major ganglioside classes. Compared to conventional state-of-the-art methods, the presented ganglioside assay offers (1) increased sensitivity, (2) superior structural elucidation, and (3) the possibility to detect novel ganglioside species. A major reason for the highly improved sensitivity is the optimized spectral readout based on the unique capability of two parallelizable mass analyzers for multistage fragmentation. We demonstrated the high-throughput universal capability of our novel analytical strategy by identifying 254 ganglioside species. As a proof of concept, 137 unique gangliosides were annotated in native and differentiated human mesenchymal stem cells including 78 potential cell-state-specific markers and 38 previously unreported gangliosides. A general increase of the ganglioside numbers upon differentiation was observed as well as cell-state-specific clustering based on the ganglioside species patterns. The combination of the developed glycolipidomics assay with the extended automated annotation tool enables comprehensive in-depth ganglioside characterization as shown on biological samples of interest. Our results suggest ganglioside patterns as a promising quality control tool for stem cells and their differentiation products. Additionally, we believe that our analytical workflow paves the way for probing glycolipid-based biochemical processes shedding light on the enigmatic processes of gangliosides and glycolipids in general.

Skin equivalents and skin explants are widely used for dermal penetration studies in the pharmacological development of drugs. Environmental parameters, such as the incubation and culture conditions affect cellular responses and thus the relevance of the experimental outcome. However, available systems such as the Franz diffusion chamber, only measure in the receiving culture medium, rather than assessing the actual conditions for cells in the tissue. We developed a sampling design that combines open flow microperfusion (OFM) sampling technology for continuous concentration measurements directly in the tissue with microfluidic biosensors for online monitoring of culture parameters. We tested our design with real-time measurements of oxygen, glucose, lactate, and pH in full-thickness skin equivalent and skin explants. Furthermore, we compared dermal penetration for acyclovir, lidocaine, and diclofenac in skin equivalents and skin explants. We observed differences in oxygen, glucose, and drug concentrations in skin equivalents compared to the respective culture medium and to skin explants.

Extracellular vesicles (EVs) are cell-derived membrane structures exerting major effects in physiological as well as pathological processes by functioning as vehicles for the delivery of biomolecules to their target cells. An increasing number of effects previously attributed to cell-based therapies have been recognized to be actually mediated by EVs derived from the respective cells, suggesting the administration of purified EVs instead of living cells for cell-based therapies. In this review, we focus on the heterogeneity of EVs derived from mesenchymal stem/stromal cells (MSC) and summarize upstream process parameters that crucially affect the resulting therapeutic properties and biological functions. Hereby, we discuss the effects of the cell source, medium composition, 3D culture, bioreactor culture and hypoxia. Furthermore, aspects of the isolation and storage strategies influences EVs are described. Conclusively, optimization of upstream process parameters should focus on controlling MSC-derived EV heterogeneity for specific therapeutic applications. Graphical Abstract

Gangliosides are an indispensable glycolipid class concentrated on cell surfaces with a critical role in stem cell differentiation. Nonetheless, owing to the lack of suitable methods for scalable analysis covering the full scope of ganglioside molecular diversity, their mechanistic properties in signaling and differentiation remain undiscovered to a large extent. This work introduces a sensitive and comprehensive ganglioside assay based on liquid chromatography, high-resolution mass spectrometry, and multistage fragmentation. Complemented by an open-source data evaluation workflow, we provide automated in-depth lipid species-level and molecular species-level annotation based on decision rule sets for all major ganglioside classes. Compared to conventional state-of-the-art methods, the presented ganglioside assay offers (1) increased sensitivity, (2) superior structural elucidation, and (3) the possibility to detect novel ganglioside species. A major reason for the highly improved sensitivity is the optimized spectral readout based on the unique capability of two parallelizable mass analyzers for multistage fragmentation. In addition to the significant technological advance, we identified 263 ganglioside species including cell-state-specific markers and previously unreported gangliosides in native and differentiated human mesenchymal stem cells. A general increase of the ganglioside numbers upon differentiation was observed as well as cell-state-specific clustering based on the ganglioside species patterns. By proving the predictive power of gangliosides as ubiquitous cell state-specific markers, we demonstrated the high throughput universal capability of our novel analytical strategy, which comes with new insights on the biological role of gangliosides in stem cell differentiation. Our analytical workflow will pave the way for new ganglioside- and glycolipid-based clusters of differentiation markers to determine stem cell phenotypes.

The use of 3D cell cultures has gained increasing importance in medical and pharmaceutical research. However, the analysis of the culture medium is hardly representative for the culture conditions within a 3D model which hinders the standardization of 3D cultures and translation of results. Therefore, we developed a modular monitoring platform combining a perfusion bioreactor with an integrated minimally invasive sampling system and implemented sensors that enables the online monitoring of culture parameters and medium compounds within 3D cultures. As a proof-of-concept, primary cells as well as cell lines were cultured on a collagen or gelatin methacryloyl (GelMA) hydrogel matrix, while monitoring relevant culture parameters and analytes. Comparing the interstitial fluid of the 3D models versus the corresponding culture medium, we found considerable differences in the concentrations of several analytes. These results clearly demonstrate that analyses of the culture medium only are not relevant for the development of standardized 3D culture processes. The presented bioreactor with an integrated sampling and sensor platform opens new horizons for the development, optimization, and standardization of 3D cultures. Furthermore, this technology holds the potential to reduce animal studies and improve the transferability of pharmaceutical in vitro studies by gaining more relevant results, bridging the gap towards clinical translation.

Matrix remodeling could be an important mode of action of multipotent mesenchymal stromal cells (MSC) in extracellular matrix (ECM) disease, but knowledge is limited in this respect. As MSC are well-known to adapt their behavior to their environment, we aimed to investigate if their mode of action would change in response to healthy versus pathologically altered ECM. Human MSC-derived ECM was produced under different culture conditions, including standard culture, culture on Matrigel-coated dishes, and stimulation with the pro-fibrotic transforming growth factor-β1 (TGFβ1). The MSC-ECM was decellularized, characterized by histochemistry, and used as MSC culture substrate reflecting different ECM conditions. MSC were cultured on the different ECM substrates or in control conditions for 2 days. Culture on ECM increased the presence of surface molecules with ECM receptor function in the MSC, demonstrating an interaction between MSC and ECM. In MSC cultured on Matrigel-ECM and TGFβ1-ECM, which displayed a fibrosis-like morphology, gene expression of collagens and decorin, as well as total matrix metalloproteinase (MMP) activity in the supernatant were decreased as compared with control conditions. These results demonstrated that MSC adapt to their ECM environment, which may include pathological adaptations that could compromise therapeutic efficacy.

Multipotent mesenchymal stromal cells (MSC) and MSC-derived products have emerged as promising therapeutic tools. To fully exploit their potential, further mechanistic studies are still necessary and bioprocessing needs to be optimized, which requires an abundant supply of functional MSC for basic research. To address this need, here we used a novel technology to establish a human adipose-derived MSC line with functional characteristics representative of primary MSC. Primary MSC were isolated and subjected to lentiviral transduction with a library of expansion genes. Clonal cell lines were generated and evaluated on the basis of their morphology, immunophenotype, and proliferation potential. One clone (K5 iMSC) was then selected for further characterization. This clone had integrated a specific transgene combination including genes involved in stemness and maintenance of adult stem cells. Favorably, the K5 iMSC showed cell characteristics resembling juvenile MSC, as they displayed a shorter cell length and enhanced migration and proliferation compared with the non-immortalized original primary MSC (p < 0.05). Still, their immunophenotype and differentiation potential corresponded to the original primary MSC and the MSC definition criteria, and cytogenetic analyses revealed no clonal aberrations. We conclude that the technology used is applicable to generate functional MSC lines for basic research and possible future bioprocessing applications.

Mesenchymal stem cells (MSCs) are of great interest for their use in cell-based therapies due to their multipotent differentiation and immunomodulatory capacities. In consequence of limited numbers following their isolation from the donor tissue, MSCs require extensive expansion performed in traditional 2D cell culture setups to reach adequate amounts for therapeutic use. However, prolonged culture of MSCs in vitro has been shown to decrease their differentiation potential and alter their immunomodulatory properties. For that reason, preservation of these physiological characteristics of MSCs throughout their in vitro culture is essential for improving the efficiency of therapeutic and in vitro modeling applications. With this objective in mind, many studies already investigated certain parameters for enhancing current standard MSC culture protocols with regard to the effects of specific culture media components or culture conditions. Although there is a lot of diversity in the final therapeutic uses of the cells, the primary stage of standard isolation and expansion is imperative. Therefore, we want to review on approaches for optimizing standard MSC culture protocols during this essential primary step of in vitro expansion. The reviewed studies investigate and suggest improvements focused on culture media components (amino acids, ascorbic acid, glucose level, growth factors, lipids, platelet lysate, trace elements, serum, and xenogeneic components) as well as culture conditions and processes (hypoxia, cell seeding, and dissociation during passaging), in order to preserve the MSC phenotype and functionality during the primary phase of in vitro culture.

When starting to work with 3D cell cultures it is essential to be aware of the differences to common 2D cultures in terms of expenses and equipment as well as the type and dimension of 3D you intend to work with. The various culture methods require different equipment, efforts, and awareness on handling and analytics. Therefore, it is crucial to choose the right structure and architecture, the respective carrier/scaffold, the equipment for generating and culturing the models, and the methodology to manipulate and analyze them to be able to perform the process for the application answering the hypothesis. There is a wide range of commercially available lab equipment, bioreactors, consumables, carriers/scaffolds, and assays necessary to establish, perform, and analyze 3D cell culture. Handling, manipulation, and analysis of 3D cultures, differing significantly from 2D cultures, with the respective requirements and efforts will be considered as well. An overview on scaffold free 3D cell culture will be provided in Chap. 9.

This chapter will provide an overview on scaffold-free 3D models focusing on aggregates, spheroids, and organoids. While often used synonymously, the differences are presented as well as the origin and advancement until the current date. Moreover, the advantages that scaffold-free systems offer and their limitations are discussed as well as fields of applications ranging from stem cell expansion, pharmacological high-throughput tumor drug screening for personalized medicine, to human-on-a-chip systems facilitating the systemic investigation of drug metabolization reducing animal experiments by considering multiple organ functions within one setup. Furthermore, approaches and requirements for the generation and cultivation strategies are outlined.

The utilization of mesenchymal stem/stromal cells raises new hopes in treatment of diseases and pathological conditions, while at the same time bringing immense challenges for researchers, manufacturers and physicians. It is essential to consider all steps along the in vitro fabrication of cell-based products in order to reach efficient and reproducible treatment outcomes. Here, the optimal protocols for isolation, cultivation and differentiation of mesenchymal stem cells are required. In this review we discuss these aspects and their influence on the final cell-based product quality. We demonstrate that physiological in vitro cell cultivation conditions play a crucial role in therapeutic functionalities of cultivated cells. We show that three-dimensional cell culture, dynamic culture conditions and physiologically relevant in vitro oxygen concentrations during isolation and expansion make a decisive contribution towards the improvement of cell-based products in regenerative medicine.

Mesenchymal stem cells (MSCs) are primary candidates in tissue engineering and stem cell therapies due to their intriguing regenerative and immunomodulatory potential. Their ability to self-assemble into three-dimensional (3D) aggregates further improves some of their therapeutic properties, e.g., differentiation potential, secretion of cytokines, and homing capacity after administration. However, high hydrodynamic shear forces and the resulting mechanical stresses within commercially available dynamic cultivation systems can decrease their regenerative properties. Cells embedded within a polymer matrix, however, lack cell-to-cell interactions found in their physiological environment. Here, we present a “semi scaffold-free” approach to protect the cells from high shear forces by a physical barrier, but still allow formation of a 3D structure with in vivo-like cell-to-cell contacts. We highlight a relatively simple method to create core–shell capsules by inverse gelation. The capsules consist of an outer barrier made from sodium alginate, which allows for nutrient and waste diffusion and an inner compartment for direct cell-cell interactions. Next to capsule characterization, a harvesting procedure was established and viability and proliferation of human adipose-derived MSCs were investigated. In the future, this encapsulation and cultivation technique might be used for MSC-expansion in scalable dynamic bioreactor systems, facilitating downstream procedures, such as cell harvest and differentiation into mature tissue grafts.

3D printing is increasingly important for the rapid prototyping of advanced and tailor-made cell culture devices. In this context, stereolithography represents a method for the rapid generation of prototypes from photocurable polymers. However, the biocompatibility of commercially available photopolymers is largely unknown. Therefore, we evaluated the cytotoxicity of six polymers, two of them certified as biocompatible according to ISO 10993-5:2009, and we evaluated, if coating with Parylene, an inert polymer widely used in medical applications, might shield cells from the cytotoxic effects of a toxic polymer. In addition, we evaluated the processability, reliability, and consistency of the details printed. Human mesenchymal stem cells (MSCs) were used for cytotoxicity testing as they are widely used and promising for numerous applications in regenerative medicine. MSCs were incubated together with printed photopolymers, and the cytotoxicity was assessed. All photopolymers significantly reduced the viability of MSCs while the officially biocompatible resins displayed minor toxic effects. Further, coating with Parylene completely protected MSCs from toxic effects. In conclusion, none of the tested polymers can be fully recommended for rapid prototyping of cell culture devices. However, coating with Parylene can shield cells from toxic effects and thus might represent a viable option until more compatible materials are available.

The standard cell culture oxygen concentration of 21 percent O2 does not represent the physiologic environment of stem cells. Indeed, hypoxic (< 21 percent O2) conditions heavily affect cellular processes such as growth, apoptosis and energy metabolism. In the context of clinical trials a fast ex vivo expansion of stem cells while maintaining their stem cell properties is crucial. However, maintaining hypoxic conditions during cultivation is challenging and puts high requirements on laboratory equipment.

Targeted nanomedicine builds on the concept that nanoparticles can be directed to specific tissues while remaining inert to others organs. Many studies have been performed on the synthesis and cellular interactions of core-shell nanoparticles, in which a functional inorganic core is coated with a biocompatible polymer layer that should reduce nonspecific uptake and cytotoxicity. However, work is lacking that relates structural parameters of the core-shell structure and colloidal properties directly to interactions with cell membranes and further correlates these interactions to cell uptake. We have synthesized monodisperse (SD10%), single-crystalline, and superparamagnetic iron oxide nanoparticles (SPION) of different core size (3-8 nm) that are densely grafted with nitrodopamine-poly(ethylene glycol) (NDA-PEG(5 kDa)) brushes. We investigated the interactions of the PEGylated SPION with biomimetic membranes and cancer and kidney cells. It is shown that a dense homogeneous PEG shell suppresses membrane interactions and cell uptake but that nanoparticle curvature can influence membrane interactions for similarly grafted nanoparticles. Weak adsorption to anionic lipid membranes is shown to correlate with eukaryote cell uptake and is attributed to double-layer interactions without direct membrane penetration. This attraction is strongly suppressed during physiological conditions and leads to unprecedented low cell uptake and full cell viability when compared to those of traditional dextran-coated SPION. Less curved (larger core) PEGylated SPION show weaker membrane adsorption and lower cell uptake due to effectively denser shells. These results provide a better understanding of design criteria for core-shell nanoparticles in terms of avoiding nonspecific uptake by cells, reducing toxicity, and increasing circulation time.

The p-value is the most prominent established metric for statistical significance in non-targeted metabolomics. However, its adequacy has repeatedly been the subject of discussion criticizing its uncertainty and its dependence on sample size and statistical power. These issues compromise non-targeted metabolomics in model systems, where studies typically investigate 5–10 samples per group. In this paper we propose a different approach for assessing the relevance of fold change (FC) data, where the FC is treated as a quantitative value and is validated by uncertainty budgeting. For the purpose of large-scale application in non-targeted metabolomics, we present a simplified approach for uncertainty propagation using experimental standard deviations of metabolite intensities as type A-summarized standard uncertainties. The resulting expanded FC uncertainty can be used to derive a minimum relevant FC as a complementary criterion in metabolomics data evaluation. This concept overcomes the need for a uniform p-value cut-off for all metabolites by considering the experimental uncertainty for each metabolite individually. The proposed procedure is part of analytical method validation, however the concept has not previously been applied to non-targeted metabolomics. A case study on mesenchymal stem cells cultured in normoxia and hypoxia demonstrates the practical value of this approach, in particular for studies with a small sample size. An online two-dimensional LC method coupled to mass spectrometry was crucial in providing both broad metabolome coverage and excellent experimental precision (

Mesenchymal stem/stromal cells (MSCs) display a variety of therapeutically relevant effects, such as the induction of angiogenesis, particularly under hypoxic conditions. It is generally recognized that MSCs exert their effects by secretion of paracrine factors and by stimulation of host cells. Furthermore, there is increasing evidence that some therapeutically relevant effects of MSCs are mediated by MSC-derived extracellular vesicles (EVs). Since our current knowledge on MSC-derived EVs released under hypoxic conditions is very limited, we aimed to characterize MSC-derived EVs from normoxic vs. hypoxic conditions (5% O2). Adipose-derived MSCs were grown under normoxic and hypoxic conditions, and EVs were analyzed by flow cytometry using lactadherin as a marker for EVs exposing phosphatidylserine, CD63 and CD81 as EV markers, as well as CD73 and CD90 as MSC surface markers. Particle concentration and size distribution were measured by nanoparticle tracking analysis (NTA), and the EV surface antigen signature was characterized using bead-based multiplex flow cytometry. Furthermore, we evaluated the potential of MSC-derived EVs obtained under hypoxic conditions to support angiogenesis using an in vitro assay with an hTERT-immortalized human umbilical vein endothelial cell (HUVEC) line. Proliferation and viability of MSCs were increased under hypoxic conditions. EV concentration, size, and surface signature did not differ significantly between normoxic and hypoxic conditions, with the exception of CD44, which was significantly upregulated on normoxic EVs. EVs from hypoxic conditions exhibited increased tube formation as compared to normoxic EVs or to the corresponding supernatants from both groups, indicating that tube formation is facilitated by EVs rather than by soluble factors. In conclusion, hypoxia conditioned MSC-derived EVs appear to be functionally more potent than normoxic MSC-derived EVs regarding the induction of angiogenesis.

Mesenchymal stem cells (MSCs) are considered as primary candidates for cell-based therapies due to their multiple effects in regenerative medicine. Pre-conditioning of MSCs under physiological conditions—such as hypoxia, three-dimensional environments, and dynamic cultivation—prior to transplantation proved to optimize their therapeutic efficiency. When cultivated as three-dimensional aggregates or spheroids, MSCs display increased angiogenic, anti-inflammatory, and immunomodulatory effects as well as improved stemness and survival rates after transplantation, and cultivation under dynamic conditions can increase their viability, proliferation, and paracrine effects, alike. Only few studies reported to date, however, have utilized dynamic conditions for three-dimensional aggregate cultivation of MSCs. Still, the integration of dynamic bioreactor systems, such as spinner flasks or stirred tank reactors might pave the way for a robust, scalable bulk expansion of MSC aggregates or MSC-derived extracellular vesicles. This review summarizes recent insights into the therapeutic potential of MSC aggregate cultivation and focuses on dynamic generation and cultivation techniques of MSC aggregates.

This chapter gives insight into commercially available automated cultivation systems for cell culture technologies as well as the theoretical background of process automation and modeling. Exemplary bioreactor systems with sensors, actors, and process principles are described, ranging from the classical stirred tank reactor to more advanced perfused systems. Further, this chapter gives an introduction to principles of process modeling and simulation as well as a theoretical background in process automation and control.

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Introduction Generation of adipose tissue for burn patients that suffer from an irreversible loss of the hypodermis is still one of the most complex challenges in tissue engineering. Electrospun materials with their micro- and nanostructures are already well established for their use as extracellular matrix substitutes. Gelatin is widely used in tissue engineering to gain thickness and volume. Under conventional static cultivation methods the supply of nutrients and transport of toxic metabolites is controlled by diffusion and therefore highly dependent on size and porosity of the biomaterial. A widely used method in order to overcome these limitations is the medium perfusion of 3D biomaterial-cell-constructs. In this study we combined perfusion bioreactor cultivation techniques with electrospun poly( l -lactide-co-glycolide) (P(LLG)) and gelatin hydrogels together with adipose-derived stem cells (ASCs) for a new approach in soft tissue engineering. Methods ASCs were seeded on P(LLG) scaffolds and in gelatin hydrogels and cultivated for 24 hours under static conditions. Thereafter, biomaterials were cultivated under static conditions or in a bioreactor system for three, nine or twelve days with a medium flow of 0.3 ml/min. Viability, morphology and differentiation of cells was monitored. Results ASCs seeded on P(LLG) scaffolds had a physiological morphology and good viability and were able to migrate from one electrospun scaffold to another under flow conditions but not migrate through the mesh. Differentiated ASCs showed lipid droplet formations after 21 days. Cells in hydrogels were viable but showed rounded morphology. Under flow conditions, morphology of cells was more diffuse. Discussion ASCs could be cultivated on P(LLG) scaffolds and in gelatin hydrogels under flow conditions and showed good cell viability as well as the potential to differentiate. These results should be a next step to a physiological three-dimensional construct for soft tissue engineering and regeneration.

Background aims The discovery of regenerative and immunosuppressive capacities of mesenchymal stromal cells (MSCs) raises hope for patients with tissue-damaging or severe, treatment-refractory autoimmune disorders. We previously presented a method to expand human MSCs in a bioreactor under standardized Good Manufacturing Practice conditions. Now we characterized the impact of critical treatment conditions on MSCs with respect to immunosuppressive capabilities and proliferation. Methods MSC proliferation and survival after γ irradiation were determined by 5-carboxyfluorescein diacetate N-succinimidyl ester and annexinV/4′,6-diamidino-2-phenylindole (DAPI) staining, respectively. T-cell proliferation assays were used to assess the effect of γ irradiation, passaging, cryopreservation, post-thaw equilibration time and hypoxia on T-cell suppressive capacities of MSCs. Quantitative polymerase chain reaction and β-galactosidase staining served as tools to investigate differences between immunosuppressive and non-immunosuppressive MSCs. Results γ irradiation of MSCs abrogated their proliferation while vitality and T-cell inhibitory capacity were preserved. Passaging and long cryopreservation time decreased the T-cell suppressive function of MSCs, and postthaw equilibration time of 5 days restored this capability. Hypoxic culture markedly increased MSC proliferation without affecting their T-cell-suppressive capacity and phenotype. Furthermore, T-cell suppressive MSCs showed higher CXCL12 expression and less β-galactosidase staining than non-suppressive MSCs. Discussion We demonstrate that γ irradiation is an effective strategy to abrogate MSC proliferation without impairing the cells' immunosuppressive function. Hypoxia significantly enhanced MSC expansion, allowing for transplantation of MSCs with low passage number. In summary, our optimized MSC expansion protocol successfully addressed the issues of safety and preservation of immunosuppressive MSC function after ex vivo expansion for therapeutic purposes.

Mesenchymal stem cells (MSC) exhibit a high self-renewal capacity, multilineage differentiation potential and immunomodulatory properties. This set of exceptional features makes them an attractive tool for research and clinical application. However, MSC are far from being a uniform cell type, which makes standardization difficult. The exact properties of human MSC (hMSC) can vary greatly depending on multiple parameters including tissue source, isolation method and medium composition. In this review we address the most important influence factors. We highlight variations in the differentiation potential of MSC from different tissue sources. Furthermore, we compare enzymatic isolation strategies with explants cultures focusing on adipose tissue and umbilical cords as two relevant examples. Additionally, we address effects of medium composition and serum supplementation on MSC expansion and differentiation. The lack of standardized methods for hMSC isolation and cultivation mandates careful evaluation of different protocols regarding efficiency and cell quality. MSC characterization based on a set of minimal criteria defined by the International Society for Cellular Therapy is a widely accepted practice, and additional testing for MSC functionality can provide valuable supplementary information. The MSC secretome has been identified as an important signaling mechanism to affect other cells. In this context, extracellular vesicles (EVs) are attracting increasing interest. The thorough characterization of MSC-derived EVs and their interaction with target cells is a crucial step toward a more complete understanding of MSC-derived EV functionality. Here, we focus on flow cytometric approaches to characterize free as well as cell bound EVs and address potential differences in the bioactivity of EVs derived from stem cells from different sources. © 2017 International Society for Advancement of Cytometry.

Extensive expansion of mesenchymal stem cells (MSCs) for cell-based therapies remains challenging since long-term cultivation and excessive passaging in two-dimensional conditions result in a loss of essential stem cell properties. Indeed, low survival rate of cells, alteration of surface marker profiles, and reduced differentiation capacity are observed after in vitro expansion and reduce therapeutic success in clinical studies. Remarkably, cultivation of MSCs in three-dimensional aggregates preserve stem cell properties. Hence, the large scale formation and cultivation of MSC aggregates is highly desirable. Besides other effects, MSCs cultivated under hypoxic conditions are known to display increased proliferation and genetic stability. Therefore, in this study we demonstrate cultivation of adipose derived human MSC aggregates in a stirred tank reactor under hypoxic conditions. Although aggregates were exposed to comparatively high average shear stress of 0.2 Pa as estimated by computational fluid dynamics, MSCs displayed a viability of 78-86% and maintained their surface marker profile and differentiation potential after cultivation. We postulate that cultivation of 3D MSC aggregates in stirred tank reactors is valuable for large-scale production of MSCs or their secreted compounds after further optimization of cultivation parameters.

It is crucial but challenging to keep physiologic conditions during the cultivation of 3D cell scaffold constructs for the optimization of 3D cell culture processes. Therefore, we demonstrate the benefits of a recently developed miniaturized perfusion bioreactor together with a specialized incubator system that allows for the cultivation of multiple samples while screening different conditions. Hence, a decellularized bone matrix was tested towards its suitability for 3D osteogenic differentiation under flow perfusion conditions. Subsequently, physiologic shear stress and hydrostatic pressure (HP) conditions were optimized for osteogenic differentiation of human mesenchymal stem cells (MSCs). X-ray computed microtomography and scanning electron microscopy (SEM) revealed a closed cell layer covering the entire matrix. Osteogenic differentiation assessed by alkaline phosphatase activity and SEM was found to be increased in all dynamic conditions. Furthermore, screening of different fluid shear stress (FSS) conditions revealed 1.5 mL/min (equivalent to ∼10 mPa shear stress) to be optimal. However, no distinct effect of HP compared to flow perfusion without HP on osteogenic differentiation was observed. Notably, throughout all experiments, cells cultivated under FSS or HP conditions displayed increased osteogenic differentiation, which underlines the importance of physiologic conditions. In conclusion, the bioreactor system was used for biomaterial testing and to develop and optimize a 3D cell culture process for the osteogenic differentiation of MSCs. Due to its versatility and higher throughput efficiency, we hypothesize that this bioreactor/incubator system will advance the development and optimization of a variety of 3D cell culture processes.

Collagen is a main component of the extracellular matrix. It is often used in medical applications to support tissue regeneration, hemostasis, or wound healing. Due to different sources of collagen, the properties and performance of available products can vary significantly. In this in vitro study, a comparison of seven different collagen matrices derived from bovine, equine, and porcine sources was performed. As performance indicators, the scaffold function for fibroblasts and platelet aggregation were used. We found strong variation in platelet aggregation and fibroblast growth on the different collagen materials. The observed variations could not be attributed to species differences alone, but were highly dependent on differences in the manufacturing process.

The combination of microfabrication-based technologies with cell biology has laid the foundation for the development of advanced in vitro diagnostic systems capable of analyzing cell cultures under physiologically relevant conditions. In the present review, we address recent lab-on-a-chip developments for stem cell analysis. We highlight in particular the tangible advantages of microfluidic devices to overcome most of the challenges associated with stem cell identification, expansion and differentiation, with the greatest advantage being that lab-on-a-chip technology allows for the precise regulation of culturing conditions, while simultaneously monitoring relevant parameters using embedded sensory systems. State-of-the-art lab-on-a-chip platforms for in vitro assessment of stem cell cultures are presented and their potential future applications discussed.

The use of decellularized tendon tissue as a scaffold for tendon tissue engineering provides great opportunities for future clinical and current research applications. The aim of this study was to assess the effect of repetitive freeze-thaw cycles and two different detergents, t-octyl-phenoxypolyethoxyethanol (Triton X-100) and sodium dodecyl sulfate (SDS), on decellularization effectiveness and cytocompatibility in large tendons. Freshly collected equine superficial and deep digital flexor tendons were subjected to decellularization according to four different protocols (1 and 2: freeze-thaw cycles combined with either Triton X-100 or SDS; 3 and 4: Triton X-100 or SDS). Decellularization effectiveness was assessed based on the reduction of vital cell counts, histologically visible nuclei, and DNA content. Transmission electron microscopy was performed to evaluate cellular and extracellular matrix integrity. Further, cytocompatibility of scaffolds that had been decellularized according to the protocols including freeze-thaw cycles (protocols 1 and 2) was assessed by seeding the scaffolds with superparamagnetic iron oxide labeled mesenchymal stromal cells and monitoring the cells histologically and by magnetic resonance imaging for two weeks. Decellularization was significantly more effective when using the protocols including freeze-thaw cycles, leaving only roughly 1% residual nuclei and 20% residual DNA, whereas samples that had not undergone additional freeze-thaw cycles contained roughly 20% residual nuclei and 40% residual DNA. No morphological extracellular matrix alterations due to decellularization could be observed. Scaffolds prepared by both protocols including freeze-thaw cycles were cytocompatible, but the cell distribution into the scaffold tended to be better in scaffolds that had been decellularized using freeze-thaw cycles combined with Triton X-100 instead of SDS.

The molecular study of fat cell development in the human body is essential for our understanding of obesity and related diseases. Mesenchymal stem/stromal cells (MSC) are the ideal source to study fat formation as they are the progenitors of adipocytes. In this work, we used human MSCs, received from surgery waste, and differentiated them into fat adipocytes. The combination of several layers of information coming from lipidomics, metabolomics and proteomics enabled network analysis of the biochemical pathways in adipogenesis. Simultaneous analysis of metabolites, lipids, and proteins in cell culture is challenging due to the compound&rsquo, s chemical difference, so most studies involve separate analysis with unimolecular strategies. In this study, we employed a multimolecular approach using a two&ndash, phase extraction to monitor the crosstalk between lipid metabolism and protein-based signaling in a single sample (~105 cells). We developed an innovative analytical workflow including standardization with in-house produced 13C isotopically labeled compounds, hyphenated high-end mass spectrometry (high-resolution Orbitrap MS), and chromatography (HILIC, RP) for simultaneous untargeted screening and targeted quantification. Metabolite and lipid concentrations ranged over three to four orders of magnitude and were detected down to the low fmol (absolute on column) level. Biological validation and data interpretation of the multiomics workflow was performed based on proteomics network reconstruction, metabolic modelling (MetaboAnalyst 4.0), and pathway analysis (OmicsNet). Comparing MSCs and adipocytes, we observed significant regulation of different metabolites and lipids such as triglycerides, gangliosides, and carnitine with 113 fully reprogrammed pathways. The observed changes are in accordance with literature findings dealing with adipogenic differentiation of MSC. These results are a proof of principle for the power of multimolecular extraction combined with orthogonal LC-MS assays and network construction. Considering the analytical and biological validation performed in this study, we conclude that the proposed multiomics workflow is ideally suited for comprehensive follow-up studies on adipogenesis and is fit for purpose for different applications with a high potential to understand the complex pathophysiology of diseases.

Bone tissue engineering is an alternative approach to bone grafts. In our study we aim to develop a composite scaffold for bone regeneration made of doped zirconium oxide (ZrO2) conjugated with poly(lactic-co-glycolic acid) (PLGA) particles for the delivery of growth factors. In this composite, the PLGA microspheres are designed to release a crucial growth factor for bone formation, bone morphogenetic protein-2 (BMP2). We found that by changing the polymer's molecular weight and composition, we could control microsphere loading, release and size. The BMP2 released from PLGA microspheres retained its biological activity and increased osteoblastic marker expression in human mesenchymal stem cells (hMSCs). Uncapped PLGA microspheres were conjugated to ZrO2 scaffolds using carbodiimide chemistry, and the composite scaffold was shown to support hMSCs growth. We also demonstrated that human umbilical vein endothelial cells (HUVECs) can be co-cultured with hMSCs on the ZrO2 scaffold for future vascularization of the scaffold. The ZrO2 composite scaffold could serve as a bone substitute for bone grafting applications with the added ability of releasing different growth factors needed for bone regeneration.

Multipotent mesenchymal stromal cells (MSCs) are a promising therapeutic tool for the treatment of equine tendon and other musculoskeletal injuries. While bone marrow is considered the 'gold standard' source of these cells, various other tissues contain MSCs with potentially useful features. The aim of this study was to compare clinically relevant characteristics of MSCs derived from bone marrow, umbilical cord blood and tissue and from adipose tissue and tendon. Cell yield, proliferation, migration, tendon marker expression and differentiation into adipocytes, chondrocytes and osteoblasts was assessed, quantified and compared. MSC numbers obtained from adipose, tendon or umbilical cord tissues were 222-fold higher than those obtained from bone marrow or cord blood. Cells derived from tendon and adipose tissues exhibited most rapid proliferation. Osteogenic differentiation was most prominent in MSCs derived from bone marrow, and was weak in MSCs derived from umbilical cord blood and tissue. In contrast, the highest levels of chondrogenic differentiation were observed in MSCs derived from these sources. Collagen 1A2 expression was highest in adipose- and tendon-derived MSCs, while scleraxis expression was highest in cord blood- and in tendon-derived MSCs. The findings indicate that MSCs from different sources display significantly diverse properties that may impact on their therapeutic application.

Mesenchymal stem or stromal cells (MSC) have proven to offer great promise for cell-based therapies and tissue engineering applications, as these cells are capable of extensive self-renewal and display a multilineage differentiation potential. Furthermore, MSC were shown to exhibit immunomodulatory properties and display supportive functions through parakrine effects. Besides bone marrow (BM), still today the most common source of MSC, these cells were found to be present in a variety of postnatal and extraembryonic tissues and organs as well as in a large variety of fetal tissues. Over the last decade, the human umbilical cord and human amnion have been found to be a rich and valuable source of MSC that is bio-equivalent to BM-MSC. Since these tissues are discarded after birth, the cells are easily accessible without ethical concerns.

Surface modification is an important step in production of medical implants. Surface roughening creates additional surface area to enhance the bonding between the implant and the bone. Recent research provided a means to alter the microstructure of titanium by severe plastic deformation (SPD) in order to increase its strength, and thereby reduce the size of the implants (specifically, their diameter). The purpose of the present study was to examine the effect of bulk microstructure of commercially pure titanium with coarse-grained (CG) and ultrafine-grained (UFG) bulk structure on the surface state of these materials after surface modification by sand blasting and acid etching (SLA). It was shown that SLA-modified surface characteristics, in particular, roughness, chemistry, and wettability, were affected by prior SPD processing. Additionally, biocompatibility of UFG titanium was examined using osteosarcoma cell line SaOS-2 and primary human adipose-derived mesenchymal stem cell (adMSC) cultures. Enhanced cell viability as well as increased matrix mineralization during osteogenic differentiation of MSCs on the surface of ultrafine-grained titanium was shown.

Gold(I), gold(III), silver(I) and copper(I) complexes with modified amino acid esters and phosphine ligands have been prepared in order to test their cytotoxic activity. Two different phosphine fragments, PPh and PPhpy (py = pyridine), have been used. The amino acid esters have been modified by introducing an aromatic amine as pyridine that coordinates metal fragments through the nitrogen atom, giving complexes of the type [M(L)(PR)] or [AuCl(L)] (L = l-valine-N-(4-pyridylcarbonyl) methyl ester (L1), l-alanine-N-(4-pyridylcarbonyl) methyl ester (L2), l-phenylalanine-N-(4-pyridylcarbonyl) methyl-ester) (L3); M = Au(I), Ag(I), Cu(I), PR = PPh, PPhpy). The in vitro cytotoxic activity of metal complexes was tested against four tumor human cell lines and one tumor mouse cell line. A metabolic activity test (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT) was used and IC values were compared with those obtained for cisplatin. Several complexes displayed significant cytotoxic activities. In order to determine whether antiproliferation and cell death are associated with apoptosis, NIH-3T3 cells were exposed to five selected complexes (Annexin V + FITC, PI) and analyzed by flow cytometry. These experiments showed that the mechanism by which the complexes inhibit cell proliferation inducing cell death in NIH-3T3 cells is mainly apoptotic., The authors thank the Ministerio de Economía y Competitividad-FEDER CTQ2013-48635-C2-1-P and DGA-FSE (E77) for financial support.

Tendon and ligament pathologies are still a therapeutic challenge, due to the difficulty in restoring the complex extracellular matrix architecture and biomechanical strength. While progress is being made in cell-based therapies and tissue engineering approaches, comprehensive understanding of the fate of progenitor cells in tendon healing is still lacking. The aim of this study was to investigate the effect of decellularized tendon matrix and moderate cyclic stretching as natural stimuli which could potentially direct tenogenic fate. Equine adipose-derived mesenchymal stromal cells (MSC) were seeded on decellularized tendon matrix scaffolds. Mechanical stimulation was applied in a custom-made cyclic strain bioreactor. Assessment was performed 4 h, 8 h, and 24 h following mechanical stimulation. Scaffold culture induced cell alignment and changes in expression of tendon-related genes, although cell viability was decreased compared to monolayer culture. Short mechanical stimulation periods enhanced most of the scaffold-induced effects. Collagen 1A2 expression levels were decreased, while collagen 3A1 and decorin levels were increased. Tenascin-C and scleraxis expression showed an initial decrease but had increased 24 h after stimulation. The results obtained suggest that decellularized tendon matrix, supported by cyclic stretching, can induce tenogenic differentiation and the synthesis of tendon components important for matrix remodeling.

Corresponding author:Thomas ScheperInstitute of Technial ChemistryLeibniz University HannoverCallinstrasse 530167 Hannoverphone: +49511-762/2509fax:+49511-762/3004email:scheper@iftc.uni-hannover.deThis article has been accepted for publication and undergone full peer review but has not beenthrough the copyediting, typesetting, pagination and proofreading process, which may lead todifferences between this version and the Version of Record. Please cite this article asdoi: 10.1002/elsc.201200041”

Potato fruit juice as a by-product of the starch industry contains proteins with interesting functionalities such as protease inhibitors or patatin with its high nutritional value. Due to their functional properties, these proteins are principally of industrial interest. A drawback for the application of these potato proteins is the separation and isolation under maintenance of the biological activity. So far, there are no methods in literature, which are satisfying concerning the costs or the separation performance. In this study, we show a chromatographic approach using natural clay minerals as cation exchangers to separate two protein fractions in potato fruit juice. Additionally, the content of glycoalkaloids naturally occurring in potatoes is significantly reduced in a single step together with the separation of the patatins and the protease inhibitors.

We present a laminar flow reactor for bone tissue engineering that was developed based on a computational fluid dynamics model. The bioreactor design permits a laminar flow field through its specific internal shape. An integrated bypass system that prevents pressure build-up through bypass openings for pressure release allows for a constant pressure environment during the changing of permeability values that are caused by cellular growth within a porous scaffold. A macroporous ceramic scaffold, composed of zirconium dioxide, was used as a test biomaterial that studies adipose stem cell behavior within a controlled three-dimensional (3D) flow and pressure environment. The topographic structure of the material provided a basis for stem cell proliferation and differentiation toward the osteogenic lineage. Dynamic culture conditions in the bioreactor supported cell viability during long-term culture and induced cell cluster formation and extra-cellular matrix deposition within the porous scaffold, though no complete closure of the pores with new-formed tissue was observed. We postulate that our system is suitable for studying fluid shear stress effects on stem cell proliferation and differentiation toward bone formation in tissue-engineered 3D constructs.

Basic fibroblast growth factor (FGF-2) is a multifunctional cytokine that regulates various cellular processes both in vitro and in vivo. FGF-2 is extensively used in embryonic stem cell cultures since it can maintain the cells in an undifferentiated state. However, the high price of FGF-2 has limited its application in stem cell research. Here we present a fast and efficient process for the purification of FGF-2 from recombinant Escherichia coli cultures using reusable membrane adsorbers. A high expression level of FGF-2 (42 mg/g dry cell) was achieved by fed-batch cultivation of E. coli BL21(DE3). A new combination of cation exchange membrane chromatography and heparin-sepharose affinity chromatography was used for the purification of the protein. A novel anion exchange membrane chromatography was used in the polishing step to remove endotoxins and DNA. In this new process, about 200 mg soluble FGF-2 was yielded from 1.9 L culture broth with a purity of 98%. The purified protein was identified to be endotoxin-free and bioactive. It was successfully tested to keep primate embryonic stem cell and human-induced pluripotent stem cell pluripotent. Our approach, in which a controlled cultivation process is combined with an optimized fast and versatile downstreaming process, is suitable for low-cost preparation of bioactive FGF-2 at bench-scale and may be beneficial to the effective production of other cytokines.

Fur eine naturliche Funktionalitat von Zellkulturen z. B. bei der Entwicklung von Biopharmazeutika ist die 3-dimensionale (3D) Umgebung notwendig. Daher werden verstarkt Technologien entwickelt, um Zellen in einer naturlicheren, gewebe-ahnlichen Umgebung zu kultivieren. Ein entscheidender Schritt zur industriellen Anwendung von organotypischen 3D-Kulturen ist die Entwicklung von automatisierbaren Technologien, die Hochdurchsatz-Produktionsverfahren ermoglichen. Eine neue Technologie zur Generierung von Mikrogeweben und deren Implementierung in einen automatisierten Produktionsprozess wird vorgestellt. Sie ermoglicht die Generierung einer hangenden Tropfenkultur in analoger Weise zu 2D-Multi-Well-Platten. Anhand der Produktion von Dickdarm-Tumor-Mikrogeweben und primarem Rattenleber-Mikrogewebe wird gezeigt, dass der Produktionsprozess mit gleicher Genauigkeit gefuhrt werden kann wie Standardprozesse. For native functionality of cell cultures, e.g. in production of biopharmaceuticals, 3-dimensional (3D) environment is required. Therefore, new technologies are emerging to grow cells in a 3D, tissue-like environment. A decisive step towards the industrial application of 3D cell cultures is the development of automation-compatible technologies enabling high throughput. A new production technology for microtissues and its implementation in an automated production process is presented. The technology allows the formation of hanging drop cultures in a manner analogous to 2-dimemsionale multi-well plates. Using the example of the production of colon tumor and rat liver microtissues it could be shown that the production process can be performed with the same accuracy as conventional standard processes.

In this study, the potential use of a synthetic Mg/Al hydrotalcite (layered double hydroxide) as a novel chromatography material for protein purification was investigated. The hydrotalcite is present in its carbonate form and is characterized by an Al/Mg-ratio of 1.85. Zetapotential measurements confirm a positive surface potential up to pH 10 suggesting applicability as anion exchanger. The binding of model proteins covering a broad range of isoelectric points and molecular weights was performed at different pH-values under batch conditions to evaluate the binding behaviour of the hydrotalcite. Furthermore, static binding capacities were exemplarily determined for hemoglobin and human serum albumin. Additionally, the adsorption and elution of hemoglobin was studied under dynamic conditions. The binding behaviour of the hydrotalcite was compared to commercially available anion exchangers and was found to be a function of pH, depending on the model protein. Variant adsorption behaviour is explained by further interactions like hydrogen bonds and by an unequal charge distribution over the protein surfaces. The hydrotalcite reveals high adsorption capacities under static (260 mg/g) as well as under dynamic conditions (88 mg/g at 34 cm/h; 61 mg/g at 340 cm/h). With appropriate buffers like 500 mM carbonate (pH 10) the adsorbed proteins can be nearly completely desorbed making regeneration possible. Due to the binding and elution properties it is concluded, that the hydrotalcite can serve anion exchange material for chromatographic protein separations.