The role of substrate morphology for the cytokine release profile of immature human primary macrophages.

There is increasing evidence that the physicochemical nature of any given material is a dominant factor for the release of cytokines by innate immune cells, specifically of macrophages, and thus majorly influences their interaction with other cell types. Recently, we could show that the 3D structure of star shaped polytheylene oxide-polypropylene oxide co-polymers (sP(EO-stat-PO))-hydrogel coated substrates has a stronger influence on the release pattern of cytokines after 7 days of culture than surface chemistry. Here, we focused on the analysis of cytokine release over time and a more detailed analysis of cell morphology by scanning electron microscopy (SEM).

Expansion and differentiation of germline-derived pluripotent stem cells on biomaterials.

Stem cells with broad differentiation potential, such as the recently described germline-derived pluripotent stem cells (gPS cells), are an appealing source for tissue engineering strategies. Biomaterials can inhibit, support, or induce proliferation and differentiation of stem cells. Here we identified (1) polymers that maintain self-renewal and differentiation potential of gPS cells for feeder-free expansion and (2) polymers supporting the cardiomyogenic fate of gPS cells by analyzing a panel of polymers of an established biomaterial bank previously used to assess growth of diverse stem cell types.

Novel insights into osteogenesis and matrix remodelling associated with calcific uraemic arteriolopathy.

Background: Calcific uraemic arteriolopathy (CUA) or calciphylaxis is a rare, life-threatening disease predominantly occurring in patients with end-stage renal disease. Its pathogenesis has been suggested to include ectopic osteogenesis in soft tissue and the vasculature associated with extracellular matrix (ECM) remodelling.

Methods: To gain further insights into the pathogenesis of CUA, we performed systematic analyses of skin specimens obtained from seven CUA patients including histology, immunohistochemistry, electron microscopy, electron dispersive X-ray analysis (EDX) and quantitative real-time RT-PCR.

Cord blood-hematopoietic stem cell expansion in 3D fibrin scaffolds with stromal support.

Expansion of multipotent, undifferentiated and proliferating cord blood (CB)-hematopoietic stem cells (HSC) in vitro is limited and insufficient. Bone marrow (BM) engineering in vitro allows mimicking the main components of the hematopoietic niche compared to conventional expansion strategies. In this study, four different 3D biomaterial scaffolds (PCL, PLGA, fibrin and collagen) were tested for freshly isolated cord blood (CB)-CD34(+) cell expansion in presence of (i) efficient exogenous cytokine supplementation and (ii) umbilical cord (UC)-mesenchymal stem cells (MSC).

Two-dimensional polymer-based cultures expand cord blood-derived hematopoietic stem cells and support engraftment of NSG mice.

Currently, ex vivo expansion of hematopoietic stem cells (HSC) is still insufficient. Traditional approaches for HSC expansion include the use of stromal cultures, growth factors, and/or bioreactors. Biomaterial-based strategies provide new perspectives.

Inducing healing-like human primary macrophage phenotypes by 3D hydrogel coated nanofibres.

Immune cells are present in the blood and in resident tissues, and the nature of their reaction towards biomaterials is decisive for materials success or failure. Macrophages may for example be classically activated to trigger inflammation (M1), or alternatively activated which supports healing and vascularisation (M2). Here, we have generated 3D nanofibrous meshes in different porosities and precisely controlled surface chemistries comprising PLGA, hydrogel-coated protein repellant and protein repellant endowed with the bioactive peptide sequences GRGDS or GLF.

3D co-culture of hematopoietic stem and progenitor cells and mesenchymal stem cells in collagen scaffolds as a model of the hematopoietic niche.

Here, we propose a collagen-based three-dimensional (3D) environment for hematopoietic stem and progenitor cells (HPC) with mesenchymal stem cells (MSC) derived either from bone marrow (BM) or umbilical cord (UC), to recapitulate the main components of the BM niche. Mechanisms described for HPC homeostasis were systematically analyzed in comparison to the conventional liquid HPC culture. The 3D-cultivation allows dissecting two sub-populations of HPC: (I) HPC in suspension above the collagen gel and (II) migratory HPC in the collagen fibres of the collagen gel.

Transcriptome analysis of MSC and MSC-derived osteoblasts on Resomer® LT706 and PCL: impact of biomaterial substrate on osteogenic differentiation.

Background: Mesenchymal stem cells (MSC) represent a particularly attractive cell type for bone tissue engineering because of their ex vivo expansion potential and multipotent differentiation capacity. MSC are readily differentiated towards mature osteoblasts with well-established protocols. However, tissue engineering frequently involves three-dimensional scaffolds which (i) allow for cell adhesion in a spatial environment and (ii) meet application-specific criteria, such as stiffness, degradability and biocompatibility.

Platelets display potent antimicrobial activity and release human beta-defensin 2.

Platelet-rich plasma (PRP) is a potent agent that improves soft tissue and bone healing. By the release of growth factors and cytokines, PRP is believed to locally boost physiologic healing processes. Recently, antimicrobial activity of PRP has been demonstrated against S.

Exposure to uremic serum induces a procalcific phenotype in human mesenchymal stem cells.

Objective: Medial artery calcification in patients with chronic kidney disease proceeds through intramembranous ossification resulting from osteoblast-induced calcification of the collagen extracellular matrix. The current study is based on the hypothesis that mesenchymal stem cells (MSC) constitute critical cells for procalcific extracellular matrix remodeling in patients with chronic kidney disease.

Methods And Results: Human MSC were cultured in media supplemented with pooled sera from either healthy or uremic patients (20%).

The role of biomaterials in the direction of mesenchymal stem cell properties and extracellular matrix remodelling in dermal tissue engineering.

Recently, a new generation of dermal equivalents (DE) was presented which are solely generated on a human fibroblast-derived dermal matrix. Since human mesenchymal stem cells from bone marrow (BM-MSC) and Wharton's Jelly of the umbilical cord (UC-MSC) are characterised by a distinct biosynthetic and paracrine activity, they are an appealing alternative approach for generating cell-based DE. This study compares the epithelial-mesenchymal interaction and extracellular matrix (ECM) remodelling of cell-based and collagen-based DE using fibroblasts, BM-MSC or UC-MSC, respectively, in co-culture with the keratinocyte cell line HaCaT.

Three-dimensional epidermis-like growth of human mesenchymal stem cells on dermal equivalents: contribution to tissue organization by adaptation of myofibroblastic phenotype and function.

Human mesenchymal stem cells (hMSC) are able to differentiate into mature cells of various mesenchymal tissues. Recent studies have reported that hMSC may even give rise to cells of ectodermal origin. This indication of plasticity makes hMSC a promising donor source for cell-based therapies.

Long-term histological and scanning electron microscopy results of endovascular and operative treatments of experimentally induced aneurysms in the rabbit.

Objective: Treatment strategies of cerebral aneurysms include surgical clipping and endovascular therapies. To determine the long-term results of these therapeutic strategies, the vessel wall reaction close to the former aneurysm was studied according to the assumption that an intact endothelial layer over the former aneurysm neck constitutes complete vessel wall reconstruction and stable aneurysm obliteration.

Methods: Aneurysms were created in 40 rabbits by intraluminal elastase incubation of the common carotid artery.

Morphological effects of nanosecond- and femtosecond-pulsed laser ablation on human middle ear ossicles.

We evaluate the feasibility of nanosecond-pulsed and femtosecond-pulsed lasers for otologic surgery. The outcome parameters are cutting precision (in micrometers), ablation rate (in micrometers per second), scanning speed (in millimeters per second), and morphological effects on human middle ear ossicles. We examine single-spot ablations by a nanosecond-pulsed, frequency-tripled Nd:YAG laser (355 nm, beam diameter 10 microm, pulse rate 2 kHz, power 250 mW) on isolated human mallei.