Toward in situ tissue engineering: chemokine-guided stem cell recruitment.

Chemokines are potent stem cell homing and mobilization factors, and artificially increasing the concentrations of specific chemokines at injury sites is an up-to-date strategy to potentiate and prolong the recruitment of endogenous stem cells and to amplify in situ tissue regeneration. We briefly outline the latest progress in stem cell recruitment focusing on the interactions of mesenchymal stem cells (MSCs) with chemokines, complement cascade peptides, bioactive lipids, and glycosaminoglycans (GAGs). We present recent advances in state-of-the-art chemokine delivery devices suitable for various applications and critically evaluate the perspectives and challenges of the chemokine-guided in situ strategy for translation in regenerative medicine.

Chitosan-based injectable hydrogel as a promising in situ forming scaffold for cartilage tissue engineering.

Chitosan-beta glycerophosphate-hydroxyethyl cellulose (CH-GP-HEC) is a biocompatible and biodegradable scaffold exhibiting a sol-gel transition at 37°C. Chondrogenic factors or mesenchymal stem cells (MSCs) can be included in the CH-GP-HEC, and injected into the site of injury to fill the cartilage tissue defects with minimal invasion and pain. The possible impact of the injectable CH-GP-HEC on the viability of the encapsulated MSCs was assessed by propidium iodide-fluorescein diacetate staining.

Osteoarthritis synovial fluid activates pro-inflammatory cytokines in primary human chondrocytes.

Purpose: Two of the most common joint diseases are rheumatoid arthritis (RA) and osteoarthritis (OA). Cartilage degradation and erosions are important pathogenetic mechanisms in both joint diseases and have presently gained increasing interest. The aim of the present study was to investigate the effects of the synovial fluid environment of OA patients in comparison with synovial fluids of RA patients on human chondrocytes in vitro.

Hemoglobin-based oxygen carrier microparticles: synthesis, properties, and in vitro and in vivo investigations.

Bovine hemoglobin microparticles (Hb-MPs) as suitable oxygen carriers are fabricated easily by three key steps: coprecipitation of Hb and CaCO(3) to make Hb-CaCO(3)-microparticles (Hb-CaCO(3)-MPs), cross-linking by glutaraldehyde (GA) to polymerize the Hb and dissolution of CaCO(3) template to obtain pure Hb-MPs. The Hb entrapment efficiency ranged from 8 to 50% corresponding to a hemoglobin quantity per Hb-MP of at least one-third of that in one erythrocyte. The Hb-MPs are spherical, with an average diameter of 3.

Highly efficient magnetic stem cell labeling with citrate-coated superparamagnetic iron oxide nanoparticles for MRI tracking.

Tracking of transplanted stem cells is essential to monitor safety and efficiency of cell-based therapies. Magnetic resonance imaging (MRI) offers a very sensitive, repetitive and non-invasive in vivo detection of magnetically labeled cells but labeling with commercial superparamagnetic iron oxide nanoparticles (SPIONs) is still problematic because of low labeling efficiencies and the need of potentially toxic transfection agents. In this study, new experimental citrate-coated SPIONs and commercial Endorem and Resovist SPIONs were investigated comparatively in terms of in vitro labeling efficiency, effects on stem cell functionality and in vivo MRI visualization.

Preferred use of polyhexanide in orthopedic surgery.

In orthopedic and trauma surgery, the most frequently used antiseptic is polyhexanide. Its favored application is based on prepossessing tissue compatibility in contrast to various antiseptics and a high antimicrobiological effect. Recent studies showed toxic effects of this antiseptic on human chondrocytes.

Biodegradable insulin-loaded PLGA microspheres fabricated by three different emulsification techniques: investigation for cartilage tissue engineering.

Growth, differentiation and migration factors facilitate the engineering of tissues but need to be administered with defined gradients over a prolonged period of time. In this study insulin as a growth factor for cartilage tissue engineering and a biodegradable PLGA delivery device were used. The aim was to investigate comparatively three different microencapsulation techniques, solid-in-oil-in-water (s/o/w), water-in-oil-in-water (w/o/w) and oil-in-oil-in-water (o/o/w), for the fabrication of insulin-loaded PLGA microspheres with regard to protein loading efficiency, release and degradation kinetics, biological activity of the released protein and phagocytosis of the microspheres.

Tissue-engineered cartilage of porcine and human origin as in vitro test system in arthritis research.

The increasing prevalence of cartilage destruction during arthritis has entailed an intensified amount for in vitro cartilage models to analyze pathophysiological processes and to screen for antirheumatic drugs. Tissue engineering offers the opportunity to establish highly organized 3D cell cultures facilitating the formation of in vitro models that reflect the human situation. We report the comparison of porcine chondrocyte pellet and alginate bead cultures as model systems for human cartilage and the further development into a human system that was applied in an arthritis model.

Chemokine profile of human serum from whole blood: migratory effects of CXCL-10 and CXCL-11 on human mesenchymal stem cells.

Autologous human serum is used in cartilage repair and may exert its effect by the recruitment of mesenchymal stem and progenitor cells (MSC). Aim of our study was to analyze the chemokine profile of human serum and to verify chemotactic activity of selected chemokines on MSC. Human MSC were isolated from iliac crest bone marrow aspirates.

Antirheumatic drug response signatures in human chondrocytes: potential molecular targets to stimulate cartilage regeneration.

Introduction: Rheumatoid arthritis (RA) leads to progressive destruction of articular cartilage. This study aimed to disclose major mechanisms of antirheumatic drug action on human chondrocytes and to reveal marker and pharmacological target genes that are involved in cartilage dysfunction and regeneration.

Methods: An interactive in vitro cultivation system composed of human chondrocyte alginate cultures and conditioned supernatant of SV40 T-antigen immortalised human synovial fibroblasts was used.

Migration potential and gene expression profile of human mesenchymal stem cells induced by CCL25.

Recruitment of mesenchymal stem cells (MSC) to tissue damages is a promising approach for in situ tissue regeneration. The physiological mechanisms and regulatory processes of MSC trafficking to injured tissue remain poorly understood. However, the pivotal role of chemokines in MSC recruitment has already been shown.

Key regulatory molecules of cartilage destruction in rheumatoid arthritis: an in vitro study.

Background: Rheumatoid arthritis (RA) is a chronic, inflammatory and systemic autoimmune disease that leads to progressive cartilage destruction. Advances in the treatment of RA-related destruction of cartilage require profound insights into the molecular mechanisms involved in cartilage degradation. Until now, comprehensive data about the molecular RA-related dysfunction of chondrocytes have been limited.

The TraA relaxase autoregulates the putative type IV secretion-like system encoded by the broad-host-range Streptococcus agalactiae plasmid pIP501.

The conjugative multiple antibiotic resistance plasmid pIP501 can be transferred and stably maintained in a variety of Gram-positive genera, including multicellular Streptomyces lividans, as well as in Gram-negative Escherichia coli. The 15 putative pIP501 transfer (tra) genes are organized in an operon-like structure terminating in a strong transcriptional terminator. This paper reports co-transcription of the pIP501 tra genes in exponentially growing Enterococcus faecalis JH2-2 cells, as shown by RT-PCR.