Publications by authors named "Heinz Redl"

318 Publications

Cre mRNA Is Not Transferred by EVs from Endothelial and Adipose-Derived Stromal/Stem Cells during Vascular Network Formation.

Int J Mol Sci 2021 Apr 14;22(8). Epub 2021 Apr 14.

AUVA Research Centre, Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, 1200 Vienna, Austria.

Coculture systems employing adipose tissue-derived mesenchymal stromal/stem cells (ASC) and endothelial cells (EC) represent a widely used technique to model vascularization. Within this system, cell-cell communication is crucial for the achievement of functional vascular network formation. Extracellular vesicles (EVs) have recently emerged as key players in cell communication by transferring bioactive molecules between cells. In this study we aimed to address the role of EVs in ASC/EC cocultures by discriminating between cells, which have received functional EV cargo from cells that have not. Therefore, we employed the Cre-loxP system, which is based on donor cells expressing the Cre recombinase, whose mRNA was previously shown to be packaged into EVs and reporter cells containing a construct of floxed dsRed upstream of the eGFP coding sequence. The evaluation of Cre induced color switch in the reporter system via EVs indicated that there is no EV-mediated RNA transmission either between EC themselves or EC and ASC. However, since Cre mRNA was not found present in EVs, it remains unclear if Cre mRNA is generally not packaged into EVs or if EVs are not taken up by the utilized cell types. Our data indicate that this technique may not be applicable to evaluate EV-mediated cell-to-cell communication in an in vitro setting using EC and ASC. Further investigations will require a functional system showing efficient and specific loading of Cre mRNA or protein into EVs.
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http://dx.doi.org/10.3390/ijms22084050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8070972PMC
April 2021

Lugol's solution but not formaldehyde affects bone microstructure and bone mineral density parameters at the insertion site of the rotator cuff in rats.

J Orthop Surg Res 2021 Apr 13;16(1):254. Epub 2021 Apr 13.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.

Background: This study aimed to investigate whether rodent shoulder specimens fixed in formaldehyde for histological and histomorphometric investigations and specimens stained using Lugol's solution for soft tissue visualization by micro-computed tomography (microCT) are still eligible to be used for bone architecture analysis by microCT.

Methods: In this controlled laboratory study, 11 male Sprague-Dawley rats were used. After sacrifice and exarticulation both shoulders of healthy rats were assigned into three groups: (A) control group (n = 2); (B) formaldehyde group (n = 4); (C) Lugol group (n = 5). Half of the specimens of groups B and C were placed in a 4% buffered formaldehyde or Lugol's solution for 24 h, whereas the contralateral sides and all specimens of group A were stored without any additives. MicroCT of both sides performed in all specimens focused on bone mineral density (BMD) and bone microstructure parameters.

Results: BMD measurements revealed higher values in specimens after placement in Lugol's solution (p < 0.05). Bone microstructure analyses showed increased BV/TV and Tb.Th values in group C (p < 0.05). Specimens of group C resulted in clearly decreased Tb.Sp values (p < 0.05) in comparison to the control group. Formaldehyde fixation showed minimally altered BMD and bone microstructure measurements without reaching any significance.

Conclusions: MicroCT scans of bone structures are recommended to be conducted natively and immediately after euthanizing rats. MicroCT scans of formaldehyde-fixed specimens must be performed with caution due to a possible slight shift of absolute values of BMD and bone microstructure. Bone analysis of specimens stained by Lugol's solution cannot be recommended.
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http://dx.doi.org/10.1186/s13018-021-02394-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8045387PMC
April 2021

Longitudinal Changes of Circulating miRNAs During Bisphosphonate and Teriparatide Treatment in an Animal Model of Postmenopausal Osteoporosis.

J Bone Miner Res 2021 Feb 17. Epub 2021 Feb 17.

TAmiRNA GmbH, Vienna, Austria.

MicroRNAs regulate bone homeostasis, and circulating microRNAs have been proposed as novel bone biomarkers. The effect of anti-osteoporotic treatment on circulating microRNAs has not been described in detail. Therefore, we performed a comprehensive analysis of microRNA serum levels in ovariectomized (OVX) and sham-operated (SHAM) rats over 12 weeks of antiresorptive or osteoanabolic treatment. Forty-two Sprague Dawley rats underwent SHAM surgery (n = 10) or ovariectomy (n = 32). After 8 weeks, OVX rats were randomized to antiresorptive treatment with zoledronate (n = 11), osteoanabolic treatment with teriparatide (n = 11), or vehicle treatment (n = 10). Serum samples were collected at weeks 8, 12, 16, and 20 after surgery. A total of 91 microRNAs were analyzed by RT-qPCR in serum samples collected at week 20. Based on the results, 29 microRNAs were selected for longitudinal analysis at all four study time points. Changes in bone mineral density and microstructure were followed up by in vivo micro-CT and ex vivo nano-CT. Ovariectomy resulted in the loss of trabecular bone, which was reversed by osteoanabolic and antiresorptive treatment. Differential expression analysis identified 11 circulating miRNAs that were significantly regulated after treatment. For example, miR-107 and miR-31-5p increased in vehicle-treated OVX animals, whereas they decreased during teriparatide treatment. Additional miRNAs were identified that showed significant correlations to bone microstructure or bone miRNA expression, including miR-203a-3p, which exhibited a significant negative correlation to vertebral and tibial trabecular bone volume fraction (%). Longitudinal analysis confirmed eight microRNAs with significant changes in serum over time that were prevented by teriparatide and zoledronate treatment (miR-34a-5p, miR-31-5p, miR-30d-3p, miR-378a-5p) or teriparatide treatment only (miR-375-3p, miR-183-5p, miR-203a-3p, miR-203b-3p). Gene target network analysis identified WNT and Notch signaling as the main signaling pathways controlled by these miRNAs. Thus, ovariectomy results in time-dependent deregulation of circulating miRNAs compared with SHAM animals. Anti-osteoporotic treatments can rescue this effect, showing that bone-related miRNAs might act as novel biomarkers for treatment monitoring. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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http://dx.doi.org/10.1002/jbmr.4276DOI Listing
February 2021

Crosslinking strategies for silk fibroin hydrogels: promising biomedical materials.

Biomed Mater 2021 Feb 17;16(2):022004. Epub 2021 Feb 17.

Biomedical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran. Maryam Farokhi and Mina Aleemardani contributed equally.

Due to their strong biomimetic potential, silk fibroin (SF) hydrogels are impressive candidates for tissue engineering, due to their tunable mechanical properties, biocompatibility, low immunotoxicity, controllable biodegradability, and a remarkable capacity for biomaterial modification and the realization of a specific molecular structure. The fundamental chemical and physical structure of SF allows its structure to be altered using various crosslinking strategies. The established crosslinking methods enable the formation of three-dimensional (3D) networks under physiological conditions. There are different chemical and physical crosslinking mechanisms available for the generation of SF hydrogels (SFHs). These methods, either chemical or physical, change the structure of SF and improve its mechanical stability, although each method has its advantages and disadvantages. While chemical crosslinking agents guarantee the mechanical strength of SFH through the generation of covalent bonds, they could cause some toxicity, and their usage is not compatible with a cell-friendly technology. On the other hand, physical crosslinking approaches have been implemented in the absence of chemical solvents by the induction of β-sheet conformation in the SF structure. Unfortunately, it is not easy to control the shape and properties of SFHs when using this method. The current review discusses the different crosslinking mechanisms of SFH in detail, in order to support the development of engineered SFHs for biomedical applications.
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http://dx.doi.org/10.1088/1748-605X/abb615DOI Listing
February 2021

Polymer Based Bioadhesive Biomaterials for Medical Application-A Perspective of Redefining Healthcare System Management.

Polymers (Basel) 2020 Dec 16;12(12). Epub 2020 Dec 16.

Footwear Research Centre, University Institute, Tomas Bata University in Zlin, University Institute & Tomas Bata University in Zlin, Nad Ovčírnou 3685, 76001 Zlín, Czech Republic.

This article deliberates about the importance of polymer-based bioadhesive biomaterials' medical application in healthcare and in redefining healthcare management. Nowadays, the application of bioadhesion in the health sector is one of the great interests for various researchers, due to recent advances in their formulation development. Actually, this area of study is considered as an active multidisciplinary research approach, where engineers, scientists (including chemists, physicists, biologists, and medical experts), material producers and manufacturers combine their knowledge in order to provide better healthcare. Moreover, while discussing the implications of value-based healthcare, it is necessary to mention that health comprises three main domains, namely, physical, mental, and social health, which not only prioritize the quality healthcare, but also enable us to measure the outcomes of medical interventions. In addition, this conceptual article provides an understanding of the consequences of the natural or synthetic polymer-based bioadhesion of biomaterials, and its significance for redefining healthcare management as a novel approach. Furthermore, the research assumptions highlight that the quality healthcare concept has recently become a burning topic, wherein healthcare service providers, private research institutes, government authorities, public service boards, associations and academics have taken the initiative to restructure the healthcare system to create value for patients and increase their satisfaction, and lead ultimately to a healthier society.
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http://dx.doi.org/10.3390/polym12123015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766067PMC
December 2020

The vertical course of bone regeneration in maxillary sinus floor augmentations: A histomorphometric analysis of human biopsies.

J Periodontol 2021 02 19;92(2):263-272. Epub 2020 Aug 19.

Division of Oral Surgery, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.

Background: Maxillary sinus floor augmentation (MSFA) is a well-established and predictable augmentation method in severely resorbed maxillae. However, data on the vertical course of bone graft consolidation within the maxillary sinus are rare. The aim of the present study was to quantify the vertical distribution of new bone formation (nBF) in MSFA and to characterize the vertical gradient of bone graft consolidation.

Methods: Eighty-five human sinus biopsies were harvested 6 ± 1 months after MSFA. Histological thin-ground sections were prepared and histomorphometrically analyzed. The volume of newly formed bone (nBV/TV) was measured in serial zones of 100 μm proceeding from the bottom of the sinus floor (SF) up to the apical top of the biopsy. The gradient of nBV/TV within the augmentation area was determined by the vertical distribution of nBV/TV along these zones.

Results: In the premolar region, nBV/TV slightly declined from 20.4% in the zone adjacent to the SF to 17.7% at a distance of 8 mm. The gradient was steeper in the molar region: nBV/TV decreased from 18.7% to 12.8%. This decline was even more distinct when the volume fraction and the height of the residual bone of the SF were low.

Conclusions: nBF follows a gradient from native bone of the SF towards the apical part of the augmentation area. The distance to primordial bone thus plays a critical role for bone regeneration in MSFA, particularly in the molar region.
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http://dx.doi.org/10.1002/JPER.19-0656DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7984041PMC
February 2021

Zoledronic Acid Substantially Improves Bone Microarchitecture and Biomechanical Properties After Rotator Cuff Repair in a Rodent Chronic Defect Model.

Am J Sports Med 2020 07 16;48(9):2151-2160. Epub 2020 Jun 16.

AUVA Trauma Center Vienna-Meidling, Department for Trauma Surgery, Vienna, Austria.

Background: Bone mineral density at the humeral head is reduced in patients with chronic rotator cuff tears. Bone loss in the humeral head is associated with repair failure after rotator cuff reconstruction. Bisphosphonates (eg, zoledronic acid) increase bone mineral density.

Hypothesis: Zoledronic acid improves bone mineral density of the humeral head and biomechanical properties of the enthesis after reconstruction of chronic rotator cuff tears in rats.

Study Design: Controlled laboratory study.

Methods: A total of 32 male Sprague-Dawley rats underwent unilateral (left) supraspinatus tenotomy with delayed transosseous rotator cuff reconstruction after 3 weeks. All rats were sacrificed 8 weeks after rotator cuff repair. Animals were randomly assigned to 1 of 2 groups. At 1 day after rotator cuff reconstruction, the intervention group was treated with a single subcutaneous dose of zoledronic acid at 100 µg/kg bodyweight, and the control group received 1 mL of subcutaneous saline solution. In 12 animals of each group, micro-computed tomography scans of both shoulders were performed as well as biomechanical testing of the supraspinatus enthesis of both sides. In 4 animals of each group, histological analyses were conducted.

Results: In the intervention group, bone volume fraction (bone volume/total volume [BV/TV]) of the operated side was higher at the lateral humeral head ( = .005) and the medial humeral head ( = .010) compared with the control group. Trabecular number on the operated side was higher at the lateral humeral head ( = .004) and the medial humeral head ( = .001) in the intervention group. Maximum load to failure rates on the operated side were higher in the intervention group ( < .001). Cortical thickness positively correlated with higher maximum load to failure rates in the intervention group ( = 0.69; = .026). Histological assessment revealed increased bone formation in the intervention group.

Conclusion: Single-dose therapy of zoledronic acid provided an improvement of bone microarchitecture at the humeral head as well as an increase of maximum load to failure rates after transosseous reconstruction of chronic rotator cuff lesions in rats.

Clinical Relevance: Zoledronic acid improves bone microarchitecture as well as biomechanical properties after reconstruction of chronic rotator cuff tears in rodents. These results need to be verified in clinical investigations.
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http://dx.doi.org/10.1177/0363546520926471DOI Listing
July 2020

Stiffness Matters: Fine-Tuned Hydrogel Elasticity Alters Chondrogenic Redifferentiation.

Front Bioeng Biotechnol 2020 30;8:373. Epub 2020 Apr 30.

Faculty of Technical Chemistry, Institute of Applied Synthetic Chemistry and Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria.

Biomechanical cues such as shear stress, stretching, compression, and matrix elasticity are vital in the establishment of next generation physiological tissue models. Matrix elasticity, for instance, is known to guide stem cell differentiation, influence healing processes and modulate extracellular matrix (ECM) deposition needed for tissue development and maintenance. To better understand the biomechanical effect of matrix elasticity on the formation of articular cartilage analogs , this study aims at assessing the redifferentiation capacity of primary human chondrocytes in three different hydrogel matrices of predefined matrix elasticities. The hydrogel elasticities were chosen to represent a broad spectrum of tissue stiffness ranging from very soft tissues with a Young's modulus of 1 kPa up to elasticities of 30 kPa, representative of the perichondral-space. In addition, the interplay of matrix elasticity and transforming growth factor beta-3 (TGF-β3) on the redifferentiation of primary human articular chondrocytes was studied by analyzing both qualitative (viability, morphology, histology) and quantitative (RT-qPCR, sGAG, DNA) parameters, crucial to the chondrotypic phenotype. Results show that fibrin hydrogels of 30 kPa Young's modulus best guide chondrocyte redifferentiation resulting in a native-like morphology as well as induces the synthesis of physiologic ECM constituents such as glycosaminoglycans (sGAG) and collagen type II. This comprehensive study sheds light onto the mechanobiological impact of matrix elasticity on formation and maintenance of articular cartilage and thus represents a major step toward meeting the need for advanced tissue models to study both re- and degeneration of articular cartilage.
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http://dx.doi.org/10.3389/fbioe.2020.00373DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7204401PMC
April 2020

SVF-derived extracellular vesicles carry characteristic miRNAs in lipedema.

Sci Rep 2020 04 29;10(1):7211. Epub 2020 Apr 29.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Linz/Vienna, Austria.

Lipedema is a chronic, progressive disease of adipose tissue with lack of consistent diagnostic criteria. The aim of this study was a thorough comparative characterization of extracellular microRNAs (miRNAs) from the stromal vascular fraction (SVF) of healthy and lipedema adipose tissue. For this, we analyzed 187 extracellular miRNAs in concentrated conditioned medium (cCM) and specifically in small extracellular vesicles (sEVs) enriched thereof by size exclusion chromatography. No significant difference in median particle size and concentration was observed between sEV fractions in healthy and lipedema. We found the majority of miRNAs located predominantly in cCM compared to sEV enriched fraction. Surprisingly, hierarchical clustering of the most variant miRNAs showed that only sEVmiRNA profiles - but not cCMmiRNAs - were impacted by lipedema. Seven sEVmiRNAs (miR-16-5p, miR-29a-3p, miR-24-3p, miR-454-p, miR-144-5p, miR-130a-3p, let-7c-5p) were differently regulated in lipedema and healthy individuals, whereas only one cCMmiRNA (miR-188-5p) was significantly downregulated in lipedema. Comparing SVF from healthy and lipedema patients, we identified sEVs as the lipedema relevant miRNA fraction. This study contributes to identify the potential role of SVF secreted miRNAs in lipedema.
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http://dx.doi.org/10.1038/s41598-020-64215-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7190633PMC
April 2020

Evaluation of BMP-2 Minicircle DNA for Enhanced Bone Engineering and Regeneration.

Curr Gene Ther 2020 ;20(1):55-63

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.

Background: To date, the significant osteoinductive potential of bone morphogenetic protein 2 (BMP-2) non-viral gene therapy cannot be fully exploited therapeutically. This is mainly due to weak gene delivery and brief expression peaks restricting the therapeutic effect.

Objective: Our objective was to test the application of minicircle DNA, allowing prolonged expression potential. It offers notable advantages over conventional plasmid DNA. The lack of bacterial sequences and the resulting reduction in size, enables safe usage and improved performance for tissue regeneration.

Methods: We inserted an optimized BMP-2 gene cassette with minicircle plasmid technology. BMP-2 minicircle plasmids were produced in E. coli yielding plasmids lacking bacterial backbone elements. Comparative studies of these BMP-2 minicircles and conventional BMP-2 plasmids were performed in vitro in cell systems, including bone marrow derived stem cells. Tests performed included gene expression profiles and cell differentiation assays.

Results: A C2C12 cell line transfected with the BMP-2-Advanced minicircle showed significantly elevated expression of osteocalcin, alkaline phosphatase (ALP) activity, and BMP-2 protein amount when compared to cells transfected with conventional BMP-2-Advanced plasmid. Furthermore, the plasmids show suitability for stem cell approaches by showing significantly higher levels of ALP activity and mineralization when introduced into human bone marrow stem cells (BMSCs).

Conclusion: We have designed a highly bioactive BMP-2 minicircle plasmid with the potential to fulfil clinical requirements for non-viral gene therapy in the field of bone regeneration.
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http://dx.doi.org/10.2174/1566523220666200427121350DOI Listing
January 2020

A novel fluorescent hydroxyapatite based on iron quantum cluster template to enhance osteogenic differentiation.

Mater Sci Eng C Mater Biol Appl 2020 Jun 24;111:110775. Epub 2020 Feb 24.

Department of Nanobiotechnology/Biophysics, Faculty of Biological Science, Tarbiat Modares University, 14115-154 Tehran, Iran. Electronic address:

Template-mediated self-assembly synthesis has produced a diverse range of biomimetic materials with unique physicochemical properties. Here, we fabricated novel fluorescent three-dimensional (3-D) hydroxyapatite (HAP) nanorod-assembled microspheres using iron quantum cluster (FeQC) as a hybrid template, containing three organic components: hemoglobin chains, piperidine, and iron clusters. The material characterization indicated that the synthesized HAP possessed a uniform rod-like morphology, ordered 3-D architecture, high crystallinity, self-activated fluorescence, and remarkable photostability. Our study proposed that this FeQC template is a promising regulating agent to fabricate fluorescent self-assembled HAP microspheres with a controlled morphology. The effect of HAP on stem cell fate and their osteogenic differentiation was investigated by culturing human bone marrow-derived mesenchymal stromal/stem cells (BMSCs) with HAP microspheres. Significant increases in collagen matrix production and gene expression of osteogenic markers, including osteocalcin (OCN), Runt-related transcription factor 2 (Runx2), bone sialoprotein (BSP) and alkaline phosphatase (ALP), were observed compared to the controls after 21 days of culture. Taken together, our data suggest that synthetic HAP nanorod-assembled microspheres represent a promising new biomaterial which exhibits enhanced fluorescent properties and osteoinductive effects on human BMSCs.
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http://dx.doi.org/10.1016/j.msec.2020.110775DOI Listing
June 2020

The course of recovery of locomotor function over a 10-week observation period in a rat model of femoral nerve resection and autograft repair.

Brain Behav 2020 04 25;10(4):e01580. Epub 2020 Feb 25.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in the AUVA Trauma Research Center, Vienna, Austria.

Background: A great extent of knowledge on peripheral nerve regeneration has been gathered using the rat sciatic nerve model. The femoral nerve model of the rat offers an interesting alternative, as it lacks disadvantageous features such as automutilation. For the analysis of locomotor behavior in rats after sciatic nerve injury, the CatWalk XT Gait Analysis System is often used. However, lesions of the femoral nerve in the rat have yet remained unstudied with this method.

Material And Methods: Ten male Sprague Dawley rats were evaluated with the CatWalk XT to study their gait after a 6-mm resection of the right femoral nerve and reconstruction with an autologous nerve graft. Animals were observed for 10 weeks after surgery.

Results: Print Area, Print Length, Swing Speed, and Duty Cycle decreased to a minimum of 40% of baseline 2 weeks after surgery. Swing Time was elevated more than twofold at this time point. However, all these parameters recovered back to >90% of baseline values at 10 weeks after surgery. This degree of functional recovery has not been reported after sciatic nerve resection and autograft repair. Base of support varied minimally postoperatively in contrast to a strong decrement after sciatic nerve resection and repair.

Conclusion: We hereby provide a comprehensive in-depth analysis of how to study functional recovery after injury of the femoral nerve in the rat via the CatWalk XT. We place special emphasis on highlighting the differences between the femoral nerve and sciatic nerve injury model in this context.
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http://dx.doi.org/10.1002/brb3.1580DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177579PMC
April 2020

Motor and sensory Schwann cell phenotype commitment is diminished by extracorporeal shockwave treatment in vitro.

J Peripher Nerv Syst 2020 03 5;25(1):32-43. Epub 2020 Feb 5.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology/AUVA Research Center, Vienna, Austria.

The gold standard for peripheral nerve regeneration uses a sensory autograft to bridge a motor/sensory defect site. For motor nerves to regenerate, Schwann cells (SC) myelinate the newly grown axon. Sensory SCs have a reduced ability to produce myelin, partially explaining low success rates of autografts. This issue is masked in pre-clinical research by the excessive use of the rat sciatic nerve defect model, utilizing a mixed nerve with motor and sensory SCs. Aim of this study was to utilize extracorporeal shockwave treatment as a novel tool to influence SC phenotype. SCs were isolated from motor, sensory and mixed rat nerves and in vitro differences between them were assessed concerning initial cell number, proliferation rate, neurite outgrowth as well as ability to express myelin. We verified the inferior capacity of sensory SCs to promote neurite outgrowth and express myelin-associated proteins. Motor Schwann cells demonstrated low proliferation rates, but strongly reacted to pro-myelination stimuli. It is noteworthy for pre-clinical research that sciatic SCs are a strongly mixed culture, not representing one or the other. Extracorporeal shockwave treatment (ESWT), induced in motor SCs an increased proliferation profile, while sensory SCs gained the ability to promote neurite outgrowth and express myelin-associated markers. We demonstrate a strong phenotype commitment of sciatic, motor, and sensory SCs in vitro, proposing the experimental use of SCs from pure cultures to better mimic clinical situations. Furthermore we provide arguments for using ESWT on autografts to improve the regenerative capacity of sensory SCs.
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http://dx.doi.org/10.1111/jns.12365DOI Listing
March 2020

Mesenchymal Stromal Cell-Based Bone Regeneration Therapies: From Cell Transplantation and Tissue Engineering to Therapeutic Secretomes and Extracellular Vesicles.

Front Bioeng Biotechnol 2019 27;7:352. Epub 2019 Nov 27.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Vienna, Austria.

Effective regeneration of bone defects often presents significant challenges, particularly in patients with decreased tissue regeneration capacity due to extensive trauma, disease, and/or advanced age. A number of studies have focused on enhancing bone regeneration by applying mesenchymal stromal cells (MSCs) or MSC-based bone tissue engineering strategies. However, translation of these approaches from basic research findings to clinical use has been hampered by the limited understanding of MSC therapeutic actions and complexities, as well as costs related to the manufacturing, regulatory approval, and clinical use of living cells and engineered tissues. More recently, a shift from the view of MSCs directly contributing to tissue regeneration toward appreciating MSCs as "cell factories" that secrete a variety of bioactive molecules and extracellular vesicles with trophic and immunomodulatory activities has steered research into new MSC-based, "cell-free" therapeutic modalities. The current review recapitulates recent developments, challenges, and future perspectives of these various MSC-based bone tissue engineering and regeneration strategies.
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http://dx.doi.org/10.3389/fbioe.2019.00352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6890555PMC
November 2019

MicroRNA levels in bone and blood change during bisphosphonate and teriparatide therapy in an animal model of postmenopausal osteoporosis.

Bone 2020 02 1;131:115104. Epub 2019 Nov 1.

TAmiRNA GmbH, Leberstrasse 20, 1110 Vienna, Austria; Austrian Cluster for Tissue Regeneration, Austria. Electronic address:

MicroRNAs control the activity of a variety of genes that are pivotal to bone metabolism. Therefore, the clinical utility of miRNAs as biomarkers and drug targets for bone diseases certainly merits further investigation. This study describes the use of an animal model of postmenopausal osteoporosis to generate a comprehensive dataset on miRNA regulation in bone tissue and peripheral blood during bone loss and specifically anti-resorptive and osteo-anabolic treatment. Forty-two Sprague-Dawley rats were randomized to SHAM surgery (n=10) or ovariectomy (OVX, n=32). Eight weeks after surgery, OVX animals were further randomized to anti-resorptive treatment with zoledronate (n=11), osteo-anabolic treatment with teriparatide (n=11), or vehicle treatment (n=10). After 12 weeks of treatment, bone and serum samples were used for microRNA analysis using next-generation sequencing (NGS), mRNA levels using RT-qPCR, and bone microarchitecture analysis using nanoCT. Ovariectomy resulted in loss of trabecular bone, which was fully rescued using osteo-anabolic treatment, and partially rescued using anti-resorptive treatment. NGS revealed that both, anti-resorptive and anabolic treatment had a significant impact on miRNA levels in bone tissue and serum: out of 426 detected miRNAs, 46 miRNAs were regulated by teriparatide treatment an d 10 by zoledronate treatment (p-adj.<0.1). Interestingly, teriparatide and zoledronate treatment were able to revert miRNA changes in tissue and serum of untreated OVX animals, such as the up-regulation of miR-203a-3p, a known osteo-inhibitory miRNA. We confirmed previously established mechanisms of miR-203a by analyzing its direct target Dlx5 in femoral head. Our data reveal a significant effect of ovariectomy-induced bone loss, as well as the two major types of anti-osteoporotic treatment on miRNA transcription in femoral head tissue. These changes are associated with altered activity of target genes relevant to bone formation, such as Dlx5. The observed effects of bone loss and treatment response on miRNA levels in bone are also reflected in the peripheral blood, suggesting the possibility of minimally-invasive monitoring of bone-derived miRNAs using liquid biopsies.
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http://dx.doi.org/10.1016/j.bone.2019.115104DOI Listing
February 2020

Purinergic P2Y receptors modulate endothelial sprouting.

Cell Mol Life Sci 2020 Mar 5;77(5):885-901. Epub 2019 Jul 5.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Donaueschingenstrasse 13, 1200, Vienna, Austria.

Purinergic P2 receptors are critical regulators of several functions within the vascular system, including platelet aggregation, vascular inflammation, and vascular tone. However, a role for ATP release and P2Y receptor signalling in angiogenesis remains poorly defined. Here, we demonstrate that blood vessel growth is controlled by P2Y receptors. Endothelial sprouting and vascular tube formation were significantly dependent on P2Y expression and inhibition of P2Y using a selective antagonist blocked microvascular network generation. Mechanistically, overexpression of P2Y in endothelial cells induced the expression of the proangiogenic molecules CXCR4, CD34, and angiopoietin-2, while expression of VEGFR-2 was decreased. Interestingly, elevated P2Y expression caused constitutive phosphorylation of ERK1/2 and VEGFR-2. However, stimulation of cells with the P2Y agonist UTP did not influence sprouting unless P2Y was constitutively expressed. Finally, inhibition of VEGFR-2 impaired spontaneous vascular network formation induced by P2Y overexpression. Our data suggest that P2Y receptors have an essential function in angiogenesis, and that P2Y receptors present a therapeutic target to regulate blood vessel growth.
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http://dx.doi.org/10.1007/s00018-019-03213-2DOI Listing
March 2020

Substantial Biomechanical Improvement by Extracorporeal Shockwave Therapy After Surgical Repair of Rodent Chronic Rotator Cuff Tears.

Am J Sports Med 2019 07 17;47(9):2158-2166. Epub 2019 Jun 17.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.

Background: Characteristics of chronic rotator cuff tears include continuous loss of tendon structure as well as tendon elasticity, followed by a high failure rate after surgical reconstruction. Several studies have already shown the beneficial effect of extracorporeal shockwave therapy (ESWT) on tissue regeneration in tendon pathologies.

Hypothesis: ESWT improves biomechanical tendon properties as well as functional shoulder outcomes in chronic rotator cuff reconstruction in rodents.

Study Design: Controlled laboratory study.

Methods: After tendon detachment and 3 weeks of degeneration, a subsequent transosseous reattachment of the supraspinatus tendon was performed in 48 adult male Sprague-Dawley rats (n = 16 per group). Rodents were randomly assigned to 3 study groups: no ESWT/control group, intraoperative ESWT (IntraESWT), and intra- and postoperative ESWT (IntraPostESWT). Shoulder joint function, as determined by gait analysis, was assessed repeatedly during the observation period. Eight weeks after tendon reconstruction, the rats were euthanized, and biomechanical and gene expression analyses were performed.

Results: Macroscopically, all repairs were intact at the time of euthanasia, with no ruptures detectable. Biomechanical analyses showed significantly improved load-to-failure testing results in both ESWT groups in comparison with the control group (control, 0.629; IntraESWT, 1.102; IntraPostESWT, 0.924; IntraESWT vs control, ≤ .001; IntraPostESWT vs control, ≤ .05). Furthermore, functional gait analyses showed a significant enhancement in intensity measurements for the IntraPostESWT group in comparison with the control group (≤ .05). Gene expression analysis revealed no significant differences among the 3 groups.

Conclusion: Clearly improved biomechanical results were shown in the single-application and repetitive ESWT groups. Furthermore, functional evaluation showed significantly improved intensity measurements for the repetitive ESWT group.

Clinical Relevance: This study underpins a new additional treatment possibility to prevent healing failure. Improved biomechanical stability and functionality may enable faster remobilization as well as an accelerated return to work and sports activities. Furthermore, as shockwave therapy is a noninvasive, easy-to-perform, cost-effective treatment tool with no undesired side effects, this study is of high clinical relevance in orthopaedic surgery. Based on these study results, a clinical study has already been initiated to clinically confirm the improved functionality by ESWT.
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http://dx.doi.org/10.1177/0363546519854760DOI Listing
July 2019

Spatiotemporal Differences in Gene Expression Between Motor and Sensory Autografts and Their Effect on Femoral Nerve Regeneration in the Rat.

Front Cell Neurosci 2019 8;13:182. Epub 2019 May 8.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.

To improve the outcome after autologous nerve grafting in the clinic, it is important to understand the limiting variables such as distinct phenotypes of motor and sensory Schwann cells. This study investigated the properties of phenotypically different autografts in a 6 mm femoral nerve defect model in the rat, where the respective femoral branches distally of the inguinal bifurcation served as homotopic, or heterotopic autografts. Axonal regeneration and target reinnervation was analyzed by gait analysis, electrophysiology, and wet muscle mass analysis. We evaluated regeneration-associated gene expression between 5 days and 10 weeks after repair, in the autografts as well as the proximal, and distal segments of the femoral nerve using qRT-PCR. Furthermore we investigated expression patterns of phenotypically pure ventral and dorsal roots. We identified highly significant differences in gene expression of a variety of regeneration-associated genes along the central - peripheral axis in healthy femoral nerves. Phenotypically mismatched grafting resulted in altered spatiotemporal expression of neurotrophic factor BDNF, GDNF receptor GFRα1, cell adhesion molecules Cadm3, Cadm4, L1CAM, and proliferation associated Ki67. Although significantly higher quadriceps muscle mass following homotopic nerve grafting was measured, we did not observe differences in gait analysis, and electrophysiological parameters between treatment paradigms. Our study provides evidence for phenotypic commitment of autologous nerve grafts after injury and gives a conclusive overview of temporal expression of several important regeneration-associated genes after repair with sensory or motor graft.
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http://dx.doi.org/10.3389/fncel.2019.00182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6519304PMC
May 2019

Neuroectodermal Stem Cells Grafted into the Injured Spinal Cord Induce Both Axonal Regeneration and Morphological Restoration via Multiple Mechanisms.

J Neurotrauma 2019 11 10;36(21):2977-2990. Epub 2019 Jul 10.

Department of Anatomy, Histology, and Embryology, Faculty of Medicine, University of Szeged, Szeged, Hungary.

Spinal cord contusion injury leads to severe loss of gray and white matter and subsequent deficit of motor and sensory functions below the lesion. In this study, we investigated whether application of murine clonal embryonic neuroectodermal stem cells can prevent the spinal cord secondary damage and induce functional recovery. Stem cells (NE-GFP-4C cell line) were grafted intraspinally or intravenously immediately or one week after thoracic spinal cord contusion injury. Control animals received cell culture medium or fibrin intraspinally one week after injury. Functional tests (Basso, Beattie, Bresnahan, CatWalk) and detailed morphological analysis were performed to evaluate the effects of grafted cells. Stem cells applied either locally or intravenously induced significantly improved functional recovery compared with their controls. Morphologically, stem cell grafting prevented the formation of secondary injury and promoted sparing of the gray and white matters. The transplanted cells integrated into the host tissue and differentiated into neurons, astrocytes, and oligodendrocytes. In intraspinally grafted animals, the corticospinal tract axons regenerated along the ventral border of the cavity and have grown several millimeters, even beyond the caudal end of the lesion. The extent of regeneration and functional improvement was inversely related to the amounts of chondroitin sulphate and ephrin-B2 molecules around the cavity and to the microglial and astrocytic reactions in the injured segment early after injury. The grafts produced glial cell derived neurotrophic factor, macrophage inflammatory protein-1a, interleukin (IL)-6 and IL-10 in a paracrine fashion for at least one week. Treating the grafted cords with neutralizing antibodies against these four factors through the use of osmotic pumps nearly completely abolished the effect of the graft. The non-significant functional improvement after function blocking is likely because the stem cell derivatives settled in the injured cord. These data suggest that grafted neuroectodermal stem cells are able to prevent the secondary spinal cord damage and induce significant regeneration via multiple mechanisms.
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http://dx.doi.org/10.1089/neu.2018.6332DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6791485PMC
November 2019

Iodine-Enhanced Micro-CT Imaging of Soft Tissue on the Example of Peripheral Nerve Regeneration.

Contrast Media Mol Imaging 2019 27;2019:7483745. Epub 2019 Mar 27.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Vienna, Austria.

Microcomputed tomography (CT) is widely used for the study of mineralized tissues, but a similar use for soft tissues is hindered by their low X-ray attenuation. This limitation can be overcome by the recent development of different staining techniques. Staining with Lugol's solution, a mixture of one part iodine and two parts potassium iodide in water, stands out among these techniques for its low complexity and cost. Currently, Lugol staining is mostly used for anatomical examination of tissues. In the present study, we seek to optimize the quality and reproducibility of the staining for visualization of soft tissues in the context of a peripheral nerve regeneration model in the rat. We show that the staining result not only depends on the concentration of the staining solution but also on the amount of stain in relation to the tissue volume and composition, necessitating careful adaptation of the staining protocol to the respective specimen tissue. This optimization can be simplified by a stepwise staining which we show to yield a similar result compared to staining in a single step. Lugol staining solution results in concentration-dependent tissue shrinkage which can be minimized but not eliminated. We compared the shrinkage of tendon, nerve, skeletal muscle, heart, brain, and kidney with six iterations of Lugol staining. 60 ml of 0.3% Lugol's solution per cm of tissue for 24 h yielded good results on the example of a peripheral nerve regeneration model, and we were able to show that the regenerating nerve inside a silk fibroin tube can be visualized in 3D using this staining technique. This information helps in deciding the region of interest for histological imaging and provides a 3D context to histological findings. Correlating both imaging modalities has the potential to improve the understanding of the regenerative process.
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http://dx.doi.org/10.1155/2019/7483745DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6458925PMC
July 2020

An Efficacy Comparison of Two Hemostatic Agents in a Porcine Liver Bleeding Model: Gelatin/Thrombin Flowable Matrix versus Collagen/Thrombin Powder.

J Invest Surg 2020 Oct 24;33(9):828-838. Epub 2019 Mar 24.

Baxter Medical Products GmbH, Vienna, Austria.

Management of bleeding during surgery can be aided by the application of topical hemostatic agents. This study compared the hemostatic efficacy of a new powder agent containing collagen, chondroitin sulfate, and thrombin (PCCT) with a flowable gelatin-thrombin matrix with smooth particles (SmGM) in a porcine liver bleeding model. Lesions 4-6 mm deep and ∼10 mm in diameter were created in porcine livers and treated with either SmGM or PCCT. Bleeding rate and grade were quantified before and 3, 7, and 11 minutes after treatment. Thirty-two lesions each were treated with SmGM or PCCT; the median (Q1, Q3) initial bleeding rate was comparable between the two groups (8.43 [6.18, 10.68] g/min and 7.15 [5.16, 9.63] g/min, respectively). The residual bleeding rate was significantly lower at all time-points post treatment for SmGM compared with PCCT (3 minutes: 0.14 [0.07, 0.21] versus 0.46 [0.20, 1.20] g/min,  < 0.0001; 7 minutes: 0.07 [0.04, 0.11] versus 0.12 [0.08, 0.39] g/min,  = 0.001; 11 minutes: 0.05 [0.03, 0.08] versus 0.07 [0.05, 0.12] g/min,  = 0.043). Bleeding grade at 3 minutes was also significantly lower for SmGM compared with PCCT (median [Q1, Q3] 0.0 [0.0, 0.0] versus 1.0 [1.0, 2.0],  < 0.0001). PCCT required reapplication in approximately one-third of applications due to insufficient hemostasis 4 minutes after initial application and showed a tendency to stick to the wet gauze during approximation. In this bleeding model, treatment with SmGM resulted in reduced blood loss, no need for reapplication and was easier to apply compared with PCCT.
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http://dx.doi.org/10.1080/08941939.2019.1571130DOI Listing
October 2020

Physical stimulation by REAC and BMP4/WNT-1 inhibitor synergistically enhance cardiogenic commitment in iPSCs.

PLoS One 2019 23;14(1):e0211188. Epub 2019 Jan 23.

Department of Biomedical Sciences, University of Sassari, Sassari, Italy.

It is currently known that pluripotent stem cells can be committed in vitro to the cardiac lineage by the modulation of specific signaling pathways, but it is also well known that, despite the significant increase in cardiomyocyte yield provided by the currently available conditioned media, the resulting cardiogenic commitment remains a highly variable process. Previous studies provided evidence that radio electric fields asymmetrically conveyed through the Radio Electric Asymmetric Conveyer (REAC) technology are able to commit R1 embryonic stem cells and human adipose derived stem cells toward a cardiac phenotype. The present study aimed at investigating whether the effect of physical stimulation by REAC in combination with specific chemical inductors enhance the cardiogenic potential in human induced pluripotent stem cells (iPSCs). The appearance of a cardiac-like phenotype in iPSCs cultured in the presence of a cardiogenic medium, based upon BMP4 and a WNT-inhibitor, was consistently increased by REAC treatment used only during the early fate differentiation for the first 72 hours. REAC-exposed iPSCs exhibited an upregulation in the expression of specific cardiogenic transcripts and morphologically in the number of beating clusters, as compared to cells cultured in the cardiogenic medium alone. Our results indicate that physical modulation of cellular dynamics provided by the REAC offers an affordable strategy to mimic iPSC cardiac-like fates in the presence of a cardiogenic milieu.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0211188PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6343882PMC
October 2019

Osteointegration of a Novel Silk Fiber-Based ACL Scaffold by Formation of a Ligament-Bone Interface.

Am J Sports Med 2019 03 17;47(3):620-627. Epub 2019 Jan 17.

Austrian Cluster for Tissue Regeneration, Vienna, Austria.

Background: Given the unsatisfactory results and reported drawbacks of anterior cruciate ligament (ACL) reconstruction, such as donor site morbidity and the limited choice of grafts in revision surgery, new regenerative approaches based on tissue-engineering strategies are currently under investigation.

Purposes: To determine (1) if a novel silk fiber-based ACL scaffold is able to initiate osteointegration in the femoral and tibial bone tunnels under in vivo conditions and (2) if the osteointegration process will be improved by intraoperatively seeding the scaffolds with the autologous stromal vascular fraction, an adipose-derived, stem cell-rich isolate from knee fat pads.

Study Design: Controlled laboratory study.

Methods: A total of 33 sheep underwent ACL resection and were then randomly assigned to 2 experimental groups: ACL reconstruction with a scaffold alone and ACL reconstruction with a cell-seeded scaffold. Half of the sheep in each group were randomly chosen and euthanized 6 months after surgery and the other half at 12 months. To analyze the integration of the silk-based scaffold in the femoral and tibial bone tunnels, hard tissue histology and micro-computed tomography measurements were performed.

Results: Hard tissue histological workup showed that in all treatment groups, with or without the application of the autologous stromal vascular fraction, an interzone of collagen fibers had formed between bone and silk-based graft. This collagen-fiber continuity partly consisted of Sharpey fibers, comparable with tendon-bone healing known for autografts and allografts. Insertion sites were more broad based at 6 months and more concentrated on the slightly protruding, bony knoblike structures at 12 months. Histologically, no differences between the treatment groups were detectable. Analysis of micro-computed tomography measurements revealed a significantly higher tissue density for the cell-seeded scaffold group as compared with the scaffold-alone group in the tibial but not femoral bone tunnel after 12 months of implantation.

Conclusion: The novel silk fiber-based scaffold for ACL regeneration demonstrated integration into the bone tunnels via the formation of a fibrous interzone similar to allografts and autografts. Histologically, additional cell seeding did not enhance osteointegration. No significant differences between 6 and 12 months could be detected. After 12 months, there was still a considerable amount of silk present, and a longer observation period is necessary to see if a true ligament-bone enthesis will be formed.

Clinical Relevance: ACL regeneration with a silk fiber-based scaffold with and without additional cell seeding may provide an alternative treatment option to current techniques of surgical reconstruction.
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http://dx.doi.org/10.1177/0363546518818792DOI Listing
March 2019

Environmental Influences on Stem Cell Behavior.

Stem Cells Int 2018 10;2018:7415460. Epub 2018 Dec 10.

AO Research Institute Davos, Davos, Switzerland.

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http://dx.doi.org/10.1155/2018/7415460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6311709PMC
December 2018

Oxygen Tension Strongly Influences Metabolic Parameters and the Release of Interleukin-6 of Human Amniotic Mesenchymal Stromal Cells .

Stem Cells Int 2018 28;2018:9502451. Epub 2018 Oct 28.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Donaueschingenstraße 13, 1200 Vienna, Austria.

The human amniotic membrane (hAM) has been used for tissue regeneration for over a century. (), cells of the hAM are exposed to low oxygen tension (1-4% oxygen), while the hAM is usually cultured in atmospheric, meaning high, oxygen tension (20% oxygen). We tested the influence of oxygen tensions on mitochondrial and inflammatory parameters of human amniotic mesenchymal stromal cells (hAMSCs). Freshly isolated hAMSCs were incubated for 4 days at 5% and 20% oxygen. We found 20% oxygen to strongly increase mitochondrial oxidative phosphorylation, especially in placental amniotic cells. Oxygen tension did not impact levels of reactive oxygen species (ROS); however, placental amniotic cells showed lower levels of ROS, independent of oxygen tension. In contrast, the release of nitric oxide was independent of the amniotic region but dependent on oxygen tension. Furthermore, IL-6 was significantly increased at 20% oxygen. To conclude, short-time cultivation at 20% oxygen of freshly isolated hAMSCs induced significant changes in mitochondrial function and release of IL-6. Depending on the therapeutic purpose, cultivation conditions of the cells should be chosen carefully for providing the best possible quality of cell therapy.
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http://dx.doi.org/10.1155/2018/9502451DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6230389PMC
October 2018

Hydrostatic pressure-generated reactive oxygen species induce osteoarthritic conditions in cartilage pellet cultures.

Sci Rep 2018 11 19;8(1):17010. Epub 2018 Nov 19.

Department Life Science Engineering, University of Applied Sciences Technikum Wien, 1200, Vienna, Austria.

Osteoarthritis (OA) is one of the most common causes of disability and represents a major socio-economic burden. Despite intensive research, the molecular mechanisms responsible for the initiation and progression of OA remain inconclusive. In recent years experimental findings revealed elevated levels of reactive oxygen species (ROS) as a major factor contributing to the onset and progression of OA. Hence, we designed a hydrostatic pressure bioreactor system that is capable of stimulating cartilage cell cultures with elevated ROS levels. Increased ROS levels in the media did not only lead to an inhibition of glycosaminoglycans and collagen II formation but also to a reduction of already formed glycosaminoglycans and collagen II in chondrogenic mesenchymal stem cell pellet cultures. These effects were associated with the elevated activity of matrix metalloproteinases as well as the increased expression of several inflammatory cytokines. ROS activated different signaling pathways including PI3K/Akt and MAPK/ERK which are known to be involved in OA initiation and progression. Utilizing the presented bioreactor system, an OA in vitro model based on the generation of ROS was developed that enables the further investigation of ROS effects on cartilage degradation but can also be used as a versatile tool for anti-oxidative drug testing.
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http://dx.doi.org/10.1038/s41598-018-34718-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6242959PMC
November 2018

Microvascular Networks From Endothelial Cells and Mesenchymal Stromal Cells From Adipose Tissue and Bone Marrow: A Comparison.

Front Bioeng Biotechnol 2018 25;6:156. Epub 2018 Oct 25.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.

A promising approach to overcome hypoxic conditions in tissue engineered constructs is to use the potential of endothelial cells (EC) to form networks when co-cultured with a supporting cell type in a 3D environment. Adipose tissue-derived stromal cells (ASC) as well as bone marrow-derived stromal cells (BMSC) have been shown to support vessel formation of EC , but only very few studies compared the angiogenic potential of both cell types using the same model. Here, we aimed at investigating the ability of ASC and BMSC to induce network formation of EC in a co-culture model in fibrin. While vascular structures of BMSC and EC remained stable over the course of 3 weeks, ASC-EC co-cultures developed more junctions and higher network density within the same time frame. Both co-cultures showed positive staining for neural glial antigen 2 (NG2) and basal lamina proteins. This indicates that vessels matured and were surrounded by perivascular cells as well as matrix molecules involved in stabilization. Gene expression analysis revealed a significant increase of vascular endothelial growth factor (VEGF) expression in ASC-EC co-culture compared to BMSC-EC co-culture. These observations were donor-independent and highlight the importance of organotypic cell sources for vascular tissue engineering.
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http://dx.doi.org/10.3389/fbioe.2018.00156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209673PMC
October 2018

Effect of Coagulation Factor Concentrates on Markers of Endothelial Cell Damage in Experimental Hemorrhagic Shock.

Shock 2019 11;52(5):497-505

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Trauma Research Center, Vienna, Austria.

Background: Plasma-based resuscitation showed protective effects on the endothelial glycocalyx compared with crystalloid resuscitation. There is paucity of data regarding the effect of coagulation factor concentrates (CFC) on the glycocalyx in hemorrhagic shock (HS). We hypothesized that colloid-based resuscitation supplemented with CFCs offers a therapeutic value to treat endothelial damage following HS.

Methods: Eighty-four rats were subjected to pressure-controlled (mean arterial pressure (MAP) 30-35 mm Hg) and lab-guided (targeted cutoff: lactate >2.2. mmol/L and base deficit > 5.5 mmol/L) HS. Animals were resuscitated with fresh frozen plasma (FFP), human albumin (HA) or Ringer's lactate (RL) and RL or HA supplemented with fibrinogen concentrate (FC) or prothrombin complex concentrate (PCC). Serum epinephrine and the following markers of endothelial damage were assessed at baseline and at the end-of-observation (120 min after shock was terminated): syndecan-1, heparan sulfate, and soluble vascular endothelial growth factor receptor 1 (sVEGFR 1).

Results: Resuscitation with FFP had no effect on sVEGFR1 compared with crystalloid-based resuscitation (FFP: 19.3 ng/mL vs. RL: 15.9 ng/mL; RL+FC: 19.7 ng/mL; RL+PCC: 18.9 ng/mL; n.s.). At the end-of-observation, syndecan-1 was similar among all groups. Interestingly, HA+FC treated animals displayed the highest syndecan-1 concentration (12.07 ng/mL). Resuscitation with FFP restored heparan sulfate back to baseline (baseline: 36 ng/mL vs. end-of-observation: 36 ng/mL).

Conclusion: The current study revealed that plasma-based resuscitation normalized circulating heparan sulfate but not syndecan-1. Co-administration of CFC had no further effect on glycocalyx shedding suggesting a lack of its therapeutic potential.

Level Of Evidence: VExperimental in vivo study.
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http://dx.doi.org/10.1097/SHK.0000000000001286DOI Listing
November 2019

A large animal model for standardized testing of bone regeneration strategies.

BMC Vet Res 2018 Nov 6;14(1):330. Epub 2018 Nov 6.

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in AUVA research center, Vienna, Austria.

Background: The need for bone graft substitutes including those being developed to be applied together with new strategies of bone regeneration such as tissue engineering and cell-based approaches is growing. No large animal model of bone regeneration has been accepted as a standard testing model. Standardization may be the key to moving systematically towards better bone regeneration. This study aimed to establish a model of bone regeneration in the sheep that lends itself to strict standardization and in which a number of substances can be tested within the same animal. To this end the caudal border of the ovine scapula was used as a consistent bed of mineralized tissue that provided sufficient room for a serial alignment of multiple experimental drill holes.

Results: The findings show that for the sake of standardization, surgery should be restricted to the middle part of the caudal margin, an area at least 80 mm proximal from the Glenoid cavity, but not more than 140 mm away from it, in the adult female Land Merino sheep. A distance of 5 mm from the caudal margin should also be observed.

Conclusions: This standardized model with defined uniform defects and defect sites results in predictable and reproducible bone regeneration processes. Defects are placed unilaterally in only one limb of the animal, avoiding morbidity in multiple limbs. The fact that five defects per animal can be evaluated is conducive to intra-animal comparisons and reduces the number of animals that have to be subject to experimentation.
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http://dx.doi.org/10.1186/s12917-018-1648-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6220560PMC
November 2018