The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Per Aspenberg - One of the best experts on this subject based on the ideXlab platform.
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Trombocytkoncentrat mot tendinos tycks lovande. Randomiserade studier pågår – viktigt invänta resultaten : [Promising outcome with Thrombocyte Concentrate against tendinosis. Ongoing randomized controlled trials--important to await results]
Lakartidningen, 2008Co-Authors: Per AspenbergAbstract:Platelet Concentrates have been implicated in bone and soft tissue repair for decades, but results from both preclinical and clinical studies have been meagre and conflicting. In a small animal model, a locally injected platelet Concentrate accelerated the repair of injured Achilles tendons. This has raised a hope for clinical success in the treatment of tendon pathology. Treatment of tendinosis with platelet Concentrates has been heavily marketed, and there is now an increasing public demand for this treatment. At a recent meeting in Linkoping, Sweden, 2 ongoing randomised controlled studies were described, with some preliminary results. It was concluded that there is an increasing enthusiasm, but no useful clinical data.
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trombocytkoncentrat mot tendinos tycks lovande randomiserade studier pagar viktigt invanta resultaten promising outcome with Thrombocyte Concentrate against tendinosis ongoing randomized controlled trials important to await results
Läkartidningen, 2008Co-Authors: Per AspenbergAbstract:Platelet Concentrates have been implicated in bone and soft tissue repair for decades, but results from both preclinical and clinical studies have been meagre and conflicting. In a small animal model, a locally injected platelet Concentrate accelerated the repair of injured Achilles tendons. This has raised a hope for clinical success in the treatment of tendon pathology. Treatment of tendinosis with platelet Concentrates has been heavily marketed, and there is now an increasing public demand for this treatment. At a recent meeting in Linkoping, Sweden, 2 ongoing randomised controlled studies were described, with some preliminary results. It was concluded that there is an increasing enthusiasm, but no useful clinical data.
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Stimulation of tendon repair: mechanical loading, GDFs and platelets. A mini-review
International Orthopaedics, 2007Co-Authors: Per AspenbergAbstract:The repair of subcutaneous tendon ruptures can be stimulated by a single application of one of several growth factors [e.g. platelet-derived growth factor (PDGF), transforming growth factor (TGF)-beta, insulin-like growth factor (IGF)-1, vascular endothelial growth factor (VEGF), bone morphogenetic proteins (BMPs) like growth differentiation factor (GDF)-5, -6, -7] or by a Thrombocyte Concentrate (PRP). The response to these measures is dependent on the mechanical microenvironment, which is crucial for repair. So far, almost all research has been limited to rodent models, mostly using the rat Achilles tendon. Ruptured human Achilles tendons appear to be mechanically loaded in spite of immobilisation. This suggests that the mechanical microenvironment might be favourable for the clinical use of growth factors or platelets for this indication. New methods to quantitate human Achilles tendon repair have been developed. La réparation de rupture tendineuse sous cutanée peut être améliorée par une simple application d’un ou de plusieurs facteurs de croissance (PDGF, TGF-beta, IGF-1, VEGF, BMPs, GDF like -5, -6, -7) ou par un concentré de plaquettes (PRP). Ce modèle a surtout été utilisé, au niveau du tendon d’Achille des rats. Cette étude nous montre que le micro environnement mécanique peut être amélioré par l’utilisation de facteurs de croissance et de concentrés de plaquettes. De nouvelles méthodes permettant de quantifier l’importance de la réparation du tendon d’Achille humain ont été développées.
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Stimulation of tendon repair: Mechanical loading, GDFs and platelets. a mini-review
International Orthopaedics, 2007Co-Authors: Per AspenbergAbstract:The repair of subcutaneous tendon ruptures can be stimulated by a single application of one of several growth factors [e.g. platelet-derived growth factor (PDGF), transforming growth factor (TGF)-beta, insulin-like growth factor (IGF)-1, vascular endothelial growth factor (VEGF), bone morphogenetic proteins (BMPs) like growth differentiation factor (GDF)-5, -6, -7] or by a Thrombocyte Concentrate (PRP). The response to these measures is dependent on the mechanical microenvironment, which is crucial for repair. So far, almost all research has been limited to rodent models, mostly using the rat Achilles tendon. Ruptured human Achilles tendons appear to be mechanically loaded in spite of immobilisation. This suggests that the mechanical microenvironment might be favourable for the clinical use of growth factors or platelets for this indication. New methods to quantitate human Achilles tendon repair have been developed.
S. Lippross - One of the best experts on this subject based on the ideXlab platform.
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Platelet-released growth factors can accelerate tenocyte proliferation and activate the anti-oxidant response element
Histochemistry and Cell Biology, 2011Co-Authors: M. Tohidnezhad, Thomas Pufe, D. Varoga, C. J. Wruck, L. O. Brandenburg, A. Seekamp, M. Shakibaei, T. T. Sönmez, S. LipprossAbstract:Little is know about the pathophysiology of acute and degenerative tendon injuries. Although most lesions are uncomplicated, treatment is long and unsatisfactory in a considerable number of cases. Besides the common growth factors that were shown to be relevant for tendon integrity more recently protection against oxidative stress was shown to promote tendon healing. To improve tendon regeneration, many have advocated the use of platelet-rich plasma (PRP), a Thrombocyte Concentrate that can serve as an autologous source of growth factors. In this study, we investigated the effect of platelet-released growth factors (PRGF) on tenocytes. Tenocytes were isolated from the Achilles tendon of postnatal rats. Tenocyte cell cultures were stimulated with PRGF. We used a CyQuant assay and WST assay to analyse tendon cell growth and viability in different concentrations of PRGF. Migration and proliferation of cells grown in PRGF were assessed by a scratch test. A dual-luciferase assay was used to demonstrate the activation of the anti-oxidant response element (ARE) in tenocytes. A positive effect of PRGF could be shown on tendon cell growth and migratory capacity. PRGF activated the Nrf2–ARE pathway in a dose-dependent manner. Here, we provide evidence of a biological effect of PRGF on tenocytes by the promotion of tenocyte growth and activation of the Nrf2–ARE pathway. This is a novel aspect of the action of platelet Concentrates on tendon growth.
Thomas Pufe - One of the best experts on this subject based on the ideXlab platform.
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Platelet-Released Growth Factors and Platelet-Rich Fibrin Induce Expression of Factors Involved in Extracellular Matrix Organization in Human Keratinocytes
International journal of molecular sciences, 2020Co-Authors: Andreas Bayer, Mersedeh Tohidnezhad, Thomas Pufe, Franziska Rademacher, Bernard Wijaya, Lena Möbus, Meno Rodewald, Daniel Drücke, Regine Gläser, Jürgen HarderAbstract:Platelet-released growth factor (PRGF) is a Thrombocyte Concentrate lysate which, like its clinically equivalent variations (e.g., Vivostat PRF® (platelet-rich fibrin)), is known to support the healing of chronic and hard-to-heal wounds. However, studies on the effect of PRGF on keratinocytes remain scarce. This study aims to identify genes in keratinocytes that are significantly influenced by PRGF. Therefore, we performed a whole transcriptome and gene ontology (GO) enrichment analysis of PRGF-stimulated human primary keratinocytes. This revealed an increased expression of genes involved in extracellular matrix (ECM) organization. Real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) analysis confirmed the PRGF-mediated induction of selected ECM-related factors such as transforming growth factor beta-induced protein, fibronectin 1, matrix metalloproteinase-9, transglutaminase 2, fermitin family member 1, collagen type I alpha 1 and collagen type XXII alpha 1. PRGF-induced expression of the above factors was influenced by blockade of the epidermal growth factor receptor (EGFR), a receptor playing a crucial role in wound healing. A differential induction of the investigated factors was also detected in skin explants exposed to PRGF and in experimentally generated in vivo wounds treated with Vivostat PRF®. Together, our study indicates that the induction of ECM-related factors may contribute to the beneficial wound-healing effects of PRGF-based formulations.
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Platelet-released growth factors inhibit proliferation of primary keratinocytes in vitro.
Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft, 2017Co-Authors: Andreas Bayer, Mersedeh Tohidnezhad, Rouven Berndt, Sebastian Lippross, Peter Behrendt, Tim Klüter, Thomas Pufe, Holger Jahr, Jochen Cremer, Franziska RademacherAbstract:Autologous Thrombocyte Concentrate lysates as platelet-released growth factors (PRGF) or Vivostat Platelet Rich Fibrin (PRF®) represent important tools in modern wound therapy, especially in the treatment of chronic, hard-to-heal or infected wounds. Nevertheless, underlying cellular and molecular mechanisms of the beneficial clinical effects of a local wound therapy with autologous Thrombocyte Concentrate lysates are poorly understood. Recently, we have demonstrated that PRGF induces antimicrobial peptides in primary keratinocytes and accelerates keratinocytes' differentiation. In the present study we analyzed the influence of PRGF on primary human keratinocytes' proliferation. Using the molecular proliferation marker Ki-67 we observed a concentration- and time dependent inhibition of Ki-67 gene expression in PRGF treated primary keratinocytes. These effects were independent from the EGFR- and the IL-6-R pathway. Inhibition of primary keratinocytes' proliferation by PRGF treatment was confirmed in colorimetric cell proliferation assays. Together, these data indicate that the clinically observed positive effects of autologous Thrombocytes Concentrates in the treatment of chronic, hard-to-heal wounds are not based on an increased keratinocytes proliferation.
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Platelet-released growth factors induce psoriasin in keratinocytes: Implications for the cutaneous barrier.
Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft, 2017Co-Authors: Andreas Bayer, Mersedeh Tohidnezhad, Sebastian Lippross, Peter Behrendt, Tim Klüter, Thomas Pufe, Holger Jahr, Jochen Cremer, Justus Lammel, Franziska RademacherAbstract:Millions of patients around the world suffer minor or major extremity amputation due to progressive wound healing complications of chronic or infected wounds, the therapy of which remains a challenge. One emerging therapeutic option for the treatment of these complicated wounds is the local application of an autologous Thrombocytes Concentrate lysate (e.g. platelet-released growth factors ((PRGF)) or Vivostat PRF®) that contains a multitude of chemokines, cytokines and growth factors and is therefore supposed to stimulate the complex wound healing process. Although PRGF and Vivostat PRF® are already used successfully to support healing of chronic, hard-to-heal and infected wounds the underlying molecular mechanisms are not well understood. Psoriasin, also termed S100A7, is a multifunctional antimicrobial protein expressed in keratinocytes and is involved in various processes such as wound-healing, angiogenesis, innate immunity and immune-modulation. In this study, we investigated the influence of PRGF on psoriasin expression in human primary keratinocytes in vitro and the influence of Vivostat PRF® on psoriasin expression in experimentally generated skin wounds in vivo. PRGF treatment of primary keratinocytes caused a significant concentration- and time-dependent increase of psoriasin gene and protein expression in vitro that were partially mediated by the epidermal growth factor receptor (EGFR) and the interleukin-6 receptor (IL-6R). In accordance with these cell culture data, Vivostat PRF® induced a significant psoriasin gene and protein expression when applied to artificially generated skin wounds in vivo. The observed psoriasin induction in keratinocytes may contribute to the wound healing-promoting effects of therapeutically used Thrombocyte Concentrate lysates.
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Platelet-Released Growth Factors Induce Differentiation of Primary Keratinocytes
Hindawi Limited, 2017Co-Authors: Andreas Bayer, Mersedeh Tohidnezhad, Sebastian Lippross, Peter Behrendt, Tim Klüter, Thomas Pufe, Holger Jahr, Jochen Cremer, Justus Lammel, Franziska RademacherAbstract:Autologous Thrombocyte Concentrate lysates, for example, platelet-released growth factors, (PRGFs) or their clinically related formulations (e.g., Vivostat PRF®) came recently into the physicians’ focus as they revealed promising effects in regenerative and reparative medicine such as the support of healing of chronic wounds. To elucidate the underlying mechanisms, we analyzed the influence of PRGF and Vivostat PRF on human keratinocyte differentiation in vitro and on epidermal differentiation status of skin wounds in vivo. Therefore, we investigated the expression of early (keratin 1 and keratin 10) and late (transglutaminase-1 and involucrin) differentiation markers. PRGF treatment of primary human keratinocytes decreased keratin 1 and keratin 10 gene expression but induced involucrin and transglutaminase-1 gene expression in an epidermal growth factor receptor- (EGFR-) dependent manner. In concordance with these results, microscopic analyses revealed that PRGF-treated human keratinocytes displayed morphological features typical of keratinocytes undergoing terminal differentiation. In vivo treatment of artificial human wounds with Vivostat PRF revealed a significant induction of involucrin and transglutaminase-1 gene expression. Together, our results indicate that PRGF and Vivostat PRF induce terminal differentiation of primary human keratinocytes. This potential mechanism may contribute to the observed beneficial effects in the treatment of hard-to-heal wounds with autologous Thrombocyte Concentrate lysates in vivo
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The Antimicrobial Peptide Human Beta-Defensin-3 Is Induced by Platelet-Released Growth Factors in Primary Keratinocytes
Hindawi Limited, 2017Co-Authors: Andreas Bayer, Mersedeh Tohidnezhad, Sebastian Lippross, Peter Behrendt, Tim Klüter, Thomas Pufe, Holger Jahr, Jochen Cremer, Justus Lammel, Franziska RademacherAbstract:Platelet-released growth factors (PRGF) and its related clinically used formulations (e.g., Vivostat Platelet-Rich Fibrin (PRF®)) contain a variety of chemokines, cytokines, and growth factors and are therefore used to support healing of chronic, hard-to-heal, or infected wounds. Human beta-defensin-3 (hBD-3) is an antimicrobial peptide inducibly expressed in human keratinocytes especially upon wounding. The potent antimicrobial activity of hBD-3 together with its wound closure-promoting activities suggests that hBD-3 may play a crucial role in wound healing. Therefore, we analyzed the influence of PRGF on hBD-3 expression in human primary keratinocytes in vitro. In addition, we investigated the influence of Vivostat PRF on hBD-3 expression in artificially generated human skin wounds in vivo. PRGF treatment of primary keratinocytes induced a significant, concentration- and time-dependent increase in hBD-3 gene expression which was partially mediated by the epidermal growth factor receptor (EGFR). In line with these cell culture data, in vivo experiments revealed an enhanced hBD-3 expression in experimentally produced human wounds after the treatment with Vivostat PRF. Thus, the induction of hBD-3 may contribute to the beneficial effects of Thrombocyte Concentrate lysates in the treatment of chronic or infected wounds
A. Seekamp - One of the best experts on this subject based on the ideXlab platform.
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Thrombocytes are effectors of the innate immune system releasing human beta defensin 3
Injury-international Journal of The Care of The Injured, 2011Co-Authors: Mersedeh Tohidnezhad, Thomas Pufe, Deike Varoga, A. Seekamp, Rainer Podschun, Christoph Jan Wruck, Larsove Brandenburg, Sebastian LipprossAbstract:Abstract Background Thrombocyte Concentrate i.e. platelet-rich plasma (PRP) has become a popular adjunct for many surgical procedures. It is believed to improve bone and soft tissue healing. Recently antimicrobial effects of the autologous preparation were reported by several groups. In this study we investigated the antimicrobial effect of PRP against gram-negative microbes which frequently cause severe complications in orthopaedic trauma surgery. Methods Platelet-rich plasma was produced from liquid preserved Thrombocyte Concentrates. ELISA, Western blot and immunohistochemistry were preformed to investigate the release and content of platelet Concentrates. A radial diffusion assay was used to detect antimicrobial effects of PRP. Results We detected the human beta defensin-3 in bactericidal concentrations in platelet preparations by ELISA, Western blot and immunohistochemistry. In antimicrobial testing we demonstrated effective inhibition of Escherichia coli (ATCC 11303), Bacterium megaterium (ATCC 14581), Klebsiella pneumoniae (ATCC 13883), Enterococcus faecalis (ATCC 29212) and Proteus mirabilis (ATCC21100). Conclusion With this study we demonstrate antimicrobial action of a popular adjunct for orthopaedic and trauma surgery against gram-positive and gram-negative bacteria. We have identified a possible mechanism of action via the secretion of HBD-3 as a first line defence in contaminated wounds and in elective application of PRP. This finding supports a broader spectrum of clinical indications for an autologous platelet preparation.
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Platelet-released growth factors can accelerate tenocyte proliferation and activate the anti-oxidant response element
Histochemistry and Cell Biology, 2011Co-Authors: M. Tohidnezhad, Thomas Pufe, D. Varoga, C. J. Wruck, L. O. Brandenburg, A. Seekamp, M. Shakibaei, T. T. Sönmez, S. LipprossAbstract:Little is know about the pathophysiology of acute and degenerative tendon injuries. Although most lesions are uncomplicated, treatment is long and unsatisfactory in a considerable number of cases. Besides the common growth factors that were shown to be relevant for tendon integrity more recently protection against oxidative stress was shown to promote tendon healing. To improve tendon regeneration, many have advocated the use of platelet-rich plasma (PRP), a Thrombocyte Concentrate that can serve as an autologous source of growth factors. In this study, we investigated the effect of platelet-released growth factors (PRGF) on tenocytes. Tenocytes were isolated from the Achilles tendon of postnatal rats. Tenocyte cell cultures were stimulated with PRGF. We used a CyQuant assay and WST assay to analyse tendon cell growth and viability in different concentrations of PRGF. Migration and proliferation of cells grown in PRGF were assessed by a scratch test. A dual-luciferase assay was used to demonstrate the activation of the anti-oxidant response element (ARE) in tenocytes. A positive effect of PRGF could be shown on tendon cell growth and migratory capacity. PRGF activated the Nrf2–ARE pathway in a dose-dependent manner. Here, we provide evidence of a biological effect of PRGF on tenocytes by the promotion of tenocyte growth and activation of the Nrf2–ARE pathway. This is a novel aspect of the action of platelet Concentrates on tendon growth.
M. Tohidnezhad - One of the best experts on this subject based on the ideXlab platform.
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Platelet-released growth factors can accelerate tenocyte proliferation and activate the anti-oxidant response element
Histochemistry and Cell Biology, 2011Co-Authors: M. Tohidnezhad, Thomas Pufe, D. Varoga, C. J. Wruck, L. O. Brandenburg, A. Seekamp, M. Shakibaei, T. T. Sönmez, S. LipprossAbstract:Little is know about the pathophysiology of acute and degenerative tendon injuries. Although most lesions are uncomplicated, treatment is long and unsatisfactory in a considerable number of cases. Besides the common growth factors that were shown to be relevant for tendon integrity more recently protection against oxidative stress was shown to promote tendon healing. To improve tendon regeneration, many have advocated the use of platelet-rich plasma (PRP), a Thrombocyte Concentrate that can serve as an autologous source of growth factors. In this study, we investigated the effect of platelet-released growth factors (PRGF) on tenocytes. Tenocytes were isolated from the Achilles tendon of postnatal rats. Tenocyte cell cultures were stimulated with PRGF. We used a CyQuant assay and WST assay to analyse tendon cell growth and viability in different concentrations of PRGF. Migration and proliferation of cells grown in PRGF were assessed by a scratch test. A dual-luciferase assay was used to demonstrate the activation of the anti-oxidant response element (ARE) in tenocytes. A positive effect of PRGF could be shown on tendon cell growth and migratory capacity. PRGF activated the Nrf2–ARE pathway in a dose-dependent manner. Here, we provide evidence of a biological effect of PRGF on tenocytes by the promotion of tenocyte growth and activation of the Nrf2–ARE pathway. This is a novel aspect of the action of platelet Concentrates on tendon growth.