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Öğe Acute and post-acute neuromodulation induces stroke recovery by promoting survival signaling, neurogenesis, and pyramidal tract plasticity(Frontiers Media Sa, 2019) Çağlayan, Ahmet Burak; Beker, Mustafa Çağlar; Çağlayan, Berrak; Yalçın, Esra; Çağlayan, Aysun; Yuluğ, Burak; Hanoğlu, Lütfü; Kutlu, Selim; Doeppner, Thorsten Roland; Hermann, Dirk Matthias; Kılıç, ErtuğrulRepetitive transcranial magnetic stimulation (rTMS) has gained interest as a non-invasive treatment for stroke based on the data promoting its effects on functional recovery. However, the exact action mechanisms by which the rTMS exert beneficial effects in cellular and molecular aspect are largely unknown. To elucidate the effects of high- and low-frequency rTMS in the acute-ischemic brain, we examined how rTMS influences injury development, cerebral blood flow (CBF), DNA fragmentation, neuronal survival, pro- and anti-apoptotic protein activations after 30 and 90 min of focal cerebral ischemia. In addition, inflammation, angiogenesis, growth factors and axonal outgrowth related gene expressions, were analyzed. Furthermore, we have investigated the effects of rTMS on post-acute ischemic brain, particularly on spontaneous locomotor activity, perilesional tissue remodeling, axonal sprouting of corticobulbar tracts, glial scar formation and cell proliferation, in which rTMS was applied starting 3 days after the stroke onset for 28 days. In the high-frequency rTMS received animals reduced DNA fragmentation, infarct volume and improved CBF were observed, which were associated with increased Bcl-xL activity and reduced Bax, caspase-1, and caspase-3 activations. Moreover, increased angiogenesis, growth factors; and reduced inflammation and axonal sprouting related gene expressions were observed. These results correlated with reduced microglial activation, neuronal degeneration, glial scar formation and improved functional recovery, tissue remodeling, contralesional pyramidal tract plasticity and neurogenesis in the subacute rTMS treated animals. Overall, we propose that high-frequency rTMS in stroke patients can be used to promote functional recovery by inducing the endogenous repair and recovery mechanisms of the brain.Öğe Assessing self-administration of medication: video-based evaluation of patient performance in the ablymed study(2024) Luegering, Anneke; Langner, Robert; Wilm, Stefan; Doeppner, Thorsten Roland; Hermann, Dirk Matthias; Frohnhofen, Helmut; Gronewold, JanineBackground: Older adults often face challenges in medication management due to multimorbidity and complex medication regimens, which frequently go unreported. Unrecognized problems, however, may lead to a loss of drug efficacy and harmful side effects. This study aimed to quantify the prevalence of such problems by applying a novel video-based assessment procedure in a sample of elderly patients. Methods: In this study, 67 elderly in-patients (≥70 years old and regularly taking ≥5 different drugs autonomously) from the ABLYMED study participated in a placebo-based assessment of medication management with five different dosage forms in an instructed manner while being filmed. Patient performance was quantified by the median value of two raters who evaluated each step of medication administration, which were summed to sum scores for each dosage form and an overall impression for each dosage form with a standardized and previously validated rating scheme. Results: The median (Q1;Q3) sum score for tablets was 7.0 (5.0;8.0) with a theoretical range between 4.0 and 17.0, for eye-drops 2.0 (1.0;2.0) with a theoretical range between 1.0 and 5.0, for oral drops 4.0 (3.0;6.0) with a theoretical range between 3.0 and 12.0, for pens 7.0 (5.0;9.0) with a theoretical range between 4.0 and 17.0 and for patches 5.0 (4.0;7.0) with a theoretical range between 3.0 and 15.0. The most difficult step of medication administration was peeling off the protective liner of a patch: 30% had severe difficulties or it was not possible, 21% had moderate difficulties and 49% had mild or no difficulties. Discussion: In a sample of patients with autonomous medication management, our novel assessment procedure identified a substantial fraction of patients with handling problems for each dosage form. This suggests that patients´ medication management problems should be assessed regularly in clinical routine and tackled by patient-individual training or modification of the prescribed drug regimens to achieve effective drug therapy in the elderly.Öğe Cellular prion protein promotes post-ischemic neuronal survival, angioneurogenesis and enhances neural progenitor cell homing via proteasome inhibition(Nature Publishing Group, 2015) Doeppner, Thorsten Roland; Kaltwasser, Britta; Schlechter, Jana; Jaschke, J.; Kılıç, Ertuğrul; Baehr, Mathias; Hermann, Dirk Matthias; Weise, JensAlthough cellular prion protein (PrPc) has been suggested to have physiological roles in neurogenesis and angiogenesis, the pathophysiological relevance of both processes remain unknown. To elucidate the role of PrPc in post-ischemic brain remodeling, we herein exposed PrPc wild type (WT), PrPc knockout (PrP -/-) and PrPc overexpressing (PrP+/+) mice to focal cerebral ischemia followed by up to 28 days reperfusion. Improved neurological recovery and sustained neuroprotection lasting over the observation period of 4 weeks were observed in ischemic PrP+/+ mice compared with WT mice. This observation was associated with increased neurogenesis and angiogenesis, whereas increased neurological deficits and brain injury were noted in ischemic PrP-/- mice. Proteasome activity and oxidative stress were increased in ischemic brain tissue of PrP -/- mice. Pharmacological proteasome inhibition reversed the exacerbation of brain injury induced by PrP -/-, indicating that proteasome inhibition mediates the neuroprotective effects of PrPc. Notably, reduced proteasome activity and oxidative stress in ischemic brain tissue of PrP+/+ mice were associated with an increased abundance of hypoxia-inducible factor 1 alpha and PACAP-38, which are known stimulants of neural progenitor cell (NPC) migration and trafficking. To elucidate effects of PrPc on intracerebral NPC homing, we intravenously infused GFP(+) NPCs in ischemic WT, PrP -/- and PrP+/+ mice, showing that brain accumulation of GFP+ NPCs was greatly reduced in PrP -/- mice, but increased in PrP+/+ animals. Our results suggest that PrPc induces post-ischemic long-term neuroprotection, neurogenesis and angiogenesis in the ischemic brain by inhibiting proteasome activity.Öğe Effects of normobaric oxygen and melatonin on reperfusion injury: Role of cerebral microcirculation(Impact Journals, 2015) Beker, Mustafa; Çağlayan, Ahmet Burak; Keleştemur, Taha; Ça?layan, Berrak; Yalçın, Esra; Yulu?, Burak; Kılıç, Ülkan; Hermann, Dirk Matthias; Kılıç, ErtuğrulIn order to protect the brain before an irreversible injury occurs, penumbral oxygenation is the primary goal of current acute ischemic stroke treatment. However, hyperoxia treatment remains controversial due to the risk of free radical generation and vasoconstriction. Melatonin is a highly potent free radical scavenger that protects against ischemic stroke. Considering its anti-oxidant activity, we hypothesized that melatonin may augment the survival-promoting action of normobaric oxygen (NBO) and prevent brain infarction. Herein, we exposed mice to 30 or 90 min of intraluminal middle cerebral artery occlusion (MCAo) and evaluated the effects of NBO (70% or 100% over 90 min), administered either alone or in combination with melatonin (4 mg/ kg, i.p.), on disseminate neuronal injury, neurological deficits, infarct volume, blood-brain barrier (BBB) permeability, cerebral blood flow (CBF) and cell signaling. Both NBO and particularly melatonin alone reduced neuronal injury, neurological deficits, infarct volume and BBB permeability, and increased post-ischemic CBF, evaluated by laser speckle imaging (LSI). They also improved CBF significantly in the ischemic-core and penumbra, which was associated with reduced IgG extravasation, DNA fragmentation, infarct volume, brain swelling and neurological scores. Levels of phosphorylated Akt, anti-apoptotic Bcl-xL, pro-apoptotic Bax and endothelial nitric oxide synthase (NOS) were re-regulated after combined oxygen and melatonin delivery, whereas neuronal and inducible NOS, which were increased by oxygen treatment, were not influenced by melatonin. Our present data suggest that melatonin and NBO are promising approaches for the treatment of acute-ischemic stroke, which encourage proof-of-concept studies in human stroke patients.Öğe Extracellular vesicles derived from neural progenitor cells--a preclinical evaluation for stroke treatment in mice(Springer, 2021) Zheng, Xuan; Zhang, Lin; Kuang, Yaoyun; Venkataramani, Vivek; Jin, Fengyan; Hein, Katharina; Zafeiriou, Maria Patapia; Lenz, Christof; Moebius, Wiebke; Kılıç, Ertuğrul; Hermann, Dirk Matthias; Weber, Martin S.; Urlaub, Henning; Zimmermann, Wolfram Hubertus; BäHR, Mathias; Doeppner, Thorsten RolandStem cells such as mesenchymal stem cells (MSCs) enhance neurological recovery in preclinical stroke models by secreting extracellular vesicles (EVs). Since previous reports have focused on the application of MSC-EVs only, the role of the most suitable host cell for EV enrichment and preclinical stroke treatment remains elusive. The present study aimed to evaluate the therapeutic potential of EVs derived from neural progenitor cells (NPCs) following experimental stroke. Using the PEG technique, EVs were enriched and characterized by electron microscopy, proteomics, rt-PCR, nanosight tracking analysis, and Western blotting. Different dosages of NPC-EVs displaying a characteristic profile in size, shape, cargo protein, and non-coding RNA contents were incubated in the presence of cerebral organoids exposed to oxygen-glucose deprivation (OGD), significantly reducing cell injury when compared with control organoids. Systemic administration of NPC-EVs in male C57BL6 mice following experimental ischemia enhanced neurological recovery and neuroregeneration for as long as 3 months. Interestingly, the therapeutic impact of such NPC-EVs was found to be not inferior to MSC-EVs. Flow cytometric analyses of blood and brain samples 7 days post-stroke demonstrated increased blood concentrations of B and T lymphocytes after NPC-EV delivery, without affecting cerebral cell counts. Likewise, a biodistribution analysis after systemic delivery of NPC-EVs revealed the majority of NPC-EVs to be found in extracranial organs such as the liver and the lung. This proof-of-concept study supports the idea of EVs being a general concept of stem cell-induced neuroprotection under stroke conditions, where EVs contribute to reverting the peripheral post-stroke immunosuppression.Öğe Extracellular vesicles derived from neural progenitor cells--a preclinical evaluation for stroke treatment in mice (vol 12, pg 185, 2021)(Springer, 2022) Zheng, Xuan; Zhang, Lin; Kuang, Yaoyun; Venkataramani, Vivek; Jin, Fengyan; Hein, Katharina; Zafeiriou, Maria Patapia; Lenz, Christof; Moebius, Wiebke; Kılıç, Ertuğrul; Hermann, Dirk Matthias; Weber, Martin S.; Urlaub, Henning; Zimmermann, Wolfram Hubertus; BäHR, Mathias; Doeppner, Thorsten RolandIn the version of this article initially published, there were errors on pages 5 and 6.Öğe Phosphodiesterase 10A is a critical target for neuroprotection in a mouse model of ischemic stroke(Springer, 2022) Beker, Mustafa Çağlar; Çağlayan, Ahmet Burak; Altunay, Serdar; Özbay, Elif; Ateş, Nilay; Keleştemur, Taha; Çağlayan, Berrak; Kılıç, Ülkan; Doeppner, Thorsten Roland; Hermann, Dirk Matthias; Kılıç, ErtuğrulPhosphodiesterase 10A (PDE10A) hydrolyzes adenosine 3 ',5 '-cyclic monophosphate (cAMP) and guanosine 3 ',5 '-cyclic monophosphate (cGMP). It is highly expressed in the striatum. Recent evidence implied that PDE10A may be involved in the inflammatory processes following injury, such as ischemic stroke. Its role in ischemic injury was unknown. Herein, we exposed mice to 90 or 30-min middle cerebral artery occlusion, followed by the delivery of the highly selective PDE10A inhibitor TAK-063 (0.3 mg/kg or 3 mg/kg) immediately after reperfusion. Animals were sacrificed after 24 or 72 h, respectively. Both TAK-063 doses enhanced neurological function, reduced infarct volume, increased neuronal survival, reduced brain edema, and increased blood-brain barrier integrity, alongside cerebral microcirculation improvements. Post-ischemic neuroprotection was associated with increased phosphorylation (i.e., activation) of pro-survival Akt, Erk-1/2, GSK-3 alpha/beta and anti-apoptotic Bcl-xL abundance, decreased phosphorylation of pro-survival mTOR, and HIF-1 alpha, MMP-9 and pro-apoptotic Bax abundance. Interestingly, PDE10A inhibition reduced inflammatory cytokines/chemokines, including IFN-gamma and TNF-alpha, analyzed by planar surface immunoassay. In addition, liquid chromatography-tandem mass spectrometry revealed 40 proteins were significantly altered by TAK-063. Our study established PDE10A as a target for ischemic stroke therapy.Öğe Phosphorylation of PI3K/Akt at Thr308, but not phosphorylation of MAPK kinase, mediates lithium-induced neuroprotection against cerebral ischemia in mice(Academic Press Inc., 2022) Ateş, Nilay; Çağlayan, Aysun; Balçıkanlı, Zeynep; Sertel, Elif; Beker, Mustafa Çağlar; Dilsiz, Pelin; Çağlayan, Ahmet Burak; Çelik, Süleyman; Daşdelen, Muhammed Furkan; Çağlayan, Berrak; Yiğitbaşı, Türkan; Özbek, Hanefi; Doeppner, Thorsten Roland; Hermann, Dirk Matthias; Kılıç, ErtuğrulLithium, in addition to its effect on acute and long-term bipolar disorder, is involved in neuroprotection after ischemic stroke. Yet, its mechanism of action is still poorly understood, which was only limited to its modulatory effect on GSK pathway. Therefore, we initially analyzed the dose-dependent effects of lithium on neurological deficits, infarct volume, brain edema and blood-brain barrier integrity, along with neuronal injury and survival in mice subjected to focal cerebral ischemia. Thereafter, we investigated the involvement of the PI3K/Akt and MEK signal transduction pathways and their components. Our observations revealed that 2 mmol/kg lithium significantly improved post-ischemic brain tissue survival. Although, 2 mmol/kg lithium had no negative effect on brain microcirculation, 5 and 20 mmol/kg lithium reduced brain perfusion. Furthermore, supratherapeutic dose of lithium in 20 mmol/kg lead to animal death. In addition, improvement of brain perfusion with L-arginine, did not change the effect of 5 mmol/kg lithium on brain injury. Additionally, post-stroke blood-brain barrier leakage, hemodynamic impairment and apoptosis have been reversed by lithium treatment. Interestingly, lithium-induced neuroprotection was associated with increased phosphorylation of Akt at Thr308 and suppressed GSK-3? phosphorylation at Ser9 residue. Lithium upregulated Erk-2 and downregulated JNK-2 phosphorylation. To distinguish whether neuroprotective effects of lithium are modulated by PI3K/Akt or MEK, we sequentially blocked these pathways and demonstrated that the neuroprotective activity of lithium persisted during MEK/ERK inhibition, whereas PI3K/Akt inhibition abolished neuroprotection. Collectively, we demonstrated lithium exerts its post-stroke neuroprotective activity via the PI3K/Akt pathway, specifically via Akt phosphorylation at Thr308, but not via MEK/ERK.Öğe Post-stroke transplantation of adult subventricular zone derived neural progenitor cells - A comprehensive analysis of cell delivery routes and their underlying mechanisms(Academic Press, 2015) Doeppner, Thorsten Roland; Kaltwasser, Britta; Teli, Mahesh; Sánchez-Mendoza, Eduardo; Kılıç, Ertuğrul; Baehr, Mathias; Hermann, Dirk MatthiasWith neuroprotective approaches having failed until recently, current focus on experimental stroke research has switched towards manipulation of post-ischemic neuroregeneration. Transplantation of subventricular zone (SVZ) derived neural progenitor cells (NPCs) is a promising strategy for promotion of neurological recovery. Yet, fundamental questions including the optimal cell delivery route still have to be addressed. Consequently, male C57BL6 mice were exposed to transient focal cerebral ischemia and allowed to survive for as long as 84 days post-stroke. At 6 h post-stroke, NPCs were grafted using six different cell delivery routes, i.e., intravenous, intraarterial, ipsilateral intrastriatal, contralateral intrastriatal, ipsilateral intraventricular and ipsilateral intracortical injection. Control mice received PBS only using the aforementioned delivery routes. Intralesional numbers of GFP(+) NPCs were high only after ipsilateral intrastriatal transplantation, whereas other injection paradigms only yielded comparatively small numbers of grafted cells. However, acute neuroprotection and improved functional outcome were observed after both systemic (i.e., intraarterial and intravenous) and ipsilateral intrastriatal transplantation only. Whereas systemic cell delivery induced acute and long-term neuroprotection, reduction of brain injury after ipsilateral intrastriatal cell grafting was only temporary, in line with the loss of transplanted NPCs in the brain. Both systemic and ipsilateral intrastriatal NPC delivery reduced microglial activation and leukocyte invasion, thus reducing free radical formation within the ischemic brain. On the contrary, only systemic NPC administration stabilized the blood-brain-barrier and reduced leukocytosis in the blood. Although intraarterial NPC transplantation was as effective as intravenous cell grafting, mortality of stroke mice was high using the intraarterial delivery route. Consequently, intravenous delivery of native NPCs in our experimental model is an attractive and effective strategy for stroke therapy that deserves further proof-of-concept studies.Öğe Sustained neurological recovery induced by resveratrol is associated with angioneurogenesis rather than neuroprotection after focal cerebral ischemia(Academic Press, 2015) Hermann, Dirk Matthias; Zechariah, Anil; Kaltwasser, Britta; Bosche, Bert; Çağlayan, Ahmet Burak; Kılıç, Ertuğrul; Doeppner, Thorsten RolandAccording to the French paradox, red wine consumption reduces the incidence of vascular diseases even in the presence of highly saturated fatty acid intake. This phenomenon is widely attributed to the phytoalexin resveratrol, a red wine ingredient. Experimental studies suggesting that resveratrol has neuroprotective properties mostly used prophylactic delivery strategies associated with short observation periods. These studies did not allow conclusions to be made about resveratrol's therapeutic efficacy post-stroke. Herein, we systematically analyzed effects of prophylactic, acute and post-acute delivery of resveratrol (50 mg/kg) on neurological recovery, tissue survival, and angioneurogenesis after focal cerebral ischemia induced by intraluminal middle cerebral artery occlusion in mice. Over an observation period of four weeks, only prolonged post-acute resveratrol delivery induced sustained neurological recovery as assessed by rota rod, tight rope and corner turn tests. Although prophylactic and acute resveratrol delivery reduced infarct volume and enhanced blood-brain-barrier integrity at 2 days post-ischemia by elevating resveratrol's downstream signal sirtuin-1, increasing cell survival signals (phosphorylated Akt, heme oxygenase-1, Bcl-2) and decreasing cell death signals (Bax, activated caspase-3), a sustained reduction of infarct size on day 28 was not observed in any of the three experimental conditions. Instead, enhanced angiogenesis and neurogenesis were noted in animals receiving post-acute resveratrol delivery, which were associated with elevated concentrations of GDNF and VEGF in the brain. Thus, sustained neurological recovery induced by resveratrol depends on successful brain remodeling rather than structural neuroprotection. The recovery promoting effect of delayed resveratrol delivery opens promising perspectives for stroke therapy.Öğe The indirect NMDAR antagonist acamprosate induces postischemic neurologic recovery associated with sustained neuroprotection and neuroregeneration(Nature Publishing Group, 2015) Doeppner, Thorsten Roland; Pehlke, Jens; Kaltwasser, Britta; Schlechter, Jana; Kılıç, Ertuğrul; Baehr, Mathias; Hermann, Dirk MatthiasCerebral ischemia stimulates N-methyl-D-aspartate receptors (NMDARs) resulting in increased calcium concentration and excitotoxicity. Yet, deactivation of NMDAR failed in clinical studies due to poor preclinical study designs or toxicity of NMDAR antagonists. Acamprosate is an indirect NMDAR antagonist used for patients with chronic alcohol dependence. We herein analyzed the therapeutic potential of acamprosate on brain injury, neurologic recovery and their underlying mechanisms. Mice were exposed to cerebral ischemia, treated with intraperitoneal injections of acamprosate or saline (controls), and allowed to survive until 3 months. Acamprosate yielded sustained neuroprotection and increased neurologic recovery when given no later than 12 hours after stroke. The latter was associated with increased postischemic angioneurogenesis, albeit acamprosate did not stimulate angioneurogenesis itself. Rather, increased angioneurogenesis was due to inhibition of calpain-mediated pro-injurious signaling cascades. As such, acamprosate-mediated reduction of calpain activity resulted in decreased degradation of p35, increased abundance of the pro-survival factor STAT6, and reduced N-terminal-Jun-kinase activation. Inhibition of calpain was associated with enhanced stability of the blood-brain barrier, reduction of oxidative stress and cerebral leukocyte infiltration. Taken into account its excellent tolerability, its sustained effects on neurologic recovery, brain tissue survival, and neural remodeling, acamprosate is an intriguing candidate for adjuvant future stroke treatment.Öğe The unconventional growth factors cerebral dopamine neurotrophic factor and mesencephalic astrocyte-derived neurotrophic factor promote post-ischemic neurological recovery, perilesional brain remodeling, and lesion-remote axonal plasticity(Springer, 2023) Çağlayan, Ahmet Burak; Beker, Mustafa Çağlar; Sertel Evren, Elif; Çağlayan, Berrak; Kılıç, Ülkan; Ateş, Nilay; Çağlayan, Aysun; Daşdelen, Muhammed Furkan; Doeppner, Thorsten Roland; Saarma, Mart; Hermann, Dirk Matthias; Kılıç, ErtuğrulConsiderable efforts are currently made to develop strategies that boost endogenous recovery once a stroke has occurred. Owing to their restorative properties, neurotrophic factors are attractive candidates that capitalize on endogenous response mechanisms. Non-conventional growth factors cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) promote neuronal survival and reduce neurological deficits in the acute phase of ischemic stroke in mice. Their effects on endogenous repair and recovery mechanisms in the stroke recovery phase were so far unknown. By intracerebroventricular delivery of CDNF or MANF starting 3 days post-stroke (1 mu g/day for 28 days via miniosmotic pumps), we show that delayed CDNF and MANF administration promoted functional neurological recovery assessed by a battery of behavioral tests, increased long-term neuronal survival, reduced delayed brain atrophy, glial scar formation, and, in case of CDNF but not MANF, increased endogenous neurogenesis in the perilesional brain tissue. Besides, CDNF and MANF administration increased long-distance outgrowth of terminal axons emanating from the contralesional pyramidal tract, which crossed the midline to innervate ipsilesional facial nucleus. This plasticity promoting effect was accompanied by downregulation of the axonal growth inhibitor versican and the guidance molecules ephrin B1 and B2 in the previously ischemic hemisphere at 14 dpi, which represents a sensitive time-point for axonal growth. CDNF and MANF reduced the expression of the proinflammatory cytokines IL1 beta and TNF alpha in both hemispheres. The effects of non-conventional growth factors in the ischemic brain should further be examined since they might help to identify targets for restorative stroke therapy.
