thymosin and Stroke

Thymosin β4 (Tβ4) is a 5K peptide which influences cellular migration by inhibiting organization of the actin-cytoskeleton. Treatment of acute stroke presently involves use of rt-PA and/or endovascular treatment with thrombectomy, both of which have time limitations. Therefore, development of a treatment beyond these times is necessary as most stroke patients present beyond these time limits. A drug which could be administered within 24 h from symptom onset would provide substantial benefit.. This review summarizes the data and results of two in-vivo studies testing Tβ4 in an embolic stroke model of young and aged rats. In addition, we describe in-vitro investigations of the neurorestorative and neuroprotective properties of Tβ4 in a variety of neuroprogenitor and oligoprogenitor cell models.. Tβ4 acts as a neurorestorative agent when employed in a young male rat model of embolic stroke while in an aged model it acts a neuroprotectant. However evaluation of Tβ4 as a treatment of stroke requires further preclinical evaluation in females and in males and females with comorbidities such as, hypertension and diabetes in models of embolic stroke to further define the mechanism of action and potential as a treatment of stroke in humans.

Topics: Animals; Disease Models, Animal; Female; Humans; Male; Nerve Regeneration; Neuroprotection; Rats; Stroke; Thymosin

The burden of cardiovascular disease is a growing worldwide issue that demands attention. While many clinical trials are ongoing to test therapies for treating the heart after myocardial infarction (MI) and heart failure, there are few options doctors able to currently give patients to repair the heart. This eventually leads to decreased ventricular contractility and increased systemic disease, including vascular disorders that could result in stroke. Small peptides such as thymosin β4 (Tβ4) are upregulated in the cardiovascular niche during fetal development and after injuries such as MI, providing increased neovasculogenesis and paracrine signals for endogenous stem cell recruitment to aid in wound repair. New research is looking into the effects of in vivo administration of Tβ4 through injections and coatings on implants, as well as its effect on cell differentiation. Results so far demonstrate Tβ4 administration leads to robust increases in angiogenesis and wound healing in the heart after MI and the brain after stroke, and can differentiate adult stem cells toward the cardiac lineage for implantation to the heart to increase contractility and survival. Future work, some of which is currently in clinical trials, will demonstrate the in vivo effect of these therapies on human patients, with the goal of helping the millions of people worldwide affected by cardiovascular disease.

Topics: Cardiovascular Diseases; Cardiovascular System; Cell Differentiation; Humans; Myocardial Infarction; Stroke; Thymosin; Tissue Scaffolds

Neurorestorative therapy targets multiple types of parenchymal cells in the intact tissue of injured brain tissue to increase neurogenesis, angiogenesis, oligodendrogenesis, and axonal remodeling during recovery from neurological injury. In our laboratory, we tested thymosin β4 (Tβ4) as a neurorestorative agent to treat models of neurological injury. This review discusses our results demonstrating that Tβ4 improves neurological functional outcome in a rat model of embolic stroke, a mouse model of multiple sclerosis, and a rat model of traumatic brain injury. Tβ4 is a pleiotropic peptide exhibiting many actions in several different types of tissues. One mechanism associated with improvement of neurological improvement from Tβ4 treatment is oligodendrogenesis involving the differentiation of oligodendrocyte progenitor cells to mature myelin-secreting oligodendrocytes. Moreover, our preclinical data provide a basis for movement of Tβ4 into clinical trials for treatment of these devastating neurological diseases and injuries.

Topics: Animals; Brain Injuries; Mice; Multiple Sclerosis; Rats; Stroke; Thymosin

Following stroke or traumatic damage, neuronal death via both necrosis and apoptosis causes loss of functions, including memory, sensory perception, and motor skills. As necrosis has the nature to expand, while apoptosis stops the cell death cascade in the brain, necrosis is considered to be a promising target for rapid treatment for stroke. We identified the nuclear protein, prothymosin alpha (ProTalpha) from the conditioned medium of serum-free culture of cortical neurons as a key protein-inhibiting necrosis. In the culture of cortical neurons in the serum-free condition without any supplements, ProTalpha inhibited the necrosis, but caused apoptosis. In the ischemic brain or retina, ProTalpha showed a potent inhibition of both necrosis and apoptosis. By use of anti-brain-derived neurotrophic factor or anti-erythropoietin IgG, we found that ProTalpha inhibits necrosis, but causes apoptosis, which is in turn inhibited by ProTalpha-induced neurotrophins under the condition of ischemia. From the experiment using anti-ProTalpha IgG or antisense oligonucleotide for ProTalpha, it was revealed that ProTalpha has a pathophysiological role in protecting neurons in stroke.

Topics: Apoptosis; Brain; Brain-Derived Neurotrophic Factor; Cell Death; Cerebral Cortex; Culture Media, Conditioned; Erythropoietin; Immunoproteins; Ischemia; Necrosis; Nerve Growth Factors; Neurons; Protein Precursors; Retina; Stroke; Thymosin

After stroke or traumatic damages, both necrotic and apoptotic neuronal death cause a loss of functions including memory, sensory perception, and motor skills. From the fact that necrosis has a nature to expand, while apoptosis to cease the cell death cascade in the brain, it is considered that the promising target for the rapid treatment for stroke is the necrosis. In this study, I introduce the discovery of prothymosin alpha (ProTalpha), which inhibits neuronal necrosis, and propose its potentiality of clinical use for stroke. First of all, it should be noted that ProTalpha inhibits the neuronal necrosis induced by serum-free starvation or ischemia-reperfusion stress, which causes a rapid internalization of GLUT1/4, leading a decrease in glucose uptake and cellular ATP levels. Underlying mechanisms are determined to be through an activation of Gi/o, phospholipase C and PKCbetaII. ProTalpha also causes apoptosis later through a similar mechanism. However, we found that ProTalpha-induced apoptosis is completely inhibited by the concomitant treatment with neurotrophins, which are up-regulated by ischemic stress in the brain. Of most importance is the finding that the systemic injection of ProTalpha completely inhibits the brain damages, motor dysfunction and learning memory defect induced by cerebral ischemia-reperfusion stress. As ProTalpha almost entirely prevents the focal ischemia-induced motor dysfunction 4 h after the start of ischemia, this protein seems to have a promising potentiality for clinical use.

Topics: Adenosine Triphosphate; Animals; Cell Death; Drug Delivery Systems; Glucose; Glucose Transporter Type 1; Glucose Transporter Type 4; Humans; Necrosis; Neurons; Protein Precursors; Stroke; Thymosin

Prothymosin alpha (ProTα)-mimetic hexapeptide (amino acid: NEVDQE, P6Q) inhibits cerebral or retinal ischemia-induced behavioral, electrophysiological and histological damage. P6Q also abolishes cerebral hemorrhage induced by ischemia with tissue plasminogen activator (tPA). In the present study we examined the beneficial effects of P6Q on other post-stroke prognostic psychology-related symptoms, which obstruct the motivation toward physical therapy. Intravenous (i.v.) administration with tPA (10 mg/kg) at 6 h after photochemically induced thrombosis (PIT) in mice resulted in bilateral central post-stroke pain in thermal and mechanical nociception tests and loss of social activity in the nest building test, both of which were significantly blocked by P6Q (30 mg/kg, i.v.) given at 5 h after PIT. P6Q (30 mg/kg, i.v.) also improved the memory-learning deficit in the step-through test and depression-like behavior in the tail suspension test when it was given 1 day after bilateral common carotid arteries occlusion (BCCAO) in mice. Thus, these studies suggest that P6Q could be a promising candidate to prevent negative prognostic psychological symptoms following focal and global ischemia.

Topics: Animals; Brain Ischemia; Depression; Learning; Male; Memory Disorders; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Pain; Peptide Fragments; Protein Precursors; Stroke; Thymosin; Tissue Plasminogen Activator

Thymosin β4 (Tβ4) is a 5K peptide which influences cellular migration by inhibiting organization of the actin-cytoskeleton. Tβ4 has neurorestorative properties and is a potential candidate for the treatment of sub-acute stroke. Previous research demonstrated that Tβ4 improved neurological outcome in a young (3 months) rat model of embolic stroke. We hypothesized that Tβ4 would improve neurological outcome in an aged rat model of embolic stroke when administered 24h after embolic stroke. Aged Male Wistar rats (Charles River, France 18-21 months) were subjected to embolic middle cerebral artery occlusion (MCAo). Rats were randomized to receive Tβ4 (12mg/kg, RegeneRx Biopharmaceuticals, Inc.) or control 24h after MCAo and then every 3days for 4 additional doses. The dose of 12mg/kg was the maximal dose of Tβ4 that showed functional improvement in a young rat model of embolic stroke. Functional tests (adhesive-removal test (ART), foot fault test (FFT) and the modified Neurological Severity Score (mNSS)) were performed weekly. The rats were sacrificed 56days after MCAo and lesion volumes were measured. Immunohistochemical analysis for oligodendrogenesis, myelination and gliosis was also performed. Twenty-three rats were included in the study: control group (n=12) and Tβ4 group (n=11). After randomization, there were three deaths in both the control and Tβ4 groups. The Tβ4 treatment reduced infarct volume by more than 50% (12.8%±9.3%, mean±SE, p<0.05) compared to the control group (26.0%±4.3%). However, Tβ4 did not show improvement in functional outcome compared to control. There was no significant increase in oligodendrogenesis, myelination and gliosis between control and treatment with Tβ4, however, we unexpectedly observed that overall (control and Tβ4 groups) astrocytic gliosis as measured by GFAP immunoreactivity was significantly inversely correlated with neurological outcome measured using the modified Neurological Severity Score (mNSS) (p<0.01), suggesting that greater gliosis may be related to improvement of neurological outcome in aged rats. In summary, Tβ4 treatment of stroke aged rats significantly reduces infarct volume compared to vehicle treated stroke, however, Tβ4 treatment did not show improvement in functional outcome, myelination or gliosis when compared to control. GFAP staining was significantly inversely correlated to improvement in the mNSS, suggesting that gliosis in the aged rat may be of benefit in improvement of functional outcome.

Topics: Aging; Animals; Brain; Cell Count; Gliosis; Infarction, Middle Cerebral Artery; Male; Myelin Sheath; Oligodendroglia; Rats; Recovery of Function; Stroke; Thymosin

Post-ischemic inflammation plays an important role in the progression of ischemia/reperfusion injuries. Prothymosin-α (ProT) can protect cells from necrotic death following ischemia; however, its immunostimulatory actions may counteract the neuroprotective effect. We proposed that ProTΔNLS, synthesized by deleting its nuclear localizing signal (NLS) at the C-terminal of ProT, can attenuate the immunostimulatory activity and has more salient neuroprotective effect. In this study, we examined the therapeutic effects of ProT and ProTΔNLS in a transient middle cerebral artery occlusion (tMCAO) model of rats. Rats that had sustained 90 min of tMCAO were treated with GST-vehicle, ProT, or ProTΔNLS. Therapeutic outcomes were evaluated by infarction volume assay and behavioral assessment. Changes to inflammatory mediators, including tumor necrosis factor α (TNF-α), interleukin-10 (IL-10), and myeloperoxidase (MPO) were evaluated by enzyme-linked immunosorbent assay. Activated matrix metalloproteinases 2 (MMP-2) and 9 (MMP-9) levels were evaluated by gelatin zymography. Microglial activation was identified by double-immunostaining for Iba-1 and CD68. Our results showed that while both ProT and ProTΔNLS reduce infarction volume and improve functional outcome, ProTΔNLS provides the best therapeutic outcome. ProT increases TNF-α but decreases IL-10 secretion after ischemic injury, reflecting its pro-inflammatory activity. ProTΔNLS suppresses expression of TNF-α, MPO, and activity of MMPs in ischemic brain tissue. It also suppresses activation of microglia in penumbral cortex. These data demonstrate the immunesuppressive activities of ProTΔNLS. In conclusion, ProT has pro-inflammatory effect that may counteract its neuroprotective effect. Deletion of NLS from ProT may attenuate post-ischemic inflammation and enhance the neuroprotective effects of ProT.

Topics: Animals; Gene Deletion; Ischemic Attack, Transient; Male; Neuroprotective Agents; Nuclear Localization Signals; Protein Precursors; Rats; Rats, Sprague-Dawley; Stroke; Thymosin; Treatment Outcome

Thymosin β4 (Tβ4) is a 5K actin binding peptide. Tβ4 improves neurological outcome in a rat model of embolic stroke and research is now focused on optimizing its dose for clinical trials. The purpose of this study was to perform a dose-response study of Tβ4 to determine the optimal dose of neurological improvement in a rat model of embolic stroke.. Male Wistar rats were subjected to embolic middle cerebral artery occlusion (MCAo). Rats were divided into 4 groups of 10 animals/group: control, 2, 12 and 18 mg/kg. Tβ4 was administered intraperitoneally 24h after MCAo and then every 3 days for 4 additional doses in a randomized controlled fashion. Neurological tests were performed after MCAo and before treatment and up to 8 weeks after treatment. The rats were sacrificed 56 days after MCAo and lesion volumes measured. Generalized estimating equation was used to compare the treatment effect on long term functional recovery at day 56. A quartic regression model was used for an optimal dose determination.. Tβ4 significantly improved neurological outcome at dose of 2 and 12 mg/kg at day 14 and extended to day 56 (p-values <0.05). The higher dose of 18 mg/kg did not show significant improvement. The estimated optimal dose of 3.75 mg/kg would provide optimal neurological improvement.. This study shown that Tβ4 significantly improved the long term neurological functional recovery at day 56 after MCAo with an optimal dose of 3.75 mg/kg. These results provide preclinical data for human clinical trials.

Topics: Acute Disease; Adenomatous Polyposis Coli; Animals; Brain; Bromodeoxyuridine; Disease Models, Animal; Dose-Response Relationship, Drug; Infarction, Middle Cerebral Artery; Male; Myelin Basic Protein; Neuroimaging; Neurologic Examination; Rats; Stroke; Thymosin; Time Factors; Treatment Outcome; Versicans

Neurorestorative therapy is the next frontier in the treatment of stroke. An expanding body of evidence supports the theory that after stroke, certain cellular changes occur that resemble early stages of development. Increased expression of developmental proteins in the area bordering the infarct suggest an active repair or reconditioning response to ischemic injury. Neurorestorative therapy targets parenchymal cells (neurons, oligodendrocytes, astrocyes, and endothelial cells) to enhance endogenous neurogenesis, angiogenesis, axonal sprouting, and synaptogenesis to promote functional recovery. Pharmacological treatments include statins, phosphodiesterase 5 inhibitors, erythropoietin, and nitric oxide donors that have all improved functional outcome after stroke in the preclinical arena. Thymosin beta4 (Tbeta4) is expressed in both the developing and adult brain and it has been shown to stimulate vasculogenesis, angiogenesis, and arteriogenesis in the postnatal and adult murine cardiac myocardium. In this manuscript, we describe our rationale and techniques to test our hypothesis that Tbeta4 may be a candidate neurorestorative agent.

Topics: Adult; Brain; Endothelial Cells; Erythropoietin; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Neurogenesis; Neurons; Nitric Oxide Donors; Oligodendroglia; Recombinant Proteins; Recovery of Function; Stroke; Thymosin

Topics: Animals; Apoptosis; Brain; Cerebrovascular Disorders; Disease Models, Animal; Dose-Response Relationship, Drug; Necrosis; Protein Precursors; Rats; Stroke; Thymosin