The actin binding site on thymosin beta4 promotes angiogenesis

Exploring the Molecular Tapestry: Organ-Specific Peptide and Protein Ultrafiltrates and Their Role in Therapeutics

This study aims to characterize the proteome composition of organ-derived protein extracts from rabbits. Protein isolation was performed using soft homogenization and size exclusion via ultrafiltration. The proteome analysis of the ultrafiltrates was conducted using gel electrophoresis, and the mass spectrometry data were subjected to gene ontology analysis. Proteomic profiling revealed comprehensive protein profiles associated with RNA regulation, fatty acid binding, inflammatory response, oxidative stress, and metabolism. Additionally, our results demonstrate the presence of abundant small proteins, as observed in the mass spectrometry datasets. Small proteins and peptides are crucial in transcription modulation and various biological processes. The protein networks identified in the ultrafiltrates have the potential to enhance and complement biological therapeutic interventions. Data are available via ProteomeXchange with identifier PXD050039.

Thymosin beta 4: A potential novel adjunct treatment for bacterial keratitis

Microbial keratitis is a rapidly progressing, visually debilitating infection of the cornea that can lead to corneal scarring, endophthalmitis, and perforation. Corneal opacification or scarring, a complication of keratitis, is among the leading causes of legal blindness worldwide, second to cataracts.Pseudomonas aeruginosaandStaphylococcus aureusare the two bacteria most commonly associated with this type of infection. Risk factors include patients who are immunocompromised, those who have undergone refractive corneal surgery, and those with prior penetrating keratoplasty, as well as extended wear contact lens users. Current treatment of microbial keratitis primarily addresses the pathogen using antibiotics. Bacterial clearance is of utmost importance yet does not guarantee good visual outcome. Clinicians are often left to rely upon the eye's innate ability to heal itself, as there are limited options beyond antibiotics and corticosteroids for treating patients with corneal infection. Beyond antibiotics, agents in use, such as lubricating ointments, artificial tears, and anti-inflammatory drops, do not fully accommodate clinical needs and have many potential harmful complications. To this end, treatments are needed that both regulate the inflammatory response and promote corneal wound healing to resolve visual disturbances and improve quality of life. Thymosin beta 4 is a small, naturally occurring 43-amino-acid protein that promotes wound healing and reduces corneal inflammation and is currently in Phase 3 human clinical trials for dry eye disease. Our previous work has shown that topical Tβ4 as an adjunct to ciprofloxacin treatment reduces inflammatory mediators and inflammatory cell infiltrates (neutrophils/PMN and macrophages) while enhancing bacterial killing and wound healing pathway activation in an experimental model ofP. aeruginosa-induced keratitis. Adjunctive thymosin beta 4 treatment holds novel therapeutic potential to regulate and, optimally, resolve disease pathogenesis in the cornea and perhaps other infectious and immune-based inflammatory disease. We plan to establish the importance of thymosin beta 4 as a therapeutic agent in conjunction with antibiotics with high impact for immediate clinical development.

Promoting effect of Tmsb4x on the differentiation of peripheral blood mononuclear cells to dendritic cells during septicemia

BACKGROUND

Thymosin beta 4 × (Tmsb4x) has been highlighted as an important regulator in immune and inflammation responses. Promoted differentiation of mononuclear cells into dendritic cells (DCs) exert a beneficial effect on septicemia. Herein, we investigated the effects of Tmsb4x on the mononuclear cells to affect immune responses during septicemia.

METHODS

Initially, we isolated peripheral blood samples from healthy individuals and patients with septicemia for extraction of mononuclear cells, followed by Tmsb4x expression quantification. A cell model was constructed with mononuclear cells through lipopolysaccharide stimulation. The viability and apoptosis were evaluated in response to Tmsb4x silencing or re-expression. Additionally, the proportion of DCs was assessed by determining levels of inflammatory factors as well as by flow cytometric analysis. A mouse septicemia model was developed for in vivo validation.

RESULTS

Cell and animal models demonstrated decreased Tmsb4x expression in the setting of septicemia, which led to increased inflammatory response and reduced proportion of DCs, along with inhibited mononuclear cell viability and promoted apoptosis. However, restoration of Tmsb4x facilitated the differentiation of mononuclear cells into DCs.

CONCLUSION

To conclude, upregulated Tmsb4x promoted the generation of DCs from mononuclear cells, which contributed to deep understanding of underpinning mechanisms in the development of septicemia.

Germinal peptide eye drop promotes corneal epithelial and stromal defect healing in rabbit model

OBJECTIVE

Corneal defect is a common disease in ophthalmology caused by trauma, inflammation, drug toxicity, or surgery. To investigate the effect of germinal peptide eye drop on corneal epithelial and stromal defects after lamellar keratectomy in rabbit model.

METHODS

Eighty-five male New Zealand white rabbits were divided into five groups: Germinal Peptide eye drop at three different concentration groups, normal saline (negative control group), recombinant human epidermal growth factor (rh-EGF) eye drop (positive control group). Corneal epithelial and stromal defects of around 150-200 μm in depth were created with an 8 mm diameter trephine in the center of the right eyes of all animals.

RESULTS

Germinal peptide eye drop with the concentration of 0.001%, 0.002%, and 0.004% and rh-EGF eye drop were more effective in promoting healing, reducing opacity, and edema during the process of corneal epithelial and stromal defect regeneration compared with 0.9% normal saline. No significant difference was observed among the three different doses of germinal peptide eye drop. Compared with the saline control group, the structures of the regenerated corneas were more orderly and less inflammatory cell infiltration was observed in the germinal peptide eye drop groups and the rh-EGF eye drop group.

CONCLUSION

Germinal peptide eye drop (0.001%, 0.002%, and 0.004%) can significantly stimulate the regeneration of corneal epithelia and stroma and reduce corneal opacity and edema. Dose dependency was not observed in the current study.

Thymosin beta-4 improves endothelial function and reparative potency of diabetic endothelial cells differentiated from patient induced pluripotent stem cells

Background

Prior studies show that signature phenotypes of diabetic human induced pluripotent stem cells derived endothelial cells (dia-hiPSC-ECs) are disrupted glycine homeostasis, increased senescence, impaired mitochondrial function and angiogenic potential as compared with healthy hiPSC-ECs. In the current study, we aimed to assess the role of thymosin β-4 (Tb-4) on endothelial function using dia-hiPSC-ECs as disease model of endothelial dysfunction.

Methods and results

Using dia-hiPSC-ECs as models of endothelial dysfunction, we determined the effect of Tb-4 on cell proliferation, senescence, cyto-protection, protein expression of intercellular adhesion molecule-1 (ICAM-1), secretion of endothelin-1 and MMP-1, mitochondrial membrane potential, and cyto-protection in vitro and angiogenic potential for treatment of ischemic limb disease in a mouse model of type 2 diabetes mellitus (T2DM) in vivo. We found that 600 ng/mL Tb4 significantly up-regulated AKT activity and Bcl-XL protein expression, enhanced dia-hiPSC-EC viability and proliferation, limited senescence, reduced endothelin-1 and MMP-1 secretion, and improved reparative potency of dia-hiPSC-ECs for treatment of ischemic limb disease in mice with T2DM. However, Tb4 had no effect on improving mitochondrial membrane potential and glycine homeostasis and reducing intercellular adhesion molecule-1 protein expression in dia-hiPSC-ECs.

Conclusions

Tb-4 improves endothelial dysfunction through enhancing hiPSC-EC viability, reducing senescence and endothelin-1 production, and improves angiogenic potency in diabetes.

Thymosin β4 increases cardiac cell proliferation, cell engraftment, and the reparative potency of human induced-pluripotent stem cell-derived cardiomyocytes in a porcine model of acute myocardial infarction

Rationale: Previous studies have shown that human embryonic stem cell-derived cardiomyocytes improved myocardial recovery when administered to infarcted pig and non-human primate hearts. However, the engraftment of intramyocardially delivered cells is poor and the effectiveness of clinically relevant doses of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in large animal models of myocardial injury remains unknown. Here, we determined whether thymosin β4 (Tb4) could improve the engraftment and reparative potency of transplanted hiPSC-CMs in a porcine model of myocardial infarction (MI). Methods: Tb4 was delivered from injected gelatin microspheres, which extended the duration of Tb4 administration for up to two weeks in vitro. After MI induction, pigs were randomly distributed into 4 treatment groups: the MI Group was injected with basal medium; the Tb4 Group received gelatin microspheres carrying Tb4; the CM Group was treated with 1.2 × 10⁸ hiPSC-CMs; and the Tb4+CM Group received both the Tb4 microspheres and hiPSC-CMs. Myocardial recovery was assessed by cardiac magnetic resonance imaging (MRI), arrhythmogenesis was monitored with implanted loop recorders, and tumorigenesis was evaluated via whole-body MRI. Results: In vitro, 600 ng/mL of Tb4 protected cultured hiPSC-CMs from hypoxic damage by upregulating AKT activity and BcL-XL and promoted hiPSC-CM and hiPSC-EC proliferation. In infarcted pig hearts, hiPSC-CM transplantation alone had a minimal effect on myocardial recovery, but co-treatment with Tb4 significantly enhanced hiPSC-CM engraftment, induced vasculogenesis and the proliferation of cardiomyocytes and endothelial cells, improved left ventricular systolic function, and reduced infarct size. hiPSC-CM implantation did not increase incidence of ventricular arrhythmia and did not induce tumorigenesis in the immunosuppressed pigs. Conclusions: Co-treatment with Tb4-microspheres and hiPSC-CMs was safe and enhanced the reparative potency of hiPSC-CMs for myocardial repair in a large-animal model of MI.

Germinal peptide eye drops promote corneal wound healing and decrease inflammation after alkali injury

Germinal peptide is being developed to treat corneal injuries. The purpose of this study was to investigate its effect on corneal epithelial cells in vitro and its ability to promote healing in an alkali injury model in vivo. Cultured rabbit corneal epithelial cells were treated with germinal peptide at three concentrations. Cell proliferation and migration were assessed and compared with the effect of recombinant human epidermal growth factor (rh-EGF). In vivo, the corneas of New Zealand albino rabbits were chemically burned with 1 mol/l NaOH for 30 s. The injured eyes were topically treated with germinal peptide (10, 20, and 40 μg/ml), rh-EGF, or phosphate-buffered saline thrice daily. At fixed time points post injury, the healing of the cornea and its histopathology were evaluated. There was no difference in the effect of germinal peptide on cultured cell proliferation. However, cell migration was significantly higher than that in the control groups, with germinal peptide at concentrations of 20 and 40 μg/ml being the most efficacious. In vivo, 20 and 40 μg/ml germinal peptide significantly alleviated corneal opacity and edema. By day 21, the areas of corneal neovascularization in the germinal peptide-treated groups were smaller than those in the rh-EGF and control groups. The repaired corneas in the germinal peptide- and rh-EGF-treated groups also had more corneal epithelial layers and fewer inflammatory cells than the controls. Germinal peptide may be developed as a novel topical treatment agent for corneal wound healing in clinical settings.

Multiple functions of thymosin β4 in the pearl oyster Pinctada fucata suggest its multiple potential roles in artificial pearl culture

Thymosin β4 is a multifunctional protein in vertebrates that participates in physiological processes, such as wound healing, immune response, cell proliferation and migration. We assessed the multifarious roles of this small peptide in Pinctada fucata, an oyster commonly used in pearl culture in China. Our results showed that when P. fucata was challenged by bacterial pathogens or LPS, the relative expression level of Pfthymosin β4 mRNA was significantly up-regulated, suggesting its involvement in immune response of the animal. Recombinant Pfthymosin β4 (rPfthymosin β4) was produced and showed in vitro different antibacterial activities against different pathogenic bacteria; the inhibitory effect of rPfthymosin β4 on bacterial growth was relatively stronger in the broth culture than agar culture. The overexpression of Pfthymosin β4 in Escherichia coli BL21(DE3) cells could improve their resistance to Cu²⁺, Zn²⁺, Cd²⁺, and H₂O₂, suggesting that Pfthymosin β4 is likely involved with antioxidant. rPfthymosin β4 also significantly promoted the proliferation and migration of mouse aortic vascular smooth muscle cells as indicated by MTT assay and cell scratch assay, respectively. In addition, chemically synthesized or recombinant Pfthymosin β4 could transiently increase the circulating total hemocytes counts but down-regulated by RNAi in P. fucata. Taking together above results and previous studies suggested that Pfthymosin β4 is potentially able to promote wound healing through enhancing antibacterial activity and antioxidant capacity, promotion of cell proliferation and migration, and increase of circulating hemocytes in P. fucata due to nucleus implantation injury. Thus, the future of recombinant Pfthymosin β4 should be promising in the culture of pearls in P. fucata.

Transplantation of Endothelial Progenitor Cells in Obese Diabetic Rats Following Myocardial Infarction: Role of Thymosin Beta-4

Endothelial progenitor cells (EPCs) are bone-marrow derived cells that are critical in the maintenance of endothelial wall integrity and protection of ischemic myocardium through the formation of new blood vessels (vasculogenesis) or proliferation of pre-existing vasculature (angiogenesis). Diabetes mellitus (DM) and the metabolic syndrome are commonly associated with ischemic heart disease through its pathological effects on the endothelium and consequent endothelial dysfunction. Thymosin-β4 (Tβ4) which expressed in the embryonic heart is critical in epicardial and coronary artery formation. In this study, we explored the effects of Tβ4 treatment on diabetic EPCs in vitro and intramyocardial injection of Tβ4-treated and non-Tβ4 treated EPCs following acute myocardial infarction (MI) of diabetic rats in vivo. It was found that 10 ng/mL Tβ4 increased migration, tubule formation, and angiogenic factor secretion of diabetic EPCs in vitro. In vivo, although implantation of Tβ4 treated diabetic EPCs significantly increased capillary density and attracted more c-Kit positive progenitor cells into the infarcted hearts as compared with implantation of non-Tβ4 treated diabetic EPCs, the significantly improved left ventricular ejection fraction was only found in the rats which received non-Tβ4 treated EPCs. The data suggests that a low dose Tβ4 increases diabetic EPC migration, tubule formation, and angiogenic factor secretion. However, it did not improve the effects of EPCs on left ventricular pump function in diabetic rats with MI.

Metallacarboranes as a tool for enhancing the activity of therapeutic peptides

Metallacarboranes are anionic boron clusters with high affinity to serum albumin, ability to cross biological membranes, and no apparent toxicity in vitro and in vivo. Thus, conjugation with cobalt bis(1,2-dicarbollide), [COSAN]^- , ([3,3'-Co(1,2-C₂ B₉ H₁₁ )₂ ]^- ) may improve the properties of therapeutic peptides or proteins at both molecular and systemic levels. Here, we conjugated [COSAN]^- with the therapeutic peptide thymosin β4 (Tβ4), which has a pleiotropic activity that results in enhanced healing and regeneration of injured tissues. Using fluorescence quenching of human serum albumin and surface plasmon resonance techniques, we showed that the conjugates have a high affinity to human serum albumin. Using an in vitro wound closure assay, we showed that conjugation with [COSAN]^- enhances the activity of Tβ4 toward fibroblasts (MSU1.1 cell line). These results indicate an application of metallacarboranes in the development of analogs of various therapeutic peptides/proteins with superior pharmacological properties.

Induced pluripotent stem cell derived cardiac models: effects of Thymosin β4

INTRODUCTION

The establishment of induced pluripotent stem cells (iPSCs) and cardiomyocytes differentiated from them generated a new platform to study pathophysiological processes and to generate drug screening platforms and iPSC-derived tissues as therapeutic agents. Although major advances have been made in iPSC-reprogramming, cardiac differentiation and EHT production, reprogramming efficiency and the maturity of iPSC-CMs need to be further improved.

AREAS COVERED

In this review, the authors summarize the current state of the field of iPSC research, the methodology of cardiac differentiation of iPSCs, the use of iPSC-CMs as disease models and toxicity screening platforms, and the potential of EHTs as therapeutic agents. The authors furthermore highlight the mechanisms by which Thymosin β4 might enhance the production of iPSC-CMs and EHTs to improve their maturity and performance.

EXPERT OPINION

iPSCs derived cardiomyocytes and EHTs represent a still young research field with many problems and pitfalls that need to be resolved to realize the full potential of iPSC-CMs and EHTs. Given that Thymosin β4 directly enhances cardiac differentiation while also promoting angiogenic sprouting and vessel maturation, Tβ4 might be of particular interest as a novel agent in tackling the difficulty of iPSC-CMs and engineered heart tissue grafts.

Chimeric Adeno-Associated Virus-Mediated Cardiovascular Reprogramming for Ischemic Heart Disease

Here, we demonstrated chimeric adeno-associated virus (chimeric AAV), AAV-DJ-mediated cardiovascular reprogramming strategy to generate new cardiomyocytes and limit collagen deposition in cardiac fibroblasts by inducing synergism of chimeric AAV-expressing Gata4, Mef2c, Tbx5 (AAV-GMT)-mediated heart reprogramming and chimeric AAV-expressing thymosin β4 (AAV-Tβ4)-mediated heart regeneration. AAV-GMT promoted a gradual increase in expression of cardiac-specific genes, including Actc1, Gja1, Myh6, Ryr2, and cTnT, with a gradual decrease in expression of a fibrosis-specific gene, procollagen type I and here AAV-Tβ4 help to induce GMT expression, providing a chimeric AAV-mediated therapeutic cell reprogramming strategy for ischemic heart diseases.

Engineered phage nanofibers induce angiogenesis

Herein, we exploited a bioinspired M13 bacteriophage as an angiogenic nanofiber for soft tissue engineering applications. We demonstrated that engineered phage nanofibers induce angiogenesis with specific biochemical and topological cues. Specifically, nanofibrous phage structures provided a novel therapeutic platform for stem cell technologies in ischemic diseases.

Thymosin β4 in rheumatoid arthritis: Friend or foe

Rheumatoid arthritis (RA) has characteristic pannus tissues, which show tumor-like growth of the synovium through chronic joint inflammation. The synovium is highly penetrated by various immune cells, and the synovial lining becomes hyperplastic due to increased numbers of macrophage-like and fibroblast-like synoviocytes. Thus, a resultant hypoxic condition stimulates the expression of inflammation-related genes in various cells, in particular, vascular endothelial growth factor. Thymosin β4 (Tβ4), a 5-kDa protein, is known to play a significant role in various biological activities, such as actin sequestering, cell motility, migration, inflammation, and damage repair. Recent studies have provided evidence that Tβ4 may have a role in RA pathogenesis. The Tβ4 level has been shown to increase significantly in the joint fluid and serum of RA patients. However, whether Tβ4 stimulates or inhibits activation of RA immune responses remains to be determined. In the present study, we discuss the logical and clinical justifications for Tβ4 as a potential target for RA therapeutics.

Effects of exogenous thymosin β4 on carbon tetrachloride-induced liver injury and fibrosis

The present study investigated the effects of exogenous thymosin β4 (TB4) on carbon tetrachloride (CCl₄)-induced acute liver injury and fibrosis in rodent animals. Results showed that both in mice and rats CCl₄ rendered significant increases in serum alanine aminotransferase and aspartate aminotransferase, hepatic malondialdehyde formation, decreases in antioxidants including superoxide dismutase and glutathione, and up-regulated expressions of transforming growth factor-β1, α-smooth muscle actin, tumor necrosis factor-α and interleukin-1β in the liver tissues. Hydroxyproline contents in the rat livers were increased by CCl₄. Histopathological examinations indicated that CCl₄ induced extensive necrosis in mice livers and pseudo-lobule formations, collagen deposition in rats livers. However, all these changes in mice and rats were significantly attenuated by exogenous TB4 treatment. Furthermore, up-regulations of nuclear factor-κB p65 protein expression by CCl₄ treatment in mice and rats livers were also remarkably reduced by exogenous TB4 administration. Taken together, findings in this study suggested that exogenous TB4 might prevent CCl₄-induced acute liver injury and subsequent fibrosis through alleviating oxidative stress and inflammation.

The expression of thymosin β4 in chronic hepatitis B combined nonalcoholic fatty liver disease

The aim of the study was to detect the expression level of thymosin β4 (Tβ4) in serum and tissues of patients with chronic hepatitis B (CHB) combined nonalcoholic fatty liver disease (NAFLD). The effects of Tβ4 in hepatic steatosis, chronic inflammation, and fibrosis development in CHB combined NAFLD patients were also discussed. The study included 46 patients in the case group with CHB and NAFLD and 42 patients in the control group with CHB. ELISA was applied to detect serum Tβ4 and TNF-α level. Furthermore, the correlation analysis of Tβ4 levels with biochemical index, pathological index, and TNF-α level was performed. The Tβ4 immunohistochemical levels of different inflammation fibrosis levels were compared, and the correlation analysis with TNF expression was performed. The Tβ4 levels in patients with CHB combined NAFLD showed no statistical difference when compared to the control group. In patients with CHB combined NAFLD group, the Tβ4 level had no correlation with ALT, AST, TG, FGP, hepatitis B virus (HBV)-DNA levels, and fat grading, but had negative correlation with inflammation score and fibrosis score (P <0.01). The immunohistochemical results of hepatic tissues showed that the expression intensity of severe inflammation fibrosis group had statistical significance compared with that of slight group, and the Tβ4 expression both in serum and in liver tissue negatively correlated with TNF-α expression. Tβ4 could be involved in the regulation of chronic inflammation and fibrosis and plays a defense role in the disease progression of CHB combined NAFLD patients.

Thymosin beta 4 silencing suppresses proliferation and invasion of non-small cell lung cancer cells by repressing Notch1 activation

Thymosin beta 4 (Tβ4), a pleiotropic actin-sequestering polypeptide that is involved in wound healing and developmental processes, has been reported to be strongly associated with tumorigenesis. A recent tissue microarray analysis showed that Tβ4 was highly expressed in certain tumor cells, including lung cancer. However, the exact expression pattern and the role of Tβ4 in non-small cell lung cancer (NSCLC) have not to our knowledge been investigated. In the present study, we confirmed that Tβ4 expression was increased in NSCLC tissues and cell lines. Tβ4 gene silencing in A549 and H1299 cells inhibited cell proliferation, migration, and invasion in vitro and decreased tumor growth in vivo Mechanistic investigations revealed a significant decrease in Notch1 activation in Tβ4 gene-silenced cells. Moreover, restoring the Notch1 expression attenuated the function of Tβ4 silencing in NSCLC cells. Taken together, these findings suggest that Tβ4 may play an oncogenic role in NSCLC progression and may be a novel molecular target for anti-NSCLC therapy.

Thymosin β4 inhibits microglia activation through microRNA 146a in neonatal rats following hypoxia injury

Neuroinflammation mediated by activated microglia plays a pivotal role in the pathogenesis of neurological disorders, including hypoxic injury of the developing brain. Thymosin β4 (Tβ4), the major G-actin-sequestering molecule, has an anti-inflammatory effect and has been used to treat various neurological diseases. However, the effect of Tβ4 on hypoxia-induced microglia activation in the developing brain remains unclear. We investigate here the effect of Tβ4 on microglia activation of neonatal rats after hypoxia exposure. Tβ4 treatment was carried out on 1-day-old rats and BV-2 cells. Tβ4 expression in microglia was determined by quantitative real time-PCR, western blotting, and immunofluorescence staining. Secretion of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and nitric oxide (NO) was assessed by enzyme-linked immunosorbent assay and colorimetric assay. mRNA expression of TNF-α and IL-1β, and microRNA 146a expression was determined by quantitative real time-PCR. We showed that Tβ4 treatment significantly inhibited secretion of inflammatory mediators in the cerebellum of neonatal rats following hypoxia injury. Increased expression of endogenous Tβ4 in microglia was observed both in hypoxic rats and in BV-2 cells. Tβ4 treatment significantly inhibited the expression and secretion of hypoxia-induced TNF-α, IL-1β, and NO. Remarkably, microRNA 146a expression was found to have increased in Tβ4-treated BV-2 cells. We demonstrated the anti-inflammatory effect of Tβ4 in neonatal rats following hypoxic brain injury. More importantly, our data reveal, for the first time, that Tβ4 inhibits microglia activation in vitro. Therefore, this study contributes to understanding the role and mechanism of Tβ4 function in central nervous system diseases.

Effect of Antifibrotic MicroRNAs Crosstalk on the Action of N-acetyl-seryl-aspartyl-lysyl-proline in Diabetes-related Kidney Fibrosis

N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) is an endogenous antifibrotic peptide. We found that suppression of AcSDKP and induction of dipeptidyl peptidase-4 (DPP-4), which is associated with insufficient levels of antifibrotic microRNA (miR)s in kidneys, were imperative to understand the mechanisms of fibrosis in the diabetic kidneys. Analyzing streptozotocin (STZ)-induced diabetic mouse strains, diabetic CD-1 mice with fibrotic kidneys could be differentiated from less-fibrotic diabetic 129Sv mice by suppressing AcSDKP and antifibrotic miRs (miR-29s and miR-let-7s), as well as by the prominent induction of DPP-4 protein expression/activity and endothelial to mesenchymal transition. In diabetic CD-1 mice, these alterations were all reversed by AcSDKP treatment. Transfection studies in culture endothelial cells demonstrated crosstalk regulation of miR-29s and miR-let-7s against mesenchymal activation program; such bidirectional regulation could play an essential role in maintaining the antifibrotic program of AcSDKP. Finally, we observed that AcSDKP suppression in fibrotic mice was associated with induction of both interferon-γ and transforming growth factor-β signaling, crucial molecular pathways that disrupt antifibrotic miRs crosstalk. The present study provides insight into the physiologically relevant antifibrotic actions of AcSDKP via antifibrotic miRs; restoring such antifibrotic programs could demonstrate potential utility in combating kidney fibrosis in diabetes.

Thymosin β4 Promotes Dermal Healing

No agent has been identified that significantly accelerates the repair of chronic dermal wounds in humans. Thymosin beta 4 (Tβ4) is a small, abundant, naturally occurring regenerative protein that is found in body fluids and inside cells. It was found to have angiogenic and antiinflammatory activity and to be high in platelets that aggregate at the wound site. Thus we used Tβ4 initially in dermal healing. It has since been shown to have many activities important in tissue protection, repair, and regeneration. Tβ4 increases the rate of dermal healing in various preclinical animal models, including diabetic and aged animals, and is active for burns as well. Tβ4 also accelerated the rate of repair in phase 2 trials with patients having pressure ulcers, stasis ulcers, and epidermolysis bullosa wounds. It is safe and well tolerated and will likely have additional uses in the skin and in injured organs for tissue repair and regeneration.

Development of the intein-mediated method for production of recombinant thymosin β4 from the acetylated in vivo fusion protein

Thymosin β4 is a 43 amino acid long peptide with an acetylated N-terminal serin that has a high potential as a remedy for healing ulcers, wounds and burns. Although protein biosynthesis offers attractive opportunities in terms of a large-scale production, currently thymosin β4 is mainly produced by chemical synthesis. The problems that hinder the successful commercialization of the biotechnological approach are associated with the small peptides expression and N-terminal acetylation. This work presents an innovative biotechnological method for thymosin β4 production that employs the peptide acetylation in vivo. A genetically engineered construct was created, where the Tβ4 coding sequence fused with the intein Mxe GyrA sequence and chitin-binding domain was combined with the acetyltransferase coding sequence to form a polycistronic construct under a stringent control of T7 promoter. This plasmid construct provided for the expression of the Tβ4-intein fusion protein. In the process of the post-translational modification in vivo formyl methionine was completely removed from the target peptide N-terminus and followed by the Tβ4 precursor N-terminal acetylation. The use of the intein-mediated expression system made it possible to extract thymosin β4 in only 2 chromatographic runs. The method is straightforward to implement and scale up.

Oral Administration of N-Acetyl-seryl-aspartyl-lysyl-proline Ameliorates Kidney Disease in Both Type 1 and Type 2 Diabetic Mice via a Therapeutic Regimen

Kidney fibrosis is the final common pathway of progressive kidney diseases including diabetic nephropathy. Here, we report that the endogenous antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), the substrate of angiotensin-converting enzyme (ACE), is an orally available peptide drug used to cure kidney fibrosis in diabetic mice. We utilized two mouse models of diabetic nephropathy, streptozotocin- (STZ-) induced type 1 diabetic CD-1 mice and type 2 diabetic nephropathy model db/db mice. Intervention with the ACE inhibitor imidapril, oral AcSDKP, or imidapril + oral AcSDKP combination therapy increased urine AcSDKP levels. AcSDKP levels were significantly higher in the combination group compared to those of the other groups. AcSDKP oral administration, either AcSDKP alone or in addition to imidapril, ameliorated glomerulosclerosis and tubulointerstitial fibrosis. Plasma cystatin C levels were higher in both models, at euthanasia, and were restored by all the treatment groups. The levels of antifibrotic miRs, such as miR-29 or let-7, were suppressed in the kidneys of both models; all treatments, especially the combination of imidapril + oral AcSDKP, restored the antifibrotic miR levels to a normal value or even higher. AcSDKP may be an oral antifibrotic peptide drug that would be relevant to combating fibroproliferative kidney diseases such as diabetic nephropathy.

Enhancing endothelial progenitor cell for clinical use

Circulating endothelial progenitor cells (EPCs) have been demonstrated to correlate negatively with vascular endothelial dysfunction and cardiovascular risk factors. However, translation of basic research into the clinical practice has been limited by the lack of unambiguous and consistent definitions of EPCs and reduced EPC cell number and function in subjects requiring them for clinical use. This article critically reviews the definition of EPCs based on commonly used protocols, their value as a biomarker of cardiovascular risk factor in subjects with cardiovascular disease, and strategies to enhance EPCs for treatment of ischemic diseases.

Thymosin-β4-mediated therapeutic neovascularization: role of the PI3K/AKT pathway

OBJECTIVES

Thymosin β4 (Tβ4) is known to have pro-angogenic abilities in vitro and in vivo, and its cardioprotective effect is PI3/AKT-dependent. Tβ4-induced vessel formation requires transcriptional activation via the MRTF/SRF pathway. However, the relevance of PI3/AKT signaling for Tβ4-induced angiogenesis remains unclear. Here, we analyzed the PI3K/AKT cascade after Tβ4 transduction in models of chronic hindlimb ischemia.

METHODS

Tube formation assays of endothelial cells transfected with Tβ4 ± AKT-dn or PI3Kα/Rho inhibition were performed. In mice, rAAV.Tβ4 was injected (intramuscular [i.m.]) 14 days before femoral artery ligation. In addition, either rAAV.AKT-dn was co-applied or Rho/PI3K/AKT pathways were inhibited. Capillary density and hindlimb perfusion were obtained. In rabbits, chronic ischemia was induced by femoral artery excision and subsequent i.m. injection of rAAV.Tβ4 ± rAAV.AKT-dn. Analyses of capillary density, collateral formation and perfusion were performed.

RESULTS

Tβ4-induced ring formation was blunted by inhibiting the Rho-kinase (ROCK) or the PI3K/AKT pathway. In vivo, Tβ4 transduction induced angiogenesis and perfusion, an effect abrogated by inhibition of Rho-signaling, or PI3Kα/AKT. In the rabbit model, inhibition of AKT in the lower limb not only abolished angiogenesis but also collateral formation.

CONCLUSION

Tβ4 requires PI3Kα/AKT pathway signaling for induction of therapeutic neovascularization in ischemic limb disease.

Thymosin β4 administration enhances fracture healing in mice

Thymosin β4 (Tβ4 ) is a regenerative peptide that we hypothesized would promote healing of fractured bone. Mice received a bilateral fibular osteotomy and were given i.p. injections of either Tβ4 (6 mg/kg) or saline. Calluses from saline- and Tβ4 -treated mice were analyzed for: (1) biomechanical properties and (2) composition using micro-computed tomography (µCT) and histomorphometry. Biomechanical analysis showed that Tβ4 -treated calluses had a 41% increase in peak force to failure (p < 0.01) and were approximately 25% stiffer (p < 0.05) than saline-treated controls. µCT analysis at 21 days post-fracture showed that the fractional volume of new mineralized tissue and new highly mineralized tissue were respectively 18% and 26% greater in calluses from Tβ4 -treated mice compared to controls (p < 0.01; p < 0.05, respectively). Histomorphometry complemented the µCT data; at 21 days post-fracture, Tβ4 -treated calluses were almost 23% smaller (p < 0.05), had nearly 47% less old cortical bone (p < 0.05) and had a 31% increase in new trabecular bone area/total callus area fraction compared with controls (p < 0.05). Our finding of enhanced biomechanical properties of fractures in mice treated with Tβ4 provides novel evidence of the therapeutic potential of this peptide for treating bone fractures.

In vivo growth suppression of CT-26 mouse colorectal cancer cells by adenovirus-expressed small hairpin RNA specifically targeting thymosin beta-4 mRNA

Thymosin beta-4 (Tβ4) is known to be involved in tumorigenesis. Overexpression of this polypeptide has been observed in a wide variety of cancers, including colorectal carcinoma (CRC). Accordingly, Tβ4 has been proposed to be a novel therapeutic target for CRC, especially in its metastatic form. Although in vitro tumor-suppressive effects of Tβ4 gene silencing mediated by small hairpin RNA (shRNA) have already been demonstrated, the in vivo efficacy of such an approach has not yet been reported. Herein, we demonstrated that infection with recombinant adenovirus expressing an shRNA targeting Tβ4 markedly reduced the growth of and robustly induced apoptosis in CT-26 mouse CRC cells in culture. Additionally, tumors grown in nude mice from the CT-26 cells whose Tβ4 expression already been downregulated by virus infection were also drastically reduced. Most importantly, significant growth arrest of tumors derived from the parental CT-26 cells was observed after multiple intratumoral injections of these viruses. Together, our results show for the first time that in vivo silencing of Tβ4 expression by its shRNA generated after adenoviral infection can suppress CRC growth. These results further demonstrate the feasibility of treating CRC by a Tβ4 knockdown gene therapeutic approach.

The biological significance of angiotensin-converting enzyme inhibition to combat kidney fibrosis

Both angiotensin-converting enzyme inhibitor (ACE-I) and angiotensin II receptor blocker have been recognized as renin-angiotensin system (RAS) inhibitors. These two RAS inhibitors are rarely recognized as drugs with distinct pharmacological effects in the clinic or most clinical trials. Some preclinical basic research and clinical trials indicate that ACE-I might display superior organ-protective effects, especially anti-fibrotic effects. Such anti-fibrotic effects of ACE-I could be associated with an endogenous anti-fibrotic peptide, N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP). In this review, we focused on the anti-fibrotic effects of RAS inhibition and the endogenous anti-fibrotic peptide AcSDKP.

Thymosinβ4: a novel assessed biomarker of the prognosis of acute-on-chronic liver failure patient?

BACKGROUND AND AIM

In the previous study, we found serum thymosin β4 (Tβ4) levels were associated with mortality in liver failure patients. In this study, we try to evaluate the prognostic value of Tβ4 in acute-on-chronic liver failure (AoCLF) patients by comparing with the Child-Pugh (CTP) and Model for End-Stage Liver Disease (MELD) scores.

METHODS

Serum Tβ4 levels were measured by enzyme-linked immunosorbent assay (ELISA), and the CTP and MELD scores were calculated for each patient.

RESULTS

Serum Tβ4 levels of AoCLF patients [0.4120 (0.2447-0.7492)μg/mL] were lower than healthy controls [9.2710 (5.1660-13.2485)μg/mL] (P<0.001). AoCLF patients were divided into survival and death group. Compared to survivors, lower Tβ4 concentrations, higher CTP and MELD scores (P<0.001, respectively) were observed in AoCLF patients who died. There were negative correlations between Tβ4 levels and CTP scores (P<0.001), MELD scores (P<0.001). A CTP score of 11.5, a MELD score of 21.63 and a Tβ4 concentration of 0.3840μg/mL were identified as the cut-off values for the stratification of AoCLF patients. MELD≥21.63 combined with Tβ4<0.3840μg/mL can more exactly discriminate between the patients who would survive and die.

CONCLUSIONS

Serum Tβ4 concentration has appreciable value to evaluate the short-term prognosis of AoCLF patients, although Tβ4 is not superior to MELD. The combination of Tβ4 and MELD scores are more effective in assessing the prognosis of AoCLF patients.

N-acetyl-seryl-aspartyl-lysyl-proline: a valuable endogenous anti-fibrotic peptide for combating kidney fibrosis in diabetes

Fibroproliferative diseases are responsible for 45% of deaths in the developed world. Curing organ fibrosis is essential for fibroproliferative diseases. Diabetic nephropathy is a common fibroproliferative disease of the kidney and is associated with multiorgan dysfunction. However, therapy to combat diabetic nephropathy has not yet been established. In this review, we discuss the novel therapeutic possibilities for kidney fibrosis in diabetes focusing on the endogenous anti-fibrotic peptide, N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), which is the substrate for angiotensin-converting enzyme and exhibits meaningful anti-fibrotic effects in various experimental models of fibrotic disease.

N-acetyl-seryl-aspartyl-lysyl-proline inhibits diabetes-associated kidney fibrosis and endothelial-mesenchymal transition

Endothelial-to-mesenchymal transition (EndMT) emerges as an important source of fibroblasts. MicroRNA let-7 exhibits anti-EndMT effects and fibroblast growth factor (FGF) receptor has been shown to be an important in microRNA let-7 expression. The endogenous antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) is a substrate of angiotensin-converting enzyme (ACE). Here, we found that AcSDKP inhibited the EndMT and exhibited fibrotic effects that were associated with FGF receptor-mediated anti-fibrotic program. Conventional ACE inhibitor plus AcSDKP ameliorated kidney fibrosis and inhibited EndMT compared to therapy with the ACE inhibitor alone in diabetic CD-1 mice. The endogenous AcSDKP levels were suppressed in diabetic animals. Cytokines induced cultured endothelial cells into EndMT; coincubation with AcSDKP inhibited EndMT. Expression of microRNA let-7 family was suppressed in the diabetic kidney; antifibrotic and anti-EndMT effects of AcSDKP were associated with the restoration of microRNA let-7 levels. AcSDKP restored diabetes- or cytokines-suppressed FGF receptor expression/phosphorylation into normal levels both in vivo and in vitro. These results suggest that AcSDKP is an endogenous antifibrotic molecule that has the potential to cure diabetic kidney fibrosis via an inhibition of the EndMT associated with the restoration of FGF receptor and microRNA let-7.

Quantitative analysis of thymosin β4 in whole saliva by capillary electrophoresis–mass spectrometry using multiple ions monitoring (CE-MIM-MS.)

Thymosin β4 (Tβ4) is a peptide present in almost any tissue and in extracellular media in mammals, having multiple amazing functions as wound healing, stimulation of angiogenesis, and suppression of inflammation. This study describes its determination in saliva through CE-MS using multiple ions monitoring scan mode by isolating the four most intense multicharged ions present in the MS spectra of the peptide. This scan modality, by reducing the baseline noise and interferences, increases the sensitivity and specificity in biological matrices. The CE-MS separation was optimized by studying different parameters influencing CE analysis, sample injection, and MS ionization, that is, the nebulizer gas flow, the sheath liquid, and BGE composition. The proposed technique can unambiguously identify in short time Tβ4 in saliva after a very fast and reduced sample pretreatment procedure. The method was validated for quantitation showing linearity of the response in the range 0.25 (lower limit of quantification) to 4 μM (average R2 0.996 ± 0.005) and intra- and interassay precision and accuracy at three different concentrations with RSD values in the range of 7–16%. It was successfully applied to the analysis of Tβ4 in whole saliva showing a variable peptide content from individual to individual (in the range of 0.3–1.4 μM) and in different days from the same individual. CE-MS in multiple ions monitoring scan mode provides a fast, selective, and economic method requiring only very few microliters of sample.

Thymosin β4 increases the potency of transplanted mesenchymal stem cells for myocardial repair

BACKGROUND

Thymosin β4 (Tβ4) has been shown to enhance the survival of cultured cardiomyocytes. Here, we investigated whether the cytoprotective effects of Tβ4 can increase the effectiveness of transplanted swine mesenchymal stem cells (sMSCs) for cardiac repair in a rat model of myocardial infarction (MI).

METHODS AND RESULTS

Under hypoxic conditions, cellular damage (lactate dehydrogenase leakage), apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labelingc cells), and caspase-8 activity were significantly lower, whereas B-cell lymphoma-extra large protein expression was significantly higher, in sMSCs cultured with Tβ4 (1 μg/mL) than in sMSCs cultured without Tβ4, and Tβ4 also increased sMSC proliferation. For in vivo experiments, animals were treated with basal medium (MI: n=6), a fibrin patch (Patch: n=6), a patch containing sMSCs (sMSC: n=9), or a patch containing sMSCs and Tβ4 (sMSC/Tβ4: n=11); Tβ4 was encapsulated in gelatin microspheres to extend Tβ4 delivery. Four weeks after treatment, echocardiographic assessments of left-ventricular ejection fraction and fractional shortening were significantly better (P<0.05) in sMSC/Tβ4 animals (left-ventricular ejection fraction=51.7 ± 1.1%; fractional shortening=26.7 ± 0.7%) than in animals from MI (39 ± 3%; 19.5 ± 1.7%) and Patch (43 ± 1.4%; 21.6 ± 0.9%) groups. Histological assessment of infarct wall thickness was significantly higher (P<0.05) in sMSC/Tβ4 animals (50%, [45%, 80%]) than in animals from MI (25%, [20%, 25%]) group. Measurements in sMSC (left-ventricular ejection fraction=45 ± 2.6%; fractional shortening=22.9 ± 1.6%; TH = 43% [25%, 45%]), Patch, and MI animals were similar. Tβ4 administration also significantly increased vascular growth, the retention/survival of the transplanted sMSCs, and the recruitment of endogenous c-Kit(+) progenitor cells to the infarcted region.

CONCLUSIONS

Extended-release Tβ4 administration improves the retention, survival, and regenerative potency of transplanted sMSCs after myocardial injury.

Regulation of PTEN/Akt pathway enhances cardiomyogenesis and attenuates adverse left ventricular remodeling following thymosin β4 Overexpressing embryonic stem cell transplantation in the infarcted heart

Thymosin β4 (Tβ4), a small G-actin sequestering peptide, mediates cell proliferation, migration, and angiogenesis. Whether embryonic stem (ES) cells, overexpressing Tβ4, readily differentiate into cardiac myocytes in vitro and in vivo and enhance cardioprotection following transplantation post myocardial infarction (MI) remains unknown. Accordingly, we established stable mouse ES cell lines, RFP-ESCs and Tβ4-ESCs, expressing RFP and an RFP-Tβ4 fusion protein, respectively. In vitro, the number of spontaneously beating embryoid bodies (EBs) was significantly increased in Tβ4-ESCs at day 9, 12 and 15, compared with RFP-ESCs. Enhanced expression of cardiac transcriptional factors GATA-4, Mef2c and Txb6 in Tβ4-EBs, as confirmed with real time-PCR analysis, was accompanied by the increased number of EB areas stained positive for sarcomeric α-actin in Tβ4-EBs, compared with the RFP control, suggesting a significant increase in functional cardiac myocytes. Furthermore, we transplanted Tβ4-ESCs into the infarcted mouse heart and performed morphological and functional analysis 2 weeks after MI. There was a significant increase in newly formed cardiac myocytes associated with the Notch pathway, a decrease in apoptotic nuclei mediated by an increase in Akt and a decrease in levels of PTEN. Cardiac fibrosis was significantly reduced, and left ventricular function was significantly augmented in the Tβ4-ESC transplanted group, compared with controls. It is concluded that genetically modified Tβ4-ESCs, potentiates their ability to turn into cardiac myocytes in vitro as well as in vivo. Moreover, we also demonstrate that there was a significant decrease in both cardiac apoptosis and fibrosis, thus improving cardiac function in the infarcted heart.

Application of peripheral-blood-derived endothelial progenitor cell for treating ischemia-reperfusion injury and infarction: a preclinical study in rat models

Background

Our aim was to explore the therapeutic effects of peripheral blood-derived endothelial progenitor cells (PB-EPC) in cardiac ischemia-reperfusion infarction models in rats and in in vitro culture systems.

Methods

Rat models of ischemia reperfusion and myocardial infarction were developed using male, Sprague–Dawley rats. Cardiomyocyte and endothelial cell cultures were also established. Therapeutic effects of PB-EPCs were examined in vivo and in vitro in both models. Rats underwent either cardiac ischemia-reperfusion (n = 40) or infarction (n = 56) surgeries and were transplanted with genetically modified EPCs. Treatment efficacy in the ischemia-reperfusion group was measured by infarct size, myocardial contraction velocity, and myeloperoxidase activity after transplantation. Cardiomyocyte survival and endothelial cell apoptosis were investigated in vitro. Vascular growth-associated protein expression and cardiac function were evaluated in the myocardial infarction group by western blot and echocardiography, respectively.

Results

Infarct size and myeloperoxidase activity were significantly decreased in the ischemia-reperfusion group, whereas myocardial contractility was significantly increased in the EPC and Tβ4 groups compared with that in the control group. In contrast, no differences were found between EPC + shRNA Tβ4 and control groups. Rates of cardiomyocyte survival and endothelial cell apoptosis were significantly higher and lower, respectively, in the EPC and Tβ4 groups than in the control group, whereas no differences were found between the EPC + shRNA Tβ4 and control group. Four weeks after myocardial infarction, cardiac function was significantly better in the EPC group than in the control group. Expressions of PDGF, VEGF, and Flk-1 were significantly higher in EPC group than in control group.

Conclusions

Study findings suggest that PB-EPCs are able to protect cardiomyocytes from ischemia-reperfusion or infarction-induced damage via a Tβ4-mediated mechanism. EPCs may also provide protection through increased expression of proteins involved in mediating vascular growth. Autologous peripheral-blood-derived EPCs are readily available for efficient therapeutic use without the concerns of graft rejection.

Neuroprotective and neurorestorative effects of thymosin β4 treatment following experimental traumatic brain injury

Traumatic brain injury (TBI) remains a leading cause of mortality and morbidity worldwide. No effective pharmacological treatments are available for TBI because all phase II/III TBI clinical trials have failed. This highlights a compelling need to develop effective treatments for TBI. Endogenous neurorestoration occurs in the brain after TBI, including angiogenesis, neurogenesis, synaptogenesis, oligodendrogenesis, and axonal remodeling, which may be associated with spontaneous functional recovery after TBI. However, the endogenous neurorestoration following TBI is limited. Treatments amplifying these neurorestorative processes may promote functional recovery after TBI. Thymosin beta 4 (Tβ4) is the major G-actin-sequestering molecule in eukaryotic cells. In addition, Tβ4 has other properties including antiapoptosis and anti-inflammation, promotion of angiogenesis, wound healing, stem/progenitor cell differentiation, and cell migration and survival, which provide the scientific foundation for the corneal, dermal, and cardiac wound repair multicenter clinical trials. Here, we describe Tβ4 as a neuroprotective and neurorestorative candidate for treatment of TBI.

Molecular and cellular mechanisms of thymosin β4-mediated cardioprotection

Coronary heart disease is still the leading cause of death in industrialized nations. Reduction of infarct size after acute myocardial infarction and, in addition, improvement of myocardial function and perfusion in acute and chronic myocardial ischemia would enhance cardiac survival. Thymosin β4, a 43-amino acid water-soluble peptide with pleiotropic abilities seems to be a promising candidate for the treatment of ischemic heart disease. During cardiac development, thymosin β4 is essential for vascularization of the myocardium, by targeting all three parts of vessel development, that is, vasculogenesis, angiogenesis, and arteriogenesis. In the adult, thymosin β4 is capable of inducing angiogenesis via activation of survival kinases in an actin-dependent and -independent manner. In addition, thymosin β4 has anti-inflammatory properties by reducing NF-κB p65 activation. These protective effects are further enhanced through increased myocyte and endothelial cell survival accompanied by differentiation of epicardial progenitor cells.

Thymosin β4 stabilizes hypoxia-inducible factor-1α protein in an oxygen-independent manner

The small actin-binding protein thymosin β4 (Tβ4) is understood to stimulate angiogenesis. Previously, we reported that Tβ4 induces angiogenesis by increasing vascular endothelial growth factor (VEGF) expression, but the mechanism underlying how Tβ4 upregulates VEGF expression remain unknown. To identify the mechanism of VEGF induction by Tβ4, we measured VEGF promoter activity and analyzed the effect of Tβ4 on VEGF RNA stability. The Tβ4 peptide had no effect on either VEGF promoter activity or VEGF RNA stability. We focused on the possibility that Tβ4 may indirectly induce VEGF expression via hypoxia-inducible factor (HIF)-1α. We determined that Tβ4 increased the stability of HIF-1α protein under normoxic conditions. These data suggest that Tβ4 indirectly induces VEGF expression by increasing the protein stability of HIF-1α in an oxygen-independent manner.

Controlled delivery of thymosin β4 for tissue engineering and cardiac regenerative medicine

Thymosin β4 (Tβ4) is a peptide with multiple biological functions. Here, we focus on the role of Tβ4 in vascularization, and review our studies of the controlled delivery of Tβ4 through its incorporation in biomaterials. Tβ4 promotes vascularization through VEGF induction and AcSDKP-induced migration and differentiation of endothelial cells. We developed a collagen-chitosan hydrogel for the controlled release of Tβ4 over 28 days. In vitro, the Tβ4-encapsulated hydrogel increased migration of endothelial cells and tube formation from epicardial explants that were cultivated on top of the hydrogel, compared to Tβ4-free hydrogel and soluble Tβ4 in the culture medium. In vivo, subcutaneously injected Tβ4-containing collagen-chitosan hydrogel in rats led to enhanced vascularization compared to Tβ4-free hydrogel and collagen hydrogel with Tβ4. Furthermore, the injection of the Tβ4-encapsulated hydrogel in the infarct region improved angiogenesis, reduced tissue loss, and retained left ventricular wall thickness after myocardial infarction in rats.

Thymosin β4 is a novel potential prognostic marker in gastrointestinal stromal tumors

Thymosin beta-4 (Tβ(4)) is a major actin-sequestering molecule that contributes to cell growth, differentiation, motility, survival, mitosis and angiogenesis. It is overexpressed in certain type of carcinoma and fibrosarcoma cell lines and is associated with metastatic potential. The aim of this study was to investigate the relationship between Tβ(4) expression and clinicopathologic features and VEGF status in gastrointestinal stromal tumors (GISTs). Retrospectively, 60 GISTs were re-examined and immunohistochemistry for Tβ(4) and VEGF was performed. Increased expression of Tβ(4) and VEGF was observed in 26 (43.3%) and in 19 (31.6%) of the tumors, respectively. Tβ(4) expression was positively correlated with VEGF expression (p < 0.01). Tβ(4) and VEGF expression were significantly associated with tumor size (p = 0.00 and p = 0.02, respectively) and high mitosis (p = 0.03 and p = 0.00, respectively). Although Tβ(4) expression was positively associated with pleomorphism (p = 0.01), VEGF expression was positively associated with necrosis (p = 0.03). Tβ(4) expression was related with local recurrence and/or metastasis (p = 0.03), but VEGF expression was not (p = 0.12). We firstly demonstrate the presence of Tβ(4) protein in GISTs. Our study reveals that increased expression of Tβ(4) could be considered as an indicator of aggressive behavior of tumor.