Dextran induces differentiation of circulating endothelial progenitor cells

Mobilization of endothelial progenitor cells after implantation of CD34 antibody-covered sirolimus-eluting COMBO® stent: assessment with EPC colony-forming assay

The COMBO® stent is a unique stent on which the CD34 antibody is mounted to capture CD34 + endothelial progenitor cells (EPCs) and from which sirolimus is eluted to suppress neointimal hyperplasia. The COMBO® stent aims to induce early re-endothelialization and vascular healing and to prevent restenosis. In the clinical setting, however, the effects of the COMBO® stent have not been validated in terms of EPC biology. In this study, we assessed the kinetics of circulating EPCs, not only quantitatively by flow cytometric analysis but also qualitatively by an EPC colony-forming assay, in 25 patients undergoing COMBO® stent implantation. Among all patients, flow cytometric analysis indicated that the number of circulating CD34 + /KDR + EPCs did not change after COMBO® stent implantation compared with baseline (before stent implantation). The EPC colony-forming assay demonstrated that the number of small-type EPC colonies increased on day 2 (3 [2, 9] to 6 [4, 9]/dish, P = 0.026) and that of large-type EPC colonies more prominently increased on day 2 (1 [0, 4] to 5 [1, 10]/dish, P < 0.001) and day 7 (to 2 [1, 7], P = 0.006) after COMBO® stent implantation. Based on the results of optical coherence tomography at 3 months after stent implantation, the patients were divided into two groups: well (uncovered strut ratio < 10%, n = 14) and poor (uncovered strut ratio ≥ 10%, n = 10) stent coverage. Compared with baseline values, the number of large-type EPC colonies increased on day 2 (2.9 ± 0.8 to 7.3 ± 2.0, P = 0.026) and tended to increase on day 7 (6.8 ± 2.0/dish, P = 0.062) after COMBO® stent implantation in the well coverage group, while it did not change in the poor coverage group. Thus, the COMBO® stent might induce mature EPCs in the circulation, which might be associated with subsequent healing processes in vessel sites with stent-induced injury.

α-Glucan derivatives as selective blockers of aldolase A: Computer-aided structure optimization and the effects on HCC

Aldolase A (ALDOA) promotes hepatocellular carcinoma (HCC) growth and is a potential therapeutic target. A previous study found an α-D-glucan (α-D-(1,6)-Glcp-α-D-(1,4)-Glcp, 10.0:1.0), named HDPS-4II, that could specifically inhibit ALDOA but its activity was not high enough. In this study, the derivatives of α-D-glucan binding to ALDOA were optimized using molecular docking, and its sulfated modification demonstrated the highest affinity with ALDOA among sulfated, carboxylated, and aminated derivatives. Sulfated HDPS-4II and dextrans with different molecular weights (1000 Da, 3000 Da, and 4000 Da) were prepared. Using MST assay, 3-O-sulfated HDPS-4II (SHDPS-4II) and 1000 Da dextran (SDextran1) showed higher affinities to ALDOA with Kd of 1.83 μM and 85.04 μM, respectively. Furthermore, SHDPS-4II and SDextran1 markedly inhibited the proliferation of HCC cells both in vitro and in vivo by blocking ALDOA. These results demonstrate that sulfated modification of α-D-glucans could enhance their affinities with ALDOA and anti-HCC effects.

Effects of the factor Xa inhibitor rivaroxaban on the differentiation of endothelial progenitor cells

BACKGROUND

We evaluated the efficacy of the factor Xa inhibitor rivaroxaban on the differentiation ability of vascular endothelial progenitor cells (EPCs), which play roles in vascular injury repair and atherogenesis. Antithrombotic treatment in patients with atrial fibrillation undergoing percutaneous coronary intervention (PCI) is challenging, and current guidelines recommend oral anticoagulant monotherapy 1 year or more after PCI. However, biological evidence of the pharmacological effects of anticoagulants is insufficient.

METHODS

EPC colony-forming assays were performed using peripheral blood-derived CD34-positive cells from healthy volunteers. Adhesion and tube formation of cultured EPCs were assessed in human umbilical cord-derived CD34-positive cells. Endothelial cell surface markers were assessed using flow cytometry, and Akt and endothelial nitric oxide synthase (eNOS) phosphorylation were examined using western blot analysis of EPCs. Adhesion, tube formation and endothelial cell surface marker expression was observed in EPCs transfected with small interfering RNA (siRNA) against protease-activated receptor (PAR)-2. Finally, EPC behaviors were assessed in patients with atrial fibrillation undergoing PCI in whom warfarin was changed to rivaroxaban.

RESULTS

Rivaroxaban increased the number of large EPC colonies and increased the bioactivities of EPCs, including adhesion and tube formation. Rivaroxaban also increased vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, Tie-2, and E-selectin expression as well as Akt and eNOS phosphorylation. PAR-2 knockdown increased the bioactivities of EPCs and endothelial cell surface marker expression. Patients in whom the number of large colonies increased after switching to rivaroxaban showed better vascular repair.

CONCLUSIONS

Rivaroxaban increased the differentiation ability of EPCs, leading to potential advantages in the treatment of coronary artery disease.

A Comprehensive Assessment on the Pivotal Role of Hydrogels in Scaffold-Based Bioprinting

The past a few decades have seen exponential growth in the field of regenerative medicine. What began as extirpative (complete tissue or organ removal), with little regard to the effects of tissue loss and/or disfigurement, has evolved towards fabricating engineered tissues using personalized living cells (e.g., stem cells), and customizing a matrix or structural organization to support and guide tissue development. Biofabrication, largely accomplished through three-dimensional (3D) printing technology, provides precise, controlled, and layered assemblies of cells and biomaterials, emulating the heterogenous microenvironment of the in vivo tissue architecture. This review provides a concise framework for the bio-manufacturing process and addresses the contributions of hydrogels to biological modeling. The versatility of hydrogels in bioprinting is detailed along with an extensive elaboration of their physical, mechanical, and biological properties, as well as their assets and limitations in bioprinting. The scope of various hydrogels in tissue formation has been discussed through the case studies of biofabricated 3D constructs in order to provide the readers with a glimpse into the barrier-breaking accomplishments of biomedical sciences. In the end, the restraints of bioprinting itself are discussed, accompanied with the identification of available engineering strategies to overcome them.

Bioactive potential of natural biomaterials: identification, retention and assessment of biological properties

Biomaterials have had an increasingly important role in recent decades, in biomedical device design and the development of tissue engineering solutions for cell delivery, drug delivery, device integration, tissue replacement, and more. There is an increasing trend in tissue engineering to use natural substrates, such as macromolecules native to plants and animals to improve the biocompatibility and biodegradability of delivered materials. At the same time, these materials have favourable mechanical properties and often considered to be biologically inert. More importantly, these macromolecules possess innate functions and properties due to their unique chemical composition and structure, which increase their bioactivity and therapeutic potential in a wide range of applications. While much focus has been on integrating these materials into these devices via a spectrum of cross-linking mechanisms, little attention is drawn to residual bioactivity that is often hampered during isolation, purification, and production processes. Herein, we discuss methods of initial material characterisation to determine innate bioactivity, means of material processing including cross-linking, decellularisation, and purification techniques and finally, a biological assessment of retained bioactivity of a final product. This review aims to address considerations for biomaterials design from natural polymers, through the optimisation and preservation of bioactive components that maximise the inherent bioactive potency of the substrate to promote tissue regeneration.

Heat induces myogenic transcription factors of myoblast cells via transient receptor potential vanilloid 1 (Trpv1)

Exercise generates heat, blood flow, and metabolic changes, thereby inducing hypertrophy of skeletal muscle cells. However, the mechanism by which heat incudes hypertrophy in response to heat is not well known. Here, we hypothesized that heat would induce differentiation of myoblast cells. We investigated the underlying mechanism by which myoblast cells respond to heat. When mouse myoblast cells were exposed to 42 °C for over 30 min, the phosphorylation level of protein kinase C (PKC) and heat shock factor 1 (Hsf1) increased, and the mRNA and protein expression level of heat shock protein 70 (Hsp70) increased. Inhibitors of transient receptor potential vanilloid 1 (Trpv1), calmodulin, PKC, and Hsf1, and the small interfering RNA‐mediated knockdown of Trpv1 diminished those heat responses. Heat exposure increased the phosphorylation levels of thymoma viral proto‐oncogene 1 (Akt), mammalian target of rapamycin (mTOR), eukaryotic translation initiation factor 4E binding protein 1 (Eif4ebp1), and ribosomal protein S6 kinase, polypeptide 1 (S6K1). The knockdown of Trpv1 decreased these heat‐induced responses. Antagonists of Hsp70 inhibited the phosphorylation level of Akt. Finally, heat increased the protein expression level of skeletal muscle markers such as myocyte enhancer factor 2D, myogenic factor 5, myogenic factor 6, and myogenic differentiation 1. Heat also increased myotube formation. Knockdown of Trpv1 diminished heat‐induced increases of those proteins and myotube formation. These results indicate that heat induces myogenic transcription factors of myoblast cells through the Trpv1, calmodulin, PKC, Hsf1, Hsp70, Akt, mTOR, Eif4ebp1, and S6K1 pathway. Moreover, heat increases myotube formation through Trpv1.

Heat induces interleukin-6 in skeletal muscle cells via TRPV1/PKC/CREB pathways

Interleukin-6 (IL-6) is released from skeletal muscle cells and induced by exercise, heat, catecholamine, glucose, lipopolysaccharide, reactive oxygen species, and inflammation. However, the mechanism that induces release of IL-6 from skeletal muscle cells remains unknown. Thermosensitive transient receptor potential (TRP) proteins such as TRPV1-4 play vital roles in cellular functions. In this study we hypothesized that TRPV1 senses heat, transmits a signal into the nucleus, and produces IL-6. The purpose of the present study is to investigate the underlying mechanisms whereby skeletal muscle cells sense and respond to heat. When mouse myoblast cells were exposed to 37-42°C for 2 h, mRNA expression of IL-6 increased in a temperature-dependent manner. Heat also increased IL-6 secretion in myoblast cells. A fura 2 fluorescence dual-wavelength excitation method showed that heat increased intracellular calcium flux in a temperature-dependent manner. Intracellular calcium flux and IL-6 mRNA expression were increased by the TRPV1 agonists capsaicin and N-arachidonoyldopamine and decreased by the TRPV1 antagonists AMG9810 and SB366791 and siRNA-mediated knockdown of TRPV1. TRPV2, 3, and 4 agonists did not change intracellular calcium flux. Western blotting with inhibitors demonstrated that heat increased phosphorylation levels of TRPV1, followed by PKC and cAMP response element-binding protein (CREB). PKC inhibitors, Gö6983 and staurosporine, CREB inhibitors, curcumin and naphthol AS-E, and knockdown of CREB suppressed the heat-induced increases in IL-6. These results indicate that heat increases IL-6 in skeletal muscle cells through the TRPV1, PKC, and CREB signal transduction pathway.NEW & NOTEWORTHY Heat increases the release of interleukin-6 (IL-6) from skeletal muscle cells. IL-6 has been shown to serve immune responses and metabolic functions in muscle. It can be anti-inflammatory as well as proinflammatory. However, the mechanism that induces release of IL-6 from skeletal muscle cells remains unknown. Here we show that heat increases IL-6 in skeletal muscle cells through the transient receptor potential vannilloid 1, PKC, and cAMP response element-binding protein signal transduction pathway.

Comparison of dextran-based sirolimus-eluting stents and PLA-based sirolimus-eluting stents in vitro and in vivo

The aim of this study was to compare dextran and Poly(l-lactide) (PLLA) polymer stent coatings as mediators for sirolimus (SRL) drug elution in a porcine coronary model. The bare metal stent (BMS) surface was first coated with a layer of SRL and then either dextran (DSS, a natural polymer) or PLA (PSS, a synthetic polymer). The release velocity of SRL was slightly faster in DSS than PSS over the first 7 days (78.5% and 62.3%, respectively, n = 10, p < 0.05) and continued to 28 days in both groups. The contact angle was dramatically decreased in DSS (38.7° ± 1.24) compared to BMS and PSS groups (72.7° ± 5.32 and 81.1º ± 1.70, respectively, n = 10, p < 0.05). Smooth muscle cell migration was arrested in both the DSS and PSS-treated groups compared to that in the nontreated group (4.2% ± 0.31, 5.8% ± 0.60, 80.0% ± 4.4, respectively, n = 10, p < 0.05). In the animal study, there were no significant differences in the injury score, the internal elastic lamina, and the lumen area among the groups. However, percent area stenosis was significantly decreased in the SRL-containing group (27.5% ± 2.52 in DSS and 27.9% ± 3.30 in PSS) compared to BMS (35.9% ± 3.51, p < 0.05). The fibrin score was higher in the PSS (2.9 ± 0.31) than BMS (2.1 ± 0.12) and DSS (2.5 ± 0.66). The inflammation score in the DSS (0.7 ± 0.21) was similar to that in the BMS (0.7 ± 0.12), which was dramatically lower than that PSS (1.5 ± 0.18, p < 0.005). Immunofluorescence analysis revealed that endothelialization was increased and inflammation prevented in the DSS. These results suggest that dextran may be useful for the fabrication of drug eluting stent as an alternative existing synthetic polymer. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 301-310, 2017.

Comparative Evaluation for Potential Differentiation of Endothelial Progenitor Cells and Mesenchymal Stem Cells into Endothelial-Like Cells

Understanding the mechanisms of vascular remodeling could lead to more effective treatments for ischemic conditions. We aimed to compare between the abilities of both human Wharton jelly derived mesenchymal stem cells (hMSCs) and human cord blood endothelial progenitor cells (hEPCs) and CD34⁺ to induce angiogenesis in vitro. hMSCs, hEPCs, and CD34⁺ were isolated from human umbilical cord blood using microbead (MiniMacs). The cells characterization was assessed by flow cytometry following culture and real-time PCR for vascular endothelial growth factor receptor 2 (VEGFR2) and von Willebrand factor (vWF) to prove stem cells differentiation. The study revealed successful isolation of hEPCs, CD34⁺, and hMSCs. The hMSCs were identified by gaining CD29⁺ and CD44⁺ using FACS analysis. The hEPCs were identified by having CD133⁺, CD34⁺, and KDR. The potential ability of hEPCs and CD34⁺ to differentiate into endothelial-like cells was more than hMSCs. This finding was assessed morphologically in culture and by higher significant VEGFR2 and vWF genes expression (p<0.05) in differentiated hEPCs and CD34⁺ compared to differentiated hMSCs. hEPCs and CD34⁺ differentiation into endothelial-like cells were much better than that of hMSCs.

Sirolimus-eluting dextran and polyglutamic acid hybrid coatings on AZ31 for stent applications

Magnesium (Mg)-based cardiovascular stents are promising candidate as the next generation of novel stents. Clinical studies have revealed encouraging outcomes, but late restenosis and thrombogenesis still largely exist. Blood and vascular biocompatible coatings with drug-eluting features could be the solution to such problems.

OBJECTIVE

This study was to investigate the feasibility of a three-layer hybrid coating on Mg alloy AZ31 with sirolimus-eluting feature for cardiovascular stent application.

MATERIALS AND METHODS

The first and third layers were low molecular weight dextran loaded with sirolimus, and the second layer was polyglutamic acid (PGA) to control sirolimus release. The hybrid coating was verified by scanning electron microscope (SEM). DC polarization and immersion tests were used to evaluate corrosion rate of the materials. Indirect cell viability and cell proliferation tests were performed by culturing cells with extract solutions of AZ31 samples. Blood compatibility was assessed using hemolysis assay.

RESULTS

Coated samples had an enhanced corrosion resistance than that of uncoated controls, more PGA slower corrosion. Sirolimus had a burst release for the initial ∼3 days and then a slower release until reached a plateau. The PGA thickness was able to control the sirolimus release, the thicker of PGA the slower release. The overall cell viability was extract concentration-dependent, and improved by the hybrid coatings. Cell proliferation was correlated to coating thickness and was inhibited by sirolimus. In addition, all coated AZ31 samples were non-hemolytic.

CONCLUSION

Results demonstrated that such a three-layer hybrid coating may be useful to improve the vascular biocompatibility of Mg stent materials.

Dextran induces differentiation of circulating endothelial progenitor cells

Endothelial progenitor cells (EPCs) have been demonstrated to be effective for the treatment of cardiovascular diseases. However, the differentiation process from circulation to adhesion has not been clarified because circulating EPCs rarely attached to dishes in EPC cultures previously. Here we investigated whether immature circulating EPCs differentiate into mature adhesive EPCs in response to dextran. When floating‐circulating EPCs derived from ex vivo expanded human cord blood were cultured with 5% and 10% dextran, they attached to fibronectin‐coated dishes and grew exponentially. The bioactivities of adhesion, proliferation, migration, tube formation, and differentiated type of EPC colony formation increased in EPCs exposed to dextran. The surface protein expression rate of the endothelial markers vascular endothelial growth factor (VEGF)‐R1/2, VE‐cadherin, Tie2, ICAM1, VCAM1, and integrin αv/β3 increased in EPCs exposed to dextran. The mRNA levels of VEGF‐R1/2, VE‐cadherin, Tie2, endothelial nitric oxide synthase, MMP9, and VEGF increased in EPCs treated with dextran. Those of endothelium‐related transcription factors ID1/2, FOXM1, HEY1, SMAD1, FOSL1, NFkB1, NRF2, HIF1A, EPAS1 increased in dextran‐treated EPCs; however, those of hematopoietic‐ and antiangiogenic‐related transcription factors TAL1, RUNX1, c‐MYB, GATA1/2, ERG, FOXH1, HHEX, SMAD2/3 decreased in dextran‐exposed EPCs. Inhibitor analysis showed that PI3K/Akt, ERK1/2, JNK, and p38 signal transduction pathways are involved in the differentiation in response to dextran. In conclusion, dextran induces differentiation of circulating EPCs in terms of adhesion, migration, proliferation, and vasculogenesis. The differentiation mechanism in response to dextran is regulated by multiple signal transductions including PI3K/Akt, ERK1/2, JNK, and p38. These findings indicate that dextran is an effective treatment for EPCs in regenerative medicines.