5 research outputs found

    RoY Peptide-Modified Chitosan-Based Hydrogel to Improve Angiogenesis and Cardiac Repair under Hypoxia

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    Myocardial infarction (MI) still represents the “Number One Killer” in the world. The lack of functional vasculature of the infracted myocardium under hypoxia is one of the main problems for cardiac repair. In this study, a thermosensitive chitosan chloride-RoY (CSCl-RoY) hydrogel was developed to improve angiogenesis under hypoxia after MI. First, RoY peptides were conjugated onto the CSCl chain via amide linkages, and our data show that the conjugation of RoY peptide to CSCl does not interfere with the temperature sensitivity. Then, the effect of CSCl-RoY hydrogels on vascularization in vitro under hypoxia was investigated using human umbilical vein endothelial cells (HUVECs). Results show that CSCl-RoY hydrogels can promote the survival, proliferation, migration and tube formation of HUVECs under hypoxia compared with CSCl hydrogel. Further investigations suggest that CSCl-RoY hydrogels can modulate the expression of membrane surface GRP78 receptor of HUVECs under hypoxia and then activate Akt and ERK1/2 signaling pathways related to cell survival/proliferation, thereby enhancing angiogenic activity of HUVECs under hypoxia. To assess its therapeutic properties in vivo, a MI model was induced in rats by the left anterior descending artery ligation. CSCl or CSCl-RoY hydrogels were injected into the border of infracted hearts. The results demonstrate that the introduction of RoY peptide can not only improve angiogenesis at MI region but also improve the cardiac functions. Overall, we conclude that the CSCl-RoY may represent an ideal scaffold material for injectable cardiac tissue engineering

    The quantitative expression of N-cadherin and Cx43 cultured for 3, 7 and 14 days.

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    <p>(<b>A, B, D, E</b>) N-Cadherin, PKP2 and PG significantly decreased at day 7 but significantly increased at day 14. (<b>A, C</b>) Cx43 increased a little at day 7 and then dramatically decreased at day 14. **<i>p</i><0.01; *<i>p</i><0.05.</p

    Immunofluorescent staining and quantification of ID-related proteins of the EHTs cultured for 3, 7 and 14 days.

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    <p>(<b>A–D</b>) At day 3, the cell membranes were positively stained with N-cadherin, Cx43, PKP2 and PG. (<b>E–H</b>) At day 7, N-cadherin (<b>E</b>), PKP2 (<b>G</b>) and PG (<b>H</b>) staining were positive and mainly localized to the contact sites of adjacent cells (arrow). Whereas the Cx43 positive staining was distributed along the whole plasma membrane in a punctuate pattern (<b>F</b>). (<b>I–L</b>) At day 14, ID-related proteins concentrated at the polar ends (arrow) of cardiomyocytes. (<b>M</b>) The FI of N-Cadherin, PKP2 and PG decreased from day 3 to 7 but increased at day 14. Cx43 was expressed the opposite. **<i>p</i><0.01; *<i>p</i><0.05.</p

    Ultra-structures of the nascent ID in the EHTs cultured for 3 and 7 days.

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    <p>(<b>A</b>) Closely apposed cell membranes at day 3 with scarce plaque-like structure (black arrow), subplasmalemmal vesicles (dotted-line area) and fibril-like structure (arrowhead). (<b>B</b>) Adherens junctions (white arrow) and desmosomes (black arrow) dispersed among the ID at day 7. New intercellular junctions were forming (black-line area) and a single gap junction profile appeared (arrowhead). Note an adhesion region with a dense plaque of adherens junction (star) anchoring actin filaments and a desmosome (black arrow). Myo: myofibril; Z: Z-line; Nc: nucleus.</p

    Immunofluorescent staining and quantification of ID-related proteins in primary cultured neonatal rat cardiomyocytes at different time point, adult and neonatal rat heart.

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    <p>(<b>A</b>) ID-related proteins were progressively changed their localization from the cells periphery to cell-cell contact sites. (<b>B</b>) ID-related proteins significantly increased at day 7 but slightly decreased (N-Cadherin, PKP2 and PG) or kept unchanged (Cx43) at day 14. **<i>p</i><0.01; *<i>p</i><0.05. (<b>C–D</b>) ID-related proteins accumulated in the contact sites of adjoining cells in neonatal and adult rat hearts. RC: rat cardiomyocytes; RH: rat heart.</p