Magnetic Nanoparticle-Embedded Hydrogel Sheet with a Groove Pattern for Wound Healing Application

Endothelial progenitor cells (EPCs) can induce a pro-angiogenic response during tissue repair. Recently, EPC transplantations have been widely investigated in wound healing applications. To maximize the healing efficacy by EPCs, a unique scaffold design that allows cell retention and function would be desirable for in situ delivery. Herein, we fabricated an alginate/poly-l-ornithine/gelatin (alginate-PLO-gelatin) hydrogel sheet with a groove pattern for use as a cell delivery platform. In addition, we demonstrate the topographical modification of the hydrogel sheet surface with a groove pattern to modulate cell proliferation, alignment, and elongation. We report that the patterned substrate prompted morphological changes of endothelial cells, increased cell–cell interaction, and resulted in the active secretion of growth factors such as PDGF-BB. Additionally, we incorporated magnetic nanoparticles (MNPs) into the patterned hydrogel sheet for the magnetic field-induced transfer of cell-seeded hydrogel sheets. As a result, enhanced wound healing was observed via efficient transplantation of the EPCs with an MNP-embedded patterned hydrogel sheet (MPS). Finally, enhanced vascularization and dermal wound repair were observed with EPC seeded MPS

CD31 aptamers interact with human EPCs.

<p>(A) Flow cytometry analysis of EPCs after individual incubation with various concentrations (0, 0.2, 2, 20, and 200 nM) of three CD31 aptamer clones (AT-1, AT-2, and AT-3, Cy5-labeled) is shown. (B) Flow cytometry analysis of EPCs after incubation with various concentrations (0, 0.2, 2, 20, and 200 nM) of control aptamers (FITC-labeled) is shown (n = 5).</p

CD31 aptamers specifically stain EPCs for visualization with fluorescence microscopy.

<p>(A) EPCs or 293FT cells were stained with CD31 antibodies (Alexa Fluor 488-labeled) and DAPI (blue). Images were taken by confocal microscope (Olympus FluoView FV1000). (B) EPCs or 293FT cells were stained with CD31 aptamers (AT-1, biotin-labeled, 400 nM) at 37°C for 1 h with or without 0.2 mM dextran sulfate, followed by staining with streptavidin-Alexa Fluor 488 and DAPI (blue). Images were taken by confocal microscope (Olympus FluoView FV1000). Scale bar = 40 μm (n = 3).</p

Dextran sulfate effectively reduces the non-specific interaction of CD31 aptamers.

<p>(A) 293FT cells were incubated with various concentrations (0, 0.2, 2, 20, and 200 nM) of CD31 aptamer clone 1 (AT-1, Cy5-labeled) or control aptamers (FITC-labeled) and subjected to flow cytometry analysis (n = 5). (B) EPCs or 293FT cells were separately incubated with control aptamers (Ctrl AT, FITC-labeled) or CD31 aptamers (AT-1, Cy5-labeled, 200 nM) with or without 0.2 mM dextran sulfate and subjected to flow cytometry. The overlap of histograms from 0 and 0.2 mM dextran sulfate experiments is shown (n = 5). (C) The mixture of EPCs and 293FT cells was incubated with CD31 aptamers (AT-1, Cy5-labeled, 200 nM) and various concentrations (0, 0.2, 1, and 5 mM) of dextran sulfate, followed by flow cytometry analysis (n = 3). (D) EPCs were incubated with CD31 antibodies (FITC-labeled) alone, CD31 aptamers alone (AT-1, Cy5-labeled, 200 nM), or with both CD31 antibodies and CD31 aptamers and subjected to flow cytometry analysis. Two-dimensional plots are shown (n = 5).</p