Research ArticleHEALTH AND MEDICINE

An innovative biologic system for photon-powered myocardium in the ischemic heart

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Science Advances  14 Jun 2017:
Vol. 3, no. 6, e1603078
DOI: 10.1126/sciadv.1603078
  • Fig. 1 S. elongatus successfully cocultured with rat cardiomyocytes.

    (A) False-colored scanning electron micrograph of multiple S. elongatus cyanobacteria (green) with a single rat cardiomyocyte (red). (B and C) Representative images of a live/dead assay of cardiomyocytes alone (B) and cardiomyocytes cocultured with S. elongatus (C). The cytoplasm of live cells is stained green, and the nuclei of dead cells are stained red; the autofluorescent rod-shaped S. elongatus are distinct from the circular dead nuclei. (D) Results of the live/dead assay demonstrating that the presence of S. elongatus does not affect cardiomyocyte survival. (E) In vitro oxygen measurements of cardiomyocytes alone, S. elongatus alone, and cardiomyocytes cocultured with S. elongatus under light and dark conditions in normoxia. In cultures containing S. elongatus alone and S. elongatus with cardiomyocytes, oxygen tension was significantly higher in the presence of light (P < 0.01 and P = 0.03, respectively), suggesting active photosynthesis. Cardiomyocytes cocultured with S. elongatus in the light demonstrated a positive trend toward increased oxygen when compared to cardiomyocytes alone (P = 0.1). When compared to cultures with S. elongatus alone, cultures with cardiomyocytes and S. elongatus demonstrated significantly reduced oxygen in light and dark (P = 0.01 and P < 0.01, respectively), suggesting oxygen consumption by cardiomyocytes. (F) Cellular viability was assessed using a WST-1 cell proliferation assay. Cardiomyocytes cultured with S. elongatus demonstrated significantly enhanced cellular metabolism in the presence of light as compared to dark (P < 0.01). All data are reported as means ± SEM. *P < 0.05 using two-tailed unpaired Student’s t test.

  • Fig. 2 Enhancement of oxygenation, metabolism, and cardiac function in acute ischemia.

    Animals were randomized to receive saline control (n = 5), S. elongatus therapy in light (n = 5), and S. elongatus therapy in dark (n = 5). (A) Phosphorescent probe technology was used to quantify tissue oxygenation at baseline, time of ischemia, and 10 and 20 min after therapy. Oxygen tension was significantly higher in the S. elongatus (light)–treated group compared with controls and S. elongatus (dark) groups at 10 (group-time interaction, P = 0.004) and 20 (group-time interaction, P = 0.003) min after injection. (B) Compared with the control and S. elongatus (dark) groups, the S. elongatus (light)–treated group showed significantly elevated levels of tissue oxygenation at 10 (P = 0.002) and 20 (P = 0.004) min after injection with an almost 25-fold increase relative to the time of ischemia. (C) Thermal imaging was used to quantify epicardial surface temperature as a measure of myocardial energetics. S. elongatus–treated animals demonstrated significantly increased surface temperature at 20 min after therapy (P = 0.04) with a positive trajectory. (D) Representative thermal images. (E and F) Pressure-volume assessment revealed significantly enhanced maximum LV pressure (E) (P = 0.04) and dP/dt (F) (P = 0.02) at 45 min after therapy. (G) An ascending aortic flow probe was used to measure CO. At 45 min after therapy, CO in the S. elongatus (light) group was significantly higher than the control group and S. elongatus (dark) group (group-time interaction, P = 0.05). All data are reported as means ± SEM. *P < 0.05 using a repeated-measures analysis of variance (ANOVA) for (A), (B), and (G) and two-tailed unpaired Student’s t test for (C), (E), and (F).

  • Fig. 3 Long-term protective and functional benefit of photosynthetic therapy.

    Animals underwent myocardial IR injury and were randomized to saline control (n = 7), S. elongatus therapy (n = 10), or sham surgery (n = 7). (A) Serum troponin at 24 hours after injury was substantially reduced in the S. elongatus group compared with saline controls (P = 0.05), indicating ameliorated myocardial injury. (B) LV ejection fraction was increased in the S. elongatus group (P = 0.02) determined by cardiac MRI. (C) End-systolic volume was decreased in the S. elongatus–treated animals (P = 0.03), illustrating reduced pathologic remodeling. (D and E) Representative four-chamber cardiac MRI images. (F to H) S. elongatus therapy resulted in a greater slope of the LV pressure-volume relationship during inferior vena cava occlusion (P = 0.01), indicating enhanced ventricular contractility. All data reported as means ± SEM. *P < 0.05 using two-tailed unpaired Student’s t test.

  • Fig. 4 S. elongatus therapy does not elicit a pathologic immune response nor persist in tissue long-term.

    (A) Flow cytometry of blood at 0, 16, 40, and 88 hours after intravenous administration of saline (n = 4) or S. elongatus (n = 4), demonstrating no difference in CD8+ T cell and CD19+ B cell frequencies. PE, phycoerythrin; FITC, fluorescein isothiocyanate. (B) No differences in peripheral CD4+ T cell frequencies at 0, 1, 2, and 7 days were observed (means ± SD). (C and D) Immunohistochemistry of heart sections at 1 hour after injection (C) and 24 hours after injection (D), demonstrating marked reduction of S. elongatus present in the tissue. (E) Representative hematoxylin and eosin–stained heart section revealing no abscess at 4 weeks after therapy. (F and G) Immunohistochemistry of heart sections at 4 weeks, illustrating no evidence of retained S. elongatus. All data reported as means ± SEM. DAPI, 4′,6-diamidino-2-phenylindole.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/6/e1603078/DC1

    fig. S1. High-resolution grayscale scanning electron micrograph before false coloring.

    fig. S2. High-resolution false-colored scanning electron micrograph.

    fig. S3. In vivo rodent model of acute myocardial infarction.

    table S1. Effect of S. elongatus therapy on myocardial oxygenation in acute ischemia model.

    table S2. Effect of S. elongatus therapy on myocardial surface temperature in acute ischemia model.

    table S3. Effect of S. elongatus therapy on LV hemodynamics in acute ischemia model.

    table S4. Effect of S. elongatus therapy on CO in acute ischemia model.

    table S5. Long-term effect of S. elongatus therapy on LV function in IR model.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. High-resolution grayscale scanning electron micrograph before false coloring.
    • fig. S2. High-resolution false-colored scanning electron micrograph.
    • fig. S3. In vivo rodent model of acute myocardial infarction.
    • table S1. Effect of S. elongatus therapy on myocardial oxygenation in acute ischemia model.
    • table S2. Effect of S. elongatus therapy on myocardial surface temperature in acute ischemia model.
    • table S3. Effect of S. elongatus therapy on LV hemodynamics in acute ischemia model.
    • table S4. Effect of S. elongatus therapy on CO in acute ischemia model.
    • table S5. Long-term effect of S. elongatus therapy on LV function in IR model.

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