Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Mar 24:8:237.
doi: 10.3389/fbioe.2020.00237. eCollection 2020.

Cyanobacteria-Based Bio-Oxygen Pump Promoting Hypoxia-Resistant Photodynamic Therapy

Tao Sun  1   2 , Yingying Zhang  3 , Chaonan Zhang  3 , Hanjie Wang  3 , Huizhuo Pan  3 , Jing Liu  3 , Zhixiang Li  2   4   5 , Lei Chen  2   4   5 , Jin Chang  3 , Weiwen Zhang  1   2   4   5
Affiliations

Cyanobacteria-Based Bio-Oxygen Pump Promoting Hypoxia-Resistant Photodynamic Therapy

Tao Sun et al. Front Bioeng Biotechnol. .

Abstract

Hypoxia not only alters tumor microenvironment but leads to the tumor progression and metastasis as well as drug resistance. As a promising strategy, photodynamic therapy (PDT) can inhibit tumor by catalyzing O2 to cytotoxic reactive oxygen species. However, its effects were limited by hypoxia and in turn deteriorate hypoxia due to O2 consumption. Hereon, aiming to alleviate hypoxia and promote PDT, a bio-oxygen pump was created based on cyanobacteria, which are the only prokaryotic organisms performing oxygenic photosynthesis. Detailly, controlled-release PDT via loading indocyanine green into mesoporous silica nanoparticles was established. Then bio-oxygen pump based on a fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 was tested and further packaged together with PDT to create an injectable hydrogel. The packaged hydrogel showed stable oxygen production and synergetic therapy effect especially toward hypoxia 4T1 cells in vitro. More importantly, strong in vivo therapeutic effect reaching almost 100% inhibition on tumor tissues was realized using PDT equipped with oxygen pump, with only negligible in vivo side effect on healthy mice from S. elongatus UTEX 2973. The new photo-oxygen-dynamic therapy presented here provided a promising strategy against hypoxia-resistant tumor and may worth further modifications for therapeutic application.

Keywords: hypoxia; indocyanine green; injectable hydrogels; nanoparticles; oxygenic cyanobacteria; photodynamic therapy.

PubMed Disclaimer

Figures

FIGURE 1
FIGURE 1
Schematic illustration of the photo-oxygen-dynamic therapy. (A) S. 2973 and MSN loaded with photosensitizer ICG were mixed with sodium alginate to make injectable hydrogels (ALG-MI-S2973). (B) The hydrogels ALG-MI-S2973 was intratumorally injected and then formed gels at the tumor site. The tumor tissue was exposed to 640 nm laser to support survival of S. 2973 to generate O2, which alleviated the hypoxia microenvironment and further enhanced PDT effects. After releasing, ICG excited by 808 nm laser could exert efficient PDT effects to inhibit tumor growth. MSN, mesoporous silica nanoparticles; ICG, indocyanine green; ALG, hydrogels based on sodium alginate; MI, ICG-loaded MSN; ALG-MI-S2973, hydrogels packaging MSN-ICG and S. 2973.
FIGURE 2
FIGURE 2
The preparation and characterization of MSN-ICG. (A) The preparation process of MSN-ICG. (B) TEM images of MSN before and after ICG loading. (C,D) Live/dead staining and cell apoptosis analysis of 4T1 cells treated with control, ICG or MSN-ICG with or without 808 nm laser irradiation under normoxic or hypoxic condition. (E) Measurements of hypoxia and ROS for 4T1 cells treated with control, ICG or MSN-ICG with 808 nm laser irradiation under normoxia. * p < 0.05, ** p < 0.01 compared with control group by Student’s t-test. MSN-ICG, indocyanine green-loaded mesoporous silica nanoparticles.
FIGURE 3
FIGURE 3
Construction and characterization of the bio-oxygen pump in vitro. (A) Scheme of oxygen generation system based on S. 2973 under 640 nm red laser irradiation. (B) Absorption spectrum and OD750 nm of S. 2973 irradiated using 640 nm laser with different intensities. (C) Absorption spectrum and OD750 nm of S. 2973 irradiated using 640 nm laser with 0.25 W/cm2 for different times. (D) Oxygen evolution of S. 2973 under 640 nm red laser irradiation. (E) Cell viability and AM/PI staining of 4T1 cells with or without treatments (i.e., 640 nm laser irradiation, co-cultivation with S. 2973 or both of them) for 24 h. (F) Phenotypes of S. 2973 treated with different concentrations of ICG exposed to 2 W/cm2 of 808 nm laser for 5 min.
FIGURE 4
FIGURE 4
Construction and characterization of injectable hydrogels packing MSN-ICG and/or S. 2973. (A) The preparation of injectable hydrogels packing MSN-ICG and S. 2973 (i.e., ALG-MI-S2973). (B) Growth investigation of S. 2973 directly in BG11 or packaged in ALG-MI-S2973 cultivated under normal or 640 nm irradiation. (C) The ROS generation in 4T1 cells after treatment of ALG-MI-S2973 with different amounts of S. 2973. (D,E) AM/PI staining and cell apoptosis analysis of 4T1 cells treated with or without ALG-MI-S2973 under control, 808 nm irradiation or both 640 and 808 nm irradiation. (F) Measurements of hypoxia and ROS of normoxia 4T1 cells treated with or without ALG-MI-S2973 under control, 808 nm irradiation or both 640 and 808 nm irradiation. * p < 0.05, ** p < 0.01 compared with untreated group by Student’s t-test. MSN-ICG, indocyanine green-loaded mesoporous silica nanoparticles; ALG-MI-S2973, hydrogels packaging MSN-ICG and S. 2973.
FIGURE 5
FIGURE 5
The in vivo long-toxicity evaluation of S. 2973 and ALG-S2973. Each group contained three mice. (A) The schedule of animal experiments for toxicity evaluation. (B) Photos of the injection site of BALB/c mice. (C) Detection of immune factors of mice with different treatments at the 1st, 4th, and 7th day. (D) Hematological index of the mice with different treatments at the 1st, 7th, and 21st day. * p < 0.05, ** p < 0.01 compared with untreated group by Student’s t-test. ALG-S2973, hydrogels packaging S. 2973.
FIGURE 6
FIGURE 6
In vivo investigation of anti-tumor effects based on ALG-MI-S2973. Each group contained five mice. (A) Schematic diagram of animal experiments. (B) Viability measurement of S. 2973 in tumor sections using fluorescence imaging excited by 561 nm. (C,D) Body weight changes and tumor growth curves of control and 4T1 tumor-bearing mice with different treatments. ** p < 0.01 compared with untreated group by Student’s t-test. (E,F) Volumes and weight of tumors from 4T1 tumor-bearing mice with different treatments; (G) Tumor inhibition rates of different treatments. (H) H&E, TUNEL and immunohistochemical staining of HIF-1α protein in tumor tissues from 4T1 tumor-bearing mice with different treatments. ALG-MI, hydrogels packaging MSN-ICG; ALG-MI-S2973, hydrogels packaging MSN-ICG and S. 2973.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Bradley E. C., Barr J. W. (1968). Determination of blood volume using indocyanine green (cardio-green) dye. Life Sci. 7 1001–1007. 10.1016/0024-3205(68)90108-90102 - DOI - PubMed
    1. Bray F., Ferlay J., Soerjomataram I., Siegel R. L., Torre L. A., Jemal A. (2018). Global cancer statistics 2018: globocan estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J. Clin. 68 394–424. 10.3322/caac.21492 - DOI - PubMed
    1. Cohen J. E., Goldstone A. B., Paulsen M. J., Shudo Y., Steele A. N., Edwards B. B., et al. (2017). An innovative biologic system for photon-powered myocardium in the ischemic heart. Sci. Adv. 3:e1603078. 10.1126/sciadv.1603078 - DOI - PMC - PubMed
    1. Desterro J., Bak-Gordon P., Carmo-Fonseca M. (2019). Targeting mRNA processing as an anticancer strategy. Nat. Rev. Drug Discov. 19 112–129. 10.1038/s41573-019-0042-43 - DOI - PubMed
    1. Dolmans D. E., Fukumura D., Jain R. K. (2003). Photodynamic therapy for cancer. Nat. Rev. Cancer 3 380–387. 10.1038/nrc1071 - DOI - PubMed