Treatment of natural mammary gland tumors in canines and felines using gold nanorods-assisted plasmonic photothermal therapy to induce tumor apoptosis

Abstract

Plasmonic photothermal therapy (PPTT) is a cancer therapy in which gold nanorods are injected at the site of a tumor before near-infrared light is transiently applied to the tumor causing localized cell death. Previously, PPTT studies have been carried out on xenograft mice models. Herein, we report a study showing the feasibility of PPTT as applied to natural tumors in the mammary glands of dogs and cats, which more realistically represent their human equivalents at the molecular level. We optimized a regime of three low PPTT doses at 2-week intervals that ablated tumors mainly via apoptosis in 13 natural mammary gland tumors from seven animals. Histopathology, X-ray, blood profiles, and comprehensive examinations were used for both the diagnosis and the evaluation of tumor statuses before and after treatment. Histopathology results showed an obvious reduction in the cancer grade shortly after the first treatment and a complete regression after the third treatment. Blood tests showed no obvious change in liver and kidney functions. Similarly, X-ray diffraction showed no metastasis after 1 year of treatment. In conclusion, our study suggests the feasibility of applying the gold nanorods-PPTT on natural tumors in dogs and cats without any relapse or toxicity effects after 1 year of treatment.

Keywords:

• gold nanorods
• natural mammary tumors
• plasmonic photothermal therapy
• canine
• feline

Supplementary materials

Figure S1 Modulation of PPTT toward inducing cancer cell apoptosis.

Notes: (A–D) Shows the MCF-7 cell apoptosis/necrosis states of the in vitro experiment. (A) Cells without AuNRs. (B) Cells incubated with AuNRs (no laser). (C) Cells incubated with AuNRs and 2 minutes laser irradiation. (D) Cells incubated with AuNRs and 5 minutes laser irradiation. (E) Laser irradiation spots of animals. The 5-minute irradiation caused burning of the tumor, whereas 2-minute irradiation shows no obvious change in appearance. The in vitro and in vivo experiments were conducted at the same condition.

Abbreviations: PPTT, plasmonic photothermal therapy; AuNRs, gold nanorods; ctrl, control.

Figure S2 Photographs complete for Case 7 (Tumor 6: caudo-inguinal opened tumor and Tumor 10: anterior thoracic tumors) showing tumor regression after each treatment.

Note: (A) Before treatment, (B) 2 weeks after the third treatment, and (C) 1 year after the third treatment.

Figure S3 Case 2 before treatment.

Notes: (A) The X-ray shows there is no metastasis in the internal organs. (B) Ultrasound shows the tumor location, shape, and dimensions.

Figure S4 Photographs for Case 2 (Tumor 4: left caudothoracic mammary gland and Tumor 9: right abdominal mammary gland) showing the tumor regression 2 weeks after first treatment (A) and 1 year after the third treatment (B).

Figure S5 Photographs for case 3 (Tumor 2: left caudothoracic mammary gland and Tumor 13: right abdominal mammary gland) showing the tumor regression after each treatment.

Note: (A) Before treatment, (B) 2 weeks after the third treatment, and (C) 1 year after the third treatment.

Figure S6 Histopathology images (stained with H&E [×400]) for Case 3.

Notes: (A) Well-differentiated tubular adenocarcinoma before treatment. Carcinoma arranged in tubular pattern. Mass characterized by an intra-acinar deeply basophilic secretion and corpora amylecea. Connective tissue stroma infiltrated with mononuclear cells (tumor Grade III). (B) 2 weeks after the third treatment, there was absence of epithelial lining of acini and absence of acini and basement membrane. Also, loss of acinar pattern proliferation of fibrous connective stroma was seen (tumor Grade 0). Magnification of histopathology images stained with H&E: (A) ×200; (B) ×100.

Abbreviation: H&E, hematoxylin and eosin.

Figure S7 X-ray lateral exposure for Case 3 after treatment.

Note: (A) 2 weeks after third treatment, (B) 1 year after third treatment, showing there is no metastasis.

Acknowledgments

We thank Yue Wu (El-Sayed lab, Georgia Tech) for her advice and critical proofreading. We also thank Dr Haithem Farghali and Prof Ahmed Osman (Veterinary Medicine, Cairo University) for their help in collecting the samples and analyzing the histopathology data. We are grateful to Robert Rankin (UCLA), Nicholas Kovacs (Georgia Tech), Rajiv Jaini (Georgia Tech), and the undergraduate research assistants Savita Chapman, Tsion Assaye, Cecily Ritch, and Hannah Orr for their critical reading of the manuscript. We also thank Prof Mahmoud Sakr and Prof Mahmoud Zawra for the Joint Collaborative Efforts of Egyptian Expatriates and Scientific Organizations Towards Tackling National R&D Challenges (JESOR) for funding this research.

Disclosure

The authors report no conflicts of interest in this work.