RGD-functionalised melanin nanoparticles for intraoperative photoacoustic imaging-guided breast cancer surgery.

PURPOSE: Obtaining tumour-free margins is critical for avoiding re-excision and reducing local recurrence following breast-conserving surgery; however, it remains challenging. Imaging-guided surgery provides precise detection of residual lesions and assists surgical resection. Herein, we described water-soluble melanin nanoparticles (MNPs) conjugated with cyclic Arg-Gly-Asp (cRGD) peptides for breast cancer photoacoustic imaging (PAI) and surgical navigation. METHODS: The cRGD-MNPs were synthesised and characterized for morphology, photoacoustic characteristics and stability. Tumour targeting and toxicity of cRGD-MNPs were determined by using either breast cancer cells, MDA-MB-231 tumour-bearing mice or the FVB/N-Tg (MMTV-PyVT) 634Mul/J mice model. PAI was used to locate the tumour and guide surgical resection in MDA-MB-231 tumour-bearing mice. RESULTS: The cRGD-MNPs exhibited excellent in vitro and in vivo tumour targeting with low toxicity. Intravenous administration of cRGD-MNPs to MDA-MB-231 tumour-bearing mice showed an approximately 2.1-fold enhancement in photoacoustic (PA) intensity at 2 h, and the ratio of the PA intensity at the tumour site to that in the surrounding normal tissue was 3.2 ± 0.1, which was higher than that using MNPs (1.7 ± 0.3). Similarly, the PA signal in the spontaneous breast cancer increased ~ 2.5-fold at 2 h post-injection of cRGD-MNPs in MMTV-PyVT transgenic mice. Preoperative PAI assessed tumour volume and offered three-dimensional (3D) reconstruction images for accurate surgical planning. Surgical resection following real-time PAI showed high consistency with histopathological analysis. CONCLUSION: These results highlight that cRGD-MNP-mediated PAI provide a powerful tool for breast cancer imaging and precise tumour resection. cRGD-MNPs with fine PA properties have great potential for clinical translation.

Human Serum Albumin Decorated Indocyanine Green Improves Fluorescence-Guided Resection of Residual Lesions of Breast Cancer in Mice.

OBJECTIVE: Achieving negative resection margin is critical but challenging in breast-conserving surgery. Fluorescence-guided surgery allows the surgeon to visualize the tumor bed in real-time and to facilitate complete resection. We envisioned that intraoperative real-time fluorescence imaging with a human serum albumin decorated indocyanine green probe could enable complete surgical removal of breast cancer in a mouse model. METHODS: We prepared the probe by conjugating indocyanine green (ICG) with human serum albumin (HSA). In vitro uptake of the HSA-ICG probe was compared between human breast cancer cell line MDA-MB-231 and normal breast epithelial cell line MCF 10A. In vivo probe selectivity for tumors was examined in nude mice bearing MDA-MB-231-luc xenografts and the FVB/N-Tg (MMTV-PyMT) 634Mul/J mice model with spontaneous breast cancer. A positive-margin resection mice model bearing MDA-MB-231-luc xenograft was established and the performance of the probe in assisting surgical resection of residual lesions was examined. RESULTS: A significantly stronger fluorescence intensity was detected in MDA-MB-231 cells than MCF 10A cells incubated with HSA-ICG. In vivo fluorescence imaging showed that HSA-ICG had an obvious accumulation at tumor site at 24 h with tumor-to-normal tissue ratio of 8.19 ± 1.30. The same was true in the transgenic mice model. The fluorescence intensity of cancer tissues was higher than that of non-cancer tissues (58.53 ± 18.15 vs 32.88 ± 11.34). During the surgical scenarios, the residual tumors on the surgical bed were invisible with the naked eye, but were detected and resected with negative margin under HSA-ICG guidance in all the mice (8/8). Recurrence rate among mice that underwent resection with HSA-ICG (0/8) was significantly lower than the rates among mice with ICG (4/8), as well as the control group under white light (7/7). CONCLUSIONS: This study suggests that real-time in vivo visualization of breast cancer with an HSA-ICG fluorescent probe facilitates complete surgical resection of breast cancer in a mouse xenograft model.