Near Infrared Fluorescence Imaging of Intraperitoneal Ovarian Tumors in Mice Using Erythrocyte-Derived Optical Nanoparticles and Spatially-Modulated Illumination

Erythrocyte nano-ghosts with dual optical and magnetic resonance characteristics

Significance

Fluorescent organic dyes provide imaging capabilities at cellular and sub-cellular levels. However, a common problem associated with some of the existing dyes such as the US FDA-approved indocyanine green (ICG) is their weak fluorescence emission. Alternative dyes with greater emission characteristics would be useful in various imaging applications. Complementing optical imaging, magnetic resonance (MR) imaging enables deep tissue imaging. Nano-sized delivery systems containing dyes with greater fluorescence emission as well as MR contrast agents present a promising dual-mode platform with high optical sensitivity and deep tissue imaging for image-guided surgical applications.

Aim

We have engineered a nano-sized platform, derived from erythrocyte ghosts (EGs), with dual near-infrared fluorescence and MR characteristics by co-encapsulation of a brominated carbocyanine dye and gadobenate dimeglumine (Gd-BOPTA).

Approach

We have investigated the use of three brominated carbocyanine dyes (referred to as BrCy106, BrCy111, and BrCy112) with various degrees of bromination, structural symmetry, and acidic modifications for encapsulation by nano-sized EGs (nEGs) and compared their resulting optical characteristics with nEGs containing ICG.

Results

We find that asymmetric dyes (BrCy106 and BrCy112) with one dibromobenzene ring offer greater fluorescence emission characteristics. For example, the relative fluorescence quantum yield ( ϕ ) for nEGs fabricated using 100    μ M of BrCy112 is ∼ 41 -fold higher than nEGs fabricated using the same concentrations of ICG. The dual-mode nEGs containing BrCy112 and Gd-BOPTA show a nearly twofold increase in their ϕ as compared with their single optical mode counterpart. Cytotoxicity is not observed upon incubation of SKOV3 cells with nEGs containing BrCy112.

Conclusions

Erythrocyte nano-ghosts with dual optical and MR characteristics may ultimately prove useful in various biomedical imaging applications such as image-guided tumor surgery where MR imaging can be used for tumor staging and mapping, and fluorescence imaging can help visualize small tumor nodules for resection.

New insights into red blood cells in tumor precision diagnosis and treatment

Red blood cells (RBCs), which function as material transporters in organisms, are rich in materials that are exchanged with metabolically active tumor cells. Recent studies have demonstrated that tumor cells can regulate biological changes in RBCs, including influencing differentiation, maturation, and morphology. RBCs play an important role in tumor development and immune regulation. Notably, the novel scientific finding that RBCs absorb fragments of tumor-carrying DNA overturns the conventional wisdom that RBCs do not contain nucleic acids. RBC membranes are excellent biomimetic materials with significant advantages in terms of their biocompatibility, non-immunogenicity, non-specific adsorption resistance, and biodegradability. Therefore, RBCs provide a new research perspective for the development of tumor liquid biopsies, molecular imaging, drug delivery, and other tumor precision diagnosis and treatment technologies.

Cell-nanocarrier drug delivery system: a promising strategy for cancer therapy

Tumor targeting has been a great challenge for drug delivery systems. A number of nanotechnology-derived drug carriers have been developed for cancer treatment to improve efficacy and biocompatibility. Among them, the emergence of cell-nanocarriers has attracted great attention, which simulates cell function and has good biocompatibility. They can also escape the clearance of reticuloendothelial system, showing a long-cycle effect. The inherent tumor migration and tumor homing ability of cells increase their significance as tumor-targeting vectors. In this review, we focus on the combination of stem cells, immune cells, red blood cells, and cell membranes to nanocarriers, which enable chemotherapy agents to efficiently target lesion sites and improve drug distribution while being low toxic and safe. In addition, we discuss the pros and cons of these nanoparticles as well as the challenges and opportunities that lie ahead. Although research to address these limitations is still ongoing, this promising tumor-targeted drug delivery system will provide a safe and effective platform against cancer.

Membrane cholesterol enrichment and folic acid functionalization lead to increased accumulation of erythrocyte-derived optical nano-constructs within the ovarian intraperitoneal tumor implants in mice

Cytoreductive surgery remains as the gold standard to treat ovarian cancer, but with limited efficacy since not all tumors can be intraoperatively visualized for resection. We have engineered erythrocyte-derived nano-constructs that encapsulate the near infrared (NIR) fluorophore, indocyanine green (ICG), as optical probes for NIR fluorescence imaging of ovarian tumors. Herein, we have enriched the membrane of these nano-constructs with cholesterol, and functionalized their surface with folic acid (FA) to target the folate receptor-α. Using a mouse model, we show that the average fraction of the injected dose per tumor mass for nano-constructs with both membrane cholesterol enrichment and FA functionalization was ~ sixfold higher than non-encapsulated ICG, ~ twofold higher than nano-constructs enriched with cholesterol alone, and 33 % higher than nano-constructs with only FA functionalization at 24-h post-injection. These results suggest that erythrocyte-derived nano-constructs containing both cholesterol and FA present a platform for improved fluorescence imaging of ovarian tumors.

Preclinical Activity of Two Paclitaxel Nanoparticle Formulations After Intraperitoneal Administration in Ovarian Cancer Murine Xenografts

Background

Epithelial ovarian cancer is associated with high mortality due to diagnosis at later stages associated with peritoneal involvement. Several trials have evaluated the effect of intraperitoneal treatment. In this preclinical study, we report the efficacy, pharmacokinetics and pharmacodynamics of intraperitoneal treatment with two approved nanomolecular formulations of paclitaxel (nab-PTX and mic-PTX) in a murine ovarian cancer xenograft model.

Methods

IC50 was determined in vitro on three ovarian cancer cell lines (OVCAR-3, SK-OV-3 and SK-OV-3-Luc IP1). EOC xenografts were achieved using a modified subperitoneal implantation technique. Drug treatment was initiated 2 weeks after engraftment, and tumor volume and survival were assessed. Pharmacokinetics and drug distribution effects were assessed using UHPLC-MS/MS and MALDI imaging mass spectrometry, respectively. Pharmacodynamic effects were analyzed using immunohistochemistry and transmission electron microscopy using standard protocols.

Results

We demonstrated sub-micromolar IC50 concentrations for both formulations on three EOC cancer cell lines in vitro. Furthermore, IP administration of nab-PTX or mic-PTX lead to more than 2-fold longer survival compared to a control treatment of IP saline administration (30 days in controls, 66 days in nab-PTX treated animals, and 76 days in mic-PTX animals, respectively). We observed higher tissue uptake of drug following nab-PTX administration when compared to mic-PTX, with highest uptake after 4 hours post-treatment, and confirmed this lower uptake of mic-PTX using HPLC on digested tumor samples. Furthermore, apoptosis was not increased in tumor implants up to 24h post-treatment.

Conclusion

Intraperitoneal administration of both nab-PTX and mic-PTX results in a significant anticancer efficacy and survival benefit in a mouse OC xenograft model.

The Application of Nanoparticle-Based Imaging and Phototherapy for Female Reproductive Organs Diseases

Various female reproductive disorders affect millions of women worldwide and bring many troubles to women's daily life. Let alone, gynecological cancer (such as ovarian cancer and cervical cancer) is a severe threat to most women's lives. Endometriosis, pelvic inflammatory disease, and other chronic diseases-induced pain have significantly harmed women's physical and mental health. Despite recent advances in the female reproductive field, the existing challenges are still enormous such as personalization of disease, difficulty in diagnosing early cancers, antibiotic resistance in infectious diseases, etc. To confront such challenges, nanoparticle-based imaging tools and phototherapies that offer minimally invasive detection and treatment of reproductive tract-associated pathologies are indispensable and innovative. Of late, several clinical trials have also been conducted using nanoparticles for the early detection of female reproductive tract infections and cancers, targeted drug delivery, and cellular therapeutics. However, these nanoparticle trials are still nascent due to the body's delicate and complex female reproductive system. The present review comprehensively focuses on emerging nanoparticle-based imaging and phototherapies applications, which hold enormous promise for improved early diagnosis and effective treatments of various female reproductive organ diseases.

Design of erythrocyte-derived carriers for bioimaging applications

Erythrocytes are physiological entities that have been exploited in both preclinical and clinical trials for the delivery of exogenous agents. Over the years, diverse erythrocyte-derived carriers (ECs) have been developed with related patents granted for industrial and commercial purposes. However, most ECs have only been exploited for drug delivery. Serious discussions regarding their applications in imaging are scarce. This article reviews the role of ECs in enhancing imaging efficiency and subsequently delineates strategies for engineering and optimising their preclinical and clinical performance. With a snapshot of the latest developments and use of ECs in imaging, directions to streamline the clinical translation of related technologies can be attained for future research.

An Acid Response IR780-Based Targeted Nanoparticle for Intraoperative Near-Infrared Fluorescence Imaging of Ovarian Cancer

INTRODUCTION

Complete resection of all visible disease (R0 resection) is critical for the treatment of ovarian cancer patients, and accurate real-time guidance provided by intraoperative near-infrared (NIR) fluorescence images is beneficial for achieving complete resection of all visible disease.

METHODS

Based on the optical properties of IR780 and the characteristics of the acidic tumor microenvironment, we develop a new smart nanoparticle (eg, FA-IR780&PFOB-SNPs) by using the pH response nano framework (FA-PEG-PLGA-PEOz) and adjusting the amount of IR780. The FA-IR780&PFOB-SNPs was characterized for morphology, microstructure, particle size, pH-response, drug-loading efficiency and biological safety. The ultraclear fluorescence Navigation Endoscopy System was applied to evaluate the tumor recognition of FA-IR780&PFOB-SNPs in vivo.

RESULTS

The structure of FA-IR780&PFOB-SNPs was stable in a neutral environment, and the near-infrared (NIR) fluorescence was turned off, while the structure of FA-IR780&PFOB-SNPs was degraded in the acidic tumour microenvironment, and the NIR fluorescence was turned on. Through the ovarian subcutaneous xenograft tumour and ovarian intraperitoneal xenograft tumour models, it was confirmed that FA-IR780&PFOB-SNPs could clearly display the boundaries of abdominal micron-sized tumours through near-infrared fluorescence imaging, with a TBR greater than 5.

CONCLUSION

The FA-IR780&PFOB-SNPs have the potential to provide to ovarian cancer intraoperative near infrared fluorescence navigation during precision tumour resection to achieve R0 and improve the prognosis of ovarian cancer patients.

Membrane Cholesterol Enrichment of Red Blood Cell-Derived Microparticles Results in Prolonged Circulation

Particles fabricated from red blood cells (RBCs) can serve as vehicles for delivery of various biomedical cargos. Flipping of phosphatidylserine (PS) from the inner to the outer membrane leaflet normally occurs during the fabrication of such particles. PS externalization is a signal for phagocytic removal of the particles from circulation. Herein, we demonstrate that membrane cholesterol enrichment can mitigate the outward display of PS on microparticles engineered from RBCs. Our in-vitro results show that the phagocytic uptake of cholesterol-enriched particles by murine macrophages takes place at a lowered rate, resulting in reduced uptake as compared to RBC-derived particles without cholesterol enrichment. When administered via tail-vein injection into healthy mice, the percent of injected dose (ID) per gram of extracted blood for cholesterol-enriched particles was ∼1.5 and 1.8 times higher than the particles without cholesterol enrichment at 4 and 24 h, respectively. At 24 h, ∼43% ID/g of the particles without cholesterol enrichment was eliminated or metabolized while ∼94% ID/g of the cholesterol-enriched particles were still retained in the body. These results indicate that membrane cholesterol enrichment is an effective method to reduce PS externalization on the surface of RBC-derived particles and increase their longevity in circulation.

Cell Membrane-Cloaked Nanotherapeutics for Targeted Drug Delivery

Cell membrane cloaking technique is bioinspired nanotechnology that takes advantage of naturally derived design cues for surface modification of nanoparticles. Unlike modification with synthetic materials, cell membranes can replicate complex physicochemical properties and biomimetic functions of the parent cell source. This technique indeed has the potential to greatly augment existing nanotherapeutic platforms. Here, we provide a comprehensive overview of engineered cell membrane-based nanotherapeutics for targeted drug delivery and biomedical applications and discuss the challenges and opportunities of cell membrane cloaking techniques for clinical translation.