In vivo distribution of (131)I and (125)I dual-labeled gelatin microspheres after implantation into rabbit liver

131I-Labeled Silk Fibroin Microspheres for Radioembolic Therapy of Rat Hepatocellular Carcinoma

Transarterial radioembolization (TARE) is a promising technology in hepatocellular carcinoma (HCC) therapy, which utilizes radionuclide-labeled microspheres to achieve arterial embolization and internal irradiation. However, the therapeutic effect of liver cancer can be affected by low radionuclide labeling rate and stability, as well as poor biocompatibility, and non-biodegradability of microspheres. Here, ¹³¹I-labeled silk fibroin microspheres (¹³¹I-SFMs) were developed as radioembolization material for effective TARE therapy against HCC. Silk fibroin rich in 10.03% of tyrosine was extracted from silkworm cocoons and then emulsified and genipin-crosslinked to prepare SFMs. SFMs show a good settlement rate, biodegradability, hemocompatibility, and low cytotoxicity. Afterward, ¹³¹I-SFMs were obtained by radiolabeling ¹³¹I onto the SFMs through the chloramine-T method. ¹³¹I-SFMs possess a high ¹³¹I labeling rate of over 84% and good radioactive stability and are thus conducive to internal radiotherapy. Significantly, ¹³¹I-SFMs with diameters around 11 μm were successfully radioembolized at the hepatic artery. ¹³¹I-SFMs were diffused in the liver, indicating the favorable biodistribution and biosafety in vivo. Based on the combination of embolization and local radiotherapy, the administration of ¹³¹I-SFMs shows a favorable inhibitive effect against the progression of HCC. Overall, the newly developed ¹³¹I-SFMs as radioembolization microspheres provide a promising application for effective TARE therapy against liver cancer.

Transarterial Radioembolization Agents: a Review of the Radionuclide Agents and the Carriers

Liver tumors, both primary and secondary to metastatic disease, remain a major challenge, with an increasing incidence. In this context, taking advantage of the dual blood supply of the liver, and the fact that liver tumors derive majority of their blood supply from the hepatic artery, intraarterial therapies are gaining popularity. Intraarterial liver-directed therapy (IALDT) is the option when the surgery is not feasible due to the number of metastases or for other reasons. Transarterial radioembolization (TARE) is a specific type of IALDT, where a carrier particle/microsphere is labeled with a radioactive substance and then is injected into hepatic artery for therapeutic purposes. As this field is rapidly evolving, with multiple agents being investigated and being introduced into clinical practice, it is hard for the practitioners and researchers to encompass all the available information concisely. This article aims to present a comprehensive review of the prominent TARE technologies.

131Iodine-DEM TACE vs. conventional TACE in cirrhotic patients with hepatocellular carcinoma: a single center experiment

Background

To evaluate the safety and efficacy of transcatheter arterial chemoembolization (TACE) with ¹³¹iodine-doxorubicin-eluting gelatin microspheres (¹³¹I-DEM TACE) compared with conventional TACE (cTACE) with polyvinyl alcohol foam (PVA) embolization microspheres.

Methods

A total of 22 patients diagnosed with hepatocellular carcinoma were equally divided into 2 groups. The patients who underwent TACE with ¹³¹I-DEM (25.7×10⁷ Bq of 131iodine and 10 mg of doxorubicin) were compared to controls who received cTACE with PVA embolization microspheres. Therapeutic effects were evaluated by the tumor regression rates, levels of alpha-fetoprotein in serum, survival rates, and complications.

Results

The operative complications of the 2 groups were not significantly different (P=0.753). The radioactivity ratio of the tumor to the liver was approximately 4.1:1 for the ¹³¹I-DEM TACE group. In the ¹³¹I-DEM TACE group, 54.5% of patients achieved tumor regression of more than 50%, compared to 36.6% of patients in the cTACE group. AFP levels in serum declined in 100% of patients in the ¹³¹I-DEM TACE group and 50% of patients in the cTACE group. The median survival time of the patients was 12.0±3.3 months for the ¹³¹I-DEM TACE group and 10.0±3.3 months for the cTACE group. There were no significant differences in survival between the 2 groups (P=0.414).

Conclusions

¹³¹I-DEM may become a potential radiochemoembolization agent to treat patients with unresectable hepatocellular carcinoma through TACE.

Progress of gelatin-based microspheres (GMSs) as delivery vehicles of drug and cell

Gelatin has various attractive features as biomedical materials, for instance, biocompatibility, low immunogenicity, biodegradability, and ease of manipulation. In recent years, various gelatin-based microspheres (GMSs) have been fabricated with innovative technologies to serve as sustained delivery vehicles of drugs and genetic materials as well as beneficial bacteria. Moreover, GMSs have exhibited promising potentials to act as both cell carriers and 3D scaffold components in tissue engineering and regenerative medicine, which not only exhibit excellent injectability but also could be integrated into a macroscale construct with the laden cells. Herein, we aim to thoroughly summarize the recent progress in the preparations and biomedical applications of GMSs and then to point out the research direction in future. First, various methods for the fabrication of GMSs will be described. Second, the recent use of GMSs in tumor embolization and in the delivery of cells, drugs, and genetic material as well as bacteria will be presented. Finally, several key factors that may enhance the improvement of GMSs were suggested as delivery vehicles.

Biodegradable 131 Iodine-Labeled Microspheres: Potential Transarterial Radioembolization Biomaterial for Primary Hepatocellular Carcinoma Treatment

Transarterial radioembolization with radionuclide-labeled microspheres is successfully used in hepatocellular carcinoma (HCC) treatment, but the non-biodegradability and rapid settlement of the microsphere material are associated with unsatisfied distribution and unable for multiple administrations. In this study, a novel biodegradable chitosan-collagen composite microsphere (CCM) with ideal settlement rate is prepared. The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) results indicate CCMs have desirable shapes with diameters around 10 µm, and considerable biodegradability within 12 weeks. These CCMs are successfully radiolabeled with ¹³¹ I and processed efficiency of 70.4 MBq mg^-1 of microspheres as well as favorable stability in vitro. Then, ¹³¹ I-CCMs are injected into rats with orthotopic HCC via the hepatic artery which effectively improves the median overall survival from 19 to 44 days (p < 0.05). Single photon emission computed tomography (SPECT/CT) imaging and immunohistochemical analysis indicate well-localized biodistribution and consistent stability of ¹³¹ I-CCMs in the liver over 28 days. Magnetic resonance imaging (MRI) and gross specimens monitoring confirm the inhibited tumor growth after ¹³¹ I-CCMs treatment. In conclusion, these biodegradable ¹³¹ I-CCMs exhibit optimal radiolabeling efficiency, stability, and favorably radioembolization effect for orthotopic HCC in a rodent model, suggesting potential for interventional cancer therapy.

Radiolabelled Polymeric Materials for Imaging and Treatment of Cancer: Quo Vadis?

Owing to their tunable blood circulation time and suitable plasma stability, polymer-based nanomaterials hold a great potential for designing and utilising multifunctional nanocarriers for efficient imaging and effective treatment of cancer. When tagged with appropriate radionuclides, they may allow for specific detection (diagnosis) as well as the destruction of tumours (therapy) or even customization of materials, aiming to both diagnosis and therapy (theranostic approach). This review provides an overview of recent developments of radiolabelled polymeric nanomaterials (natural and synthetic polymers) for molecular imaging of cancer, specifically, applying nuclear techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Different approaches to radiolabel polymers are evaluated from the methodical radiochemical point of view. This includes new bifunctional chelating agents (BFCAs) for radiometals as well as novel labelling methods. Special emphasis is given to eligible strategies employed to evade the mononuclear phagocytic system (MPS) in view of efficient targeting. The discussion encompasses promising strategies currently employed as well as emerging possibilities in radionuclide-based cancer therapy. Key issues involved in the clinical translation of radiolabelled polymers and future scopes of this intriguing research field are also discussed.

Interventional therapy for human breast cancer in nude mice with 131I gelatin microspheres (¹³¹I-GMSs) following intratumoral injection

Introduction

The aim of this study was to investigate the effects of ¹³¹I gelatin microspheres (¹³¹I-GMS) on human breast cancer cells (MCF-7) in nude mice and the biodistribution of ¹³¹I-GMSs following intratumoral injections.

Methods

A total of 20 tumor-bearing mice were divided into a treatment group and control group and received intratumoral injections of 2.5 mci ¹³¹I-GMSs and nonradioactive GMSs, respectively. Tumor size was measured once per week. Another 16 mice received intratumoral injections of 0.4 mci ¹³¹I-GMSs and were subjected to single photon emission computed tomography (SPECT) scans and tissue radioactivity concentration measurements on day 1, 4, 8 and 16 postinjection. The 20 tumor-bearing mice received intratumoral injections of 0.4 mci [¹³¹I] sodium iodide solution and were subjected to SPECT scans and intratumoral radioactivity measurements at 1, 6, 24, 48 and 72 h postinjection. The tumors were collected for histological examination.

Results

The average tumor volume in the ¹³¹I-GMSs group on post-treatment day 21 decreased to 86.82 ± 63.6%, while it increased to 893.37 ± 158.12% in the control group (P < 0.01 vs. the ¹³¹I-GMSs group). ¹³¹I-GMSs provided much higher intratumoral retention of radioactivity, resulting in 19.93 ± 5.24% of the injected radioactivity after 16 days, whereas the control group retained only 1.83 ± 0.46% of the injected radioactivity within the tumors at 1 h postinjection.

Conclusions

¹³¹I-GMSs suppressed the growth of MCF-7 in nude mice and provided sustained intratumoral radioactivity retention. The results suggest the potential of ¹³¹I-GMSs for clinical applications in radiotherapy for breast cancer.