Integrin αvβ3 Receptor Overexpressing on Tumor-Targeted Positive MRI-Guided Chemotherapy

A dual-targeted Gd-based contrast agent for magnetic resonance imaging in tumor diagnosis

Enhanced magnetic resonance imaging (MRI) has important clinical value in the diagnosis of tumors. Much effort has been made to improve the relaxivity and specificity of contrast agents (CAs) in tumor diagnosis over the past few decades. However, there is still a lack of CAs which not only enhance the signal intensity of tumors rather than surrounding tissues in MRI but also maintain a high signal intensity prolonged for a long time. Herein, we synthesized a dual-targeted CA, RGD-(DOTA-Gd)-TPP (RDP), in which RGD is used to target the αvβ3 integrin receptor overexpressed in tumor cells and TPP is used to bind to a mitochondrion further. The structure of RDP was characterized and its properties, such as relaxivity and biosafety, were measured and in vitro and in vivo MRI assays were carried out. It has been proven that RDP has higher relaxivity of aqueous solution than Magnevist used in clinics. Moreover, RDP achieved higher signal intensity and a longer signal duration in tumor imaging. Therefore, RDP can be applied as the potential dual-targeted MRI CA for clinical tumor diagnosis.

Magnetic Resonance Imaging of Macrophage Response to Radiation Therapy

BACKGROUND

Magnetic resonance imaging (MRI) is a non-invasive imaging modality which, in conjunction with biopsies, provide a qualitative assessment of tumor response to treatment. Intravenous injection of contrast agents such as fluorine (19F) nanoemulsions labels systemic macrophages, which can, then, be tracked in real time with MRI. This method can provide quantifiable insights into the behavior of tumor-associated macrophages (TAMs) in the tumor microenvironment and macrophage recruitment during therapy.

METHODS

Female mice received mammary fat pad injections of murine breast or colon cancer cell lines. The mice then received an intravenous 19F nanoemulsion injection, followed by a baseline 19F MRI. For each cancer model, half of the mice then received 8 Gy of localized radiation therapy (RT), while others remained untreated. The mice were monitored for two weeks for tumor growth and 9F signal using MRI.

RESULTS

Across both cohorts, the RT-treated groups presented significant tumor growth reduction or arrest, contrary to the untreated groups. Similarly, the fluorine signal in treated groups increased significantly as early as four days post therapy. The fluorine signal change correlated to tumor volumes irrespective of time.

CONCLUSION

These results demonstrate the potential of 19F MRI to non-invasively track macrophages during radiation therapy and its prognostic value with regard to tumor growth.

Nanocarrier-based delivery of arsenic trioxide for hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) poses a severe threat to human health and economic development. Despite many attempts at HCC treatment, most are inevitably affected by the genetic instability and variability of tumor cells. Arsenic trioxide (ATO) has shown to be effective in HCC. However, time-consuming challenges, especially the optimal concentration in tumor tissue and bioavailability of ATO, remain to be overcome for its transition from the bench to the bedside. To bypass these issues, nanotechnology-based delivery systems have been developed for prevention, diagnosis, monitoring and treatment in recent years. This article is a systematic overview of the latest contributions and detailed insights into ATO-loaded nanocarriers, with particular attention paid to strategies for improving the efficacy of nanocarriers of ATO.

Functional cRGD-Conjugated Polymer Prodrug for Targeted Drug Delivery to Liver Cancer Cells

To overcome the limitation of conventional nanodrugs in tumor targeting efficiency, coupling targeting ligands to polymeric nanoparticles can enhance the specific binding of nanodrugs to tumors. Cyclo(Arg-Gly-Asp-d-Phe-Lys) (abbreviated as c(RGDfK)) peptide has been widely adopted due to its high affinity to the tumor marker α_vβ₃ integrin receptor. In this study, we develop a cRGD peptide-conjugated camptothecin (CPT) prodrug, which enables self-assembly of nanoparticles for precise targeting and enrichment in tumor tissue. We first synthesized a camptothecin derivative (CPT-ss-N₃) with a reduction-sensitive bond and simultaneously modified PEG to obtain cRGD-PEG-N₃. After ring-opening polymerization of the 2-(but-3-yn-1-yolxy)-2-oxo-1,3,2-dioxaphospholane (BYP), an amphiphilic polymeric prodrug, referred to as cRGD-PEG-g-(PBYP-ss-CPT), was obtained via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The self-assembly in buffer solution of the cRGD-functional prodrug was studied through DLS and TEM. The in vitro drug release behavior of cRGD-PEG-g-(PBYP-ss-CPT) nanoparticles was investigated. The results show that the nanoparticles are reduction-responsive and the bonded CPT can be released. Endocytosis and MTT assays demonstrate that the cRGD-conjugated prodrug has better affinity for tumor cells, accumulates more intracellularly, and is therefore, more effective. The in vivo drug metabolism studies show that nanoparticles greatly prolong the retention time in circulation. By monitoring drug distribution in tumor and in various tissues, we find that free CPT can be rapidly metabolized, resulting in low accumulation in all tissues. However, cRGD-PEG-g-(PBYP-ss-CPT) nanoparticles accumulate in tumor tissues in higher amounts than PEG-g-(PBYP-ss-CPT) nanoparticles, except for the inevitable capture by the liver. This indicates that the nanomedicine with cRGD has a certain targeting property, which can improve drug delivery efficiency.

Targeted Molecular Imaging Probes Based on Magnetic Resonance Imaging for Hepatocellular Carcinoma Diagnosis and Treatment

Hepatocellular carcinoma (HCC) is the sixth most commonly malignant tumor and the third leading cause of cancer-related death in the world, and the early diagnosis and treatment of patients with HCC is core in improving its prognosis. The early diagnosis of HCC depends largely on magnetic resonance imaging (MRI). MRI has good soft-tissue resolution, which is the international standard method for the diagnosis of HCC. However, MRI is still insufficient in the diagnosis of some early small HCCs and malignant nodules, resulting in false negative results. With the deepening of research on HCC, researchers have found many specific molecular biomarkers on the surface of HCC cells, which may assist in diagnosis and treatment. On the other hand, molecular imaging has progressed rapidly in recent years, especially in the field of cancer theranostics. Hence, the preparation of molecular imaging probes that can specifically target the biomarkers of HCC, combined with MRI testing in vivo, may achieve the theranostic purpose of HCC in the early stage. Therefore, in this review, taking MR imaging as the basic point, we summarized the recent progress regarding the molecular imaging targeting various types of biomarkers on the surface of HCC cells to improve the theranostic rate of HCC. Lastly, we discussed the existing obstacles and future prospects of developing molecular imaging probes as HCC theranostic nanoplatforms.

Macrophage membrane- and cRGD-functionalized thermosensitive liposomes combined with CPP to realize precise siRNA delivery into tumor cells

Despite the success of small interfering RNAs (siRNAs) in clinical settings, their fast clearance and poor delivery efficiency to target cells still hinder their therapeutic effect. Herein, a new treatment system was constructed by combining thermosensitive liposomes with the macrophage membrane, tumor-targeting cyclic Arg-Gly-Asp peptide, a cell-penetrating peptide, and thermotherapy. The constructed system was found to be thermosensitive and stable; the proteins were inherited from the macrophage membrane. This new system combined with thermotherapy displayed the least uptake by macrophages, the greatest uptake by HepG2 cells, the most obvious HepG2 cell apoptosis, and the strongest inhibition of Bcl-2 mRNA and Bcl-2 protein in HepG2 cells. Moreover, 24 h after system administration in tumor-bearing mice, the most prominent distribution of siRNA was observed in tumors, while almost no siRNA was found in other organs. The strongest inhibition of Bcl-2 mRNA, Bcl-2 protein, and tumors was found in mice that had received the proposed system. In summary, when using the constructed system both in vitro and in mice, less uptake by the reticuloendothelial system, greater accumulation in tumor cells, and improved therapeutic efficacy were observed. Therefore, this new system can deliver siRNA selectively and efficiently, and it is a promising therapeutic candidate for precise tumor-targeted therapy.

An activated excretion-retarded tumor imaging strategy towards metabolic organs

Intraoperative fluorescence-based tumor imaging plays a crucial role in performing the oncological safe tumor resection with the advantage of differentiating tumor from normal tissues. However, the application of these fluorescence contrast agents in renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC) was dramatically hammered as a result of lacking active targeting and poor retention time in tumor, which limited the Signal to Noise Ratio (SNR) and narrowed the imaging window for complicated surgery. Herein, we reported an activated excretion-retarded tumor imaging (AERTI) strategy, which could be in situ activated with MMP-2 and self-assembled on the surface of tumor cells, thereby resulting in a promoted excretion-retarded effect with an extended tumor retention time and enhanced SNR. Briefly, the AERTI strategy could selectively recognize the Integrin α_vβ₃. Afterwards, the AERTI strategy would be activated and in situ assembled into nanofibrillar structure after specifically cleaved by MMP-2 upregulated in a variety of human tumors. We demonstrated that the AERTI strategy was successfully accumulated at the tumor sites in the 786-O and HepG2 xenograft models. More importantly, the modified modular design strategy obviously enhanced the SNR of AERTI strategy in the imaging of orthotopic RCC and HCC. Taken together, the results presented here undoubtedly confirmed the design and advantage of this AERTI strategy for the imaging of tumors in metabolic organs.

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Fluorescence-based tumor imaging plays a crucial role in performing the oncological safe tumor resection.

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Self-assembled peptide possesses the advantage of active targeting and long-term retention time in tumor.

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The activated excretion-retarded tumor imaging strategy extended the tumor retention time and enhanced SNR.

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Assembly-mediated peptide probe successfully achieved the accurate identification of tumor boundaries and detection of minimal tumors (<2 mm).

Smart MSN-Drug-Delivery System for Tumor Cell Targeting and Tumor Microenvironment Release

Tumor-targeted delivery and controlled release of antitumor drugs are promising strategies for increasing chemotherapeutic efficacy and reducing adverse effects. Although mesoporous silica nanoparticles (MSNs) have been known as a potential delivery system for doxorubicin (DOX), they have restricted applications due to their uncontrolled leakage and burst release from their large open pores. Herein, we engineered a smart drug-delivery system (smart MSN-drug) based on MSN-drug loading, cell membrane mimetic coating, on-demand pore blocking/opening, and tumor cell targeting strategies. The pore size of DOX-loaded MSNs was narrowed by polydopamine coating, and the pores/channels were blocked with tumor-targeting ligands anchored by tumor environment-rupturable -SS- chains. Furthermore, a cell membrane mimetic surface was constructed to enhance biocompatibility of the smart MSN-drug. Confocal microscopy results demonstrate highly selective uptake (12-fold in comparison with L929 cell) of the smart MSN-drug by HeLa cells and delivery into the HeLa cellular nuclei. Further in vitro IC₅₀ studies showed that the toxicity of the smart MSN-drug to HeLa cells was 4000-fold higher than to the normal fibroblast cells. These exciting results demonstrate the utility of the smart MSN-drug capable of selectively killing tumor cells and saving the normal cells.

Modifications of polysaccharide-based biomaterials under structure-property relationship for biomedical applications

Polysaccharides are well accepted biomaterials that have attracted considerable attention. Compared with other materials under research, polysaccharides show unique advantages: they are available in nature and are normally easily acquired, those acquired from nature show favorable immunogenicity, and are biodegradable and bioavailable. The bioactivity and possible applications are based on their chemical structure; however, naturally acquired polysaccharides sometimes have unwanted flaws that limit further applications. For this reason, carefully summarizing the possible modifications of polysaccharides to improve them is crucial. Structural modifications can not only provide polysaccharides with additional functional groups but also change their physicochemical properties. This review based on the structure-property relation summarizes the common chemical modifications of polysaccharides, the related bioactivity changes, possible functionalization methods, and major possible biomedical applications based on modified polysaccharides.

Peptide-Chitosan Engineered Scaffolds for Biomedical Applications

Peptides are signaling epitopes that control many vital biological events. Increased specificity, synthetic feasibility with concomitant lack of toxicity, and immunogenicity make this emerging class of biomolecules suitable for different applications including therapeutics, diagnostics, and biomedical engineering. Further, chitosan, a naturally occurring linear polymer composed of d-glucosamine and N-acetyl-d-glucosamine units, possesses anti-microbial, muco-adhesive, and hemostatic properties along with excellent biocompatibility. As a result, chitosan finds application in drug/gene delivery, tissue engineering, and bioimaging. Despite these applications, chitosan demonstrates limited cell adhesion and lacks biosignaling. Therefore, peptide-chitosan hybrids have emerged as a new class of biomaterial with improved biosignaling properties and cell adhesion properties. As a result, recent studies encompass increased application of peptide-chitosan hybrids as composites or conjugates in drug delivery, cell therapy, and tissue engineering and as anti-microbial material. This review discusses the recent investigations involving chitosan-peptide materials and uncovers various aspects of these interesting hybrid materials for biomedical applications.

A multicomponent-based microemulsion for boosting ovarian cancer therapy through dual modification with transferrin and SA-R6H4

Balancing the antitumor activity and systemic toxicity of tripterine still faces a big challenge due to the narrow therapeutic window. To address this issue, we report a microemulsion system based on tripterine, brucea oil, and glycyrrhizin, and dual modified with both transferrin and cell-penetrating peptide SA-R₆H₄ (Tf/SA-R₆H₄-TBG-MEs) for combinational and tumor-targeted cancer therapy. Such a microemulsion exhibited a spherical shape with a size of ~50 nm and a mildly-negative charge. The half-maximal inhibitory concentration (IC₅₀) of Tf/SA-R₆H₄-TBG-MEs against ovarian cancer SKOV3 cells was 0.27 ± 0.43 μg tripterine/mL, which was 5.85 times lower than that of free tripterine. The cellular uptake of tripterine after treatment with Tf/SA-R₆H₄-TBG-MEs was 1.56 times higher than that of TBG-MEs (non-modified microemulsion). In pharmacokinetics studies, the area under the curve of Tf/SA-R₆H₄-TBG-MEs increased by 1.97 times compared with that of the physical mixture group. The tumoral accumulation of tripterine was significantly improved in Tf/SA-R₆H₄-TBG-MEs group than TBG-MEs-treated group. In antitumor efficacy in vivo, Tf/SA-R₆H₄-TBG-MEs exhibited the strongest inhibition of tumor growth and the longest survival period among all the groups, which is associated with the rational combination, microemulsion system, and dual modification with tumor-targeted ligands. Importantly, Tf/SA-R₆H₄-TBG-MEs significantly reduced the toxicity of tripterine against the liver and kidney. Our design provides a new approach for efficient and safe ovarian cancer therapy based on a multicomponent combination.

Functional gadolinium-based nanoscale systems for cancer theranostics

Cancer theranostics is a new strategy for combating cancer that integrates cancer imaging and treatment through theranostic agents to provide an efficient and safe way to improve cancer prognosis. Design and synthesis of these cancer theranostic agents are crucial since these agents are required to be biocompatible, tumor-specific, imaging distinguishable and therapeutically efficacious. In this regard, several types of gadolinium (Gd)-based nanomaterials have been introduced to combine different therapeutic agents with Gd to enhance the efficacy of therapeutic agents. At the same time, the entire treatment procedure could be monitored via imaging tools due to incorporation of Gd ions, Gd chelates and Gd/other imaging probes in the theranostic agents. This review aims to overview recent advances in the Gd-based nanomaterials for cancer theranostics and perspectives for Gd nanomaterial-based cancer theranostics are provided.