Starch-Based Hydrogels as a Drug Delivery System in Biomedical Applications.

Starch-based hydrogels have gained significant attention in biomedical applications as a type of drug delivery system due to their biocompatibility, biodegradability, and ability to absorb and release drugs. Starch-based hydrogels can serve as effective carriers for pharmaceutical compounds such as drugs and proteins to develop drug-loaded hydrogel systems, providing controlled release over an extended period. The porous structure of a hydrogel allows for the diffusion of drugs, ensuring sustained and localized delivery to the target site. Moreover, starch-based hydrogels have been used as a powerful option in various biomedical fields, including cancer and infectious disease treatment. In addition, starch-based hydrogels have shown promise in tissue engineering applications since hydrogels can be used as scaffolds or matrices to support cell growth and tissue regeneration. Depending on techniques such as chemical crosslinking or physical gelation, it can create a three-dimensional network structure that tunes its mechanical properties and mimics the extracellular matrix. Starch-based hydrogels can also provide a supportive environment for cell attachment, proliferation, and differentiation to promote specific cellular responses and tissue regeneration processes with the loading of growth factors, cytokines, or other bioactive molecules. In this review, starch-based hydrogels as a versatile platform for various biomedical applications are discussed.

Stem Cell-Derived Extracellular Vesicles for Cancer Therapy and Tissue Engineering Applications.

Recently, stem cells and their secretomes have attracted great attention in biomedical applications, particularly extracellular vesicles (EVs). EVs are secretomes of cells for cell-to-cell communication. They play a role as intercellular messengers as they carry proteins, nucleic acids, lipids, and therapeutic agents. They have also been utilized as drug-delivery vehicles due to their biocompatibility, low immunogenicity, stability, targetability, and engineerable properties. The therapeutic potential of EVs can be further enhanced by surface engineering and modification using functional molecules such as aptamers, peptides, and antibodies. As a consequence, EVs hold great promise as effective delivery vehicles for enhancing treatment efficacy while avoiding side effects. Among various cell types that secrete EVs, stem cells are ideal sources of EVs because stem cells have unique properties such as self-renewal and regenerative potential for transplantation into damaged tissues that can facilitate their regeneration. However, challenges such as immune rejection and ethical considerations remain significant hurdles. Stem cell-derived EVs have been extensively explored as a cell-free approach that bypasses many challenges associated with cell-based therapy in cancer therapy and tissue regeneration. In this review, we summarize and discuss the current knowledge of various types of stem cells as a source of EVs, their engineering, and applications of EVs, focusing on cancer therapy and tissue engineering.

Mesenchymal Stem Cell-Mediated Deep Tumor Delivery of Gold Nanorod for Photothermal Therapy.

Gold nanoparticles (AuNPs) with various sizes and morphologies have been extensively investigated for effective photothermal therapy (PTT) against multiple cancer types. However, a highly dynamic and complex tumor microenvironment (TME) considerably reduces the efficacy of PTT by limiting deep tumor penetration of AuNPs. Herein, we propose a mesenchymal stem cell (MSC)-mediated deep tumor delivery of gold nanorod (AuNR) for a potent PTT. First, MSCs are treated with tetraacylated N-azidomannosamine (Ac4ManNAz) to introduce modifiable azide (N3) groups on the cell surface via metabolic glycoengineering. Then, AuNRs modified with bio-orthogonal click molecules of bicyclo[6.1.0]nonyne (AuNR@BCN) are chemically conjugated to the N3 groups on the MSC surface by copper-free click chemistry reaction, resulting in AuNR@MSCs. In cultured MSCs, the appropriate condition to incorporate the AuNR into the MSCs is optimized; in addition, the photothermal efficiency of AuNR-MSCs under light irradiation are assessed, showing efficient heat generation in vitro. In colon tumor-bearing mice, intravenously injected AuNR@MSCs efficiently accumulate within the tumor tissues by allowing deep tissue penetration owing to the tumor homing effect by natural tumor tropism of AuNR@MSCs. Upon localized light irradiation, the AuNR@MSCs significantly inhibit colon tumor growth by the enhanced photothermal effect compared to conventional AuNRs. Collectively, this study shows a promising approach of MSCs-mediated deep tumor delivery of AuNR for effective PTT.

Hemagglutinin Nanoparticulate Vaccine with Controlled Photochemical Immunomodulation for Pathogenic Influenza-Specific Immunity.

Recently, viral infectious diseases, including COVID-19 and Influenza, are the subjects of major concerns worldwide. One strategy for addressing these concerns focuses on nasal vaccines, which have great potential for achieving successful immunization via safe, easy, and affordable approaches. However, conventional nasal vaccines have major limitations resulting from fast removal when pass through nasal mucosa and mucociliary clearance hindering their effectiveness. Herein a nanoparticulate vaccine (NanoVac) exhibiting photochemical immunomodulation and constituting a new self-assembled immunization system of a photoactivatable polymeric adjuvant with influenza virus hemagglutinin for efficient nasal delivery and antigen-specific immunity against pathogenic influenza viruses is described. NanoVac increases the residence period of antigens and further enhances by spatiotemporal photochemical modulation in the nasal cavity. As a consequence, photochemical immunomodulation of NanoVacs successfully induces humoral and cellular immune responses followed by stimulation of mature dendritic cells, plasma cells, memory B cells, and CD4+ and CD8+ T cells, resulting in secretion of antigen-specific immunoglobulins, cytokines, and CD8+ T cells. Notably, challenge with influenza virus after nasal immunization with NanoVacs demonstrates robust prevention of viral infection. Thus, this newly designed vaccine system can serve as a promising strategy for developing vaccines that are active against current hazardous pathogen outbreaks and pandemics.

Visible-Light-Triggered Prodrug Nanoparticles Combine Chemotherapy and Photodynamic Therapy to Potentiate Checkpoint Blockade Cancer Immunotherapy.

Immune checkpoint blockade is a promising approach for cancer immunotherapy, but many patients do not respond due to the immunosuppressive tumor microenvironment (ITM). Herein, we propose visible-light-triggered prodrug nanoparticles (LT-NPs) for reversing ITM into high immunogenic tumors to potentiate checkpoint blockade immunotherapy. The photosensitizer (verteporfin; VPF), cathepin B-specific cleavable peptide (FRRG), and doxorubicin (DOX) conjugates are self-assembled into LT-NPs without any additional carrier material. The LT-NPs are specifically cleaved to VPF and DOX in cathepsin B-overexpressing cancer cells, thereby inducing cancer-specific cytotoxicity and immunogenic cell death (ICD) upon visible light irradiation. In tumor models, LT-NPs highly accumulate within tumors via the enhanced permeability and retention effect, and photochemotherapy of VPF and DOX induces effective ICD and maturation of dendritic cells to stimulate cross-presentation of cancer-antigens to T cells. Furthermore, LT-NPs with PD-L1 blockade greatly inhibit tumor growth, tumor recurrence, and lung metastasis by initiating a strong antitumor immune response. The photochemotherapy by LT-NPs provides a promising strategy for effective checkpoint blockade immunotherapy.

Rediscovery of nanoparticle-based therapeutics: boosting immunogenic cell death for potential application in cancer immunotherapy.

Immunogenic cell death (ICD) occurring by chemical and physical stimuli has shown the potential to activate an adaptive immune response in the immune-competent living body through the release of danger-associated molecular patterns (DAMPs) into the tumor microenvironment (TME). However, limitations to the long-term immune responses and systemic toxicity of conventional ICD inducers have led to unsatisfactory therapeutic efficacy in ICD-based cancer immunotherapy. Until now, various nanoparticle-based ICD-inducers have been developed to induce an antitumor immune response without severe toxicity, and to efficiently elicit an anticancer immune response against target cancer cells. In this review, we introduce a recent advance in the designs and applications of nanoparticle-based therapeutics to elicit ICD for effective cancer immunotherapy. In particular, combination strategies of nanoparticle-based ICD inducers with typical theranostic modalities are introduced intensively. Subsequently, we discuss the expected challenges and future direction of nanoparticle-based ICD inducers to provide strategies for boosting ICD in cancer immunotherapy. These versatile designs and applications of nanoparticle-based therapeutics for ICD can provide advantages to improve the therapeutic efficacy of cancer immunotherapy.

Controlling complexation/decomplexation and sizes of polymer-based electrostatic pDNA polyplexes is one of the key factors in effective transfection.

The delivery of plasmid DNA (pDNA) using polycations has been investigated for several decades; however, obstacles that limit efficient gene delivery still hinder the clinical application of gene therapy. One of the major limiting factors is controlling pDNA binding affinity with polymers to control the complexation and decomplexation of polyplexes. To address this challenge, polycations of α-poly(L-lysine) (APL) and ε-poly(L-lysine) (EPL) were used to prepare variable complexation/decomplexation polyplexes with binding affinities ranging from too tight to too loose and sizes ranging from small to large. APL-EPL/ATP-pDNA polyplexes were also prepared to compare the effects of endosomolytic ATP on complexation/decomplexation and the sizes of polyplexes. The results showed that smaller and tighter polyplexes delivered more pDNA into the cells and into the nucleus than the larger and looser polyplexes. Larger polyplexes exhibited slower cytosolic transport and consequently less nuclear delivery of pDNA than smaller polyplexes. Tighter polyplexes exhibited poor pDNA release in the nucleus, leading to no improvement in transfection efficiency. Thus, polyplexes should maintain a balance between complexation and decomplexation and should have optimal sizes for effective cellular uptake, cytosolic transport, nuclear import, and gene expression. Understanding the effects of complexation/decomplexation and size is important when designing effective polymer-based electrostatic gene carriers.

Gemcitabine-loaded DSPE-PEG-PheoA liposome as a photomediated immune modulator for cholangiocarcinoma treatment.

To improve the therapeutic efficacy of gemcitabine (GEM) as an anticancer drug for bile duct cancer, GEM-loaded liposomes (GDPPL) prepared from a photosensitizer-conjugated lipid were investigated regarding the drug release kinetics, photodynamic therapy (PDT) efficacy, and immunomodulatory effects. The release rate of GEM from the liposomes was improved approximately 2-fold compared to non-laser irradiation groups due to lipid disruption by reactive oxygen species produced from the activated photosensitizer upon laser irradiation. Through in vitro testing using a human liver bile duct carcinoma cell line (HuCCT-1), the cytotoxicity of GDPPL with laser irradiation was enhanced due to rapid GEM release and PDT effects. Furthermore, the results of in vivo tests using a HuCCT-1 tumor-bearing xenograft mice model showed that GDPPL exhibited approximately 3-fold antitumoral effects compared to control group. Additionally, immunohistochemical analysis demonstrated the recruitment of immunostimulatory cells in tumor tissues. IHC tests in BALB/c mice indicated that GDPPL under laser irradiation dramatically enhanced the quantities of various immune cells for effective antitumoral immunotherapy against biliary tract cancer. From these results, it was concluded that GDPPL with rapid drug release behavior, PDT efficacy, and immunomodulatory effects upon laser irradiation has potential as an antitumor therapeutic agent for biliary tract cancer.

TRAIL-secreting human mesenchymal stem cells engineered by a non-viral vector and photochemical internalization for pancreatic cancer gene therapy.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising therapeutic protein to selectively induce cancer cell apoptosis. However, TRAIL exhibits low stability and short half-life due to its denaturation. Thus, delivering the TRAIL gene for stem cell-mediated gene therapy was conducted by using non-viral vectors (a less efficient but safer method). To overcome the limitation of non-viral vectors, photochemical internalization (PCI) was utilized for enhanced transfection efficiency of secreting TRAIL from human mesenchymal stem cells (hMSCs). To explore a more effective approach for cancer treatment, polyplexes were formed by using TRAIL plasmid (pTRAIL) and branched polyethyleneimine (bPEI). PCI is applied to improve polyplex entrapping in hMSCs and enhance the transfection efficiency of TRAIL into hMSCs for secretion in tumors via a homing effect. We demonstrate that PCI-mediated polyplex loading significantly enhanced TRAIL expression in stem cells and that homing ability magnified cancer targeting. The xenograft mouse model shows that polyplex loaded hMSCs (pTRAIL/bPEI@hMSCs) under laser irradiation results in a beneficial therapeutic antitumor effect compared to unloaded polyplexes and pTRAIL/bPEI@hMSCs. Taken together, the delivery of PCI-pTRAIL/bPEI@hMSCs offers exciting potential treatments in pancreatic cancer gene therapy via the enhanced the transfection efficiency of TRAIL by PCI system and the tumor homing properties of hMSCs.

Theranostics and contrast agents for magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging is one of the diagnostic tools that uses magnetic particles as contrast agents. It is noninvasive methodology which provides excellent spatial resolution. Although magnetic resonance imaging offers great temporal and spatial resolution and rapid in vivo images acquisition, it is less sensitive than other methodologies for small tissue lesions, molecular activity or cellular activities. Thus, there is a desire to develop contrast agents with higher efficiency. Contrast agents are known to shorten both T1 and T2. Gadolinium based contrast agents are examples of T1 agents and iron oxide contrast agents are examples of T2 agents. In order to develop high relaxivity agents, gadolinium or iron oxide-based contrast agents can be synthesized via conjugation with targeting ligands or functional moiety for specific interaction and achieve accumulation of contrast agents at disease sites. MAIN BODY: This review discusses the principles of magnetic resonance imaging and recent efforts focused on specificity of contrast agents on specific organs such as liver, blood, lymph nodes, atherosclerotic plaque, and tumor. Furthermore, we will discuss the combination of theranostic such as contrast agent and drug, contrast agent and thermal therapy, contrast agent and photodynamic therapy, and neutron capture therapy, which can provide for cancer diagnosis and therapeutics. CONCLUSION: These applications of magnetic resonance contrast agents demonstrate the usefulness of theranostic agents for diagnosis and treatment.

Photoresponsive Micelle-Incorporated Doxorubicin for Chemo-Photodynamic Therapy to Achieve Synergistic Antitumor Effects.

A combination of chemo-photodynamic therapy has been manifested as a promising strategy for efficient cancer treatment due to the enhanced therapeutic efficacy. Here, we designed doxorubicin (DOX)-loaded photoresponsive micelles (DPRMs) based on a combination of chlorin e6 (Ce6) and lipoic acid (LA) conjugated methoxy-poly(ethylene) glycol (mPEG-Ce6, mPEG-LA) to achieve effective drug delivery using a single system. DPRMs were optimized with different molar ratios of mPEG-Ce6 and mPEG-LA which showed uniformly spherical morphology of size ∼130 nm and approximately 9% of DOX loading contents. Photoresponsive lipoyl ring of mPEG-LA was incorporated in DPRMs in order to induce photomediated reduction resulting in 2-3-fold accelerated DOX release according to higher molar ratio of mPEG-LA and enhancement of light dose. The photoresponsive DOX release and ROS generation by Ce6 mediated cytotoxic effect of DPRMs were demonstrated in vitro using CT-26 (mouse colon cancer) and HCT-116 (human colon cancer) cells. We observed both the photosensitizer and the anticancer drug are colocalized in the tumor cells to achieve effective enhancement. Additionally, the DPRMs with laser irradiation successfully inhibited tumor growth in CT-26 tumor bearing mouse model and immunohistochemical staining verified apoptosis-mediated tumor growth inhibition. These observations demonstrated that the DPRMs showed a higher therapeutic effect than the other systems and PDT maximized the antitumor effect. Thus, DPRMs confirmed the advantages as a chemo-photodynamic dual-therapy with a synergistic therapeutic effect and great potential for cancer treatment.

Multifunctional trastuzumab-chlorin e6 conjugate for the treatment of HER2-positive human breast cancer.

Effective penetration and targeted delivery of anticancer drugs into tumor tissues are limiting factors for achieving enhanced therapeutic efficacy. In order to overcome the disadvantages of antibody therapy (limited penetration efficacy into tumor tissues) and photodynamic therapy (low targeting efficiency) on the treatment of HER2-positive human breast cancer simultaneously, an antibody and photosensitizer combined Trastuzumab-chlorin e6 conjugate (TMPC) was synthesized. TMPC exhibits high singlet oxygen generation under laser irradiation. In vitro data show that TMPC has specific HER2 selective interactions, and ROS generation ability upon laser irradiation induces significant cell death in HER2-positive breast cancer cells. The enhanced tissue penetration ability and tissue access of TMPC resulting from local tissue destruction by ROS generated from Ce6 is also demonstrated in breast cancer tissue blocks. The enhanced ability of TMPC is supported by in vivo fluorescence images of SK-BR-3 (HER2-positive cancer cells) tumor-bearing mice. The in vivo test demonstrates approximately 6-fold enhanced accumulation of TMPC in xenograft tumors with a longer retention time compared to that of the PEG-Ce6 conjugate at 24 h. Thus, trastuzumab and photosensitizer conjugation brings synergistic effects for HER2 selective targeting, where TMPC enhanced tumor tissue penetration improves tumor tissue access and responsiveness of trastuzumab in HER2 overexpressing breast cancer.

Combination of photodynamic therapy (PDT) and anti-tumor immunity in cancer therapy.

Photodynamic therapy (PDT) is performed using a photosensitizer and light of specific wavelength in the presence of oxygen to generate singlet oxygen and reactive oxygen species(ROS) in the cancer cells. The accumulated photosensitizers in target sites induce ROS generation upon light activation, then the generated cytotoxic reactive oxygen species lead to tumor cell death via apoptosis or necrosis, and damages the target sites which results tumor destruction. As a consequence, the PDT-mediated cell death is associated with anti-tumor immune response. In this paper, the effects of PDT and immune response on tumors are reviewed. Activation of an immune response regarding the innate and adaptive immune response, interaction with immune cells and tumor cells that associated with antitumor efficacy of PDT are also discussed.

Role of polymeric endosomolytic agents in gene transfection: a comparative study of poly(L-lysine) grafted with monomeric L-histidine analogue and poly(L-histidine).

Endosomal entrapment is one of the main barriers that must be overcome for efficient gene expression along with cell internalization, DNA release, and nuclear import. Introducing pH-sensitive ionizable groups into the polycationic polymers to increase gene transfer efficiency has proven to be a useful method; however, a comparative study of introducing equal numbers of ionizable groups in both polymer and monomer forms, has not been reported. In this study, we prepared two types of histidine-grafted poly(L-lysine) (PLL), a stacking form of poly(L-histidine) (PLL-g-PHis) and a mono-L-histidine (PLL-g-mHis) with the same number of imidazole groups. These two types of histidine-grafted PLL, PLL-g-PHis and PLL-g-mHis, showed profound differences in hemolytic activity, cellular uptake, internalization, and transfection efficiency. Cy3-labeled PLL-g-PHis showed strong fluorescence in the nucleus after internalization, and high hemolytic activity upon pH changes was also observed from PLL-g-PHis. The arrangement of imidazole groups from PHis also provided higher gene expression than mHis due to its ability to escape the endosome. mHis or PHis grafting reduced the cytotoxicity of PLL and changed the rate of cellular uptake by changing the quantity of free ε-amines available for gene condensation. The subcellular localization of PLL-g-PHis/pDNA measured by YOYO1-pDNA intensity was highest inside the nucleus, while the lysotracker, which stains the acidic compartments was lowest among these polymers. Thus, the polymeric histidine arrangement demonstrate the ability to escape the endosome and trigger rapid release of polyplexes into the cytosol, resulting in a greater amount of pDNA available for translocation to the nucleus and enhanced gene expression.

Bioreducible polymers as a determining factor for polyplex decomplexation rate and transfection.

Polyplex formation (complexation) and gene release from the polyplexes (decomplexation) are major events in polymeric gene delivery; however, the effect of the decomplexation rate on transfection has been rarely investigated. This study employed mixed polymers of poly((L)-lysine) (PLL: MW ~7.4 kDa) and reducible PLL (RPLL) (MW ~6.7 kDa) to design decomplexation rate-controllable PLL(100-x)RPLL(x)/pDNA complexes (PRL(x) polyplexes). The transfection efficiency of a model gene (luciferase) in MCF7 and HEK293 cell lines increased with increasing x (RPLL content) in the PRL(x) polyplexes until peaking at x = 2.5 and 10, respectively, after which point transfection efficiency declined rapidly. In MCF7 cells, PRL(2.5) polyplex produced 3 or 223 times higher gene expression than PLL or RPLL polyplexes, respectively. Similarly, the transfection efficiency of PRL(10) polyplex-transfected HEK293 cells was 3.8 or 67 times higher than that of PLL or RPLL polyplexes, respectively. The transfection results were not apparently related to the particle size, surface charge, complexation/compactness, cellular uptake, or cytotoxicity of the tested polyplexes. However, the decomplexation rate varied by RPLL content in the polyplexes, which in turn influenced the gene transfection. The nuclear localization of pDNA delivered by PRL(x) polyplexes showed a similar trend to their transfection efficiencies. This study suggests that an optimum decomplexation rate may result in high nuclear localization of pDNA and transfection. Understanding in decomplexation and intracellular localization of pDNA may help develop more effective polyplexes.