Synergistic effects of co-administration of suicide gene expressing mesenchymal stem cells and prodrug-encapsulated liposome on aggressive lung melanoma metastases in mice

Lyophilizable Stem Cell-Hybrid Liposome with Long-Term Stability and High Targeting Capacity

The hybridization of liposome with stem cell membranes is an emerging technology to prepare the nanovehicle with the capacity of disease-responsive targeting. However, the long-term storage of this hybrid liposome has received limited attention in the literature, which is essential for its potential applicability in the clinic. Therefore, the preservation of long-term activity of stem cell-hybrid liposome using freeze-drying is investigated in the present study. Mesenchymal stem cell-hybrid liposome is synthesized and its feasibility for freeze-drying under different conditions is examined. Results reveal that pre-freezing the hybrid liposome at -20 °C in Tris buffer solution (pH 7.4) containing 10% trehalose can well preserve the liposomal structure for at least three months. Notably, major membrane proteins on the hybrid liposome are protected in this formulation and CXCR4-associated targeting capacity is maintained both in vitro and in vivo. Consequently, the hybrid liposome stored for three months demonstrates a comparable tumor inhibition as the fresh-prepared one. The present study provides the first insights into the long-term storage of stem cell hybrid liposome using lyophilization, which may make an important step forward in enhancing the long-term stability of these promising biomimetic nanovehicle and ease the logistics and the freeze-storage in the potential clinical applications.

Cell Membrane Camouflaged Biomimetic Nanoparticles as a Versatile Platform for Brain Diseases Treatment

Although there are various advancements in biomedical in the past few decades, there are still challenges in the treatment of brain diseases. The main difficulties are the inability to deliver a therapeutic dose of the drug to the brain through the blood-brain barrier (BBB) and the serious side effects of the drug. Thus, it is essential to select biocompatible drug carriers and novel therapeutic tools to better enhance the effect of brain disease treatment. In recent years, biomimetic nanoparticles (BNPs) based on natural cell membranes, which have excellent biocompatibility and low immunogenicity, are widely used in the treatment of brain diseases to enable the drug to successfully cross the BBB and target brain lesions. BNPs can prolong the circulation time in vivo, are more conducive to drug aggregation in brain lesions. Cell membranes (CMs) from cancer cells (CCs), red blood cells (RBCs), white blood cells (WBCs), and so on are used as biomimetic coatings for nanoparticles (NPs) to achieve the ability to target, evade clearance, or stimulate the immune system. This review summarizes the application of different cell sources as BNPs coatings in the treatment of brain diseases and discusses the possibilities and challenges of clinical translation.

Suicide gene delivery by morphology-adaptable enantiomeric peptide assemblies for combined ovarian cancer therapy

Suicide gene therapy is a promising therapeutic model for ovarian cancer (OC), while suffering from poor gene delivery and limited therapeutic efficacy. To address this concern, here we reported the GSH-responsive morphology-transformable enantiomeric peptide assemblies as delivering vehicles for suicide genes and co-delivery of paclitaxel (PTX). Connecting a lipid-like amphiphile and a hydrophilic arginine segment through disulfide bonds led to the enantiomeric peptides. The enantiomeric peptide assemblies are able to simultaneously uptake plasmid DNA (pDNA) and PTX based on electrostatic and hydrophobic interactions. The resulting co-assemblies underwent GSH-responsive disulfide cleavage and thereby promoting their assembly from nanoparticles to nanofibers, leading to the co-release of pDNA and PTX. Cellular and animal studies confirmed the co-delivery of pDNA and PTX into OC cells and the cell apoptosis by the enantiomeric peptides. In addition, in vitro and in vivo experiments supported the advanced uptake and cytotoxicity for L-type peptide vehicles by OC cells, and their great potential for OC-imaging, growth-inhibition and apoptosis-induction compared to D-counterpart. Our results demonstrate that the GSH-responsive morphology-transformable chiral peptide assemblies accurately and simultaneously release suicide genes and chemodrugs at tumor sites, thus providing a new strategy for the development of delivering vehicles for suicide gene and establishment of new therapeutic models for ovarian cancer. STATEMENT OF SIGNIFICANCE: Appropriate delivery carriers are essential for the clinical translation of cancer gene therapy, including the emerging suicide gene therapy. By combining the advantages of morphological transformable vehicles with the chirality peptides towards their bioactivity, we developed the GSH-responsive morphology-transformable enantiomeric peptide assemblies as delivering vehicles for suicide genes and co-delivery of paclitaxel. The GSH-responsive assembly of the enantiomeric peptides allows for precise release of plasmid DNA and paclitaxel in cancer cells, and promotes the formation of nanofibrils that facilitate gene entering nuclei for transfection. The enantiomeric peptide-based vehicles show the chirality-dependent capability for inducing cell apoptosis and inhibiting tumor growth. Our findings demonstrate a new strategy for developing therapeutic models for ovarian cancer.

Engineered stem cell-based strategy: A new paradigm of next-generation stem cell product in regenerative medicine

Stem cells have garnered significant attention in regenerative medicine owing to their abilities of multi-directional differentiation and self-renewal. Despite these encouraging results, the market for stem cell products yields limited, which is largely due to the challenges faced to the safety and viability of stem cells in vivo. Besides, the fate of cells re-infusion into the body unknown is also a major obstacle to stem cell therapy. Actually, both the functional protection and the fate tracking of stem cells are essential in tissue homeostasis, repair, and regeneration. Recent studies have utilized cell engineering techniques to modify stem cells for enhancing their treatment efficiency or imparting them with novel biological capabilities, in which advances demonstrate the immense potential of engineered cell therapy. In this review, we proposed that the "engineered stem cells" are expected to represent the next generation of stem cell therapies and reviewed recent progress in this area. We also discussed potential applications of engineered stem cells and highlighted the most common challenges that must be addressed. Overall, this review has important guiding significance for the future design of new paradigms of stem cell products to improve their therapeutic efficacy.

Nanoghosts: Harnessing Mesenchymal Stem Cell Membrane for Construction of Drug Delivery Platforms Via Optimized Biomimetics

Mesenchymal stem cells (MSCs) are becoming hotspots for application in disease therapies recently, combining with biomaterials and drug delivery system. A major advantage of MSCs applied in drug delivery system is that these cells enable specific targeting and releasing of cargos to the disease sites. However, the potential tumor tropic effects of MSCs raised concerns on biosafety. To solve this problem, there are emerging methods of isolating cell membranes and developing nanoformulations to perform drug delivery, which avoids concerns on biosafety without disturbing the membrane functions of specific polarizing and locating. These cargoes are so called "nanoghosts." This review article summarizes the current applications of nanoghosts, the promising potential of MSCs to be applied in membrane isolation and nanoghost construction, and possible approaches to develop better drug delivery system harnessing from MSC ghost cell membranes.

Efficient intervention for pulmonary fibrosis via mitochondrial transfer promoted by mitochondrial biogenesis

The use of exogenous mitochondria to replenish damaged mitochondria has been proposed as a strategy for the treatment of pulmonary fibrosis. However, the success of this strategy is partially restricted by the difficulty of supplying sufficient mitochondria to diseased cells. Herein, we report the generation of high-powered mesenchymal stem cells with promoted mitochondrial biogenesis and facilitated mitochondrial transfer to injured lung cells by the sequential treatment of pioglitazone and iron oxide nanoparticles. This highly efficient mitochondrial transfer is shown to not only restore mitochondrial homeostasis but also reactivate inhibited mitophagy, consequently recovering impaired cellular functions. We perform studies in mouse to show that these high-powered mesenchymal stem cells successfully mitigate fibrotic progression in a progressive fibrosis model, which was further verified in a humanized multicellular lung spheroid model. The present findings provide a potential strategy to overcome the current limitations in mitochondrial replenishment therapy, thereby promoting therapeutic applications for fibrotic intervention.

High Targeting Specificity toward Pulmonary Inflammation Using Mesenchymal Stem Cell-Hybrid Nanovehicle for an Efficient Inflammation Intervention

Pulmonary inflammation is one of the most reported tissue inflammations in clinic. Successful suppression of inflammation is vital to prevent further inevitably fatal lung degeneration. Glucocorticoid hormone, such as methylprednisolone (MP), is the most applied strategy to control the inflammatory progression yet faces the challenge of systemic side effects caused by the requirement of large-dosage and frequent administration. Highly efficient delivery of MP specifically targeted to inflammatory lung sites may overcome this challenge. Therefore, the present study develops an inflammation-targeted biomimetic nanovehicle, which hybridizes the cell membrane of mesenchymal stem cell with liposome, named as MSCsome. This hybrid nanovehicle shows the ability of high targeting specificity toward inflamed lung cells, due to both the good lung endothelium penetration and the high uptake by inflamed lung cells. Consequently, a single-dose administration of this MP-loaded hybrid nanovehicle achieves a prominent treatment of lipopolysaccharide-induced lung inflammation, and negligible treatment-induced side effects are observed. The present study provides a powerful inflammation-targeted nanovehicle using biomimetic strategy to solve the current challenges of targeted inflammation intervention.

The Dual Role of Mesenchymal Stem Cells in Cancer Pathophysiology: Pro-Tumorigenic Effects versus Therapeutic Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells involved in numerous physiological events, including organogenesis, the maintenance of tissue homeostasis, regeneration, or tissue repair. MSCs are increasingly recognized as playing a major, dual, and complex role in cancer pathophysiology through their ability to limit or promote tumor progression. Indeed, these cells are known to interact with the tumor microenvironment, modulate the behavior of tumor cells, influence their functions, and promote distant metastasis formation through the secretion of mediators, the regulation of cell-cell interactions, and the modulation of the immune response. This dynamic network can lead to the establishment of immunoprivileged tissue niches or the formation of new tumors through the proliferation/differentiation of MSCs into cancer-associated fibroblasts as well as cancer stem cells. However, MSCs exhibit also therapeutic effects including anti-tumor, anti-proliferative, anti-inflammatory, or anti-oxidative effects. The therapeutic interest in MSCs is currently growing, mainly due to their ability to selectively migrate and penetrate tumor sites, which would make them relevant as vectors for advanced therapies. Therefore, this review aims to provide an overview of the double-edged sword implications of MSCs in tumor processes. The therapeutic potential of MSCs will be reviewed in melanoma and lung cancers.

Cell Therapy as Target Therapy against Colon Cancer Stem Cells

Cancer stem cells (CSCs) are a small subpopulation of cells within tumors with properties, such as self-renewal, differentiation, and tumorigenicity. CSCs have been proposed as a plausible therapeutic target as they are responsible for tumor recurrence, metastasis, and conventional therapy resistance. Selectively targeting CSCs is a promising strategy to eliminate the propagation of tumor cells and impair overall tumor development. Recent research shows that several immune cells play a crucial role in regulating tumor cell proliferation by regulating different CSC maintenance or proliferation pathways. There have been great advances in cellular immunotherapy using T cells, natural killer (NK) cells, macrophages, or stem cells for the selective targeting of tumor cells or CSCs in colorectal cancer (CRC). This review summarizes the CRC molecular profiles that may benefit from said therapy and the main vehicles used in cell therapy against CSCs. We also discuss the challenges, limitations, and advantages of combining conventional and/or current targeted treatments in the late stages of CRC.

Mesenchymal stem cells: A living carrier for active tumor-targeted delivery

The strategy of using mesenchymal stem cells (MSCs) as a living carrier for active delivery of therapeutic agents targeting tumor sites has been attempted in a wide range of studies to validate the feasibility and efficacy for tumor treatment. This approach reveals powerful tumor targeting and tumor penetration. In addition, MSCs have been confirmed to actively participate in immunomodulation of the tumor microenvironment. Thus, MSCs are not inert delivery vehicles but have a strong impact on the fate of tumor cells. In this review, these active properties of MSCs are addressed to highlight the advantages and challenges of using MSCs for tumor-targeted delivery. In addition, some of the latest examples of using MSCs to carry a variety of anti-tumor agents for tumor-targeted therapy are summarized. Recent technologies to improve the performance and safety of this delivery strategy will be introduced. The advances, applications, and challenges summarized in this review will provide a general understanding of this promising strategy for actively delivering drugs to tumor tissues.

The in vivo fate and targeting engineering of crossover vesicle-based gene delivery system

Exosomes and biomimetic vesicles are widely used for gene delivery because of their excellent gene loading capacity and stability and their natural targeting delivery potential. These vesicles take advantages of both cell-based bioactive delivery system and synthetical lipid-derived nanovectors to form crossover characteristics. To further optimize the specific targeting properties of crossover vesicles, studies of their in vivo fate and various engineering approaches including nanobiotechnology are required. This review describes the preparation process of exosomes and biomimetic vesicles, and summarizes the mechanism of loading and delivery of nucleic acids or gene editing systems. We provide a comprehensive overview of the techniques employed for preparing the targeting crossover vesicles based on their cellular uptake and targeting mechanism. To delineate the future prospects of crossover vesicle gene delivery systems, various challenges and clinical applications of vesicles have also been discussed.

Engineered Mesenchymal Stem Cells as a Biotherapy Platform for Targeted Photodynamic Immunotherapy of Breast Cancer

Interleukin-12 (IL12) is a pleiotropic cytokine with promising prospects for cancer immunotherapy. Though IL12 gene-based therapy can overcome the fatal hurdle of severe systemic toxicity, targeted delivery and tumor-located expression of IL12 gene remain the challenging issues yet to be solved. Photo-immunotherapy emerging as a novel and precise therapeutic strategy, which elaborately combines immune-activating agents with light-triggered photosensitizers for potentiated anticancer efficacy. Herein, an engineered stem cell-based biotherapy platform (MB/IL12-MSCs) incorporating immune gene plasmid IL12 (pIL12) and photosensitizer methylene blue (MB) is developed to realize tumor-homing delivery of therapeutic agents and photo-immunotherapy efficacy enhancement. The biotherapy platform retained tumor-tropic migration and penetration functions, which improved the intratumoral distribution of therapeutic agents, thereby promoting photodynamic effects and reinforcing immune responses. Importantly, MB/IL12-MSCs restricted the expression and distribution of IL12 at tumor site, which minimized potential toxicity while eliciting sufficient anticancer immunity. In noteworthy, activation of immunity induced by MB/IL12-MSCs established long-term systemic immunologic memory to prevent tumor relapse. The MB/IL12-MSCs outperform their monotherapy counterparts in breast tumor models, and the growth of tumor significantly arrested as well as re-challenging abscopal tumor growth slowdown. Collectively, this work reveals that MSCs-based strategy may advance more efficient, durable, and safer cancer photo-immunotherapy.

Nanoparticle encapsulated CQ/TAM combination harmonizes with MSCs in arresting progression of severity in AP mice through iNOS (IDO) signaling

Background

Sever acute pancreatitis (SAP) is a critical disease with high mortality, and lack of clinically available treatments with specificity and effectiveness. Bone marrow derived mesenchymal stem cells (BMSCs) exhibited moderate effect on AP which needs further improvement.

Methods

Pancreatic infiltrating lymphocytes were analyzed to demonstrate the intervention of BMSCs on inflammatory cell infiltration of AP. Gene silencing with siRNA and small molecule inhibitor were utilized to determine the key effector molecule of BMSCs on AP. Pharmacological regulation and nanotechnology were introduced to further ameliorate BMSCs action.

Results

It was revealed that BMSCs prevent the progression of acute pancreatitis (AP) by reducing recruitment of macrophages, neutrophils and CD4+T cells in the lesion site. The pivotal role of chemokine–iNOS–IDO axis for BMSCs to intervene AP was confirmed. Compared with any single drug, Chloroquine/Tamoxifen combination together with IFN-γ pronouncedly up-regulated the transcription of several MSC immune regulators such as COX-2, PD-L1, HO-1 especially iNOS/IDO. As expected, BMSCs and human umbilical cord mesenchymal stem cells (UMSCs) pretreated with CQ/TAM/IFN-γ exerted enhanced intervention in AP and SAP mice. Moreover, pretreatment with CQ-LPs/TAM-NPs combination not only counteracted MSCs proliferation inhibition induced by free drugs but also enhanced their efficacy.

Conclusion

Under the background of rapid progress in MSCs clinical translation, this study focuses on the urgent clinical issue and initiates an original mechanism-based strategy to promote intervention on severity progression of SAP, which promises its clinical translation in future.

The Potential Applications of Stem Cells for Cancer Treatment

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Scientists encounter many obstacles in traditional cancer therapies, including the side effects on the healthy cells, drug resistance, tumor relapse, the short half-life of employed drugs in the blood circulation, and the improper delivery of drugs toward the tumor site. The unique traits of stem cells (SCs) such as self-renewal, differentiation, tumor tropism, the release of bioactive molecules, and immunosuppression have opened a new window for utilizing SCs as a novel tool in cancer treatment. In this regard, engineered SCs can secrete anti-cancer proteins or express enzymes used in suicide gene therapy which locally induce apoptosis in neoplastic cells via the bystander effect. These cells also stand as proper candidates to serve as careers for drug-loaded nanoparticles or to play suitable hosts for oncolytic viruses. Moreover, they harbor great potential to be employed in immunotherapy and combination therapy. However, tactful strategies should be devised to allow easier transplantation and protection of SCs from in vivo immune responses. In spite of the great hope concerning SCs application in cancer therapy, there are shortcomings and challenges to be addressed. This review tends to elaborate on recent advances on the various applications of SCs in cancer therapy and existing challenges in this regard.

Uniform iron oxide nanoparticles reduce the required amount of polyethylenimine in the gene delivery to mesenchymal stem cells

Cationic polyethylenimine (PEI) is regarded as the 'golden standard' of non-viral gene vectors. However, the superiority of PEI with high positive charge density also induces its major drawback of cytotoxicity, which restricts its application for an effective and safe gene delivery to stem cells. To redress this shortcoming, herein, a magnetic gene complex containing uniform iron oxide nanoparticles (UIONPs), plasmid DNA, and free PEI is prepared through electrostatic interactions for the gene delivery to bone marrow-derived mesenchymal stem cells (BM-MSCs). Results show that UIONPs dramatically promote the gene delivery to BM-MSCs using the assistance of magnetic force. In addition, decreasing the free PEI nitrogen to DNA phosphate (N/P) ratio from 10 to 6 has little adverse impact on the transgene expression levels (over 300 times than that of PEI alone at the N/P ratio of 6) and significantly reduces the cytotoxicity to BM-MSCs. Further investigations confirmed that the decrease of free PEI has little influence on the cellular uptake after applying external magnetic forces, but that the reduced positive charge density decreases the cytotoxicity. The present study demonstrates that magnetic gene delivery not only contributes to the enhanced gene expression but also helps to reduce the required amount of PEI, providing a potential strategy for an efficient and safe gene delivery to stem cells.

Iron oxide nanoparticles augment the intercellular mitochondrial transfer-mediated therapy

The transfer of mitochondria between cells has recently been revealed as a spontaneous way to protect the injured cells. However, the utilization of this natural transfer process for disease treatment is so far limited by its unsatisfactory transfer efficiency and selectivity. Here, we demonstrate that iron oxide nanoparticles (IONPs) can augment the intercellular mitochondrial transfer from human mesenchymal stem cells (hMSCs) selectively to diseased cells, owing to the enhanced formation of connexin 43–containing gap junctional channels triggered by ionized IONPs. In a mouse model of pulmonary fibrosis, the IONP-engineered hMSCs achieve a remarkable mitigation of fibrotic progression because of the promoted intercellular mitochondrial transfer, with no serious safety issues identified. The present study reports a potential method of using IONPs to enable hMSCs for efficient and safe transfer of mitochondria to diseased cells to restore mitochondrial bioenergetics.

Photodynamic Treatment of Colorectal Cancer Using Chlorin e6-Loaded Poly(lactide-co-glycolide)- Based Nanoparticles

We prepared poly(lactide-co-glycolide) (PLGA) encapsulated with chlorin e6 (Ce6) in an effort to increase the stability and efficiency of photosensitizers for photodynamic therapy (PDT). We determined that Ce6-loaded PLGA nanoparticles (PLGA-Ce6 NPs) had drug-loading efficiency of 5%. The efficiency of encapsulation was 82%, the zeta potential was- 25 mV, and the average diameter was 130 nm. The encapsulation of Ce6 in PLGA nanoparticles showed excellent stability. The nanoparticles exhibited sustained Ce6 release profiles with 50% released at the end of 3 days, whereas free Ce6 showed rapid release within 1 day. Ce6 release patterns were controlled by encapsulation into PLGA. The uptake of PLGA-Ce6 NPs was significantly enhanced by endocytosis in the first 8 hours in the HCT-116 cell line. An intracellular reactive oxygen species assay revealed the enhanced uptake of the nanoparticles. An in vitro anti-tumor activity assay showed that the PLGA-Ce6 NPs exhibited enhanced phototoxicity toward HCT-116 cells and a slightly lower IC₅₀ value in HCT-116 cells than Ce6 solution alone. Exposure of HCT-116 cell spheroids to PLGA-Ce6 NPs penetrated more profoundly and had better phototoxicity than pure drugs. These findings suggest that PLGA-Ce6 NPs might serve as PDT for colorectal cancer.

Tumor microenvironment: a prospective target of natural alkaloids for cancer treatment

Malignant tumor has become one of the major diseases that seriously endangers human health. Numerous studies have demonstrated that tumor microenvironment (TME) is closely associated with patient prognosis. Tumor growth and progression are strongly dependent on its surrounding tumor microenvironment, because the optimal conditions originated from stromal elements are required for cancer cell proliferation, invasion, metastasis and drug resistance. The tumor microenvironment is an environment rich in immune/inflammatory cells and accompanied by a continuous, gradient of hypoxia and pH. Overcoming immunosuppressive environment and boosting anti-tumor immunity may be the key to the prevention and treatment of cancer. Most traditional Chinese medicine have been proved to have good anti-tumor activity, and they have the advantages of better therapeutic effect and few side effects in the treatment of malignant tumors. An increasing number of studies are giving evidence that alkaloids extracted from traditional Chinese medicine possess a significant anticancer efficiency via regulating a variety of tumor-related genes, pathways and other mechanisms. This paper reviews the anti-tumor effect of alkaloids targeting tumor microenvironment, and further reveals its anti-tumor mechanism through the effects of alkaloids on different components in tumor microenvironment.

Iron Oxide Nanoparticles Promote Cx43-Overexpression of Mesenchymal Stem Cells for Efficient Suicide Gene Therapy during Glioma Treatment

Background: Mesenchymal stem cells (MSCs) have been applied as a promising vehicle for tumour-targeted delivery of suicide genes in the herpes simplex virus thymidine kinase (HSV-tk)/ganciclovir (GCV) suicide gene therapy against malignant gliomas. The efficiency of this strategy is largely dependent on the bystander effect, which relies on high suicide gene expression levels and efficient transportation of activated GCV towards glioma cells. However, up to now, the methods to enhance the bystander effect of this strategy in an efficient and safe way are still lacking and new approaches to improve this therapeutic strategy are required.

Methods: In this study, MSCs were gene transfected using magnetosome-like ferrimagnetic iron oxide nanochains (MFIONs) to highly express HSV-tk. Both the suicide and bystander effects of HSV-tk expressed MSCs (MSCs-tk) were quantitatively evaluated. Connexin 43 (Cx43) expression by MSCs and glioma cells was measured under different treatments. Intercellular communication between MSCs and C6 glioma cells was examined using a dye transfer assay. Glioma tropism and the bio-distribution of MSCs-tk were observed. Anti-tumour activity was investigated in the orthotopic glioma of rats after intravenous administration of MSCs-tk followed by intraperitoneal injection of GCV.

Results: Gene transfection using MFIONs achieved sufficient expression of HSV-tk and triggered Cx43 overexpression in MSCs. These Cx43 overexpressing MSCs promoted gap junction intercellular communication (GJIC) between MSCs and glioma cells, resulting in significantly inhibited growth of glioma through an improved bystander effect. Outstanding tumour targeting and significantly prolonged survival with decreased tumour size were observed after the treatment using MFION-transfected MSCs in glioma model rats.

Conclusion: Our results show that iron oxide nanoparticles have the potential to improve the suicide gene expression levels of transfected MSCs, while promoting the GJIC formation between MSCs and tumour cells, which enhances the sensitivity of glioma cells to HSV-tk/GCV suicide gene therapy.

Mesenchymal Stem/Stromal Cell-Based Delivery: A Rapidly Evolving Strategy for Cancer Therapy

Mesenchymal stem/stromal cell (MSC)-based therapy has become an attractive and advanced scientific research area in the context of cancer therapy. This interest is closely linked to the MSC-marked tropism for tumors, suggesting them as a rational and effective vehicle for drug delivery for both hematological and solid malignancies. Nonetheless, the therapeutic application of the MSCs in human tumors is still controversial because of the induction of several signaling pathways largely contributing to tumor progression and metastasis. In spite of some evidence supporting that MSCs may sustain cancer pathogenesis, increasing proofs have indicated the suppressive influences of MSCs on tumor cells. During the last years, a myriad of preclinical and some clinical studies have been carried out or are ongoing to address the safety and efficacy of the MSC-based delivery of therapeutic agents in diverse types of malignancies. A large number of studies have focused on the MSC application as delivery vehicles for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), chemotherapeutic drug such as gemcitabine (GCB), paclitaxel (PTX), and doxorubicin (DOX), prodrugs such as 5-fluorocytosine (5-FC) and ganciclovir (GCV), and immune cell-activating cytokines along with oncolytic virus. In the current review, we evaluate the latest findings rendering the potential of MSCs to be employed as potent gene/drug delivery vehicle for inducing tumor regression with a special focus on the in vivo reports performed during the last two decades.

Systemic administration of mesenchymal stem cells loaded with a novel oncolytic adenovirus carrying IL-24/endostatin enhances glioma therapy

Oncolytic adenovirus-mediated gene therapy shows promise for cancer treatment; however, the systemic delivery of oncolytic adenovirus to tumors remains challenging. Recently, mesenchymal stem cells (MSCs) have emerged as potential vehicles for improving delivery. Yet, because the oncolytic adenovirus replicates in MSCs, balancing MSC viability with viral load is key to achieving optimal therapeutic effect. We thus developed an all-in-one Tet-on system that can regulate replication of oncolytic adenovirus. Then, we loaded the novel oncolytic adenovirus carrying interleukin (IL)-24 and/or Endostatin in human umbilical cord blood-mesenchymal stem cells (hUCB-MSCs) for glioma therapy. In vitro assays demonstrated that this novel oncolytic adenovirus could efficiently replicate and kill glioma cells while sparing normal cells. Moreover, doxycycline effectively regulated oncolytic adenovirus replication in the hUCB-MSCs. The doxycycline induction group with dual expression of IL-24 and Endostatin exhibited significantly greater antitumor effects than other groups in a xenograft model of glioma. Thus, this strategy for systemic delivery of oncolytic adenovirus with its oncolytic activity controlled by a Tet-on system is a promising method for achieving antitumor efficacy in glioma, especially for metastatic tumors.

Active stealth and self-positioning biomimetic vehicles achieved effective antitumor therapy

Mesenchymal stem cells (MSCs) are recognized as promising drug delivery vehicles. However, the limitation of drug loading capacity and safety considerations are two obstacles to the further application of MSCs. Here, we report MSC membrane-coated mesoporous silica nanoparticles (MSN@M) that maintain the active stealth and self-positioning drug delivery abilities of MSCs and resolve issues related to MSCs-mediated drug delivery. MSN@M was established through uniformly integrating MSC membrane onto a mesoporous silica nanoparticle (MSN) core by sonication. Reduced clearance of phagocytes mediated by CD47 marker on MSC membrane was observed in vitro, which explained the only ~ 25% clearance rate of MSN@M compared with MSN in vivo within 24 h. MSN@M also showed stronger tumor targeting and penetration ability compared with MSN in HepG2 tumor bearing mice. Simultaneously, MSN@M exhibited strong capacity for drug loading and sustained drug release ability of MSN when loaded with doxorubicin (DOX), the drug loading of MSN@M increased ~ 5 folds compared with MSC membrane. In HepG2 xenograft mice, DOX-loaded MSN@M effectively inhibited the growth of tumors and decreased the side effects of treatment by decreasing the exposure of other tissues to DOX. Consequently, our MSN@M may serve as alternative vehicles for MSCs and provide more options for antitumor treatment.

Generation of a Three-Dimensional in Vitro Ovarian Cancer Co-Culture Model for Drug Screening Assays

In vitro 3D culture models have emerged in the cancer field due to their ability to recapitulate characteristics of the in vivo tumor. Herein, we described the establishment and characterization of 3D multicellular spheroids using ovarian cancer cells (SKOV-3) in co-culture with mesenchymal cells (MUC-9) or fibroblasts (CCD27-Sk). We demonstrated that SKOV-3 cells in co-culture were able to form regular and compact spheroids with diameters ranging from 300 to 400 µm and with a roundness close to 1.0 regardless of the type of stromal cell used. In the 3D culture an increase was not observed in spheroid diameter nor was there significant cell growth. What is more, the 3D co-cultures presented an up regulation of genes related to tumorigenesis, angiogenesis and metastases (MMP2, VEGFA, SNAI1, ZEB1 and VIM) when compared with 2D and 3D monoculture. As expected, both 3D cultures (mono and co-cultures) exhibited a higher Paclitaxel chemoresistance when compared to 2D condition. Although we did not observe differences in the Paclitaxel resistance between the 3D mono and co-cultures, the gene expression results indicate that the presence of mesenchymal cells and fibroblasts better recapitulate the in vivo tumor microenvironment, being able, therefore, to more accurately evaluate drug efficacy for ovarian cancer therapy.

Current advances and challenges of mesenchymal stem cells-based drug delivery system and their improvements

Mesenchymal stem cells (MSCs) have recently emerged as a promising living carrier for targeted drug delivery. A wealth of literature has shown evidence for great advances in MSCs-based drug delivery system (MSCs-DDS) in the treatment of various diseases. Nevertheless, as this field of study rapidly advances, several challenges associated with this delivery strategy have arisen, mainly due to the inherent limitations of MSCs. To this end, several novel technologies are being developed in parallel to improve the efficiency or safety of this system. In this review, we introduce recent advances and summarize the present challenges of MSCs-DDS. We also highlight some potential technologies to improve MSCs-DDS, including nanotechnology, genome engineering technology, and biomimetic technology. Finally, prospects for application of artificially improved MSCs-DDS are addressed. The technologies summarized in this review provide a general guideline for the improvement of MSCs-DDS.

Engineered microtissues for the bystander therapy against cancer

Thymidine kinase expressing human adipose mesenchymal stem cells (TK-hAMSCs) in combination with ganciclovir (GCV) are an effective platform for antitumor bystander therapy in mice models. However, this strategy requires multiple TK-hAMSCs administrations and a substantial number of cells. Therefore, for clinical translation, it is necessary to find a biocompatible scaffold providing TK-hAMSCs retention in the implantation site against their rapid wash-out. We have developed a microtissue (MT) composed by TKhAMSCs and a scaffold made of polylactic acid microparticles and cell-derived extracellular matrix deposited by hAMSCs. The efficacy of these MTs as vehicles for TK-hAMSCs/GCV bystander therapy was evaluated in a rodent model of human prostate cancer. Subcutaneously implanted MTs were integrated in the surrounding tissue, allowing neovascularization and maintenance of TK-hAMSCs viability. Furthermore, MTs implanted beside tumors allowed TK-hAMSCs migration towards tumor cells and, after GCV administration, inhibited tumor growth. These results indicate that TK-hAMSCs-MTs are promising cell reservoirs for clinical use of therapeutic MSCs in bystander therapies.

Bacteria-Derived Nanoparticles: Multifunctional Containers for Diagnostic and Therapeutic Applications

In recent decades, investigations on bacteria-derived materials have progressed from being a proof of concept to a means for improving traditional biomaterials. Owing to their unique characteristics, such as gene manipulation, rapid proliferation, and specific targeting, bacteria-derived materials have provided remarkable flexibility in applied biomedical functionalization. In this review, bacteria-derived nanoparticles are focused on as a promising biomaterial, introducing several bacterial species with great potential and useful strategies for fabrication. Through well-designed choices, bacteria-derived nanoparticles can be exploited to obtain functional bacteria-mimicking materials for a variety of applications, including cargo delivery, imaging, therapy, and immune modulation. Finally, the prospects and challenges of bacteria-derived nanoparticles are discussed. Particularly, safety concerns regarding the use of bacteria and their immunogenicity remain major obstacles to the clinical application of bacteria-derived nanoparticles and these concerns are immediate priorities for the research community.

New Insights into Biocompatible Iron Oxide Nanoparticles: A Potential Booster of Gene Delivery to Stem Cells

Gene delivery to stem cells is a critical issue of stem cells-based therapies, still facing ongoing challenges regarding efficiency and safety. Recent advances in the controlled synthesis of biocompatible magnetic iron oxide nanoparticles (IONPs) have provided a powerful nanotool for assisting gene delivery to stem cells. However, this field is still at an early stage, with well-designed and scalable IONPs synthesis highly desired. Furthermore, the potential risks or bioeffects of IONPs on stem cells are not completely figured out. Therefore, in this review, the updated researches focused on the gene delivery to stem cells using various designed IONPs are highlighted. Additionally, the impacts of the physicochemical properties of IONPs, as well as the magnetofection systems on the gene delivery performance and biocompatibility are summarized. Finally, challenges attributed to the potential impacts of IONPs on the biologic behaviors of stem cells and the large-scale productions of uniform IONPs are emphasized. The principles and challenges summarized in this review provide a general guidance for the rational design of IONPs-assisted gene delivery to stem cells.

Suicide Gene Therapy Against Malignant Gliomas by the Local Delivery of Genetically Engineered Umbilical Cord Mesenchymal Stem Cells as Cellular Vehicles

BACKGROUND

Glioblastoma (GBM) is a malignant tumor that is difficult to eliminate, and new therapies are thus strongly desired. Mesenchymal stem cells (MSCs) have the ability to locate to injured tissues, inflammation sites and tumors and are thus good candidates for carrying antitumor genes for the treatment of tumors. Treating GBM with MSCs that have been transduced with the herpes simplex virus thymidine kinase (HSV-TK) gene has brought significant advances because MSCs can exert a bystander effect on tumor cells upon treatment with the prodrug ganciclovir (GCV).

OBJECTIVE

In this study, we aimed to determine whether HSV-TK-expressing umbilical cord mesenchymal stem cells (MSCTKs) together with prodrug GCV treatment could exert a bystander killing effect on GBM.

METHODS AND RESULTS

Compared with MSCTK: U87 ratio at 1:10,1:100 and 1:100, GCV concentration at 2.5µM or 250µM, when MSCTKs were cocultured with U87 cells at a ratio of 1:1, 25 µM GCV exerted a more stable killing effect. Higher amounts of MSCTKs cocultured with U87 cells were correlated with a better bystander effect exerted by the MSCTK/GCV system. We built U87-driven subcutaneous tumor models and brain intracranial tumor models to evaluate the efficiency of the MSCTK/GCV system on subcutaneous and intracranial tumors and found that MSCTK/GCV was effective in both models. The ratio of MSCTKs and tumor cells played a critical role in this therapeutic effect, with a higher MSCTK/U87 ratio exerting a better effect.

CONCLUSION

This research suggested that the MSCTK/GCV system exerts a strong bystander effect on GBM tumor cells, and this system may be a promising assistant method for GBM postoperative therapy.

The Potential of Milk-Derived Exosomes for Drug Delivery

BACKGROUND

Exosomes, one of the extracellular vesicles, are widely present in all biological fluids and play an important role in intercellular communication. Due to their hydrophobic lipid bilayer and aqueous hydrophilic core structure, they are considered a possible alternative to liposome drug delivery systems. Not only do they protect the cargo like liposomes during delivery, but they are also less toxic and better tolerated. However, due to the lack of sources and methods for obtaining enough exosomes, the therapeutic application of exosomes as drug carriers is limited.

METHODS

A literature search was performed using the ScienceDirect and PubMed electronic databases to obtain information from published literature on milk exosomes related to drug delivery.

RESULTS

Here, we briefly reviewed the current knowledge of exosomes, expounded the advantages of milk-derived exosomes over other delivery vectors, including higher yield, the oral delivery characteristic and additional therapeutic benefits. The purification and drug loading methods of milk exosomes, and the current application of milk exosomes were also introduced.

CONCLUSION

The emergence of milk-derived exosomes is expected to break through the limitations of exosomes as therapeutic carriers of drugs. We hope to raise awareness of the therapeutic potential of milk-derived exosomes as a new drug delivery system.

Prognosis and targeting of pre-metastatic niche

As the main cause of tumoral fatality, metastasis remains to be one of the most urgent difficulties researcher struggled to overcome. During the development and progression of metastasis, the establishment of pre-metastatic niche is crucial in preparing fertile microenvironment for disseminated tumor cells settlement and colonization in distant metastatic target sites. The key participators, including the primary tumor-derived factors, bone marrow-derived cells, stromal cells of both the host and the potential metastatic sites, regulate the temporal progress of potential metastasis. Firstly, pioneers are sent from primary tumor, recruiting immunosuppressive cells; then circulating tumor cells settled and colonized; and finally, micrometastases develop. Here, we summarize the therapeutic strategies presented in recent years targeting different stages of the pre-metastatic niche formation and discuss their chances and challenges in clinical translation, providing promising approaches for metastasis prevention and therapeutic interventions.

[Progress on utilizing mesenchymal stem cells as cellular delivery system for targeting delivery of as drug/gene for anti-tumor therapy]

Mesenchymal stem cells (MSCs) have the inherent tumor-homing ability with the attraction of multiple chemokines released by tumor tissues or tumor microenvironments, which can be utilized as promising cellular carriers for targeted delivery of anti-tumor drugs and genes. In most circumstances, large amount of systemicly administrated MSCs will be firstly trapped by lungs, following with re-distribution and homing to tumor tissues after lung clearance. Several approaches like enhanced interactions between chemokines and receptors on MSCs or reducing the retention of MSCs by changes of administration methods are firstly reviewed for improving the homing of MSCs towards tumor tissues. Additionally, the potentials and gains of utilizing MSCs to carry several chemotherapeutics, such as doxorubicin, paclitaxel and gemcitabine are summarized, showing the advantages of overcoming the short half-life and poor tumor targeting of these chemotherapeutics. Moreover, the applications of MSCs to protect and deliver therapeutic genes to tumor sites for selectively tumor cells eliminating or promoting immune system are highlighted. In addition, the potentials of using MSCs for tumor-targeting delivery of diagnostic and therapeutic agents are addressed. We believed that the continuous improvement and optimization of this stem cells-based cellular delivery system will provide a novel delivery strategy and option for tumor treatment.

Co-delivery of doxorubicin and epacadostat via heparin coated pH-sensitive liposomes to suppress the lung metastasis of melanoma

High metastasis is responsible for the failure in the treatment of melanoma. Chemoimmunotherapy has shown conspicuous inhibition effects not only on the growth of tumor in situ, but also on the metastasis to distant organs. Given that the indoleamine-2,3 dioxygenase (IDO) overexpressed in the microenvironment of tumor leads to the immune escape, the combination of chemotherapeutic drug and IDO inhibitor might be a promising chemoimmunotherapy. Besides, the hematogenous metastasis mediated by platelets was supposed to be blocked by the heparin (HP). Therefore, a drug delivery system with all these elements involved might be a potential treatment for melanoma. Here, we developed a pH-sensitive liposomal dual-delivery system for doxorubicin (DOX) and epacadostat (EPA) with HP coated (HP/LDE). It was confirmed to enhance cytotoxicity and apoptosis, reverse the platelets-activated epithelial mesenchymal transformation (EMT) and prevent the invasion and migration in vitro. After systemic administration, HP/LDE provided the optimum anti-metastasis effect on the melanoma. The results of evaluation on DC maturation, CD8⁺ cytotoxic T lymphocytes (CTLs) activation and T cell mediated cytotoxicity were consistent in vitro and in vivo. Taken together, our study established a functional liposomal dual-delivery system with ideal anti-metastasis efficacy on melanoma.

Adipocyte-Based Cell Therapy in Oncology: The Role of Cancer-Associated Adipocytes and Their Reinterpretation as Delivery Platforms

Cancer-associated adipocytes have functional roles in tumor development through secreted adipocyte-derived factors and exosomes and also through metabolic symbiosis, where the malignant cells take up the lactate, fatty acids and glutamine produced by the neighboring adipocytes. Recent research has demonstrated the value of adipocytes as cell-based delivery platforms for drugs (or prodrugs), nucleic acids or loaded nanoparticles for cancer therapy. This strategy takes advantage of the biocompatibility of the delivery system, its ability to locate the tumor site and also the predisposition of cancer cells to come in functional contact with the adipocytes from the tumor microenvironment for metabolic sustenance. Also, their exosomal content can be used in the context of cancer stem cell reprogramming or as a delivery vehicle for different cargos, like non-coding nucleic acids. Moreover, the process of adipocytes isolation, processing and charging is quite straightforward, with minimal economical expenses. The present review comprehensively presents the role of adipocytes in cancer (in the context of obese and non-obese individuals), the main methods for isolation and characterization and also the current therapeutic applications of these cells as delivery platforms in the oncology sector.

Mesenchymal stromal cells mediated delivery of photoactive nanoparticles inhibits osteosarcoma growth in vitro and in a murine in vivo ectopic model

Background

Osteosarcoma (OS) is an aggressive malignant neoplasm that still suffers from poor prognosis in the case of distal metastases or occurrence of multi-drug resistance. It is therefore crucial to find novel therapeutic options able to go beyond these limitations and improve patients’ survival. The objective of this study is to exploit the intrinsic properties of mesenchymal stromal cells (MSCs) to migrate and infiltrate the tumor stroma to specifically deliver therapeutic agents directly to cancer cells. In particular, we aimed to test the efficacy of the photoactivation of MSCs loaded with nanoparticles in vitro and in a murine in vivo ectopic osteosarcoma model.

Methods

AlPcS₄@FNPs were produced by adding tetra-sulfonated aluminum phthalocyanine (AlPcS₄) to an aqueous solution of positively charged poly-methyl methacrylate core-shell fluorescent nanoparticles (FNPs). The photodynamic therapy (PDT) effect is achieved by activation of the photosensitizer AlPcS₄ in the near-infrared light with an LED source. Human MSCs were isolated from the bone marrow of five donors to account for inter-patients variability and used in this study after being evaluated for their clonogenicity, multipotency and immunophenotypic profile. MSC lines were then tested for the ability to internalize and retain the nanoparticles, along with their migratory properties in vitro. Photoactivation effect was evaluated both in a monolayer (2D) co-culture of AlPcS₄@FNPs loaded MSCs with human OS cells (SaOS-2) and in tridimensional (3D) multicellular spheroids (AlPcS₄@FNPs loaded MSCs with human OS cells, MG-63). Cell death was assessed by AnnexinV/PI and Live&Dead CalceinAM/EthD staining in 2D, while in the 3D co-culture, the cell killing effect was measured through ATP content, CalceinAM/EthD staining and TEM imaging. We also evaluated the effectiveness of AlPcS₄@FNPs loaded MSCs as delivery systems and the ability of the photodynamic treatment to kill cancer cells in a subcutaneous mouse model of OS by bioluminescence imaging (BLI) and histology.

Results

MSCs internalized AlPcS₄@FNPs without losing or altering their motility and viability in vitro. Photoactivation of AlPcS₄@FNPs loaded MSCs induced high level of OS cells death in the 2D co-culture. Similarly, in the 3D co-culture (MSCs:OS ratios 1:1 or 1:3), a substantial decrease of both MSCs and OS cells viability was observed. Notably, when increasing the MSCs:OS ratio to 1:7, photoactivation still caused more than 40% cells death. When tested in an in vivo ectopic OS model, AlPcS4@FNPs loaded MSCs were able to decrease OS growth by 68% after two cycles of photoactivation.

Conclusions

Our findings demonstrate that MSCs can deliver functional photosensitizer-decorated nanoparticles in vitro and in vivo and inhibit OS tumor growth. MSCs may be an effective platform for the targeted delivery of therapeutic nanodrugs in a clinical scenario, alone or in combination with other osteosarcoma treatment modalities.

Virus-derived materials: bury the hatchet with old foes

Viruses, with special architecture and unique biological nature, can be utilized for various biomedical applications.

A Trojan horse biomimetic delivery strategy using mesenchymal stem cells for PDT/PTT therapy against lung melanoma metastasis

Mesenchymal stem cell (MSC)-based biomimetic delivery has been actively explored for drug accumulation and penetration into tumors by taking advantage of the tumor-tropic and penetration properties of MSCs. In this work, we further demonstrated the feasibility of MSC-mediated nano drug delivery, which was characterized by the "Trojan horse"-like transport via an endocytosis-exocytosis-endocytosis process between MSCs and cancer cells. Chlorin e6 (Ce6)-conjugated polydopamine nanoparticles (PDA-Ce6) were developed and loaded into the MSCs. Phototherapeutic agents are safe to the MSCs, and their very low dark toxicity causes no impairment of the inherent properties of MSCs, including tumor-homing ability. The MSCs loaded with PDA-Ce6 (MSC-PDA-Ce6) were able to target and penetrate into tumors and exocytose 60% of the payloads in 72 h. The released PDA-Ce6 NPs could penetrate deep and be re-endocytosed by the cancer cells. MSC-PDA-Ce6 tended to accumulate in the lungs and delivered PDA-Ce6 into the tumors after intravenous injection in the mouse model with lung melanoma metastasis. Phototoxicity can be selectively triggered in the tumors by sequentially treating with near-infrared irradiation to induce photodynamic therapy (PDT) and photothermal therapy (PTT). The MSC-based biomimetic delivery of PDA-Ce6 nanoparticles is a potential method for dual phototherapy against lung melanoma metastasis.

Magnetic ternary nanohybrids for nonviral gene delivery of stem cells and applications on cancer therapy

Cancer toxic agent-expressing mesenchymal stem cells (MSCs), which possess inherent tumor migration and penetration capabilities, have received increasing attention in cancer therapy. To ensure that this approach is successful, safe and efficient gene delivery methods for stem cell engineering must be developed. Methods: In this study, a magnetic ternary nanohybrid (MTN) system comprising biodegradable cationic materials, nucleic acids, and hyaluronic acid-decorated superparamagnetic iron oxide nanoparticles was proposed to construct stem cells expressing the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) via magnetic force and receptor dual targeting. Results: The CD44/magnetic force-mediated enhanced cellular uptake of MTNs by human mesenchymal cells (hMSCs) was confirmed in vitro. Highly efficient transfection was attained using MTNs without having any detrimental effect on the tumor migration and penetration capabilities of hMSCs. TRAIL expressed by the MTN-transfected hMSCs displayed strong anticancer effects through the activation of caspase-3 apoptotic signaling. The MTN-transfected hMSCs can be clearly imaged using magnetic resonance imaging techniques in vivo. In an orthotopic xenograft cancer model, MTN-transfected TRAIL-expressing hMSCs significantly suppressed the progression of human glioma (U87MG) and prolonged the survival of the animal. Conclusions: These findings suggest the considerable potential of utilizing MTNs for effectively constructing tumor toxic agent-expressing stem cells for treating malignant cancers.

Cefquinome-Loaded Microsphere Formulations in Protection against Pneumonia with Klebsiella pneumonia Infection and Inflammatory Response in Rats

PURPOSE

This study aimed to compare in vivo activity between cefquinome (CEQ)-loaded poly lactic-co-glycolic acid (PLGA) microspheres (CEQ-PLGA-MS) and CEQ injection (CEQ-INJ) against Klebsiella pneumonia in a rat lung infection model.

METHODS

Forty-eight rats were divided into control group (sham operated without infection and drug treatment), Klebsiella pneumonia model group (KPD + Saline), CEQ-PLGA-MS and CEQ-INJ therapy groups (KPD + CEQ-PLGA-MS and KPD + INJ, respectively). In the KPD + Saline group, rats were infected with Klebsiella pneumonia ATCC 10031. In the KPD + CEQ-PLGA-MS and KPD + INJ groups, infected rats were intravenously injected with 12.5 mg/kg body weight CEQ-PLGA-MS and CEQ-INJ, respectively.

RESULTS

Compared to CEQ-INJ treatment group, CEQ-PLGA-MS treatment further decreased the number of bacteria colonies (decreased to 1.94 lg CFU/g) in lung tissues and the levels of inflammatory cytokine including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-4 (p < 0.05 or p < 0.01) in bronchoalveolar lavage fluid at 48 h. Consistently, a significant decreases of scores of inflammation severity were showed at 48 h in the KPD + CEQ-PLGA-MS treatment group, compared to the KPD + CEQ-INJ treatment group.

CONCLUSION

Our results reveal that CEQ-PLGA-MS has the better therapeutic effect than CEQ-INJ for Klebsiella pneumonia lung infections in rats. The vehicle of CEQ-PLGA-MS as the promising alternatives to control the lung infections with the important pathogens.

Recent strategies on targeted delivery of thrombolytics

Thrombus formed in blood vessel is a progressive process, which would lead to life-threatening thrombotic diseases such as ischemic stroke. Unlike other diseases, the recognition of thrombus is usually in the late stage where blood vessels are largely blocked. So acute thrombotic diseases have a narrow therapeutic window, and remain leading causes of morbidity and mortality, whereas current thrombolysis therapy has limited therapeutic effects and bleeding complications. Thrombolytic agents in unwanted sites would cause hemorrhage due to the activation of plasminogen. Moreover, untargeted thrombolysis therapy require large amounts of thrombolytic agents, which in return would enhance hemorrhage risk. To improve the efficiency while minimizing the adverse effects of traditional thrombolysis therapy, novel drug delivery systems have been investigated. Various targeting strategies including ultrasound and magnetic field directed targeting, and specific binding, have been designed to deliver thrombolytic drugs to the thrombotic sites. These strategies demonstrate promising results in reducing bleeding risk as well as allowing less dosage of thrombolytic drugs with lowered clot lysis time. In this review, we discuss recent progress on targeted delivery of thrombolytics, and summarize treatment advantages and shortcomings, potentially helping to further promote the development of targeted thrombolysis.

Mesenchymal stem cell-based drug delivery strategy: from cells to biomimetic

Owing to the diversity and ease of preparation of nanomaterials, the rational nanocarriers with a rational design have become increasingly popular in medical researches. Although nanoparticle-based drug delivery exhibits great potential, there are some challenges facing like rapid plasma clearance, triggering or aggravation of immune response, etc. Herein, cell-based targeted drug delivery systems have drawn more and more attention owing to low immunogenicity and intrinsic mutation rate, and innate ability to allow targeted delivery. Mesenchymal stem cells (MSCs) have been used in gene and drug delivery. The use of MSCs is a promising approach for the development of gene transfer systems and drug loading strategies because of their intrinsic properties, including homing ability and tumor tropism. By combining the inherent cell properties and merits of synthetic nanoparticles (NPs), cell membrane coated NPs emerge as the time requires. Overall, we provide a comprehensive overview of the utility of MSCs in drug and gene delivery as well as MSC membrane coated nanoparticles for therapy and drug delivery, aiming to figure out the significant room for development and highlight the potential future directions.

Cefquinome-loaded microsphere formulations against Klebsiella pneumonia infection during experimental infections

The aim of this study was to prepare cefquinome-loaded polylactic acid microspheres and to evaluate their in vitro and in vivo characteristics and pharmacodynamics for the therapy of pneumonia in a rat model. Microspheres were prepared using a 0.7 mm two-fluid nozzle spray drier in one step resulting in spherical and smooth microspheres of uniform size (9.8 ± 3.6 μm). The encapsulation efficiency and drug loading of cefquinome were 91.6 ± 2.6% and 18.7 ± 1.2%, respectively. In vitro release of cefquinome from the microspheres was sustained for 36 h. Cefquinome-loaded polylactic acid microspheres as a drug delivery system was successful for clearing experimental Klebsiella pneumonia lung infections. A decrease in inflammatory cells and an inhibition of inflammatory cytokines TNF-α, IL-1β and IL-8 after microspheres treatment was found. Changes in cytokine levels and types are secondary manifestations of drug bactericidal effects. Rats were considered to be microbiologically cured because the bacterial load was less than 100 CFU/g. These results also indicated that the spray-drying method of loading therapeutic drug into polylactic acid microspheres is a straightforward and safe method for lung-targeting therapy in animals.

Mesenchymal stem cells loaded with paclitaxel-poly(lactic-co-glycolic acid) nanoparticles for glioma-targeting therapy

Background

Mesenchymal stem cells (MSCs) possess inherent tropism towards tumor cells, and so have attracted increased attention as targeted-therapy vehicles for glioma treatment.

Purpose

The objective of this study was to demonstrate the injection of MSCs loaded with paclitaxel (Ptx)-encapsulated poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) for orthotopic glioma therapy in rats.

Methods

Ptx-PLGA NP-loaded MSC was obtained by incubating MSCs with Ptx-PLGA NPs. The drug transfer and cytotoxicity of Ptx-PLGA NP-loaded MSC against tumor cells were investigated in the transwell system. Biodistribution and antitumor activity was evaluated in the orthotopic glioma rats after contralateral injection.

Results

The optimal dose of MSC-loaded Ptx-PLGA NPs (1 pg/cell Ptx) had little effect on MSC-migration capacity, cell cycle, or multilineage-differentiation potential. Compared with Ptx-primed MSCs, Ptx-PLGA NP-primed MSCs had enhanced sustained Ptx release in the form of free Ptx and Ptx NPs. Ptx transfer from MSCs to glioma cells could induce tumor cell death in vitro. As for distribution in vivo, NP-loaded fluorescent MSCs were tracked throughout the tumor mass for 2 days after therapeutic injection. Survival was significantly longer after contralateral implantation of Ptx-PLGA NP-loaded MSCs than those injected with Ptx-primed MSCs or Ptx-PLGA NPs alone.

Conclusion

Based on timing and sufficient Ptx transfer from the MSCs to the tumor cells, Ptx-PLGA NP-loaded MSC is effective for glioma treatment. Incorporation of chemotherapeutic drug-loaded NPs into MSCs is a promising strategy for tumor-targeted therapy.

Enhancement of Tumor Cell Death by Combining gef Gene Mediated Therapy and New 1,4-Benzoxazepin-2,6-Dichloropurine Derivatives in Breast Cancer Cells

New treatment modalities are urgently needed to better manage advanced breast cancer. Combination therapies are usually more effective than monotherapy. In this context, the use of cyclic and acyclic O,N-acetals derivative compounds in combination with the suicide gef gene shown a potent anti-tumor activity and represent a new generation of anticancer agents. Here, we evaluate the use of the gef gene to promote and increase the anti-tumor effect of cyclic and acyclic O,N-acetals purine derivatives and elucidate their mechanisms of action. Among all compounds tested, those with a nitro group and a cyclic pattern structures (FC-30b2, FC-29c, and bozepinib) are the most benefited from the gef gene effect. These compounds, in combination with gef gene, were able to abolish tumor cell proliferation with a minimal dose leading to more effective and less toxic chemotherapy. The effect of this combined therapy is triggered by apoptosis induction which can be found deregulated in the later stage of breast cancer. Moreover, the combined therapy leads to an increase of cell post-apoptotic secondary necrosis that is able to promote the immunogenicity of cancer cells leading to a successful treatment. This data suggests that this novel combination therapy represents a promising candidate for breast cancer treatment.

Regulated Mesenchymal Stem Cells Mediated Colon Cancer Therapy Assessed by Reporter Gene Based Optical Imaging

Colorectal cancer is the most common cancer in both men and women and the second most common cause of cancer-related deaths. Suicide gene-based therapy with suicide gene-transduced mesenchymal stem cells (MSCs) is a promising therapeutic strategy. A tetracycline-controlled Tet-On inducible system used to regulate gene expression may be a useful tool for gene-based therapies. The aim of this study was to develop therapeutic MSCs with a suicide gene that is induced by an artificial stimulus, to validate therapeutic gene expression, and to monitor the MSC therapy for colon cancer using optical molecular imaging. For our study, we designed the Tet-On system using a retroviral vector and developed a response plasmid RetroX-TRE (tetracycline response element) expressing a mutant form of herpes simplex virus thymidine kinase (HSV1-sr39TK) with dual reporters (eGFP-Fluc2). Bone marrow-derived MSCs were transduced using a RetroX-Tet3G (Clontech, CA, USA) regulatory plasmid and RetroX-TRE-HSV1-sr39TK-eGFP-IRES-Fluc2, for a system with a Tet-On (MSC-Tet-TK/Fluc2 or MSC-Tet-TK) or without a Tet-On (MSC-TK/Fluc2 or MSC-TK) function. Suicide gene engineered MSCs were co-cultured with colon cancer cells (CT26/Rluc) in the presence of the prodrug ganciclovir (GCV) after stimulation with or without doxycycline (DOX). Treatment efficiency was monitored by assessing Rluc (CT26/Rluc) and Fluc (MSC-Tet-TK and MSC-TK) activity using optical imaging. The bystander effect of therapeutic MSCs was confirmed in CT26/Rluc cells after GCV treatment. Rluc activity in CT26/Rluc cells decreased significantly with GCV treatment of DOX(+) cells (p < 0.05 and 0.01) whereas no significant changes were observed in DOX(-) cells. In addition, Fluc activity in also decreased significantly with DOX(+) MSC-Tet-TK cells, but no signal was observed in DOX(-) cells. In addition, an MSC-TK bystander effect was also confirmed. We assessed therapy with this system in a colon cancer xenograft model (CT26/Rluc). We successfully transduced cells and developed a Tet-On system with the suicide gene HSV1-sr39TK. Our results confirmed the therapeutic efficiency of a suicide gene with the Tet-On system for colon cancer. In addition, our results provide an innovative therapeutic approach using the Tet-On system to eradicate tumors by administration of MSC-Tet-TK cells with DOX and GCV.

Self-sensibilized polymeric prodrug co-delivering MMP-9 shRNA plasmid for combined treatment of tumors

Polymeric prodrugs are of immense interest as anticancer drug-delivery system owing to their superior drug stability during circulation and satisfactory drug loading capacity. However, they are usually less effective than free drugs due to imperfect degradable characteristics or active sites blockage. A polymeric prodrug (HPAA-MTX) with chemotherapeutic self-sensibilization effect consisting of glutathione (GSH)-triggered hyperbranched poly(amido amine) (HPAA) and methotrexate (MTX) was designed and synthesized in this work. This prodrug not only showed better inhibition effect on the tumor cells proliferation compared with free MTX, but also displayed selective sensibilization to tumor cells rather than normal cells. Meanwhile, HPAA-MTX was also explored as a MMP-9 shRNA plasmid delivery vector due to their rich amino group of HPAA, accompanying with MTX for simultaneous inhibiting tumor cells proliferation and migration. As expected, HPAA-MTX possessed excellent gene delivery capacity with significant down-regulation expression of MMP-9 protein and further inhibition of MCF-7 cells migration. Benefiting from the self-sensibilization effect and MTX/MMP-9 co-delivery strategy, this HPAA-MTX/MMP-9 co-delivery system exhibited significantly improved therapeutic efficacy to breast cancer in a combined manner which was confirmed through in vitro and in vivo assays. The strategy established in this study provided a facile "all-in-one" platform to integrate the drug/gene co-delivery strategy and self-sensibilization effect into one single nanocomposite for potential cancer treatment.

STATEMENT OF SIGNIFICANCE

A cationic polymeric prodrug with chemotherapeutic self-sensibilization effect was designed and showed better inhibition effect on tumor cells proliferation compared with its free drug, as well displayed the selective sensibilization effect to tumor cells rather than normal cells. Moreover, the prodrug could also deliver MMP-9 shRNA plasmid for a combined therapy. As expected, the prodrug possessed excellent gene delivery capacity with significant down-regulation expression of MMP-9 protein and further inhibition of MCF-7 cells migration. Benefiting from the self-sensibilization effect and the drug/gene co-delivery strategy, this prodrug exhibited significantly improved therapeutic efficacy to breast cancer in a combined manner.