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Gene engineered mesenchymal stem cells (MSCs) have been proposed as promising tools for their various applications in biomedicine. Nevertheless, the lack of an effective and safe way to genetically modify these stem cells is still a major obstacle in the current studies. Herein, we designed novel magnetic complexes by assembling cationized pullulan derivatives with magnetic iron oxide nanoparticles for delivering target genes to MSCs. Results showed that this complexes achieved effective gene expression with the assistance of external magnetic field, and resisted the adverse effect induced by serum proteins on the gene delivery. Moreover, neither significant cytotoxicity nor the interference on the osteogenic differentiation to MSCs were observed after magnetofection. Further studies revealed that this effective and serum resistant gene transfection was partly due to the accelerated and enhanced intracellular uptake process driven by external magnetic field. To conclude, the current study presented a novel option for genetic modification of MSCs in an effective, relatively safe and serum compatible way., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Spinal cord injury (SCI) is one of the most devastating injuries. Treatment strategies for SCI are required to overcome comprehensive issues. Implantation of biomaterial scaffolds and stem cells has been demonstrated to be a promising strategy. However, a comprehensive recovery effect is difficult to achieve. In the comprehensive treatment process, the specific roles of the implanted scaffolds and of stem cells in combined strategy are usually neglected. In this study, a peptide-modified scaffold is developed based on hyaluronic acid and an adhesive peptide PPFLMLLKGSTR. Synchrotron radiation micro computed tomography measurement provides insights to the three-dimensional inner topographical property and perspective porous structure of the scaffold. The modified scaffold significantly improves cellular survival and adhesive growth of mesenchymal stem cells during 3D culture in vitro. After implantation in transected spinal cord, the modified scaffold and mesenchymal stems are found to function in synergy to restore injured spinal cord tissue, with respective strengths. Hindlimb motor function scores exhibit the most significant impact of the composite implant at 2 weeks post injury, which is the time secondary injury factors begin to take hold. Investigation on the secondary injury factors including inflammatory response and astrocyte overactivity at 10 days post injury reveals the possible underlying reason. Implants of the scaffold, cells, and especially the combination of both elicit inhibitory effects on these adverse factors. The study develops a promising implant for spinal cord tissue engineering and reveals the roles of the scaffold and stem cells. More importantly, the results provide the first understanding of the bioactive peptide PPFLMLLKGSTR concerning its functions on mesenchymal stem cells and spinal cord tissue restoration.

Repair of deep wounds by cell transplantation strongly depends on angiogenesis and on the regeneration of skin and appendages. In this study, plasmid DNA encoding vascular endothelial growth factor-165 (VEGF-165) was transduced into bone-marrow mesenchymal stem cells (MSCs) using a nonviral vector, β-cyclodextrin-linked polyethylenimine, to enhance angiogenic capacity. The effects of MSCs administered by intradermal injection or transplantation on wound closure were compared in a full-thickness excision wound model. The results showed that the MSC-seeded sponge had significantly stronger acceleration in wound closure than the MSC injection. The effects on wound repair and regeneration of transplanted MSCs and pDNA-VEGF1 65-transfected MSCs (TMSCs) with gelatin/β-tricalcium phosphate scaffold were also investigated. Compared with MSC transplantation, TMSC transplantation showed higher efficacy in stimulating wound closure, promoting dermal collagen synthesis and regulating the deposition of newly formed collagen. In addition, the angiogenic capacity of the TMSCs was higher than that of the MSCs. The results indicate that the nonviral genetic engineering of the MSCs is a promising strategy to enhance the angiogenic capacity of MSCs for wound repair and angiogenesis. Functional gene-activated MSCs may be used as cost-effective and accessible seed cells for skin tissue engineering and as novel carriers for wound gene therapy.

Mesenchymal stem cells (MSCs) are a promising tool for delivering of therapeutic agents in cancer treatment. In the present study, our findings suggested that both i.v. and intratumoral injection of MSCs could favor tumor growth under physiologic conditions. However, the anti-tumor effects of MSC-IL-12 were achieved using our strategy. Unlike the previously reported method, the genetic engineering of MSCs was conducted by non-viral transfection using the new vector, spermine-pullulan. The transfection, cytotoxicity, and the cellular internalization of this vector were evaluated. Then, the therapeutical gene, IL-12, was delivered to the MSCs using this vector. The in vitro secretions of IL-12 by MSC-IL-12 confirmed the success of using spermine-pullulan/DNA nanoparticles for the gene transfection. We used the MSC-IL-12 for the in vivo treatment of both B16F10 metastasis tumor and the established subcutaneous B16BL6 tumor. For the B16F10 metastasis tumor, treatment with MSC-IL-12 significantly reduced lung metastases. For the established subcutaneous B16BL6 tumor, intratumoral injected MSC-IL-12 cells considerably retarded tumor growth. Prolonged survival was observed when MSC-IL-12 cells were injected through the tail vein or intratumorally, indicating that the MSCs engineered with the therapeutic gene could reverse the tumor-promoting effects of MSCs using the nonviral transduction method. However, the intravenous injected MSC-IL-12 did not prevent the tumor growth of the established subcutaneous B16BL6 tumor. Thus, we examined the the in vivo distribution of MSCs in different organs and it was found that MSCs were mainly distributed in the lungs, which may explain the inability of intravenously injected MSC-IL-12 to inhibit the growth of the established subcutaneous tumor.

One of the main limitations of anti-tumor gene therapy is the lack of an effective way to deliver therapeutic genes to tumor sites. Bone marrow mesenchymal stem cells (BMSCs) have been proposed as cellular delivery vehicles to tumor sites in tumor-targeted cancer gene therapy. Here, we investigated the therapeutic effects of cytomegalovirus-thymidine kinase expressing BMSCs (TK-BMSCs) on pulmonary melanoma metastasis combined with prodrug ganciclovir. BMSCs were successfully engineered through a non-viral gene vector. The gene recombinant BMSCs migrated to the pulmonary area and were found to have the tendency to target tumor nodules after systemic delivery. In vitro results demonstrate that the engineered BMSCs have significant suicide effects in the presence of ganciclovir in a dose-dependent manner and can exert a sufficient bystander effect on B16F10 tumor cells in co-culture experiments. In vivo studies confirmed the therapeutic effects of TK-BMSCs/ganciclovir on the metastasis tumor model., From the Clinical Editor: This study investigates the possibility of gene transfer via bone marrow mesenchymal stem cells in anti-cancer gene therapy using a metastatic melanoma model and cytomegalovirus-thymidine kinase expressing stem cells, demonstrating clear therapeutic effects., (© 2013.)

The applications of targeting gene delivery systems in tumor therapy have attracted extensive attention of researchers in recent years, as they can selectively deliver the therapeutic gene to tumor sites, improve the success rate of gene therapy and reduce the side effects. Therefore, design and development of novel gene delivery vehicles have been a hot area of current research. Recent studies have shown that mesenchymal stem cells (MSCs) have the ability to migrate towards and engraft into the tumor sites. Therefore, these properties make them a great hope for efficient targeted-delivery vehicles in cancer gene therapy. In this review, we examine the promising of utilization of MSCs as a targeted-delivery vehicle for cancer gene therapy, and summarize various challenges and concerns regarding this therapy.

The success of gene therapy relies largely on an effective targeted gene delivery system. Till recently, more and more targeted delivery carriers, such as liposome, nanoparticles, microbubbles, etc., have been developed. However, the clinical applications of these systems were limited for their several disadvantages. Therefore, design and development of novel drug/gene delivery vehicles became a hot topic. Cell-based delivery systems are emerging as an alternative for the targeted delivery system as we described previously. Mesenchymal stem cells (MSCs) are an attractive cell therapy carrier for the delivery of therapeutic agents into tumor sites mainly for their tumor-targeting capacities. In the present study, a nonviral vector, PEI(600)-Cyd, prepared by linking low molecular weight polyethylenimine (PEI) and β-cyclodextrin (β-CD), was used to introduce the therapeutical gene, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), to MSCs. Meanwhile, the characterization, transfection efficiency, cytotoxicity, cellular internalization, and its mechanism of this nonviral vector were evaluated. The in vitro expression of TRAIL from MSCs-TRAIL was demonstrated by both enzyme-linked immunosorbent assay and Western blot analysis. The lung tumor homing ability of MSCs was further confirmed by the in vitro and in vivo model. Moreover, the therapeutic effects as well as the safety of MSCs-TRAIL on lung metastases bearing C57BL/6 mice and normal C57BL/6 mice were also demonstrated. Our results supported both the effectiveness of nonviral vectors in transferring the therapeutic gene to MSCs and the feasibility of using MSCs as a targeted gene delivery carrier, indicating that MSCs could be a promising tumor target delivery vehicle in cancer gene therapy based on nonviral gene recombination.

The success of conventional suicide gene therapy for cancer treatment is still limited because of lack of efficient delivery methods, as well as poor penetration into tumor tissues. Mesenchymal stem cells (MSCs) have recently emerged as potential vehicles in improving delivery issues. However, these stem cells are usually genetically modified using viral gene vectors for suicide gene overexpression to induce sufficient therapeutic efficacy. This approach may result in safety risks for clinical translation. Therefore, we designed a novel strategy that uses non-viral gene vector in modifying MSCs with suicide genes to reduce risks. In addition, these cells were co-administrated with prodrug-encapsulated liposomes for synergistic anti-tumor effects. Results demonstrate that this strategy is effective for gene and prodrug delivery, which co-target tumor tissues, to achieve a significant decrease in tumor colonization and a subsequent increase in survival in a murine melanoma lung metastasis model. Moreover, for the first time, we demonstrated the permeability of MSCs within tumor nests by using an in vitro 3D tumor spheroid model. Thus, the present study provides a new strategy to improve the delivery problem in conventional suicide gene therapy and enhance the therapeutic efficacy. Furthermore, this study also presents new findings to improve our understanding of MSCs in tumor-targeted gene delivery. [ABSTRACT FROM AUTHOR]

Abstract: One of the main limitations of anti-tumor gene therapy is the lack of an effective way to deliver therapeutic genes to tumor sites. Bone marrow mesenchymal stem cells (BMSCs) have been proposed as cellular delivery vehicles to tumor sites in tumor-targeted cancer gene therapy. Here, we investigated the therapeutic effects of cytomegalovirus-thymidine kinase expressing BMSCs (TK-BMSCs) on pulmonary melanoma metastasis combined with prodrug ganciclovir. BMSCs were successfully engineered through a non-viral gene vector. The gene recombinant BMSCs migrated to the pulmonary area and were found to have the tendency to target tumor nodules after systemic delivery. In vitro results demonstrate that the engineered BMSCs have significant suicide effects in the presence of ganciclovir in a dose-dependent manner and can exert a sufficient bystander effect on B16F10 tumor cells in co-culture experiments. In vivo studies confirmed the therapeutic effects of TK-BMSCs/ganciclovir on the metastasis tumor model. From the Clinical Editor: This study investigates the possibility of gene transfer via bone marrow mesenchymal stem cells in anti-cancer gene therapy using a metastatic melanoma model and cytomegalovirus-thymidine kinase expressing stem cells, demonstrating clear therapeutic effects. [Copyright &y& Elsevier]

This study evaluated the potential of utilizing transfected pTGFβ-1 gene-engineered rat mesenchymal stem cells (MSCs) using nonviral vector to promote cartilage regeneration. Pullulan-spermine was used as the nonviral gene vector and gelatin sponge was used as the scaffold. MSCs were engineered with TGF-β1 gene with either the three-dimensional (3D) reverse transfection system or the two-dimensional (2D) conventional transfection system. For the 3D reverse transfection system, pullulan-spermine/ pTGF-β1 gene complexes were immobilized to the gelatin sponge, followed by the seeding of MSCs. Pullulan-spermine/ pTGF-β1 gene complexes were delivered to MSCs cultured in the plate to perform the 2D conventional transfection system, and then MSCs were seeded to the gelatin sponge. Then, TGF-β1 gene-transfected MSC seeded gelatin sponge was implanted to the full-thickness cartilage defect. Compared with the control group, both groups of TGF-β1 gene-engineered MSCs improved cartilage regeneration through optical observation and histology staining. So, with pullulan-spermine as the nonviral vector, TGF-β1-gene engineered MSCs can induce cartilage regeneration in vivo. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have been regarded as potential targeting vehicles and demonstrated to exert therapeutic benefits for brain diseases. Direct homing to diseased tissue is crucial for stem cell-based therapy. In this study, a peptide-based targeting approach was established to enhance cell homing to cerebral ischemic lesion. Palmitic acid–peptide painted onto the cell membrane was able to direct MSCs to ischemic tissues without any observed cell cytotoxicity and influence on differentiation, thus reducing accumulation of cells in peripheral organs and increasing engraftment of cells in the targeted tissues. With enhanced cell homing, MSCs were used to deliver miR-133b to increase the expression level of miR-133b in an ischemic lesion and further improve therapeutic effects. This study is the first to develop MSCs co-modified with targeting peptide and microRNAs as potential targeting therapeutic agents. This targeting delivery system is expected to be applicable to other cell types and other diseases aside from stroke. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Using a facile approach established MSCs biomimetic vehicle achieved high DOX loading efficiency. • Synthesized vehicle realized tumor tropism, tumor penetration and low immunogenicity. • Realized effective anti-tumor in HepG2 tumor-bearing mice while reduced side effect on mice. [ABSTRACT FROM AUTHOR]