Predictive Value of Combined HbA1c and Neutrophil-to-Lymphocyte Ratio for Diabetic Peripheral Neuropathy in Type 2 Diabetes.

BACKGROUND Diabetic peripheral neuropathy (DPN) is a prevalent complication affecting over 60% of type 2 diabetes patients. Early diagnosis is challenging, leading to irreversible impacts on quality of life. This study explores the predictive value of combining HbA1c and Neutrophil-to-Lymphocyte Ratio (NLR) for early DPN detection. MATERIAL AND METHODS An observational study was conducted at the First People's Hospital of Linping District, Hangzhou spanning from May 2019 to July 2020. Data on sex, age, biochemical measurements were collected from electronic medical records and analyzed. Employing multivariate logistic regression analysis, we sought to comprehend the factors influencing the development of DPN. To assess the predictive value of individual and combined testing for DPN, a receiver operating characteristic (ROC) curve was plotted. The data analysis was executed using R software (Version: 4.1.0). RESULTS The univariate and multivariate logistic regression analysis identified the level of glycated hemoglobin (HbA1C) (OR=1.94, 95% CI: 1.27-3.14) and neutrophil-to-lymphocyte ratio (NLR) (OR=4.60, 95% CI: 1.15-22.62, P=0.04) as significant risk factors for the development of DPN. Receiver operating characteristic (ROC) curve analysis demonstrated that HbA1c, NLR, and their combined detection exhibited high sensitivity in predicting the development of DPN (71.60%, 90.00%, and 97.2%, respectively), with moderate specificity (63.8%, 45.00%, and 50.00%, respectively). The area under the curve (AUC) for these predictors was 0.703, 0.661, and 0.733, respectively. CONCLUSIONS HbA1c and NLR emerge as noteworthy risk indicators associated with the manifestation of DPN in patients with type 2 diabetes. The combined detection of HbA1c and NLR exhibits a heightened predictive value for the development of DPN.

Synthesis, Characterization and Biosafety Evaluation of Hollow Gold Nanospheres.

OBJECTIVES: In order to assess the biosafety of HAuNS using zebrafish models and the cancer cell lines HepG2, HEK293, and A549, this study prepared HAuNS in a variety of sizes and alterations. METHODS: By oxidizing cobalt nanoparticles encased in gold shells, HAuNS were created. In the meantime, PEG- and PEI-coated HAuNS were created. The diameters of the HAuNS that were produced were 30~40 nm, 50~60 nm, and 70~80 nm. MTT assay was used to assess the toxicity of HAuNS on HepG2, HEK293, and A549 cells. For the investigation of their toxicities, HAuNS (50~60 nm) of various concentrations were incubated with zebrafish embryos. Then, cell death was determined using acridine orange staining. RESULTS: In a cell line model, it was demonstrated that purified HAuNS exhibit lower toxicity than unpurified HAuNS. Meanwhile, it was discovered that surface-modified HAuNS was less hazardous than unmodified HAuNS. Unpurified HAuNS (50.60 nm) exposure to embryos caused deformity and increased mortality. Moreover, embryos exposed to HAuNS displayed an increase in cell death, showing that HAuNS can put zebrafish under physiological stress. CONCLUSION: The possible toxicity of HAuNS is now more understood thanks to this investigation. The details could improve our comprehension of the nanotoxicity of medication delivery systems. Comparing HAuNS (50~60 nm) to the other two particle sizes, its toxicity was quite low. Compared to unpurified HAuNS, purified HAuNS displayed less toxicity. Comparing PEI-HAuNS and HAuNS to PEG-HAuNS, cytotoxicity was found to be lower. Our data support the use of pure HAuNS, HAuNS-PEG, and HAuNS (50~60 nm) as possible photothermal conductors when seen as a whole.

Neural Stem Cells Transfected with Reactive Oxygen Species-Responsive Polyplexes for Effective Treatment of Ischemic Stroke.

Neural stem cells (NSCs), capable of ischemia-homing, regeneration, and differentiation, exert strong therapeutic potentials in treating ischemic stroke, but the curative effect is limited in the harsh microenvironment of ischemic regions rich in reactive oxygen species (ROS). Gene transfection to make NSCs overexpress brain-derived neurotrophic factor (BDNF) can enhance their therapeutic efficacy; however, viral vectors must be used because current nonviral vectors are unable to efficiently transfect NSCs. The first polymeric vector, ROS-responsive charge-reversal poly[(2-acryloyl)ethyl(p-boronic acid benzyl)diethylammonium bromide] (B-PDEA), is shown here, that mediates efficient gene transfection of NSCs and greatly enhances their therapeutics in ischemic stroke treatment. The cationic B-PDEA/DNA polyplexes can effectively transfect NSCs; in the cytosol, the B-PDEA is oxidized by intracellular ROS into negatively charged polyacrylic acid, quickly releasing the BDNF plasmids for efficient transcription and secreting a high level of BDNF. After i.v. injection in ischemic stroke mice, the transfected NSCs (BDNF-NSCs) can home to ischemic regions as efficiently as the pristine NSCs but more efficiently produce BDNF, leading to significantly augmented BDNF levels, which in turn enhances the mouse survival rate to 60%, from 0% (nontreated mice) or ≈20% (NSC-treated mice), and enables more rapid and superior functional reconstruction.

Peptide modified mesenchymal stem cells as targeting delivery system transfected with miR-133b for the treatment of cerebral ischemia.

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.

Toxicity analysis of various Pluronic F-68-coated carbon nanotubes on mesenchymal stem cells.

Carbon nanotubes (CNTs) have poor colloid stability in biological media and exert cytotoxic effects on mesenchymal stem cells (MSCs). Modification with polymeric surfactant is a widely used strategy to enhance water dispersibility of CNTs. This study investigated the toxic effects of various Pluronic F-68 (PF68)-coated multi-walled CNTs (MWCNTs) on rat bone marrow-derived MSCs.PF68-coated MWCNTs showed favorable biocompatibility to MSCs that the cell viability, apoptosis, and reactive oxygen species (ROS) were not altered after 24 h of co-incubation. Nevertheless, significant apoptosis induction and massive ROS release were found following extended exposure (48 and 72 h), and the toxic impact was dependent on the initial surface properties of the encapsulated MWCNTs. All the types of PF68-coated MWCNTs did not affect the cell-surface markers and in vivo biodistribution of MSCs. Our results suggest that proper polymer coating can reduce the acute toxicity of MWCNTs to MSCs but without altering their biological fate.

Brain Localization and Neurotoxicity Evaluation of Polysorbate 80-Modified Chitosan Nanoparticles in Rats.

The toxicity evaluation of inorganic nanoparticles has been reported by an increasing number of studies, but toxicity studies concerned with biodegradable nanoparticles, especially the neurotoxicity evaluation, are still limited. For example, the potential neurotoxicity of Polysorbate 80-modified chitosan nanoparticles (Tween 80-modified chitosan nanoparticles, TmCS-NPs), one of the most widely used brain targeting vehicles, remains unknown. In the present study, TmCS-NPs with a particle size of 240 nm were firstly prepared by ionic cross-linking of chitosan with tripolyphosphate. Then, these TmCS-NPs were demonstrated to be entered into the brain and specially deposited in the frontal cortex and cerebellum after systemic injection. Moreover, the concentration of TmCS-NPs in these two regions was found to decrease over time. Although no obvious changes were observed for oxidative stress in the in vivo rat model, the body weight was found to remarkably decreased in a dose-dependent manner after exposure to TmCS-NPs for seven days. Besides, apoptosis and necrosis of neurons, slight inflammatory response in the frontal cortex, and decrease of GFAP expression in the cerebellum were also detected in mouse injected with TmCS-NPs. This study is the first report on the sub-brain biodistribution and neurotoxicity studies of TmCS-NPs. Our results provide new insights into the toxicity evaluation of nanoparticles and our findings would help contribute to a better understanding of the neurotoxicity of biodegradable nanomaterials used in pharmaceutics.

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

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.

ScreenFect A: an efficient and low toxic liposome for gene delivery to mesenchymal stem cells.

Mesenchymal stem cells (MSCs) hold great promise in variety of therapeutic applications including tissue engineering and cancer therapy. Genetic modification of MSCs can be used to enhance the therapeutic effect of MSCs by facilitating a specific function or by transforming MSCs into more effective gene therapy tools. However, the successful generation of genetically modified MSCs is often limited by the poor transfection efficiency or high toxicity of available transfection reagents. In our previous study, we used thiol-yne click chemistry to develop new liposomal vectors, including ScreenFect(®) A (SF) (Li et al., 2012). In this study, we investigated the transfection performance of SF on MSCs. A comparative evaluation of transfection efficiency, cell viability and cellular DNA uptake was performed using the Lipofectamine™ 2000 (L2K) as a control, and the results show that SF is superior to L2K for MSC transfection. The presence of serum did not significantly influence the transfection efficiency of either SF or L2K but greatly reduced the viability of MSC transfected by L2K. The higher efficiency of SF-mediated transfection compared to L2K was also correlated with better proliferation of cells. These results were supported by monitoring the intracellular fate of DNA, which confirmed stable transportation of DNA from lysosomes and efficient nuclear localization. TGF-ß1 gene delivery by SF promoted MSC osteogenic differentiation in an osteogenic induction condition. As the first study of SF lipofection on stem cells, this study highlights a promising role of SF in gene delivery to MSCs as well as other stem cells to facilitate tissue engineering and other therapeutic effects based on genetically modified stem cells.

Reversal of tumor growth by gene modification of mesenchymal stem cells using spermine-pullulan/DNA nanoparticles.

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.

Recombinant stem cells as carriers for cancer gene therapy.

Recent studies have shown the ability of mesenchymal stem cells (MSCs) to migrate toward and engraft into the tumor sites, which provides a potential for their use as carriers for cancer gene therapy. Here, we describe the strategies of using MSCs as carriers for cancer gene therapy using a nonviral transfection method.

Gene recombinant bone marrow mesenchymal stem cells as a tumor-targeted suicide gene delivery vehicle in pulmonary metastasis therapy using non-viral transfection.

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.

[Research progress of gene recombinant mesenchymal stem cells as tumor targeting delivery vehicles].

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.

Glioma targeting and blood-brain barrier penetration by dual-targeting doxorubincin liposomes.

Effective chemotherapy for glioblastoma requires a carrier that can penetrate the blood-brain barrier (BBB) and subsequently target the glioma cells. Dual-targeting doxorubincin (Dox) liposomes were produced by conjugating liposomes with both folate (F) and transferrin (Tf), which were proven effective in penetrating the BBB and targeting tumors, respectively. The liposome was characterized by particle size, Dox entrapment efficiency, and in vitro release profile. Drug accumulation in cells, P-glycoprotein (P-gp) expression, and drug transport across the BBB in the dual-targeting liposome group were examined by using bEnd3 BBB models. In vivo studies demonstrated that the dual-targeting Dox liposomes could transport across the BBB and mainly distribute in the brain glioma. The anti-tumor effect of the dual-targeting liposome was also demonstrated by the increased survival time, decreased tumor volume, and results of both hematoxylin-eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling analysis. The dual-targeting Dox liposome could improve the therapeutic efficacy of brain glioma and were less toxic than the Dox solution, showing a dual-targeting effect. These results indicate that this dual-targeting liposome can be used as a potential carrier for glioma chemotherapy.

Overcoming drug resistance of MCF-7/ADR cells by altering intracellular distribution of doxorubicin via MVP knockdown with a novel siRNA polyamidoamine-hyaluronic acid complex.

Drug resistance is one of the critical reasons leading to failure in chemotherapy. Enormous studies have been focused on increasing intracellular drug accumulation through inhibiting P-glycoprotein (Pgp). Meanwhile, we found that major vault protein (MVP) may be also involved in drug resistance of human breast cancer MCF-7/ADR cells by transporting doxorubicin (DOX) from the action target (i.e. nucleus) to cytoplasma. Herein polyamidoamine (PAMAM) dendrimers was functionalized by a polysaccharide hyaluronic acid (HA) to effectively deliver DOX as well as MVP targeted small-interfering RNA (MVP-siRNA) to down regulate MVP expression and improve DOX chemotherapy in MCF-7/ADR cells. In comparison with DOX solution (IC50=48.5 µM), an enhanced cytotoxicity could be observed for DOX PAMAM-HA (IC50=11.3 µM) as well as enhanced tumor target, higher intracellular accumulation, increased blood circulating time and less in vivo toxicity. Furthermore, codelivery of siRNA and DOX by PAMAM-HA exhibited satisfactory gene silencing effect as well as enhanced stability and efficient intracellular delivery of siRNA, which allowed DOX access to nucleus and induced subsequent much more cytotoxicity than siRNA absent case as a result of MVP knockdown. This observation highlights a promising application of novel nanocarrier PAMAM-HA, which could co-deliver anticancer drug and siRNA, in reversing drug resistance by altering intracellular drug distribution.

Mesenchymal stem cells as a novel carrier for targeted delivery of gene in cancer therapy based on nonviral transfection.

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 ß-cyclodextrin (ß-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.

Gene-carried hepatoma targeting complex induced high gene transfection efficiency with low toxicity and significant antitumor activity.

BACKGROUND: The success of gene transfection is largely dependent on the development of a vehicle or vector that can efficiently deliver a gene to cells with minimal toxicity. METHODS: A liver cancer-targeted specific peptide (FQHPSF sequence) was successfully synthesized and linked with chitosan-linked polyethylenimine (CP) to form a new targeted gene delivery vector called CPT (CP/peptide). The structure of CPT was confirmed by (1)H nuclear magnetic resonance spectroscopy and ultraviolet spectrophotometry. The particle size of CPT/ DNA complexes was measured using laser diffraction spectrometry and the cytotoxicity of the copolymer was evaluated by methylthiazol tetrazolium method. The transfection efficiency evaluation of the CP copolymer was performed using luciferase activity assay. Cellular internalization of the CP/DNA complex was observed under confocal laser scanning microscopy. The targeting specificity of the polymer coupled to peptide was measured by competitive inhibition transfection study. The liver targeting specificity of the CPT copolymer in vivo was demonstrated by combining the copolymer with a therapeutic gene, interleukin-12, and assessed by its abilities in suppressing the growth of ascites tumor in mouse model. RESULTS: The results showed that the liver cancer-targeted specific peptide was successfully synthesized and linked with CP to form a new targeted gene delivery vector called CPT. The composition of CPT was confirmed and the vector showed low cytotoxicity and strong targeting specificity to liver tumors in vitro. The in vivo study results showed that interleukin-12 delivered by the new gene vector CPT/DNA significantly enhanced the antitumor effect on ascites tumor-bearing imprinting control region mice as compared with polyethylenimine (25 kDa), CP, and other controls, which further demonstrate the targeting specificity of the new synthesized polymer. CONCLUSION: The synthesized CPT copolymer was proven to be an effective liver cancer-targeted vector for therapeutic gene delivery, which could be a potential candidate for targeted cancer gene therapy.

Impregnation of plasmid DNA into three-dimensional PLGA scaffold enhances DNA expression of mesenchymal stem cells in vitro.

Current efforts had been made to undertake a three-dimensional (3-D) reverse transfection of bone marrow-derived mesenchymal stem cells (BM-MSCs) in PLGA scaffolds. As a kind of multipotent stem cells, BM-MSCs show great potential and tremendous capacity in the gene transfection field and PLGA 3-D scaffold has been shown to be a biomaterial that provides structural support to cells proliferation and tissue engineering. The objective of this study was to assess the transfection efficiency of BM-MSCs with a 3-D reverse transfection method by using PLGA scaffold and observe the SEM photographs of BM-MSCs cultured on PLGA scaffold. BM-MSCs were cultured in 3-D PLGA scaffold which was incorporated with pullulan-spermine/pGL3. It was shown that the gene expression duration of BM-MSCs transfected using 3D reverse method with pullulan-spermine/DNA in the presence of serum maintained 12 days at high levels as compared with the plasmid DNA in medium, and scanning electronic microscopy (SEM) photographs of BM-MSCs cultured on PLGA scaffold exhibited robust cell attachment and viability when cultured in PLGA scaffold in vitro. This study demonstrates that the 3-D reverse transfection method of BM-MSCs using PLGA scaffold could achieve long gene expression in a relatively high level, therefore this transfection system is promising in gene transfection and tissue engineering.

TGF-ß1 gene-engineered mesenchymal stem cells induce rat cartilage regeneration using nonviral gene vector.

This study evaluated the potential of utilizing transfected pTGFß-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-ß1 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-ß1 gene complexes were immobilized to the gelatin sponge, followed by the seeding of MSCs. Pullulan-spermine/pTGF-ß1 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-ß1 gene-transfected MSC seeded gelatin sponge was implanted to the full-thickness cartilage defect. Compared with the control group, both groups of TGF-ß1 gene-engineered MSCs improved cartilage regeneration through optical observation and histology staining. So, with pullulan-spermine as the nonviral vector, TGF-ß1-gene engineered MSCs can induce cartilage regeneration in vivo.

Doxorubicin-loaded PEG-PCL copolymer micelles enhance cytotoxicity and intracellular accumulation of doxorubicin in adriamycin-resistant tumor cells.

BACKGROUND: Multidrug resistance remains a major obstacle to successful cancer chemotherapy. Some chemical multidrug resistance inhibitors, such as ciclosporin and verapamil, have been reported to reverse resistance in tumor cells. However, the accompanying side effects have limited their clinical application. In this study, we have developed a novel drug delivery system, ie, a polyethyleneglycol-polycaprolactone (PEG-PCL) copolymer micelle encapsulating doxorubicin, in order to circumvent drug resistance in adriamycin-resistant K562 tumor cells. METHODS: Doxorubicin-loaded diblock copolymer PEG-PCL micelles were developed, and the physicochemical properties of these micelles, and accumulation and cytotoxicity of doxorubicin in adriamycin-resistant K562 tumor cells were studied. RESULTS: Doxorubicin-loaded micelles were prepared using a solvent evaporation method with a diameter of 36 nm and a zeta potential of +13.8 mV. The entrapment efficiency of doxorubicin was 48.6% ± 2.3%. The micelles showed sustained release, increased uptake, and cellular cytotoxicity, as well as decreased efflux of doxorubicin in adriamycin-resistant K562 tumor cells. CONCLUSION: This study suggests that PEG-PCL micelles have the potential to reverse multidrug resistance in tumor cells.

Effective gene delivery to mesenchymal stem cells based on the reverse transfection and three-dimensional cell culture system.

PURPOSE: To enhance the level and prolong the duration of gene expression for gene-engineered rat mesenchymal stem cells (MSCs) using non-viral vector. METHODS: A novel transfection system based on reverse transfection method and three-dimensional (3D) scaffold was developed. The reverse gene transfection system was evaluated for transfection efficiency compared to conventional methods. Collagen sponge and polyethylene terephthalate non-woven fabric were introduced as scaffolds to perform 3D culture with reverse transfection. pDNA coding TGFß-1 was delivered to MSCs to assess its ability in inducing chondrogenesis with the 3D non-viral reverse transfection system. RESULTS: The reverse transfection method induced higher transgene levels than the conventional transfection in the presence of serum. The electric charge of the anionic gelatin plays an important role in this system by affecting the release pattern of the gene complexes and through the adsorption of serum protein to the substrate. During a long-time in vitro culture, MSCs cultured on 3D scaffolds exhibited a higher transgene expression level and more sustained transgene expression than those cultured and transfected on the two-dimensional substrate. CONCLUSIONS: The combination of reverse transfection system with 3D cell culture scaffold benefits the cell proliferation and long-time gene transfection of MSCs.