Evaluation of the Optimal Number of Implanted Mesenchymal Stem Cells for the Treatment of Post-Traumatic Syrinx and Recovery of Motor Activity after Chronic Spinal Cord Injury

The present work aims at determining the most effective dose (number) of mesenchymal stem cells (MSC) for its transplantation in order to treat chronic spinal cord injury (SCI) in mature Sprague-Dawley rats (n=24). MSC were obtained from bone marrow of 4-6-month-old Sprague-Dawley rats. Four weeks after SCI, MSC suspension (4 μl) was injected to experimental animals into the injured area in doses of 4×105, 8×105, or 106. Using MRI, diffusion tensor imaging (DTI), diffusion tensor tractography (DTT), immunohistochemistry, histological staining, and behavioral tests, we studied the effect of transplantation of MSC in different doses on the following parameters in rats with SCI: the size of lesion cavity and post-traumatic syrinx (PTS), glial scar formation, neuronal fibers remodeling, axonal regeneration and sprouting, vascularization, expression of neuronal factors, and motor functions. MSC administration improved motor function in rats after SCI due to stimulation of regeneration and sprouting of the axons, enhanced recovery of locomotor functions, reduction of PTS and the glial scar, and stimulation of vascularization and expression of the neurotrophic factors. The effects of MSC were dose-dependent; the most effective dose was 106 cells.

Biocompatible dextran-coated gadolinium-doped cerium oxide nanoparticles as MRI contrast agents with high T1 relaxivity and selective cytotoxicity to cancer cells

Gd-based complexes are widely used as magnetic resonance imaging (MRI) contrast agents. The safety of previously approved contrast agents is questionable and is being re-assessed. The main causes of concern are possible gadolinium deposition in the brain and the development of systemic nephrogenic fibrosis after repeated use of MRI contrasts. Thus, there is an urgent need to develop a new generation of MRI contrasts that are safe and that have high selectivity in tissue accumulation with improved local contrast. Here, we report on a new type of theranostic MRI contrast, namely dextran stabilised, gadolinium doped cerium dioxide nanoparticles. These ultra-small (4-6 nm) Ce_0.9Gd_0.1O_1.95 nanoparticles have been shown to possess excellent colloidal stability and high r₁-relaxivity (3.6 mM^-1 s^-1). They are effectively internalised by human normal and cancer cells and demonstrate dose-dependent selective cytotoxicity to cancer cells.

Advances and Challenges of Nanoparticle-Based Macrophage Reprogramming for Cancer Immunotherapy

Despite the progress of modern medicine, oncological diseases are still among the most common causes of death of adult populations in developed countries. The current therapeutic approaches are imperfect, and the high mortality of oncological patients under treatment, the lack of personalized strategies, and severe side effects arising as a result of treatment force seeking new approaches to therapy of malignant tumors. During the last decade, cancer immunotherapy, an approach that relies on activation of the host antitumor immune response, has been actively developing. Cancer immunotherapy is the most promising trend in contemporary fundamental and practical oncology, and restoration of the pathologically altered tumor microenvironment is one of its key tasks, in particular, the reprogramming of tumor macrophages from the immunosuppressive M2-phenotype into the proinflammatory M1-phenotype is pivotal for eliciting antitumor response. This review describes the current knowledge about macrophage classification, mechanisms of their polarization, their role in formation of the tumor microenvironment, and strategies for changing the functional activity of M2-macrophages, as well as problems of targeted delivery of immunostimulatory signals to tumor macrophages using nanoparticles.

Comparison of the Efficiency of Transplantation of Rat and Human Olfactory Ensheathing Cells in Posttraumatic Cysts of the Spinal Cord

Olfactory ensheathing cells showed significant effects on the regeneration of the spinal cord in experimental models and in clinical trials. However, the use of these cells in the therapy of posttraumatic cysts of the spinal cord has not been studied. Cultures of human and rat olfactory mucosa were obtained according to the protocols developed by us. Passage 3-4 cultures are most enriched with olfactory ensheathing cells and are preferable for transplantation. We performed transplantation of 750,000 olfactory ensheathing cells into the region of modeled cysts. The therapeutic effect of human cells was more pronounced. The positive dynamics of recovery of motor activity in the hind limbs of rats can reflect regenerative processes in the spinal cord after transplantation of olfactory ensheathing cells into the region of posttraumatic cysts.

Preparation and Testing of Cells Expressing Fluorescent Proteins for Intravital Imaging of Tumor Microenvironment

Intravital microscopy is widely used for in vivo studies of the mechanisms of carcinogenesis and response to antitumor therapy. For visualization of tumor cells in vivo, cell lines expressing fluorescent proteins are needed. Expression of exogenous proteins can affect cell growth rate and their tumorigenic potential. Therefore, comprehensive analysis of the morphofunctional properties of transduced cells is required for creating appropriate models of tumor microenvironment. In the present study, six lines of mouse tumor cells expressing green and red fluorescent proteins were derived. Analysis of cells morphology, growth kinetics, and response to chemotherapy in vitro revealed no significant differences between wild-type and transduced cell lines. Introduction of fluorescent proteins into the genome of 4T1 (murine breast cancer) and B16-F10 (murine melanoma) cells did not affect tumor growth rate after subcutaneous implantation to mice, while both CT26-GFP and CT26-RFP cells (murine colon cancer) were rejected starting from day 8 after implantation. Elucidation of the mechanisms underlying CT26-GFP/RFP rejection is required to modify transduction technique for creating the models of tumor microenvironment accessible for in vivo visualization. Transduced 4T1 and B16-F10 cell lines can be used for intravital microscopic imaging of tumor cells, neoplastic vasculature, and leukocyte subpopulations.

Evaluation of absorbed dose distribution in melanoma B16F10 during contrast enhanced radiotherapy with intratumoral administration of dose-enhancing agent

Contrast-enhanced radiotherapy (CERT) is a binary treatment modality in which the absorbed radiation dose is not only determined by the parameters of the external radiation source but also affected by the concentration of a dose-enhancing agent (DEA) in the studied object. In this work we assessed the distribution of the absorbed dose in a murine B16F10 melanoma injected with a single dose of an aqueous Bi-DTPA solution. The mice were exposed to a single fraction of X-ray irradiation for 28.5 min. In vivo measurements of DEA concentrations were done on a micro-CT scanner using the radiopacity values of malignant tissues from the obtained CT images. We found that the presence of DEA enhanced the absorbed dose more than twofold in 6% of the tumor volume; in 29% of the tumor volume the absorbed dose increased more than onefold. The tumor growth delay time calculated for our model was 0.76 days (we only accounted for the damage caused directly by radiation), whereas in our previous research study tumor growth delay was 10 days. This discrepancy may indicate that in the tumors exposed to contrast-enhanced radiotherapy growth delay results from both the damage directly caused by radiation and other antitumor mechanisms.

Assessment of the Parameters of Adaptive Cell-Mediated Immunity in Naïve Common Marmosets (Callithrix jacchus)

Common marmosets are small New World primates that have been increasingly used in biomedical research. This report presents efficient protocols for assessment of the parameters of adaptive cell-mediated immunity in common marmosets, including the major subpopulations of lymphocytes and main markers of T- and B-cell maturation and activation using flow cytometry with a multicolor panel of fluorescently labelled antibodies. Blood samples from eight common marmosets were stained with fluorescently labeled monoclonal antibodies against their population markers (CD45, CD3, CD20, CD4, CD8) and lymphocyte maturation and activation markers (CD69, CD62L, CD45RO, CD107a and CD27) and analyzed by flow cytometry. Within the CD45+ population, 22.75.5% cells were CD3- CD20+ and 67.66.3% were CD3+CD20-. The CD3+ subpopulation included 55.75.5% CD3+CD4+CD8- and 34.33.7% CD3+CD4-CD8+ cells. Activation and maturation markers were expressed in the following lymphocyte proportions: CD62L on 54.010.7% of CD3+CD4+ cells and 74.412.1% of CD3+CD8+ cells; CD69 on 2.71.2% of CD3+CD4+ cells and 1.20.5% of CD3+CD8+ cells; CD45RO on 1.60.6% of CD3+CD4+ cells and 1.80.7% of CD3+CD8+ cells; CD107a on 0.70.5% of CD3+CD4+ cells and 0.50.3% of CD3+CD8+ cells; CD27 on 94.62.1% of CD3+ cells and 8.93.9% CD20+ cells. Female and male subjects differed in the percentage of CD3+CD4+CD45RO+ cells (1.90.5 in females vs 1.10.2 in males; p 0.05). The percentage of CD20+CD27+ cells was found to highly correlate with animals age (r = 0.923, p 0.005). The basal parameters of adaptive cell-mediated immunity in nave healthy marmosets without markers of systemic immune activation were obtained. These parameters and the described procedures are crucial in documenting the changes induced in common marmosets by prophylactic and therapeutic immune interventions.

Isolation of Rat Olfactory Ensheathing Cells and Their Use in the Therapy of Posttraumatic Cysts of the Spinal Cord

We evaluated the efficacy of rat olfactory ensheathing cells in the therapy of experimental cysts of the spinal cord. Improvement of the motor function of the hind limbs after transplantation of the olfactory ensheathing cells into the posttraumatic spinal cord cysts rats was found. We also determined the required number of cells for transplantation and demonstrated a neuroprotective effect of this dosage. For further clinical studies, autologous tissue-specific cell preparation of olfactory ensheathing cells has to be created. Cell therapy in combination surgical and pharmacological treatment will substantially improve the quality of life of patients with posttraumatic spinal cord cysts.

Assessment of the Parameters of Adaptive Cell-Mediated Immunity in Naïve Common Marmosets (Callithrix jacchus)

Common marmosets are small New World primates that have been increasingly used in biomedical research. This report presents efficient protocols for assessment of the parameters of adaptive cell-mediated immunity in common marmosets, including the major subpopulations of lymphocytes and main markers of T- and B-cell maturation and activation using flow cytometry with a multicolor panel of fluorescently labelled antibodies. Blood samples from eight common marmosets were stained with fluorescently labeled monoclonal antibodies against their population markers (CD45, CD3, CD20, CD4, CD8) and lymphocyte maturation and activation markers (CD69, CD62L, CD45RO, CD107a and CD27) and analyzed by flow cytometry. Within the CD45⁺ population, 22.7±5.5% cells were CD3- CD20⁺ and 67.6±6.3% were CD3⁺CD20-. The CD3⁺ subpopulation included 55.7±5.5% CD3⁺CD4⁺CD8- and 34.3±3.7% CD3⁺CD4-CD8⁺ cells. Activation and maturation markers were expressed in the following lymphocyte proportions: CD62L on 54.0±10.7% of CD3⁺CD4⁺ cells and 74.4±12.1% of CD3⁺CD8⁺ cells; CD69 on 2.7±1.2% of CD3⁺CD4⁺ cells and 1.2±0.5% of CD3⁺CD8⁺ cells; CD45RO on 1.6±0.6% of CD3⁺CD4⁺ cells and 1.8±0.7% of CD3⁺CD8⁺ cells; CD107a on 0.7±0.5% of CD3⁺CD4⁺ cells and 0.5±0.3% of CD3⁺CD8⁺ cells; CD27 on 94.6±2.1% of CD3⁺ cells and 8.9±3.9% CD20⁺ cells. Female and male subjects differed in the percentage of CD3⁺CD4⁺CD45RO⁺ cells (1.9±0.5 in females vs 1.1±0.2 in males; p < 0.05). The percentage of CD20⁺CD27⁺ cells was found to highly correlate with animals' age (r = 0.923, p < 0.005). The basal parameters of adaptive cell-mediated immunity in naïve healthy marmosets without markers of systemic immune activation were obtained. These parameters and the described procedures are crucial in documenting the changes induced in common marmosets by prophylactic and therapeutic immune interventions.

Luciferase Expression Allows Bioluminescence Imaging But Imposes Limitations on the Orthotopic Mouse (4T1) Model of Breast Cancer

Implantation of reporter-labeled tumor cells in an immunocompetent host involves a risk of their immune elimination. We have studied this effect in a mouse model of breast cancer after the orthotopic implantation of mammary gland adenocarcinoma 4T1 cells genetically labelled with luciferase (Luc). Mice were implanted with 4T1 cells and two derivative Luc-expressing clones 4T1luc2 and 4T1luc2D6 exhibiting equal in vitro growth rates. In vivo, the daughter 4T1luc2 clone exhibited nearly the same, and 4T1luc2D6, a lower growth rate than the parental cells. The metastatic potential of 4T1 variants was assessed by magnetic resonance, bioluminescent imaging, micro-computed tomography, and densitometry which detected 100-μm metastases in multiple organs and bones at the early stage of their development. After 3-4 weeks, 4T1 generated 11.4 ± 2.1, 4T1luc2D6, 4.5 ± 0.6; and 4T1luc2, <1 metastases per mouse, locations restricted to lungs and regional lymph nodes. Mice bearing Luc-expressing tumors developed IFN-γ response to the dominant CTL epitope of Luc. Induced by intradermal DNA-immunization, such response protected mice from the establishment of 4T1luc2-tumors. Our data show that natural or induced cellular response against the reporter restricts growth and metastatic activity of the reporter-labelled tumor cells. Such cells represent a powerful instrument for improving immunization technique for cancer vaccine applications.

Relationship between the Size of Magnetic Nanoparticles and Efficiency of MRT Imaging of Cerebral Glioma in Rats

BSA-coated Fe3O4 nanoparticles with different hydrodynamic diameters (36±4 and 85±10 nm) were synthesized, zeta potential and T2 relaxivity were determined, and their morphology was studied by transmission electron microscopy. Studies on rats with experimental glioma C6 showed that smaller nanoparticles more effectively accumulated in the tumor and circulated longer in brain vessels. Optimization of the hydrodynamic diameter improves the efficiency of MRT contrast agent.

Modeling and integral X-ray, optical, and MRI visualization of multiorgan metastases of orthotopic 4T1 breast carcinoma in BALB/c mice

A model of highly metastasizing orthotopic allogeneic breast carcinoma was reproduced and standardized in experiments on BALB/c mice. 4T1 cells characterized by high metastatic activity were transfected with red fluorescent protein (RFP) gene or firefly luciferase (Luc2) gene. Unmodified 4T1 cells and modified 4T1-RFP and 4T1-Luc2 cells were subcutaneously injected to mature female mice into the second mammary fat pads. Quantitative evaluation of the primary node and visceral metastases was performed using magnetic-resonance imaging, X-ray and optical tomography. Modification of 4T1 cells with RFP gene considerably reduced their invasive and metastatic potential and led to spontaneous regression of the primary tumor in 20% cases. Modification of 4T1 cells with Luc2 gene had practically no effect on proliferative, invasive, and metastatic characteristics of the tumor and provided the possibility of quantitative analysis of the primary tumor dynamics by the luminescence intensity. The survival median in mice receiving unmodified 4T1 cells and transfected 4T1-RFP and 4Т1-Luc2 cells was 32, 42, and 38 days, respectively. Neither primary node nor tumor metastases accumulated gadolinium-containing contrast agent and Alasens fluorescent tracer. After implantation of 4T1 and 4Т1-Luc2 cells, multiple metastases were more often detected in the lungs, liver, spleen, spine, and regional lymph nodes and less frequently in the brain, which corresponded to metastasizing profile of human breast cancer. The developed model of orthotopic breast carcinoma 4T1 in BALB/c mice with complex detection of multiple organ metastases using X-ray microCT, optical, and MRI can be recommended for preclinical studies of new antitumor preparations.

Targeted delivery of cisplatin by сonnexin 43 vector nanogels to the focus of experimental glioma C6

The aim of this study was to create a nanocontainer conjugated with monoclonal antibodies to connexin 43 (Cx43) that is actively expressed at the periphery of C6 glioma and in the astroglia roll zone. Stable vector nanogels with high (up to 35%) cisplatin load were synthesized. The antitumor effects of Cx43-modified cisplatin-loaded nanogels, free cisplatin, and nonspecific drugs were carried out on C6 glioma model. Vector nanogels reduced systemic toxicity of cisplatin, effectively inhibited tumor growth, and significantly prolonged the lifespan of animals with experimental tumors.

Magnetic resonance imaging of endothelial cells with vectorized iron oxide nanoparticles

We propose a method for obtaining superparamagnetic nanoparticles based on iron oxide and their water suspensions. The structure and size of nanoparticles were confirmed by transmission electron microscopy, dynamic light scattering, and X-ray diffraction analysis. The nanoparticles also contained a fluorescent dye Dil C18. Cytotoxicity of obtained aqueous suspension was studied by MTT assay; low toxicity of nanoparticles was demonstrated. High T2-relaxivity of nanoparticles allows using them as a contrast agent for MRI. After incubation of cerebellar sections with nanoparticles vectorized with antibodies to antigen AMVB1, specific visualization of blood vessels was detected.