The use of gene-modified bone marrow mesenchymal stem cells for cochlear cell therapy

BACKGROUND

The aim of this study was to investigate the potential of using bone marrow mesenchymal stem cells (BMSCs) for treatment of inflammation and autoimmune sensorineural hearing loss.

METHODS

Fifty-five immunized guinea pigs were divided into five groups. Group A received BMSCs expressing IL-4, group B received BMSCs expressing an empty carrier vector, group C received recombinant lentivirus expressing IL-4, group D received recombinant lentivirus expressing an empty carrier vector, and group E received phosphate-buffered saline. Auditory function was monitored using brain stem responses (ABRs) to evaluate the auditory changes. The distribution of implanted BMSCs in the inner ear was estimated using fluorescence microscopy. The distribution and expression of IL-4 gene products in the inner ear were detected via immunohistochemistry.

RESULTS

After transplantation, the ABR III wave threshold decreased significantly in BMSCs expressing exogenous IL-4 group (group A), BMSCs expressing empty carrier vector group (group B), and recombinant lentivirus expressing IL-4 group (group C) (P < 0.001), which means the auditory functions of the experimental guinea pigs were improved. Further statistical analysis revealed that BMSCs expressing exogenous IL-4 group (group A) and BMSCs expressing empty carrier vector group (group B) were able to improve the auditory function more obviously (P < 0.05). Lentivirus-infected BMSCs were able to migrate to the inner ear. Fluorescence-positive BMSCs were scattered in the scala tympani and vestibule.

CONCLUSIONS

These results demonstrated that BMSCs expressing exogenous IL-4 successfully migrated into the inner ear in an in vitro study. BMSCs expressing exogenous IL-4 and BMSCs can be used to treat inflammatory injury in autoimmune inner ear diseases.

Epimedium Polysaccharide Ameliorates Benzene-Induced Aplastic Anemia in Mice

Benzene (BZ) is an important occupational and environmental pollutant. Exposure to BZ may cause aplastic anemia which is characterized as bone marrow hematopoietic failure. In order to reduce the harmful effects of this pollutant, it is necessary to identify additional preventative measures. In this study, we investigated the protective effects of epimedium polysaccharide (EPS), a natural compound with antioxidant and immune-enhancing potency, on aplastic anemia induced by benzene exposure in mice. Male CD-1 mice were randomly divided into five groups including control, BZ (880 mg/kg), LE (EPS low-dose, 20 mg/kg + BZ), ME (EPS middle-dose, 100 mg/kg + BZ), and HE (EPS high-dose, 200 mg/kg + BZ) groups. Animals were exposed to BZ by subcutaneous injection in the presence or absence of EPS via oral administration. All mice were treated 3 times a week for 8 consecutive weeks to develop a mouse model of benzene-induced aplastic anemia (BIAA). Results showed that BZ induced a significant decrease in both white and red blood cells, platelet counts, and hemoglobin level compared with that in the control group (p < 0.01). Treatment of EPS led to a protective effect against these changes particularly in the highest-dose group (HE, p < 0.01). EPS also recovered the decreased number of nucleated cells in peripheral blood cell smears and femur biopsies by BZ exposure. The increased level of reactive oxygen species (ROS) in bone marrow mononuclear cells (BMMNCs) in mice from the BZ group was significantly lower (p < 0.01) in the mice from the highest concentration of EPS (HE) group when compared with that from the control group. In addition, BZ exposure led to a significant increase in the apoptosis rate in BMMNCs which was prevented by EPS in a dose-dependent manner (p < 0.01). The antiapoptosis effect of EPS was through reversing apoptotic proteins such as BAX, Caspase-9 and Caspase-3, and Bcl-2. Finally, EPS treatment partially restored the levels of T cells and the different subtypes except CD80⁺ and CD86⁺ compared with the BZ group (HE, p < 0.05). These results suggest that EPS has protective effects against BIAA via antioxidative stress, immune modulation, and antiapoptosis mechanisms.

[Establishment of New Zealand rabbit models of aplastic anemia]

OBJECTIVE

To screen for the optimal dose of benzene and cyclophosphamide using an orthogonal design for establishment of New Zealand rabbit models of aplastic anemia.

METHODS

Following an orthogonal experimental design, the effects of 3 levels of 4 factors, namely the dose of benzene (A), the dose of cyclophosphamide (B), the number of benzene injections (C), and the number of cyclophosphamide injections (D) were tested in the establishment of New Zealand rabbit models of aplastic anemia using a L₉ (3⁴) orthogonal table, and the optimal protocol for the model establishment was selected from the 9 experimental groups. Each rabbit received subcutaneous injection of benzene on the back every other day, followed by daily cyclophosphamide injection via the ear vein for prescribed times. The blood routine was examined every 6 days, and before modeling and at 36 days after modeling, a small sample of the femoral bone was collected for bone marrow histopathological examination.

RESULTS

Comparison of the white blood cell, erythrocyte and platelet counts among the 9 groups showed successful modeling in Groups 4-9, and daily mean reduction rates of the cell counts in Groups 7, 8, and 9 differed significantly from those in the other groups (P<0.05). In Group 7, bone marrow sections showed low myelodysplasia, reduced hematopoietic tissue, reduced or even absence of megakaryocytes, and increased fat cells. Further observation found that the rabbits in Group 7 had sustained bone marrow suppression, consistent with the clinical characteristics of the disease.

CONCLUSION

Stable models of aplastic anemia can be established efficiently in New Zealand rabbits by a combination of 8 subcutaneous injections of benzene at 1.5 mL/kg and 4 intravenous injections of cyclophosphamide at 10 mg/kg.

In vitro cell behaviors of bone mesenchymal stem cells derived from normal and postmenopausal osteoporotic rats

Postmenopausal osteoporosis (PMO) increases bone fragility and the risk of fractures, and impairs the healing procedure of bone defects in aged women. The stromal cell-derived factor-1α (SDF-1α)/CXC chemokine receptor type 4 (CXCR4) axis helps to maintain the biological and physiological functions of bone marrow mesenchymal stem cells (BMSCs) and increase the homing efficiency of BMSCs. The present study aimed to provide insights into the possible association between migration and osteogenic ability and the SDF-1α/CXCR4 axis in BMSCs derived from a rat model of PMO. In order to do this, the general and SDF-1α/CXCR4-associated biological characteristics as well as associated molecular mechanisms in BMSCs isolated from a PMO rat model (OVX-BMSCs) and normal rats (Sham-BMSCs) were investigated and compared. In comparison with Sham-BMSCs, OVX-BMSCs exhibited an impaired osteogenic ability, but a stronger adipogenic activity as well as a higher proliferative ability. In addition, OVX-BMSCs presented a lower chemotactic activity towards SDF-1α, lower expression levels of CXCR4 and reduced levels of phosphorylated AKT (p-AKT). Therefore, the lower expression levels of CXCR4 and p-AKT may be responsible for the impaired osteogenic ability and lower chemotactic activity towards SDF-1α of OVX-BMSCs.

The combined use of cytokine-induced killer cells and cyclosporine a for the treatment of aplastic anemia in a mouse model

In this study, we investigated the combined use of cytokine-induced killer (CIK) cells and cyclosporine A (CsA) to treat a mouse model of aplastic anemia (AA). CIK cells were cultured and injected alone or in combination with CsA into mice that had previously been induced into AA by busulfan and mouse interferon-γ (IFN-γ). The CIK cell-treated group had a survival rate of 55%, which was similar to the 60% survival rate observed in the CsA-treated group. The combination group showed a survival rate as high as 90%, while none of the mice in the no-treatment group survived to the end of the experiment. The CIK cells produced multiple cytokines, including several hematopoietic growth factors, which could promote the expansion of mouse bone marrow mononuclear cells in vitro. CsA reduced the proportion of CD4(+) T cells and the level of IFN-γ. The combined CIK cell and CsA treatment exhibited the best curative effect, a finding that might be due to the influence of these factors on both hematopoiesis and immunity. These data suggest that the combination of CIK cells and immunosuppressive therapy might be a candidate therapy for AA in the future.

Exogenous IL-4-expressing bone marrow mesenchymal stem cells for the treatment of autoimmune sensorineural hearing loss in a guinea pig model

Bone marrow mesenchymal stem cells (BMSCs) expressing recombinant IL-4 have the potential to remediate inflammatory diseases. We thus investigated whether BMSCs expressing exogenous IL-4 could alleviate autoimmune sensorineural hearing loss. BMSCs isolated from guinea pigs were transfected with recombinant lentivirus expressing IL-4. A total of 33 animals were divided into three groups. Group A received scala tympani injection of IL-4-expressing BMSCs, and Group B received control vector-expressing BMSCs, and Group C received phosphate-buffered saline. The distribution of implanted BMSCs in the inner ears was assessed by immunohistochemistry and fluorescence microscopy. Auditory brain-stem response (ABR) was monitored to evaluate the auditory changes. Following BMSCs transplantation, the threshold levels of ABR wave III decreased in Groups A and B and significant differences were observed between these two groups (P < 0.05). Transplanted BMSCs distributed in the scala tympani and scala vestibuli. In some ears with hearing loss, there was a decrease in the number of spiral ganglion cells and varying degrees of endolymphatic hydrops or floccule. Following transplantation, the lentivirus-infected BMSCs migrated to the inner ear and produced IL-4. Our results demonstrate that, upon transplantation, BMSCs and BMSCs expressing recombinant IL-4 have the ability to remediate the inflammatory injury in autoimmune inner ear diseases.