Flávia Helena da Silva

The Anti-Tumor Effects of Adipose Tissue Mesenchymal Stem Cell Transduced with HSV-Tk Gene on U-87-Driven Brain Tumor

Glioblastoma (GBM) is an infiltrative tumor that is difficult to eradicate. Treating GBM with mesenchymal stem cells (MSCs) that have been modified with the HSV-Tk suicide gene has brought significant advances mainly because MSCs are chemoattracted to GBM and kill tumor cells via a bystander effect. To use this strategy, abundantly present adipose-tissue-derived mesenchymal stem cells (AT-MSCs) were evaluated for the treatment of GBM in mice. AT-MSCs were prepared using a mechanical protocol to avoid contamination with animal protein and transduced with HSV-Tk via a lentiviral vector. The U-87 glioblastoma cells cultured with AT-MSC-HSV-Tk died in the presence of 25 or 50 μM ganciclovir (GCV). U-87 glioblastoma cells injected into the brains of nude mice generated tumors larger than 3.5 mm2 after 4 weeks, but the injection of AT-MSC-HSV-Tk cells one week after the U-87 injection, combined with GCV treatment, drastically reduced tumors to smaller than 0.5 mm2. Immunohistochemical analysis of the tumors showed the presence of AT-MSC-HSV-Tk cells only within the tumor and its vicinity, but not in other areas of the brain, showing chemoattraction between them. The abundance of AT-MSCs and the easier to obtain them mechanically are strong advantages when compared to using MSCs from other tissues.

Treatment of adult MPSI mouse brains with IDUA-expressing mesenchymal stem cells decreases GAG deposition and improves exploratory behavior

BackgroundMucopolysaccharidosis type I (MPSI) is caused by a deficiency in alpha-L iduronidase (IDUA), which leads to lysosomal accumulation of the glycosaminoglycans (GAGs) dermatan and heparan sulfate. While the currently available therapies have good systemic effects, they only minimally affect the neurodegenerative process. Based on the neuroprotective and tissue regenerative properties of mesenchymal stem cells (MSCs), we hypothesized that the administration of MSCs transduced with a murine leukemia virus (MLV) vector expressing IDUA to IDUA KO mouse brains could reduce GAG deposition in the brain and, as a result, improve neurofunctionality, as measured by exploratory activity.MethodsMSCs infected with an MLV vector encoding IDUA were injected into the left ventricle of the brain of 12- or 25-month-old IDUA KO mice. The behavior of the treated mice in the elevated plus maze and open field tests was observed for 1 to 2 months. Following these observations, the brains were removed for biochemical and histological analyses.ResultsAfter 1 or 2 months of observation, the presence of the transgene in the brain tissue of almost all of the treated mice was confirmed using PCR, and a significant reduction in GAG deposition was observed. This reduction was directly reflected in an improvement in exploratory activity in the open field and the elevated plus maze tests. Despite these behavioral improvements and the reduction in GAG deposition, IDUA activity was undetectable in these samples. Overall, these results indicate that while the initial level of IDUA was not sustainable for a month, it was enough to reduce and maintain low GAG deposition and improve the exploratory activity for months.ConclusionsThese data show that gene therapy, via the direct injection of IDUA-expressing MSCs into the brain, is an effective way to treat neurodegeneration in MPSI mice.

α- L-iduronidase gene-based therapy using the phiC31 system to treat mucopolysaccharidose type I mice.

Mucopolysaccharidose type I (MPSI) is a lysosomal monogenic disease caused by mutations in the gene for α‐ l‐iduronidase (IDUA). MPSI patients need a constant supply of IDUA to alleviate progression of the disease. IDUA gene transfer using integrative vectors might provide a definitive solution and support advancement to clinical trials, although studies have not yet been satisfactory. To achieve a stable IDUA gene expression in vivo, phiC31 was tested in the present study.

Autonomous growth of BALB/MK keratinocytes transfected with a retroviral vector carrying the human epidermal growth factor gene

Epidermal growth factor (EGF), which promotes epidermal regeneration and wound closure, is important for the proliferation and differentiation of epidermal and epithelial tissues in animals. Exogenous EGF is a promising therapeutic agent for wound healing, but its general use is restricted by the limited availability of this protein. In this work, we show that the transfection of mouse BALB/MK keratinocytes, which are totally dependent on EGF for growth and migration, with mature cDNA for human EGF via a retroviral vector abolished the cells requirement for exogenous EGF. The transformed cells had normal morphology and a growth rate that varied according to the source of the retroviral vector used. Keratinocyte transfection with EGF cDNA provides a time- and cost-efficient means of culturing keratinocytes and yields cells that may be useful for skin grafting.

Evaluation of Electrochemical Surface Treatments of Ti by using Mesenchymal Stem Cells Culture

New surface modifications on pure Ti for prosthetic implants were developed and tested. The following treatments and their combinations were studied: Pitting, anodizing, and chemical deposition of Ca-phosphates. Mesenchymal stem cells were cultured on these Ti substrates to evaluate the quality of the proposed treatments. The closing of superficial oxide pores produced by plasma anodization of Ti was carried out by chemical deposition of Ca-phosphates and others compounds by immersion methods in different baths in order to promote a controlled release mechanisms of pharmaceutical compounds from the implant to the organism. The results were evaluated by the statistical analysis of the reduction of the pores density. Cells culture results indicated that the surface treatments were able to promote cellular proliferation and complete coverage of the Ti surfaces. The obtained calcium phosphate deposition was efficient in closing approximately 50% of the pores, although the deposition was not homogenous on the whole surface.