Transmyocardial revascularization and vascular endothelial growth factor administration enhance effect of cell transplantation for myocardial infarct repair in rats

Salivary gland tissue engineering to attain clinical benefits: a special report

The salivary glands produce saliva, which helps in mediating the oral colonization of microbes, the repair of mucosa, the remineralization of teeth, lubrication and gustation. However, certain medications, therapeutic radiation and certain autoimmune diseases can cause a reduction in the salivary flow. The aim of this report was to review and highlight the indications and techniques of salivary gland engineering to counter hyposalivation. This report concludes that in the literature, numerous strategies have been suggested and discussed pertaining to the engineering of salivary gland, however, challenges remain in terms of its production and accurate function. Dedicated efforts are required from researchers all over the world to obtain the maximum benefits from salivary gland engineering techniques.

Improved Cell Survival in Infarcted Myocardium Using a Novel Combination Transmyocardial Laser and Cell Delivery System

Stem cell therapy has been used to treat ischemic cardiac disease with promising early results. However, there has been limited success using cell therapy in infarcted tissue. The cells have an inadequate microvascular environment in order to survive once implanted into scar tissue. The goal of this study was to create a microvascular environment into infarcted myocardial tissue using transmyocardial laser revascularization (TMR) as a pretreatment before cell implantation and evaluate cell survival afterwards. Balloon occlusion catheter-based myocardial infarct of the circumflex artery was created in a porcine model. The infarct was allowed to mature for 2 weeks. Three groups consisting of TMR alone (TMR), TMR + fluorescent-labeled allogeneic mesenchymal stem cells (MSCs) (TMR + Cells), and MSCs alone (Cells) were injected into the infarcted tissue using a combination TMR and cell delivery system (Phoenix™, Cardiogenesis). The hearts were explanted at 1 week after treatment for cell and tissue evaluation. The myocardial infarcts were verified in all animals using both ultrasound and direct visual imaging. All arms of the study were successful with a mean of 2.0 ± 106 MSCs injected per site into the scar tissue. All animals survived to explant at 1 week. On histological examination, 300 high-power fields were evaluated demonstrating that the TMR + Cells group had 25 ± 5 cells and the Cells group 5 ± 2 cells compared to baseline TMR alone by fluorescence. The use of TMR as a pretreatment for MSC injection increases early cell survival in infarcted tissue without increased adverse events. Further long-term functional and differentiation analysis will be required to evaluate the efficacy for future clinical translation.

Implications of vascular endothelial growth factor for postischemic neurovascular remodeling

Neurovascular remodeling has been recently recognized as a promising target for neurologic therapies. Hopes have emerged that, by stimulating vessel growth, it may be possible to stabilize brain perfusion, and at the same time promote neuronal survival, brain plasticity, and neurologic recovery. In this review, we outline the role of vascular endothelial growth factor (VEGF) in the ischemic brain, analyzing how this growth factor contributes to brain remodeling. Studies with therapeutic VEGF administration resulted in quite variable results depending on the route and time point of delivery. Local VEGF administration consistently enhanced neurologic recovery, whereas acute intravenous delivery exacerbated brain infarcts due to enhanced brain edema. Future studies should answer the following questions: (1) whether increased vessel density translates into improvements in blood flow in the hemodynamically compromised brain; (2) how VEGF influences brain plasticity and contributes to motor and nonmotor recovery; (3) what are the actions of VEGF not only in young animals with preserved vasculature, on which previous studies have been conducted, but also in aged animals and in animals with preexisting atherosclerosis; and (4) whether the effects of VEGF can be mimicked by pharmacological compounds or by cell-based therapies. Only on the basis of such information can more definite conclusions be made with regard to whether the translation of therapeutic angiogenesis into clinics is promising.

On approaches to the functional restoration of salivary glands damaged by radiation therapy for head and neck cancer, with a review of related aspects of salivary gland morphology and development

Radiation therapy for cancer of the head and neck can devastate the salivary glands and partially devitalize the mandible and maxilla. As a result, saliva production is drastically reduced and its quality adversely altered. Without diligent home and professional care, the teeth are subject to rapid destruction by caries, necessitating extractions with attendant high risk of necrosis of the supporting bone. Innovative techniques in delivery of radiation therapy and administration of drugs that selectively protect normal tissues can reduce significantly the radiation effects on salivary glands. Nonetheless, many patients still suffer severe oral dryness. I review here the functional morphology and development of salivary glands as these relate to approaches to preventing and restoring radiation-induced loss of salivary function. The acinar cells are responsible for most of the fluid and organic material in saliva, while the larger ducts influence the inorganic content. A central theme of this review is the extent to which the several types of epithelial cells in salivary glands may be pluripotential and the circumstances that may influence their ability to replace cells that have been lost or functionally inactivated due to the effects of radiation. The evidence suggests that the highly differentiated cells of the acini and large ducts of mature glands can replace themselves except when the respective pools of available cells are greatly diminished via apoptosis or necrosis owing to severely stressful events. Under the latter circumstances, relatively undifferentiated cells in the intercalated ducts proliferate and redifferentiate as may be required to replenish the depleted pools. It is likely that some, if not many, acinar cells may de-differentiate into intercalated duct-like cells and thus add to the pool of progenitor cells in such situations. If the stress is heavy doses of radiation, however, the result is not only the death of acinar cells, but also a marked decline in functional differentiation and proliferative capacity of all of the surviving cells, including those with progenitor capability. Restoration of gland function, therefore, seems to require increasing the secretory capacity of the surviving cells, or replacing the acinar cells and their progenitors either in the existing gland remnants or with artificial glands.

Combined transmyocardial revascularization and cell-based angiogenic gene therapy increases transplanted cell survival

We hypothesized that pretreatment of an infarcted heart by mechanical transmyocardial revascularization (TMR) before transplantation of bone marrow cells (BMCs) or BMC-expressing angiogenic growth factors would increase transplanted BMC survival and enhance myocardial repair. Female Lewis rats underwent coronary ligation 3 wk before creation of 10 needle TMR channels (3 groups) or no TMR (3 groups), followed by transplantation of 3 × 106male donor BMCs, BMC transfected with vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and insulin-like growth factor-1 (IGF-1) (BMC + VBI), or medium alone. At 1, 3, and 7 days, we evaluated transplanted cell survival, vascular densities, and left ventricular (LV) function ( N = 4 per group × 6 groups × 3 time points). At 3 days, vascular densities in the scar were increased by TMR + BMC + VBI and by BMC + VBI ( P < 0.05), and at 7 days, vascular densities were greatest in rats receiving TMR + BMC + VBI ( P < 0.05). Transplanted cell survival at 3 and 7 days was increased by TMR and by BMC + VBI. Combined therapy with TMR + BMC + VBI resulted in the greatest cell survival at 3 days ( P < 0.05) versus BMC. After 7 days, LV ejection fraction (LVEF) was lowest in rats receiving neither BMC nor TMR and greatest in rats receiving TMR + BMC + VBI ( P = 0.004). We concluded that mechanical pretreatment of infarcted myocardium by TMR enhances the effect of subsequent cell-based gene therapy on transplanted cell survival, angiogenesis, and LV function. Scar pretreatment with TMR combined with cell-based multigene therapy may maximize myocardial repair.