Tissue engineering. Part A
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The aim of this study was to assess the feasibility of transplanting mesenchymal stem cells (MSCs), genetically modified to express glial-derived neurotrophic factor (GDNF), to the contused rat spinal cord, and to subsequently assess their neural differentiation potential. MSCs expressing green fluorescent protein were transduced with a retroviral vector to express the neurotrophin GDNF. The transduction protocol was optimized by using green fluorescent protein-expressing retroviral constructs; approximately 90% of MSCs were transduced successfully after G418 selection. ⋯ In conclusion, transplanted MSCs have limited capacity for the replacement of neural cells lost as a result of a spinal cord trauma. However, they provide excellent opportunities for local delivery of neurotrophic factors into the injured tissue. This study underlines the therapeutic benefits associated with cell transplantation and provides a good example of the use of MSCs for gene delivery.
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Taking rapid and efficient formation of functional tissues as our long-term goal, we discuss in this study a new and generic approach toward formation of multilayered three-dimensional (3D) tissues using nanofibers. 3:1 poly (epsilon-caprolactone) (PCL) (8% w/v)/collagen (8.0% w/v) solution was electrospun into nanofibers with an average diameter of 454.5 +/- 84.9 nm. The culture of human dermal fibroblasts (NHDF) on PCL/collagen nanofibers showed a high initial cell adhesion (88.1 +/- 1.5%), and rapid cell spreading with spindle morphology. Three-dimensional multilayered cell-nanofiber constructs were built with alternating NHDF seeding (1 x 10(5)cells/layer) and PCL/collagen nanofiber collection on site of electrospinning, where almost all the seeded cells retained in the constructs. ⋯ By culturing either fibroblast/fiber layered constructs or keratinocyte/fibroblast/fiber layered constructs, dermal-like tissues or bilayer skin tissues (containing both epidermal and dermal layers) were consequently produced within 1 week. Taken together, the present study reports a novel approach to 3D multilayered tissue formation using a bottom-up, on-site layer-by-layer cell assembly while electrospinning. This approach has marked potentials to form functional tissues composed of multiple types of cells, heterogeneous scaffold composition, and customized specific microenvironment for cells.
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Nondegradable synthetic polymer vascular grafts currently used in cardiovascular surgery have no growth potential. Tissue-engineered vascular grafts (TEVGs) may solve this problem. In this study, we developed a TEVG using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices, and tested whether the TEVGs exhibit growth potential and vascular remodeling in vivo. ⋯ The outer diameter of three of the four TEVGs increased in proportion to increases in body weight and outer native aorta diameter. Considerable extents of expression of molecules associated with extracellular matrix (ECM) degradation (i.e., matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase) and ECM precursors (i.e., procollagen I, procollagen III, and tropoelastin) occurred in the TEVGs, indicating vascular remodeling associated with degradation of exogenous ECMs (implanted decellularized matrices) and synthesis of autologous ECMs. This study demonstrates that the TEVGs with autologous BMCs and decellularized tissue matrices exhibit growth potential and vascular remodeling in vivo of tissue-engineered artery.