The thermoresponsive surfaces of brush structure (linear polymer chains tethered on the surface) based on poly(2-isopropyl-2-oxazoline)s and copolymers of 2-ethyl-2-oxazoline and 2-nonyl-2-oxazoline were obtained using the grafting-to method. The living oxazoline (co)polymers have been synthesized by cationic ring-opening polymerization and subsequently terminated by the reactive amine groups present on the surface. The changes in the surface morphology, philicity and thickness occurring during surface modification were monitored via atomic force microscopy, contact angle and ellipsometry. The thickness of the (co)poly(2-substituted-2-oxazoline) layers ranged from 4 to 11 nm depending on the molar mass of immobilized polymer and reversibly varied with the temperature changes. This confirmed thermoresponsive properties of obtained surfaces. The obtained polymer surfaces were used as a support for dermal fibroblast culture and detachment. The fibroblasts' adhesion and proliferation on the polymer surfaces were observed when the culture temperature was above the cloud point temperature of the immobilized polymer. Lowering the temperature resulted in the detachment of the dermal fibroblast sheets from the polymer layers, which makes these surfaces suitable for the treatment of wounds and in skin tissue engineering.

Well-defined thermosensitive poly[tri(ethylene glycol) monoethyl ether methacrylate] (P(TEGMA-EE)) brushes were synthesized on a solid substrate by the surface-initiated atom transfer radical polymerization of TEGMA-EE. The polymerization reaction was initiated by 2-bromo-2-methylpropionate groups immobilized on the surface of the wafers. The changes in the surface composition, morphology, philicity, and thickness that occurred at each step of wafer functionalization confirmed that all surface modification procedures were successful. Both the successful modification of the surface and bonding of the P(TEGMA-EE) layer were confirmed by X-ray photoelectron spectroscopy (XPS) measurements. The thickness of the obtained P(TEGMA-EE) layers increased with increasing polymerization time. The increase of environmental temperature above the cloud point temperature of P(TEGMA-EE) caused the changes of surface philicity. A simultaneous decrease in the polymer layer thickness confirmed the thermosensitive properties of these P(TEGMA-EE) layers. The thermosensitive polymer surfaces obtained were evaluated for the growth and harvesting of human fibroblasts (basic skin cells). At 37 °C, seeded cells adhered to and spread well onto the P(TEGMA-EE)-coated surfaces. A confluent cell sheet was formed within 24 h of cell culture. Lowering the temperature to an optimal value of 17.5 °C (below the cloud point temperature of the polymer, TCP, in cell culture medium) led to the separation of the fibroblast sheet from the polymer layer. These promising results indicate that the surfaces produced may successfully be used as substrate for engineering of skin tissue, especially for delivering cell sheets in the treatment of burns and slow-healing wounds.

No abstract

No abstract

No abstract

No abstract

Mutations in COL1A1 or COL1A2 genes lead to osteogenesis Imperfecta (OI) in humans. There are three possiblities to successfully treat OI including (1) gene therapy, (2) mesenchymal stem cell (MSC) therapy, or (3) a combination of both. The aim of this study was to develop a model for combined gene/cell OI therapy by targeting Col1a1 and Col1a2 genes with isogenic sequences from corresponding human genes in rat bone marrow (BM)-derived MSCs. The recombination efficacy was tested for five different rat-human-rat hybrid DNAs with rat fragments that were 1 to 4 kb long. For selection of transfected clones a neomycine resistance gene was cotransfected, and clones resistant to G418 (G418(+)) were recovered and screened for integration of specific gene loci in the rat genome. Over 90% of G418(+) clones correctly integrated the rat-human-rat hybrid DNAs, and both OI loci in the rat genome were targeted to a similar degree. Longer homologous sequences integrated into rat collagen genes approximately 10 times more efficiently. Based on our data the nonviral gene targeting technology could be potentially employed to repair collagen genes in OI patients.

No abstract