Tissue engineering of composite grafts: Cocultivation of human oral keratinocytes and human osteoblast-like cells on laminin-coated polycarbonate membranes and equine collagen membranes under different culture conditions.

In complex craniomaxillofacial defects, the simultaneous reconstruction of hard and soft tissue is often necessary. Until now, oral keratinocytes and osteoblast-like cells have not been cocultivated on the same carrier. For the first time, the cocultivation of human oral keratinocytes and human osteoblast-like cells has been investigated in this study. Different carriers (laminin-coated polycarbonate and equine collagen membranes) and various culture conditions were examined. Human oral keratinocytes and human osteoblast-like cells from five patients were isolated from tissue samples, seeded on the opposite sides of the carriers and cultivated for 1 and 2 weeks under static conditions in an incubator and in a perfusion chamber. Proliferation and morphology of the cells were analyzed by EZ4U-tests, light microscopy, and scanning electron microscopy. Cocultivation of both cell-types seeded on one carrier was possible. Quantitative and qualitative growth was significantly better on collagen membranes when compared with laminin-coated polycarbonate membranes independent of the culture conditions. Using perfusion culture in comparison to static culture, the increase of cell proliferation after 2 weeks of cultivation when compared with the proliferation after 1 week was significantly lower, independent of the carriers used. In conclusion, the contemporaneous cultivation of human oral keratinocytes and human osteoblast-like cells on the same carrier is possible, a prerequisite for planned in vivo studies. As carrier collagen is superior to laminin-coated polycarbonate membranes. Regarding the development over time, the increase of proliferation rate is lower in perfusion culture. Examinations of cellular differentiation over time under various culture conditions will be subject of further investigations.

Second-sphere ligand-field effects in solid solutions of anhydrous transition-metal phosphates.

Powders of the solid solutions In1-xCrxPO4 (0 < or = x < or = 1), In1-xCrx(PO3)3 (0 < or = x < or = 1), (In1-xCrx)4(P2O7)3 (0 < or = x < or = 0.7), and In1-xMnx(PO3)3 (0 < or = x < or = 0.8) have been synthesized by solid-state reactions. Depending on the dopant concentration, these materials show striking variations in color [In1-xCrxPO4, light pink to green-brown; (In1-xCrx)4(P2O7)3, light pink to red-brown; In1-xCrx(PO3)3, pale green to green; In1-xMnx(PO3)3, light blue to purple). Powder reflectance spectra of the solid solutions were measured in the UV/vis/NIR region (5500-35000 cm(-1)). Observed d-d electronic transition energies and results of calculations within the framework of the angular overlap model (AOM) for the low-symmetry chromophores [M(III)O6] (M = Cr, Mn) are in good agreement. In the case of the mixed In/Cr phosphates, the observed color changes can be related to second-sphere ligand-field effects. Clear evidence for differences in the pi-bonding of oxygen toward Cr(3+) (d(3) ion) and In(3+) (d(10) ion) are observed. For In1-xMnx(PO3)3, the variation in color is attributed to a slightly increasing elongation of the [Mn(III)O6] chromophore with increasing dopant concentration.

New Results of Chemical Transport as a Method for the Preparation and Thermochemical Investigation of Solids.

Chemical transport experiments are a valuable aid of great potential in the synthesis and thermochemical characterization of solids. Compounds of interest can often only be crystallized by this method. The use of a transport balance allows very detailed observations, particularly of the course of the experiment over time (simultaneous or sequential deposition of multiple-phase solids). The computer program CVTRANS enables a quantitative thermochemical description of the experiment based on the cooperative transport model. A compilation of recent results illustrates the development and efficiency of the method. The transport of phosphides, anhydrous phosphates and sulfates, and rare-earth oxide and oxohalide compounds are treated in detail.