Lactoyl-poloxamine/collagen matrix for cell-containing tissue engineering modules.

Collagen-containing crosslinked, remodelable poloxamine derivatives were produced by introducing very short oligo(lactic acid) segments through the reaction of poloxamine with L-lactide and the later addition of unsaturated bonds by the reaction of modified poloxamine with methacryloyl chloride. Degradation studies on discs indicated a faster weight loss in comparison to the stability of lactoyl-free samples. Cell-containing modules (both HepG2 cells and two different umbilical vein smooth muscle cell (UVSMC) cell-types) were produced. Live/Dead assay showed high survival levels for both HepG2 and UVSMC cell types after crosslinking. While nondegradable modules did not change shape over time, lactoyl-poloxamine matrices showed a gradual shrinkage and size decrease and an increase in the roughness of the surface. These findings were consistent with the expected degradability of the lactoyl derivative. A UVSMC cell line (CRL-2481) embedded in a LA-poloxamine/collagen matrix showed the characteristic elongated shape at day 9. UVSMC primary cells behaved in a manner similar to that seen in collagen gels: these cells formed isolated clusters through the matrix that gradually lost viability. On tissue culture polystyrene the same cells aggregated and did not reach confluence. Modules with embedded CRL-2481 UVSMC led to a better initial adhesion of endothelial cells and a higher extent of surface coverage than seen with the UVSMC-free system. With embedded primary UVSMC, some EC attachment and formation of gap junctions was seen. The pattern was not well organized. With further improvement (and characterization), the lactoyl poloxamine derivative is potentially useful as a scaffold for modular tissue engineering, when tissue remodeling is an important consideration.