Cell types differential degradation

The described method is suitable to compare up to 50 drugs in one experiment. The price for this is the limited quantification, as the staining is not strictly stoichiometric, and does not allow the distinction between matrix synthesis and degradation. For more detailed assessment, radiolabeling is the better choice. The limitation of these primary culture assays lies in the elaborate preparation and isolation of the chondrocytes. Several attempts to immortalize this differentiated mesenchymal cell type have so far resulted in the loss of certain cartilage-specific properties. 

Figure 5. Polarized light microscopy photomicrograph of wet mount of waterlogged wood from a prehistoric habitation site, 100 B.C.-lOO A.D., Japan. The hydrated wood shows differential degradation of cell types. Only a few isolated cells have retained birefringent cellulose.

Certain criteria were considered necessary for an ideal matrix for cell transplantation. The matrix should be biocompatible, not inducing a tissue response in the host, and completely resorbable leaving a totally natural tissue replacement following degradation of the polymer. The matrix should be easily and reliably reproducible into a variety of shapes and structures that retain their shape when implanted. As a vehicle for cell delivery, the matrix should provide mechanical support to maintain a space for tissue to form [125]. The interaction of the surface of the matrix with cells should support differentiated cell function and growth, and in certain situations, should induce ingrowth of desirable cell types from surrounding tissue. 

Surprisingly, the use of cocultures with degradable PUs in cardiac TE systems has been limited when vascular grafts are excluded from the research. A study by Parrag et al. used murine-derived embryonic stem cells (mESCs) and mouse embryonic fibroblasts (MEEs) to TE cardiomyocyte-derived tissues. mESCs are pluripotent cells that require proper cues to differentiate into specific cell types. In the study, Parrag et al. showed that both the coculture of mESCs with MEEs and the use of aligned microfi-brous PU scaffolds provided the cues necessary to induce mESC differentiation to a functioning cardiomyocyte phenotype [104]. 

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