Physical, Spatial, and Molecular Aspects of Extracellular Matrix of In Vivo Niches and Artificial Scaffolds Relevant to Stem Cells Research

Figure 4

Biological relevance as a key to developing functional in vitro culture systems. There is a need for developing advanced, highly functional, robust, and long-term lasting in vitro culture systems for cells and organoids. In order to identify biologically active scaffolds, adhesion epitopes, and growth factors, high-throughput array approach is often used. It allows unbiased screening of large libraries of soluble compounds (proteins, peptides, and inorganic substances), as well as libraries of matrix scaffolds. However, sometimes biologically active compounds show false negative result, if the other aspects of the system are not biologically relevant. (a) The natural niche of a specific cell type can often serve a prototype for developing a highly functional in vitro culture system. Synergy of biologically relevant extracellular matrix cues and growth factors may be required in order to enable well-regulated cell function. (b) When a library of growth factors is analyzed in cell-based high-throughput screening array, the highly biologically active compounds may be identified as “false negatives” if the adhesive scaffold is not biologically relevant and does not enable co-signaling. (c) Also, if a library of scaffolds, whether natural, artificial, or mixed, is analyzed in cell-based high-throughput screening array, the truly functional scaffold may fail to provide the desired effect, if the cell culture medium lacks biologically relevant soluble factors that take part in co-signaling. (d) It is advisable, therefore, to arrange the high-throughput screening assays that would screen for a combination of growth factors library versus a scaffold library. The positive hit that can be missed in single-library screening may be identified in double-library cross-screening array.

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