Concentrated polymer brush-modified cellulose nanofibers promote chondrogenic differentiation of human mesenchymal stem cells by controlling self-assembly.

In order to develop new three-dimensional (3D) cell culture systems for articular cartilage regeneration, concentrated poly(styrene sulfonate sodium salt) brush-modified cellulose nanofibers were employed as building blocks for the self-assembly of human mesenchymal stem cells (hMSCs). Unique 3D cellular structures, such as giant spheres and sheets, were formed by controlling hMSC self-assembly.

Ultra-low fouling photocrosslinked coatings for the selective capture of cells expressing CD44.

The effective control of biointerfacial interactions is of outstanding interest in a broad range of biomedical applications, ranging from cell culture tools to biosensors and implantable medical devices. For many of these applications, highly specific interactions between cells and material surfaces are desired. Sophisticated control over these interactions requires reducing or preventing non-specific interactions on the one hand and displaying highly specific signals that can be recognized by extracellular receptors on the other. We have recently developed ultra-low fouling coatings that can be applied in a single step using photoreactive copolymers of 2-hydroxypropyl acrylamide and N-benzophenone acrylamide. Here, we have expanded this approach by incorporating polymerizable peptide monomers into these copolymers. The monomers QQGWFGAGK(acrylamide) and acrylamide-GAGQQGWF were synthesized after identifying the QQGWF sequence as a binding motif for CD44 by phage display for the first time. Our results demonstrate that UV-crosslinked coatings fabricated using the QQGWFGAGK(acrylamide) monomer are effective at selectively binding hMSC in the presence of HepG2 and HEK293 cells due to the difference in CD44 expression. Our results also demonstrate that the peptide modified coatings retain their low biofouling character using a BCA protein binding assay as well as an E. coli bacterial attachment assay over a 24 h period. Our approach provides an alternative to traditional integrin-mediated selective cell binding on surfaces and opens the door to new diagnostic applications, exploiting the fact that the transmembrane protein CD44 is highly expressed in multiple diseases.