To further validate the non-cytotoxicity of the Odex/CEC
hydrogels and in concert with exploring its potential as an in situ
gelable biomaterial for directly applying to dermal wounds, cell
encapsulation was performed using dermal fibroblast as a model
cell. As shown in Fig. 6, cells residing inside the hydrogel initially
assumed a round shape (Fig. 6A), which was apparently very
different from the pattern of the cells residing on the 2D culture
dish (Fig. 6F). Initially, the cells did not adhere to the Odex/CEC
hydrogel, which could be due to its abundance of COO, and thus
negative charges on the hydrogel network. However, there was no
evidence of cell cytotoxicity, typically manifested as excessive cell
deaths. After 1 week of incubation, some of the cells started to
adhere to the Odex/CEC hydrogels, as indicated by their assumption
of oval or rod shape (Fig. 6B–D). Fig. 6C was an image of living
cells. Clearly, cells were spreading out and cell clusters started to
form, indicating proliferation. To further examine the morphology
of the cells entrapped inside the hydrogels, cell-laden hydrogels
were fixed with 70% ethanol followed by staining with crystal
violet. The results were depicted in Fig. 6B and D at a higher
magnification. The nuclei were readily recognizable with cells
assuming a spread-out pattern (marked with ‘‘ ’’), which was
several times of their original sizes (round, unattached). This
suggested that the cells were adapting to or modifying the
hydrogel and became more tolerant to the new environment
surrounding them after several days of incubation. As depicted in
Fig. 2B, the Odex/CEC hydrogel showed a highly porous internal
structure with a pore size sufficiently large for accommodating