Figure 7B. MTT assay of C2C12 myoblast cells incubated onto
well plate (control) and cellulose acetate (CA) and cellulose acetate
nanofibers with annatto extract (CA@A) over 2 days and 7 days.
***p<0.05 (Student’s t-test)
Cells grown in a monolayer (control) were maintained under the same
conditions and used for comparison. The MTT results (Figure 7B) obtained
after 2 days of cell culture found lower cell viability in the
scaffolds, indicating that the monolayer control was more suitable than
nanofiber scaffolds for cell attachment and proliferation during the
initial days of culture.
After 7 days of culture, however, the cells in the monolayer reached
growth arrest, while the viability rate for the cells cultivated onto
the scaffolds increased. Growth arrest in the control may be regulated
by cell-cell contact or contact inhibition [43]. This was not
observed in cells cultivated onto nanofibers due to their large surface
area, indicating that scaffolds are beneficial for longer-duration cell
culture.
The viability of cells cultivated onto the CA@A nanofiber was also found
to be higher than for those cultivated onto the CA nanofiber. Previous
authors have shown annatto extract to be rich in antioxidant components
that can improve cellular proliferation [44]. Furthermore,
considering the more hydrophilic nature of cellulose acetate nanofiber
with annatto (as demonstrated by the contact angle), this surface can
also facilitate interactions between cells and matrices, leading to
improved attachment and proliferation of C2C12 myoblasts [37]. These
results suggest that CA@A nanofibers induce myoblast proliferation,
which is essential for scaffolds utilized in cultivated meat expansion.