Cell sheet based bioink for 3D bioprinting applications.

In this research, a novel development of bioink from cell sheets is presented for scaffold free bioprinting applications. Poly(N-isopropylacrylamide) (PNIPAAm) coated surfaces were first prepared by using initiated chemical vapor deposition method. Cell-sheets were then grown on these thermoresponsive pNIPAAm coated surfaces and easily detached without disturbing delicate cell-extracellular matrix (ECM) and cell-cell interactions. The detached cells sheets were used to prepare cell sheet based bioink and bioprinted to form various shapes. The results showed that the prepared cell-sheet based bioink shows an increase in the structural integrity compare to cell-aggregates suggesting that the cell sheet aggregates preserved interconnected ECM proteins. The viability of cell sheet based aggregates was also compared to single cell aggregates at three different time points in a seven-day period after printing. The developed cell-sheet based bioink has several advantages in terms of shape fidelity, reproducibility and automated deposition for bioprinting applications. The results also demonstrated that the bioprinted constructs secreted collagen type I which is a strong indication of starting ECM deposition. Moreover, the immunostaining results showed that the fibronectin in cell sheets was preserved during and after the preparation process of bioink.