[Effects of nanoporous PLLA scaffold on late endothelial progenitor cells behavior]

To observe the adhesion and proliferation of late endothelial progenitor cells (EPCs) planted on nanoporous PLLA scaffold in vitro and to provide a new approach that optimizes tissue engineered material.

Male and female New Zealand rabbits (weight 2.5-3.0 kg) were used. Isolated late EPCs from rabbit peripheral blood were cultured. Electrostatic spinning technique was adopted to prepare misaligned nanofibers, aligned nanofibers and super-aligned nanofibers, and low temperature plasma technique was applied to prepare misaligned membrane, aligned membrane and super-aligned membrane. After being divided into group A (cells only), B (misaligned membrane), C (normal membrane), D (aligned membrane) and E (super-aligned membrane), the primary late EPCs (1 x 10(5)/mL) were cultured on scaffolds and MTT method was used to detect cell proliferation ability at 3, 5, 7, 9, 11, 13, 15 and 17 days after culture. After being divided into group A (misaligned membrane), B (normal membrane), C (aligned membrane) and D (super-aligned membrane), precipitation method was applied to detect cell adhesion rate at 4, 12 and 24 hours after compound culture, and the morphologic changes of cells were observed at 4, 24 and 72 hours after compound culture.

Fiber diameters in nanofibrous PLLA scaffolds were 300-400 nm, with a porosity rate of above 90%. At 3, 5, 7, 9, 11, 13, 15 and 17 days after culture, A value of each group was increased with time and the cells in each group grew well, showing there was no significant difference between group A and group B at each time point (P > 0.05 ); during the period of 7-15 days after culture, the difference between groups C, D and E and groups A and B was significant (P < 0.05). At 4 hours after compound culture, the adhesion rate of group A was superior to that of groups B, C and D (P < 0.05); at 12 and 24 hours after compound culture, the adhesion rate of groups B, C and D was remarkably higher than that of group A (P < 0.05); significant difference was noted in each group between the time point of 4 hours and the time point of 12 and 24 hours after compound culture (P <0.05), but no significant difference between 12 hours and 24 hours was detected (P > 0.05). Morphology observation demonstrated that cells grew well on the scaffolds, the cells in groups A and B grew sporadically and disorderly, while the cells in groups C and D attached and aligned along fiber and proliferated, with an excretion of ECM. Group D was better at maintaining cell morphology.

Aligned and super-aligned nanofibers of PLLA scaffold can promote the adhesion and proliferation of seed cells on the scaffold and maintain good cell morphology, which is an appropriate candidate scaffold material for blood vessel tissue engineering. Late EPCs is an ideal cell source for blood vessel tissue engineering.