2022, Vol. 26 ›› Issue (28): 4483-4488

Preparation and in vitro evaluation of injectable microspheres loaded with cells

He Jiachen1, 2, Liu Chang1, 2, Chen Chichi1, 2, Shi Qin1, 2   

Abstract: BACKGROUND: The use of biological materials as cell carriers can provide a 3D culture microenvironment, support cell viability and function, and may expand the number and therapeutic effects of cell therapy. Therefore, it is very important to find a suitable biological material.
OBJECTIVE: To prepare injectable gelatin methacryloyl porous microspheres, and explore their biocompatibility and the potential of loaded cells for tissue engineering.
METHODS: Injectable gelatin methacryloyl porous microspheres were prepared by microfluidic technology. The microscopic morphology and hardness of microspheres were characterized. MC3T3-E1 cells were cultured in normal medium as control group and microsphere extract as experimental group. Cell proliferation was detected by CCK8 assay. Cell survival was detected by live dead cell staining. Microspheres were co-cultured with CD3+ T cells. CD3+ T cells cultured alone were used as controls. The effect of microspheres on T cell activation was observed under light microscope. The morphology of T cells loaded with microspheres was observed by Dapi staining. Flow cytometry was used to verify whether co-culture with microspheres influenced the ratio of CD4+ T cells to CD8+ T cells.
RESULTS AND CONCLUSION: (1) Under the inverted microscope, the microspheres were highly dispersed and uniform in size. The diameter size met the injectable condition. Under scanning electron microscope, the microspheres formed porous structure after freeze-drying, and pores were uniformly distributed. The elastic modulus of the microspheres was (9.76±2.04) kPa. (2) CCK-8 assay and live dead cell staining results demonstrated that the tendency and activity of proliferation of MC3T3-E1 cells cultured in the two media had no difference. (3) Under optical microscope, co-culture with microspheres for 2 days did not cause CD3+ T cell activation, and did not interfere with the activation of CD3+ T cells. CD3+ T cells were distributed on the surface and pores of the microspheres. (4) Flow cytometry results showed that microspheres did not affect the ratio of CD4+ T cells to CD8+ T cells. (5) An injectable gelatin methacryloyl porous microsphere was prepared by microfluidic technology, which has good biocompatibility and does not affect cell. It is a kind of biomaterial with broad application prospect in tissue engineering.
Key words: microfluidic, hydrogels, porous microspheres, injectable, biocompatibility, cell therapy, T cell, tissue engineering