Effects Of Physical Stimulation On The Growth Behavior Of Two Specific Cells

At present,tissue engineering has shown great potential in biomedicine.Three core elements of tissue engineering are seed cells,tissue engineering scaffolds and growth factors.Tissue engineering scaffolds provide a growth environment for cells and significantly affect cell growth.Now,a great number of investiongs have been carried out on materials and manufacturing techniques of tissue engineering scaffolds.The scaffold materials are selected from natural substances such as collagen and silk protein,artificially degradable polymers such as PCL,PLA and PGA,as well as hydrogels such as Gel MA and PEGDA.The manufacturing approaches of tissue engineering scaffold with complex 3D geometry includes pouring,electrostatic spinning,3D printing.However,the effect of tissue engineering scaffolds still have to be improve in some aspects.Therefore,this study explores the effects of mechanical strength,mechanical tensile load,and electrical stimulation on cell growth.In bone tissue engineering,the mechanical strength of the scaffold is very important for the repair of bone defects.Hydrogels are considered to be promising materials for bone tissue engineering due to their physical and structural similarity to natural tissues.However,the currently used hydrogels,such as Gel MA,PEGDA,generally have poor mechanical strength and cannot meet the requirements of bone tissue engineering scaffolds.In this study,a new type of polyion complex hydrogel(PIC)was used to maufacture grid scaffolds by 3D printing,and PIC/MWCNT scaffolds were made by PIC doping with multi-walled carbon nanotube(MWCNT)for cell experiments.The potential of new hydrogel scaffolds for bone defect repair was shown by Alizarin Red S staining and osteogenesis-related gene expression levels.In neural tissue engineering,improving the repair speed of peripheral nerve injury is an urgent problem.For nerve cells,it is necessary to increase the growth rate of axons and make them grow in a specific direction.Mechanical stretching can allow many kinds of cells to grow directionally.Therefore,commercial instruments were used for experiments that rat adrenal pheochromocytoma cells(PC12)were cultured on dynamically stretched polydimethylsiloxane(PDMS)substrates to investigate the effects of stretching frequency and strain amplitude on PC12 cell growth.It was found that PC12 cells were able to reorientation on the stretched substrates.Finally,stress fiber(SF)and focal adhesions(FA)models were used to simulate the reorientation behavior of PC12 cells during stretching.The nervous system is a large conductive network,and electrical stimulation was found to have a positive effect on the repair of nerve damage.The conductive nerve scaffolds in previous studies have the disadvantages of poor electrical conductivity and no external controllable electrical stimulation.Thus,this study used silver nanowire(Ag NW)and PDMS to make Ag NW/PDMS flexible electrodes with good conductivity and stretchability.PC12 cells were cultured on flexible electrodes,and different voltages were applied at the same time.The effect of electrical stimulation on the growth of PC12 cells was investigated.The results showed that electrical stimulation could promote the proliferation and axon elongation rate of PC12 cells.Finally,PC12 was stimulated by coupling tensile load stimulation with electrical stimulation,and the growth of PC12 cells was observed.The results showed that PC12 cells not only improved axon elongation but also redirected axons.