Design And Preparation Of Granular Hydrogels Capable Of Capturing Stem Cells

Hydrogel is a three-dimensional network formed by cross-linking hydrophilic polymer chains.It can absorb and retain a large amount of water and has ability to transport substances at the molecular level and nano level,while maintaining solid-like properties.Therefore,it can be used as a scaffold material in biomedicine for drug delivery,tissue engineering and wound healing.However,in recent years,with people’s in-depth research on human tissues and cells,higher requirements have been put forward to apply hydrogels in the fields of regenerative medicine and tissue engineering.Granular hydrogel is a new type of hydrogel with a micron-scale pore network formed by the jammed micron-scale hydrogels.Compared with bulk hydrogels,granular hydrogels have good injectability,adjustable micron-sized pores and the unique properties of modularity.Therefore,granular hydrogels can more accurately regulate cells or tissues,and are more suitable for solving complex biomedical problems as a multifunctional biomaterial.Because of the great potential of granular hydrogel in the biomedical field,this paper plans to prepare a kind of granular hydrogel with good biocompatibility,and conduct a preliminary study on its application in regenerative medicine and tissue engineering.And mainly carried out the following two tasks:1.Preparation and characterization of granular hydrogelIn this work,micro-sized spherical hydrogels(hereinafter referred to as "microspheres")were respectively prepared by micro-emulsification(water-in-oil principle)with polyethylene glycol diacrylate(PEGDA)and methacrylic silk fibroin(Sil-MA),sulfhydryl hyaluronic acid(HA-SH)was used as cross-linking agent for cross-linking between microspheres,so that microspheres were tightly stacked together by photo-radical polymerization,and then the granular hydrogel was formed.Next,the internal structure and properties of the granular hydrogel were studied.it was verified by experiments that the hydrogel had certain injectability,micron-sized pores,stable mechanical properties,better water absorption than bulk hydrogel,and the critical factor that granular hydrogel could become multifunctional composite materials-modularity.With these excellent performance characteristics,we have reason to believe that granular hydrogels have more advantages than traditional hydrogels in biomedical applications..2.Design of granular hydrogel capable of capturing stem cellsIn view of the low content of stem cells and difficulty in survival in the current stem cell therapy,the granular hydrogel was functionalized to become a biological scaffold capable of capturing stem cells.Firstly,bone mesenchymal stem cells(BMSCs)were extracted from SD rats and successfully induced into osteoblasts,chondroblasts and adipocytes,which proved that the cells were BMSCs.After verifying that APT19S,an aptamer that can bind to stem cells,has a high affinity for BMSCs,we modified APT19S on microspheres to prepare functional granular hydrogels.We made a preliminary attempt to capture stem cells by granular hydrogels.The results showed that the granular hydrogel had a higher capture rate for BMSCs than the control group.We believe that the affinity of granular hydrogels to BMSCs was enhanced by modifying APT19S,and the interconnected micron pores were suitable for cell growth,which provided a new biological scaffold material for recruiting endogenous stem cells and a new choice for tissue repair and regeneration.