Preparation Of Degradable Polymer Nanospheres Encapsulating Tea Polyphenols And Its Effect On The Performance Of Human Adipose Stem Cells

Human adipose stem cells(hASCs)are stem cells isolated from human adipose tissue.Like other adult stem cells,adult stem cells have the ability of self-renewal and multidirectional differentiation.They are very ideal seed cells for tissue engineering,so the study on their in vitro proliferation is of great significance.In this paper,tea polyphenols were added to the culture medium to cultivate hASCs,and hASCs cultured with different concentrations(0 μg/mL-50 μg/mL,gradient 10 μg/mL)of tea polyphenol culture medium were tested by cell viability testing.In vitro proliferation was analyzed,and the nucleus of hASCs was stained with DAPI,and the optimal concentration of tea polyphenol medium was selected,namely 10 μg/mL.Culture hASCs with a medium containing 10μg/mL tea polyphenols,observe the hASCs with a fluorescence microscope and microplate reader and draw cell growth curves;Immunofluorescence was used to detect the expression of Sox2,a pluripotent transcription factor,in hASCs cultured in tea polyphenols;The six surface antigens of hASCs cultured in medium containing tea polyphenols were analyzed by flow cytometry;Then,the induction differentiation experiment was performed to induce osteogenic and chondrogenic induction of hASCs cultured in the medium containing tea polyphenols;finally,the hASCs cultured in the medium containing tea polyphenols were long-term passaged.The results showed that the 10μg/mL tea polyphenol medium promoted the proliferation of hASCs in vitro,promoted the differentiation of hASCs into osteoblasts,and had no effect on the pluripotency of hASCs.And the medium containing 10 μg/mL tea polyphenols has the potential to delay the aging of hASCs when used for long-term culture of stem cells in vitro.Tea polyphenols are not easily absorbed effectively in the gastrointestinal system and are easily combined with proteins.Therefore,a p H-responsive nano hydrogel microsphere with good biocompatibility was prepared to solve the problem of low bioavailability of tea polyphenols.Poly(ε-caprolactone-co-lactide)-PEG copolymer diols(PCLA)were prepared by ring opening polymerization of ε-caprolactone and L-lactide initiated by polyethylene glycol(Mw 1000).PCLA prepolymer monomers(PCLAMA)were prepared by end capping with methacrylic anhydride.Hydrogel nanospheres were prepared by UV initiated polymerization using PCLAMA as a macromolecular cross-linker and N-vinylpyrrolidone and acrylic acid.Swelling,degradation,drug release and cytotoxicity of the hydrogel nanospheres were analyzed and showed that the swelling ratio of the hydrogel increased with pH.The drug loading of tea polyphenol in the hydrogel nanospheres was more than 57%,with cumulative drug release over 132 h reaching almost 30%.The hydrogel nanospheres were noncytotoxic as evidenced by a cell viability of over 94% after co-culture with human adipose derived stem cells for 48 h,and were also observed to successfully enter the cells.Therefore,PCLAMA-AP has the potential to sustained release of tea polyphenols directly into the cell,which may greatly improve the biological utilization efficiency of tea polyphenols.