A study of SRM engineering cells microcapsules treatment on ulcerative colitis

Objective: Ulcerative colitis(UC) is a complex disease characterized by chronic inflammation of the colon. The incidence and prevalence of UC are on the rise, and it has become a global disease.At present, The existing UC treatment drugs have defects in effectiveness and safety, thus optimizing drug delivery system has become a key point to improving the treatment efficiency. Spermidine (SPD) has strong anti-inflammatory effects and regulate oxidative stress. In this study, an overexpressing spermidine synthase (SRM) engineered cells (SEC) was established to form a new drug delivery system that can automatically produce spermidine in vivo. We used sodium alginate bio-semipermeable membrane to wrap SEC to prepare engineered cell microcapsules (SECM) which can prevent the SEC from being attacked by the recipient immune system. The efficacy of the spermidine automatic drug delivery system was explored by in vitro study and the UC mouse model. Methods: (1) We used lentivirus system and HEK293T cell line to construct SEC cell line. qRT-PCR was used to detect SRM overexpression efficiency. ELISA was performed to detect spermidine secretion of SEC; (2) The viability of microencapsulated cell was explored by AO/EB staining. ELISA was used to detect the secretion of spermidine. Flow CBA was used to detect the expression of spermidine-related pro-inflammatory cytokines; (3) SECM was implanted into the peritoneal cavity of ulcerative colitis mice model, CCK8 and trypan blue staining were used to detect the cell viability of SECM after nine days. (4) Before and after the SECM implantation, body weight, stool shape, blood in the stool and other indicators were monitored for disease activity index (DAI) scoring. (5) The treatment efficacy of SECM was evaluated by DAI, inflammation-associated histological scores, changes of colon length and spleen weight. Results: (1) The RT-PCR results showed that SRM mRNA expression in SEC was significantly higher than control group. The spermidine secreted by SEC at 48h was 1.65 times of the control group, and at 72h was 1.49 times, respectively. (2) AO/EB staining showed that the viability of the cells packed in 4×106/mL density was the best. The spermidine secreted by SECM was 1.59 times of the negative control group. The spermidine secreted by SECM and SEC was the same. The CBA results showed that the secretion of TNF-α, IL-6 and IFN-γ of SECM was significantly lower than control group. (3) The SECM and control group have the same survival rate by CCK8 test and trypan blue staining. SECM could significantly improve clinical symptoms and other pathological manifestations. And finally reduce DAI and inflammation-associated histological score. Conclusion: (1) Successfully established SEC formed a new SPD automatic drug delivery system; (2) sodium alginate microcapsules can effectively protect SEC; (3) SPD automatic drug delivery system was an efficacy way for DSS-induced UC in mice. the National Key Research and Development Program (Grant No. 2019YFA0110703). The Science and Technology Innovation Foundation of Hunan Province (Grant No. 2020SK53614). The National Natural Science Foundation of China (Grant Nos. 82272102 and 81971721).