Abstract:

Objective To compare the effects of subcutaneous injection and intravenous injection of human Umbilical Cord Mesenchymal Stem Cells （hUC-MSCs） on skin lesions， splenic immune indexes， pathological changes， and key inflammatory factors in imiquimod-induced psoriasis mice， aiming to provide experimental evidence for clinical administration selection. Methods 35 specific-pathogen-free （SPF） C57BL/6J male mice were randomly divided into 7 groups （n = 5）： a blank control group， an intravenous phosphate-buffered saline （PBS） group， a subcutaneous PBS group， a subcutaneous hUC-MSCs group， an intravenous hUC-MSCs group， a subcutaneous hUC-MSCs combined with topical rhubarb group， and a topical rhubarb alone group. A psoriasis mouse model was established by applying 5% imiquimod cream on the back for 6 consecutive days. Corresponding interventions were administered on the 2nd and 4th days of modeling. Skin lesion changes were observed and scored using the Psoriasis Area and Severity Index （PASI）. Spleen weight was measured to calculate the spleen index. Skin histopathological changes were observed through hematoxylin and eosin （HE） staining. The levels of interleukin-17A （IL-17A）， interleukin-23 （IL-23）， and tumor necrosis factor-α （TNF-α） in serum and skin tissue were detected by enzyme-linked immunosorbent assay （ELISA）. Results There were highly significant differences in PASI scores， skin lesion thickness， spleen weight， and spleen index among all groups （P 0.01）. Both subcutaneous and intravenous administration of hUC-MSCs downregulated the levels of IL-17A， IL-23， and TNF-α in serum and skin tissue （P 0.05）. Intravenous injection of hUC-MSCs was more effective than subcutaneous injection in improving skin lesions， regulating the systemic immune system， and inhibiting inflammation. The overall efficacy of subcutaneous hUC-MSCs combined with topical rhubarb was superior to that of subcutaneous hUC-MSCs alone （P 0.05）. Conclusions hUC-MSCs can effectively alleviate psoriasis-like skin lesions， as well as local and systemic inflammatory responses in mice induced by imiquimod. Intravenous injection exhibits better overall efficacy compared to subcutaneous injection. Moreover， subcutaneous hUC-MSCs combined with topical rhubarb have a synergistic effect.

Key words: psoriasis, umbilical cord mesenchymal stem cells, subcutaneous injection, intravenous injection, immunomodulation