Tryptase

UC-MSCs were obtained from the National Engineering and Research Center of Human Stem Cell, and their isolation and culture were described in the previous study^{47 (link)}. Briefly, UC-MSCs were recovered from liquid nitrogen and cultivated in cell culture dishes with MSCs culture system: DMEM-high glucose (Gibco-BRL, USA) with 10% fetal bovine serum (Gibco-BRL, USA) and 10ng/ml bFGF (Gibco-BRL, USA). The cell culture incubator was set to 37 °C and 5% CO2. The UC-MSCs at passage 3 were used for subsequent experiments. For 2D culture, 2.5 × 10⁵ MSCs were planted in the six-well plates in 2 ml medium. To form the sphere, MSCs were digested with tryptase (Gibco-BRL, USA) and collected. The collected MSCs were resuspended in the culture system with the concentration of 6250 cells/μl. A drop of 40 μl was placed on the inverted lid of a cell culture dish. The lid was then rapidly reinverted onto the culture dish that contained PBS to prevent evaporation of the drop. The cells were collected for transplantation and RNA sequencing after 72 hours. To analyze the secreted cytokines from MSCs, the medium was changed to serum-free DMEM at 48 hours, and the supernatant was collected at 72 hours. Altogether 3 dishes of cells and 3 conditioned media from 2D- and 3D-cultured UC-MSCs, respectively, were collected for RNA sequencing and cytokine immunoassay.

β‐cyclodextrin (β‐CD), sodium ascorbate, PEO‐PPO‐PEO triblock copolymer (poloxamer L64), paratoluensulfonyl chloride, N, N'‐carbonyldiiazole, Tri‐(2‐aminoethyl) amine, triethylamine, 2,4‐dinitrofluorobenzene (DNFB), copper sulfate pentahydrate, and sodium methylate were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. All reagents were used directly without further purification.
MRSA was obtained from the center of bacterial identification of the dermatology department, the First Affiliated Hospital of Jinan University. Tryptic soy broth (TSB) and Luria‐Bertani (LB) agar were purchased from Guangdong Huankai Biological Technology Co., Ltd and stored in a 4°C refrigerator. A cell counting kit‐8 (CCK‐8) was purchased from Tongren Co., Ltd. Live/Dead BacLight bacterial viability kit (L7012) was bought from Thermo Fisher Technology Co., Ltd. Dulbecco's modified eagle medium, fetal bovine serum (FBS), and tryptase were purchased from Gibco Life Technologies. Total Nitric Oxide Assay Kit was purchased from Shanghai Biyuntian Biotechnology Co., Ltd.