[Effects of cerium oxide nanoenzyme-gelatin methacrylate anhydride hydrogel in the repair of infected full-thickness skin defect wounds in mice].

Objective: To investigate the effects of cerium oxide nanoenzyme-gelatin methacrylate anhydride (GelMA) hydrogel (hereinafter referred to as composite hydrogel) in the repair of infected full-thickness skin defect wounds in mice. Methods: This study was an experimental study. Cerium oxide nanoenzyme with a particle size of (116±9) nm was prepared by hydrothermal method, and GelMA hydrogel with porous network structure and good gelling performance was also prepared. The 25 µg/mL cerium oxide nanoenzyme which could significantly promote the proliferation of human skin fibroblasts and had high superoxide dismutase activity was screened out. It was added to GelMA hydrogel to prepare composite hydrogel. The percentage of cerium oxide nanoenzyme released from the composite hydrogel was calculated after immersing it in phosphate buffer solution (PBS) for 3 and 7 d. The red blood cell suspension of mice was divided into PBS group, Triton X-100 group, cerium oxide nanoenzyme group, GelMA hydrogel group, and composite hydrogel group, which were treated with corresponding solution. The hemolysis of red blood cells was detected by microplate reader after 1 h of treatment. The bacterial concentrations of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli were determined after being cultured with PBS, cerium oxide nanoenzyme, GelMA hydrogel, and composite hydrogel for 2 h. The sample size in all above experiments was 3. Twenty-four 8-week-old male BALB/c mice were taken, and a full-thickness skin defect wound was prepared in the symmetrical position on the back and infected with MRSA. The mice were divided into control group without any drug intervention, and cerium oxide nanoenzyme group, GelMA hydrogel group, and composite hydrogel group applied with corresponding solution, with 6 mice in each group. The wound healing was observed on 3, 7, and 14 d after injury, and the remaining wound areas on 3 and 7 d after injury were measured (the sample size was 5). The concentration of MRSA in the wound exudation of mice on 3 d after injury was measured (the sample size was 3), and the blood flow perfusion in the wound of mice on 5 d after injury was observed using a laser speckle flow imaging system (the sample size was 6). On 14 d after injury, the wound tissue of mice was collected for hematoxylin-eosin staining to observe the newly formed epithelium and for Masson staining to observe the collagen situation (the sample size was both 3). Results: After immersion for 3 and 7 d, the release percentages of cerium oxide nanoenzyme in the composite hydrogel were about 39% and 75%, respectively. After 1 h of treatment, compared with that in Triton X-100 group, the hemolysis of red blood cells in PBS group, GelMA hydrogel group, cerium oxide nanoenzyme group, and composite hydrogel group was significantly decreased (P<0.05). Compared with that cultured with PBS, the concentrations of MRSA and Escherichia coli cultured with cerium oxide nanoenzyme, GelMA hydrogel, and composite hydrogel for 2 h were significantly decreased (P<0.05). The wounds of mice in the four groups were gradually healed from 3 to 14 d after injury, and the wounds of mice in composite hydrogel group were all healed on 14 d after injury. On 3 and 7 d after injury, the remaining wound areas of mice in composite hydrogel group were (29±3) and (13±5) mm2, respectively, which were significantly smaller than (56±12) and (46±10) mm2 in control group and (51±7) and (38±8) mm2 in cerium oxide nanoenzyme group (with P values all <0.05), but was similar to (41±5) and (24±9) mm2 in GelMA hydrogel group (with P values both >0.05). On 3 d after injury, the concentration of MRSA on the wound of mice in composite hydrogel group was significantly lower than that in control group, cerium oxide nanoenzyme group, and GelMA hydrogel group, respectively (with P values all <0.05). On 5 d after injury, the volume of blood perfusion in the wound of mice in composite hydrogel group was significantly higher than that in control group, cerium oxide nanoenzyme group, and GelMA hydrogel group, respectively (P<0.05). On 14 d after injury, the wound of mice in composite hydrogel group basically completed epithelization, and the epithelization was significantly better than that in the other three groups. Compared with that in the other three groups, the content of collagen in the wound of mice in composite hydrogel group was significantly increased, and the arrangement was also more orderly. Conclusions: The composite hydrogel has good biocompatibility and antibacterial effect in vivo and in vitro. It can continuously sustained release cerium oxide nanoenzyme, improve wound blood perfusion in the early stage, and promote wound re-epithelialization and collagen synthesis, therefore promoting the healing of infected full-thickness skin defect wounds in mice.

[Periconceptional maternal homocysteine and birth weight outcomes in offspring: a prospective cohort study].

Objective: To quantify the associations between periconceptional maternal homocysteine (HCY) and offspring's birth weight and risk of small for gestational age (SGA) infant. Methods: The 19 984 mother-child pairs in this prospective cohort study were recruited from the Shanghai preconception cohort; the infants were delivered from 1st September 2016 to 11th November 2022. A standardized questionnaire was used to collect the mothers' demographic information, medical history, dietary supplement use, and maternal complications during pregnancy, and their serum samples were collected. Serum HCY, folate, and vitamin B12 were measured using chemiluminescent microparticle immunoassay based on serum sample drawn at enrollment. Birth weight data were obtained from medical records. Multiple imputation methods were applied to handle missing data in key variables. Multivariable linear regression and Poisson regression models were used to analyze the relationship between maternal HCY concentration during the periconceptional period and the birth weight and SGA risk of the offspring. Results: A total of 9 452 pairs were enrolled preconceptionally and the remaining 10 532 pairs were enrolled in early pregnancy. The proportion of mothers whose pregnancy age was greater than 35 years was 9.2% (1 832/19 984), the proportion of primiparous women was 76.5% (15 283/19 984), the proportion of pre-pregnancy overweight and obesity was 14.0% (2 804/19 984), the proportion of using folic acid supplements before pregnancy was 21.4% (4 272/19 984), and the proportion of those who supplemented with folic acid during early pregnancy was 85.2% (8 976/10 532); gestational diabetes mellitus was in 6.2% (1 245/19 984), gestational hypertensive syndrome in 3.6% (711/19 984). The birth weight of the offspring was (3 297±468) g, and there were 1 962 SGA children (9.8%). The HCY concentration in the overall population in appropriate for gestational age during the periconceptional period was (7.9±3.2) µmol/L, with (8.3±3.7) µmol/L in the preconception subgroup and (7.3±2.4) µmol/L in the early pregnancy subgroup. After adjustment for the covariates of perinatal demographic information, adverse pregnancy outcomes, serum folate and vitamin B12, increased maternal periconceptional HCY was significantly associated with lower offspring birth weight (ß=-2.30, 95%CI -4.43--0.16, P=0.035). Only the early pregnancy subgroup was significantly associated with lower offspring birth weight (ß=-7.39, 95%CI-11.50--3.21, P<0.001). No association was found between peripregnancy HCY and offspring SGA risk. However, elevated HCY in early pregnancy was associated with an increased risk of SGA in the offspring (RR=1.05, 95%CI 1.01-1.08, P=0.002). Periconceptional vitamin B12 was a mediator of the association between HCY and offspring birth weight, accounting for 16.5%, 41.2% and 5.4% of its total effect in the overall periconceptional population, the pre-pregnancy subgroup and the early pregnancy subgroup, respectively. Conclusions: Maternal periconceptional HCY level is associated with lower birth weight in offspring, but not with the risk of SGA. Elevated maternal HCY in early pregnancy subgroup may be associated with increased risk of SGA in offspring.