Objective:To investigate the effects and mechanisms of allogeneic epidermal stem cells (ESCs) on the survival of allogeneic full-thickness skin grafts in nude mice with full-thickness skin defect wounds.Methods:Experimental research methods were applied. Primary ESCs that appeared paving stone-like after being cultured for 7 d were obtained by enzymatic digestion method from one 4-week-old male BALB/c-NU nude mouse (the same strain, age, and sex below). The cells of third passage were identified by flow cytometry to positively express ESC marker CD44 and negatively express CD45, meanwhile, the positive expression of ESC markers of p63 and integrin 6α, and negative expression of CD71 were identified by immunofluorescence method. The ESCs of third passage in the logarithmic growth phase were used for the following experiments. Twenty-six nude mice were equally divided into phosphate buffered saline (PBS) group and ESCs group according to the random number table. A full-thickness skin defect wound was made on the back of each nude mouse, and then the wounds of the two groups were sprayed with equal volumes of PBS and ESCs, respectively. The wounds were transplanted with full-thickness skin grafts cut from the backs of 4 other nude mice. Each ten nude mice from the two groups were selected, the wound healing and skin survival on post surgery day (PSD) 0 (immediately), 3, 7, 14, and 21 were observed, and the survival ratio and shrinkage rate of skin grafts on PSD 3, 7, 14, and 21 were calculated (the number of sample was the number of surviving skin grafts at each time point); the blood perfusion in the skin grafts on PSD 3, 7, and 14 was detected by the laser speckle blood flow imager, and the blood flow ratio of nude mice skin grafts in ESCs group to PBS group at each time point was calculated (the number of sample was the pair number of surviving skin grafts in group pairing at each time point). The skin graft tissue of each 3 nude mice remained in the two groups were collected on PSD 7, and the mRNA expressions and protein expressions of tumor necrosis factor α (TNF-α), interleukin 8 (IL-8), IL-10, type Ⅰ collagen, type Ⅲ collagen, and matrix metalloproteinase 9 (MMP-9) in the tissue were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction and Western blotting, respectively. Data were statistically analyzed with Log-rank test, analysis of variance for repeated measurement, one-way analysis of variance, independent sample t test, and Bonferroni correction. Results:Taking the condition on PSD 0 as a reference, the wounds of nude mice in the two groups healed gradually on PSD 3, 7, 14, and 21, and the shrinkage of skin grafts was gradually obvious. Among them, the shrinkage healing of wound of nude mice in PBS group was more significant than that in ESCs group. On PSD 3, the skin graft of 1 nude mouse failed in ESCs group, while the skin graft of 3 nude mice failed in PBS group. On PSD 7, the skin graft of another nude mouse failed in PBS group. The survival ratio of skin grafts of nude mice in the two groups was similar on PSD 3, 7, 14, and 21 ( P>0.05). On PSD 3, 7, 14, and 21, the shrinkage rates of skin grafts of nude mice in ESCs group were (9.2±0.4)%, (19.7±1.2)%, (53.6±3.5)%, and (62.2±5.1)%, respectively, which was significantly lower than (11.0±0.9)%, (47.8±2.8)%, (86.1±7.1)%, and (89.7±9.0)% in PBS group ( t=5.719, 26.650, 11.940, 7.617, P<0.01). On PSD 3, 7, and 14, blood perfusion signals were observed in the skin grafts of nude mice in the two groups. The average blood perfusion ratios of the skin grafts of nude mice in ESCs group to PBS group were greater than 1, and there was no statistically significant difference in the overall comparison of 3 time points ( P>0.05). On PSD 7, compared with those of PBS group, the mRNA and protein expressions of TNF-α, IL-8, type Ⅰ collagen, and type Ⅲ collagen in the skin graft tissue of nude mice in ESCs group were significantly reduced, while the mRNA and protein expressions of IL-10 and MMP-9 in the skin graft tissue of nude mice in ESCs group were significantly increased (in mRNA comparison, t=2.823, 2.934, 2.845, 2.860, 3.877, 2.916, P<0.05). Conclusions:Allogeneic ESCs can reduce the shrinkage of allogeneic full-thickness skin grafts transplanted on full-thickness skin defect wounds in nude mice, promote the formation of new blood vessels between the skin graft and the wound, reduce inflammation and collagen protein expression, and promote the expression of MMP-9, thus improving the survival quality of skin grafts.

Objective:To investigate the status of height and weight of 3-18-year-old children and adolescents in urban China, and to provide a basis for establishing puberty phase specific curves for age-specific height and age-specific weight.Methods:A cross-sectional survey of 218 185 children and adolescents aged 3-18 years in urban China was conducted by using the method of stratified random cluster sampling from January 2017 to December 2019. The sampling areas included 12 provinces municipalities in China and autonomous regions in total. Data were collected on weight, height, waist circumference, hip circumference and secondary sexual characteristics. The generalized additive model for location, scale, and shape (GAMLSS) was employed to establish percentile reference values and growth curves of height and weight for boys and girls aged 3-18 years. Wilcoxon rank sum test was applied to compare the P 50 value of height and weight between children of each Tanner stage and children of the same age ignoring the different puberty phase. Results:The 3rd, 50th, and 97th percentile curves for height and weight for age were developed for boys and girls aged 3-18 years. The 3rd, 50th, and 97th percentile curves for age-specific height and age-specific weight for each puberty phase were developed for boys and girls. Compared with all children ignoring the different puberty phase, boys aged 9 and over and girls aged 7 and over who are at Tanner stage 1 showed shorter height and lighter weight than those of the same age group (all P<0.01), the difference ranges of height at P 50 are -4.0 to -0.6 cm for boys, and -4.4 to 0.5 cm for girls; the difference ranges of weight are -4.8 to 0.4 kg for boys, and -4.0 to -0.3 kg for girls; children at Tanner stage 2 & 3 initially were taller and heavier than those of the same age group; and later grew shorter and lighter than those of the same age group, the two sets of curves cross over; boys aged 16 and under and girl aged under 14 who are at Tanner stage 4 were taller and heavier than those of the same age group (all P<0.01), the difference ranges of height at P 50 are 0.2 to 10.0 cm for boys, and 0.2 to 9.4 cm for girls; the difference ranges of weight at P 50 are 0.7 to 10.9 kg for boys, and 1.0 to 11.2 kg for girls, and the differences showed narrowing trend with age. Conclusion:The puberty phase specific growth curves of age-specific height and age-specific weight for boys and girls aged 3-18 years are established, it is useful for clinical work to evaluate physical development of children at different puberty phases.