Objective:To explore the effects and molecular mechanism of tumor necrosis factor α (TNF-α) on differentiation of mesenchymal stem cells of mice into sweat gland cells in a three-dimensional environment.Methods:(1) Five 6-8 week-old female C57BL/6 mice were used, with one 1 cm 2 deep partial-thickness to full-thickness scald wound being created on the back of each mouse with a scald apparatus. One day after injury, the full-thickness skin tissue of the wound was taken, and the concentration of TNF-α in the tissue was detected by enzyme-linked immunosorbent assay. (2) Gelatin in the mass of 0.9 g and 0.3 g sodium alginate were mixed and then dissolved in 30 mL phosphate buffer solution to make hydrogel. Full-thickness skin of the planta of 10 male and female one day newborn C57BL/6 mice was ground into dermal homogenate. The mesenchymal stem cells were isolated from femur and tibia of 10 male and female C57BL/6 mice born for 7 days and cultured. A final density of 1.5×10 5 cells/mL of bioink was made of mixture of 8 mL pre-warmed hydrogel, 1 mL mouse foot dermal homogenate, and 1 mL the second or third passage of mesenchymal stem cell suspensions. The three-dimensional bioprinter was used to print 12 cylindrical blocks arranged in a crisscross pattern in petri dish. The printed blocks were cross-linked with 25 g/L calcium chloride solution for 10 min and then cultured for 12 hours by adding a medium for mesenchymal stem cells. Subsequently, the printed blocks were divided into blank control group and TNF-α treatment group according to the random number table, with 6 plates and 6 blocks in each group. Both groups of printed blocks were cultured with fresh sweat gland induction medium, and a final mass concentration of 20 ng/mL TNF-α was added into the medium of TNF-α treatment group. After 6 hours of culture, the mRNA expression of pluripotency marker Nanog in the mesenchymal stem cells of two plates of each group was detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction (RT-PCR), and the protein expression of Nanog in the mesenchymal stem cells of one plate of each group was detected by Western blotting, both with triplicate samples. After 14 days of culture, the mRNA expression of sweat gland cell markers cytokeratin 14 (CK14), CK18, sodium potassium adenosine triphosphatase protein a1 (ATP1a1), and aquaporin 5 (AQP5) was detected by real-time fluorescent quantitative RT-PCR in the mesenchymal stem cells of 2 plates of each group ( n=3), and the protein expression distribution of CK14, CK18, ATP1a1, and AQP5 of the mesenchymal stem cells in one plate of each group was detected by immunofluorescence staining. Data were statistically analyzed with independent sample t test. Results:(1) One day after injury, the mass concentration of TNF-α in the scald wound tissue of mouse was (19±3) ng/mL. (2) After 6 hours of culture, the mRNA and protein expression levels of Nanog in the mesenchymal stem cells of printed blocks in TNF-α treatment group were 0.39±0.04 and 0.36±0.03, respectively, which were significantly lower than 1.00±0.05 and 1.00±0.07 of blank control group ( t=16.51, 14.56, P<0.01). (3) After 14 days of culture, the mRNA expression levels of CK18, CK14, ATP1a1, and AQP5 in the mesenchymal stem cells of printed blocks in TNF-α treatment group were 0.38±0.03, 0.42±0.11, 0.23±0.06, and 0.25±0.03, respectively, which were significantly less than 1.00±0.03, 1.00±0.05, 1.00±0.05, 1.00±0.07 of blank control group ( t=25.31, 8.31, 17.07, 17.06, P<0.01). (4) After 14 days of culture, the CK18, CK14, ATP1a1, and AQP5 protein were widely distributed in the cytoplasm of mesenchymal stem cells in printed blocks of blank control group, while the distribution of CK18, CK14, ATP1a1, and AQP5 protein in the cytoplasm of mesenchymal stem cells in printed blocks of TNF-α treatment group were significantly reduced in comparison. Conclusions:Exogenous TNF-α inhibits the directional differentiation of mesenchymal stem cells of mice into sweat gland cells in a three-dimensional environment, which may be related to the inhibition of the expression of Nanog mRNA and protein by TNF-α that subsequently results in the down-regulation of multi-directional differentiation potential of mesenchymal stem cells.

Objective:To explore the effects and potential molecular mechanism of age on the stiffness and the fibrotic phenotype of fibroblasts (Fbs) of human hypertrophic scar.Methods:The experimental research method was used. From January to June 2020, the surgically removed hypertrophic scar tissue of 10 scar patients (4 males and 6 females) and residual full-thickness normal skin tissue of 10 cases (5 males and 5 females, aged 7-41 years) were collected after operation in Department of Burns and Plastic Surgery of the Fourth Medical Center of the PLA General Hospital. The hypertrophic scar tissue of 6 patients aged (10.7±1.6) years was included into the young group and the hypertrophic scar tissue of 4 patients aged (40.0±2.2) years was included into the elderly group according to the age of patients. For the normal skin tissue and scar tissue in the two groups, hematoxylin eosin (HE) staining was performed to observe the tissue morphology, Masson staining was performed to observe the morphology and arrangement of collagen and quantify the content of collagen, and scanning electron microscope was used to observe the microscopic difference of dermal collagen fibers after the samples were freeze-dried and metal coated. The stiffness of scar tissue in the two groups was measured by atomic force microscope under the liquid phase. The scar tissue in the two groups was collected and the Fbs were isolated and cultured. The morphological differences of the Fbs were observed under the inverted phase contrast microscope, and the protein expression of paxillin was detected with cellular immunofluorescence to reflect the morphology of the Fbs. Cellular immunofluorescence was used to detect the expressions of pro-fibrosis protein α-smooth actin (α-SMA), transforming growth factor-β 1 (TGF-β 1), and type Ⅰ collagen, mechanotransduction-related protein Yes-associated protein (YAP), and the proliferation-related protein Ki67. Real-time fluorescent quantitative reverse transcription polymerase chain reaction was used to detect the mRNA expressions of pro-fibrosis genes of TGF- β 1, α- SMA, and type Ⅰ collagen, fibrosis inhibiting gene of TGF- β 3, and mechanotransduction-related genes of Rho-associated protein 1 ( ROCK1) and YAP. Data were statistically analyzed with one-way analysis of variance and least significant difference t test. Results:HE staining showed that the epidermal layer of normal skin was uneven, and blood vessels and sweat glands could be seen in the dermal layer; the epidermal layer of the scar tissue in the two groups was relatively flat, and blood vessels and sweat glands were rare. Masson staining and scanning electron microscopy showed that the collagen fibers in normal skin arranged loosely and disorderly, while the collagen fibers in scar tissue of the two groups arranged densely and orderly, and the collagen fibers in scar tissue of the young group were denser than those of the elderly group. The collagen content in scar tissue of the young group and the elderly group was significantly higher than that of the normal skin tissue ( t=8.02, 3.15, P<0.05 or P<0.01), and the collagen content in scar tissue of the elderly group was significantly lower than that of the young group ( t=4.84, P<0.05). The dermal stiffness of scar tissue in the elderly group was (50.3±1.1) kPa, significantly higher than (35.2±0.8) kPa in the young group ( t=11.43, P<0.05). There were no obvious differences in the morphology of scar Fbs in the two groups observed under inverted phase contrast microscope and by cellular immunofluorescence. The expressions of type Ⅰ collagen and TGF-β 1 in scar Fbs cytoplasm of the elderly group were significantly higher than those in the young group, while the expressions of α-SMA in scar Fbs cytoplasm were close in the two groups. The expressions of YAP in cytoplasm and nucleus of scar Fbs in the elderly group were significantly higher than those in the young group, while the expressions of Ki67 in scar Fbs nucleus of the two groups were close. The mRNA expressions of TGF- β 1 and type Ⅰ collagen in scar Fbs of the elderly group were significantly higher than those in the young group ( t=2.87 , 4.85, P<0.05 or P<0.01), the mRNA expression of TGF- β 3 in scar Fbs of the elderly group was significantly lower than that in the young group ( t=3.36, P<0.05), and the mRNA expressions of α- SMA in scar Fbs of the two groups were close ( t=1.14, P>0.05). The mRNA expressions of ROCK1 and YAP in scar Fbs of the elderly group were significantly higher than those in the young group ( t=2.98, 7.60, P<0.05 or P<0.01). Conclusions:The elderly are prone to scar healing after skin injury. The molecular mechanism may be attributed to the production of extracellular matrix components with higher stiffness, which increases tissue stiffness and thereby activates the expressions of ROCK and YAP/transcriptional co-activator with PDZ-binding motif genes, promoting pro-fibrosis gene and protein expression.

Objective:To report the experience of the application of internal carotid artery stent in skull base surgery, and to clarify the important role of internal carotid artery stent in skull base surgery.Methods:A retrospective study of 22 cases with skull base neoplasms implanted with internal carotid artery stents in the Department of ENT Head and Neck Surgery at the Sixth People′s Hospital affiliated with Shanghai Jiao Tong University between July 2019 and January 2021 was conducted. Among them, 17 were male and 5 were female, aged between 33 and 75 years. There were 5 cases on the left, 16 cases on the right, and 1 case on both sides. Of these, there were 4 cases of jugular paraganglioma, 1 case of chondrosarcoma in the jugular foramen, 1 case of carotid body paraganglioma, and 16 cases of nasopharyngeal carcinoma after radiotherapy.Results:The degree of internal carotid artery erosion was assessed by computed tomography angiography (CTA), magnetic resonance imaging and digital subtraction angiography (DSA) images in 22 patients before surgery. It was found that the internal carotid artery was involved to varying degrees in all patients, so internal carotid artery stents were implanted before surgery. Tumor tissue was found to surround the internal carotid artery to varying degrees. Total or subtotal tumor resection was performed in all patients, and no intraoperative and postoperative complications occurred. The postoperative follow-up was 5 months to 2 years, and all patients had no complications such as spontaneous bleeding and pseudo aneurysm. There were no signs of stenosis or occlusion of the internal carotid artery stent segment in all cases.Conclusions:For patients with skull base tumors, preoperative imaging indicates the limited involvement of the internal carotid artery, and internal carotid artery stent implantation before surgery is a safe and effective treatment.