Objective To investigate the influence of collagen on the biomechanics strength of tissue engineering tendon. Methods All of 75 nude mice were madethe defect models of calcaneous tendons, and were divided into 5 groups randomly. Five different materials including human hair, carbon fibre (CF), polyglycolic acid (PGA), human hair and PGA, and CF and PGA with exogenous collagen were cocultured with exogenous tenocytes to construct the tissue engineering tendons.These tendons were implanted to repair defect of calcaneous tendons of right hind limb in nude mice as experimental groups, while the materials without collagenwere implanted to repair the contralateral calcaneous tendons as control groups. In the 2nd, 4th, 6th, 8th and 12th weeks after implantation, the biomechanicalcharacteristics of the tissue engineering tendon was measured, meanwhile, the changes of the biomechanics strength were observed and compared. Results From the 2nd week to the 4th week after implantation, the experimental groups were ber than the control groups in biomechanics, there was statistically significantdifference (Plt;0.05). From the 6th to 12th weeks, there was no statisticallysignificant difference between the experiment and control groups (Pgt;0.05). Positivecorrelation existed between time and intensity, there was statistically significant difference (Plt;0.05). The strength of materials was good in human hair,followed by CF, and PGA was poor. Conclusion Exogenous collagen can enhance the mechanics strength of tissue engineering tendon, and is of a certain effect on affected limb rehabilitation in early repair stages.
Objective To evaluate the effect of nano-hydroxyapatit e collagen (nHAC) bone and marrow mesenchymal stem cells (MSCs) on the treatment of rabbit osteonecrosis of the femoral head (ONFH) defect. Methods From June to October 2004, animal models of ONFH defect were established i n 45 New Zealand rabbits. They were divided into 3 groups randomly:In group A, as the control group, defect was not filled with any implants; In group B with nHAC; In group C with nHAC+MSC. Imaging and histological observation were made 4, 8, 12 weeks after operation. Results group C had a better o steogenesis ability than group B and group A. group B had a better osteogenesis ability than group A. Obvious new bones and osteogenesis were observed in group C 4 weeks after operation. The defect areas in group C were almost repaired 12 weeks after operation. Conclusion nHAC has a better effect of o steoconduction and it is a superior material for repairing bone defect of ONFH a nd of great value in treating ONFH when compounded with MSCs.
Objective To develop a novel porous three-dimensional scaffold and to investigate its physico-chemical properties for tissue engineering cartilage.Methods Refined 88% deacetylation degree chitosan was prepared and dissolved in 0.2 mol/L acetate acid and fully mixed with highly purified porcine type Ⅱcollagen in 0.5 mol/L acetate acid solution in a ratio of 4 to 1 (wt/wt). Freeze-drying process was employed to fabricate the composite scaffold. The construct wascross-linked by use of 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide (EDC) and Nhydroxysuccinimide (NHS). A mechanical tester was utilized to determine the tensilestrength change before and after cross-linking. The microstructure was observed via scanning electron microscopy (SEM). The lysozyme degradation was performedto evaluate the degradability of the scaffold in vitro. Results A bulk scaffold with desired configuration was obtained. The mechanical test showed that the crosslinking treatment could enhance the mechanical strength of the scaffold. The SEM results revealed that the two constituents evenly distributed in the scaffold and that the matrix was porous, sponge-like with interconnected pore sizing 100250 μm. In vitro lysozyme degradation indicated that crosslinked or uncross-linked composite scaffolds had faster degradation rate than the chitosan matrix. Conclusion Chitosan and typeⅡcollagen can be developed into a porous three-dimensional scaffold. The related physico-chemical tests suggest that the composite socaffold meets requirements for tissue engineered scaffold and may serve as an alternative cellcarrier for tissue engineering cartilage.
OBJECTIVE: To explore the effects of nandrolone phenylpropionate (NP) on the expression level of pro alpha 1 (I) collagen after burn in rats and the possible mechanism involved in the process. METHODS: Thirty-two Wistar rats with a deep second-degree scald injury and 20% of total body surface area were randomly divided into two groups to receive either 5 mg/kg NP(NP group) or normal saline (control group) every other day. We analyzed the mean integrated optical density(mIOD) of androgen receptor (AR) to determine the distribution and expression of AR in fibroblasts by immunohistochemistry, and measured expression level of pro alpha 1 (I) collagen mRNA by quantitative fluorescent RT-PCR to find the relation between expressions of AR and pro alpha 1 (I) collagen mRNA. The total specimens were obtained from the scalded rats after 4, 7, 14 and 21 of after burn. RESULTS: The expression of pro alpha 1 (I) collagen mRNA in NP group was significantly higher than that in control group on the 7th, 14th and 21st days(P lt; 0.05), but there was no significant difference on the 4th day. The density of AR in fibroblasts had significant difference (P lt; 0.05) between the two groups after 4, 7, 14 and 21 days. A positive relationship existed between the expression of pro alpha 1 (I) collagen mRNA and quantity of AR in fibroblasts(r = 0.836). CONCLUSION: The nandrolone phenylpropionate increased the expression of pro alpha 1 (I) collagen mRNA and enhanced the density of AR in fibroblasts. The higher expression of pro alpha 1 (I) collagen mRNA had a relation with the change of quantity of AR in fibroblasts.
The aim of this paper is to explore the prevention of rabbit postoperative abdominal cavity adhesion with poly (lactic-co-glycotic acid) (PLGA) membrane and the mechanism of this prevention function. Sixty-six Japanese white rabbits were randomly divided into normal control group, model control group and PLGA membrane group. The rabbits were treated with multifactor methods to establish the postoperative abdominal cavity adhesion models except for those in the normal control group. PLGA membrane was used to cover the wounds of rabbits in the PLGA membrane group and nothing covered the wounds of rabbits in the model control group. The hematologic parameters, liver and kidney functions and fibrinogen contents were detected at different time. The rabbit were sacrificed 1, 2, 4, 6, 12 weeks after the operations, respectively. The adhesions were graded blindly, and Masson staining and immunohistochemistry methods were used to observe the proliferation of collagen fiber and the expression of transforming growth factorβ1 (TGF-β1) on the cecal tissues, respectively. The grade of abdominal cavity adhesion showed that the PLGA membrane-treated group was significant lower than that in the model control group, and it has no influence on liver and kidney function and hematologic parameters. But the fibrinogen content and the number of white blood cell in the PLGA membrane group were significant lower than those of model control group1 week and 2 weeks after operation, respectively. The density of collagen fiber and optical density of TGF-β1 in the PLGA membrane group were significant lower than those of model control group. The results demonstrated that PLGA membrane could be effective in preventing the abdominal adhesions in rabbits, and it was mostly involved in the reducing of fibrinogen exudation, and inhibited the proliferation of collagen fiber and over-expression of TGF-β1.
ObjectiveTo investigate the changes of fibrinogen and classical markers of collagen metabolism [carboxy-terminal propeptide of type Ⅰ procollagen (PICP) and carboxy-terminal cross-linked peptide of type Ⅰ collagen (ICTP)] in peripheral blood and pericardial drainage after coronary artery bypass grafting (CABG) and/or heart valve replacement (VR), and to evaluate their relationship with postoperative atrial fibrillation (POAF) after cardiac surgery. MethodsPatients who underwent CABG and/or VR in the Heart Center of Beijing Chao-Yang Hospital from March to June 2021 were included. Peripheral blood and pericardial drainage fluid samples were collected before surgery and at 0 h, 6 h, 24 h and 48 h after surgery to detect PICP, ICTP and fibrinogen levels, and preoperative, intraoperative and postoperative confounding factors were also collected. PICP, ICTP and fibrinogen levels were measured by enzyme-linked immunosorbent assay (ELISA). ResultsA total of 26 patients with 125 blood samples and 78 drainage samples were collected. There were 18 males and 8 females with an average age of 64.04±7.27 years. The incidence rate of POAF was 34.6%. Among the factors, the fibrinogen level in pericardial drainage showed two peaks within 48 h after operation (0 hand 24 h after operation) in the POAF group, while it showed a continuous downward trend in the sinus rhythm (SR) group, and the change trend of fibrinogen in pericardial drainage was significantly different over time between the two groups (P=0.022). Fibrinogen in blood, PICP and ICTP in blood and drainage showed an overall decreasing trend, and their trends over time were not significantly different between the two groups of patients (P>0.05). Univariate analysis showed that fibrinogen at 24 h and 48 h after pericardial drainage, fibrinogen in preoperative blood, PICP immediately after surgery and right atrial long axis diameter were significantly higher or longer in the POAF group than those in the SR group. Multiple regression showed that fibrinogen≥11.47 ng/mL in pericardial drainage 24 h after surgery (OR=14.911, 95%CI 1.371-162.122, P=0.026), right atrial long axis diameter≥46 mm (OR=10.801, 95%CI 1.011-115.391, P=0.049) were independent predictors of POAF. ConclusionThis study finds the regularity of changes in fibrinogen and collagen metabolic markers after CABG and/or VR surgery, and to find that fibrinogen in pericardial drainage 24 h after surgery is a potential novel and predictive factor for POAF. The results provide a new idea for exploring the mechanism of POAF, and provide a research basis for the accurate prediction and prevention of clinical POAF.
ObjectiveTo investigate the effect of dust fine particles on tumor necrosis factor-α (TNF-α), matrix metalloproteinase (MMP), transforming growth factor-β1 (TGF-β1), and collagens in the lung tissue of rats.MethodsAccording to random number table method, 96 male Wistar rats were divided into an untreated control group, a treated control group and an experimental group, with 32 rats in each group. The experimental group was exposed to the wind tunnel simulation of sandstorm (5 days per week, 5 hours per day); the untreated control group was put in the standard living environment next to the wind tunnel; the treated control group was exposed to the same wind tunnel simulation of sandstorm for 5 hours every day, the speed of wind was the same as the experimental group, but without dust; On the 30th, 60th, 90th, and 120th day, the levels of TNF-α, MMP-2, MMP-9, TGF-β1, lung collagen type Ⅰ and Ⅲ in the lung tissue of rats were determined by enzyme linked immunosorbent assay.ResultsCompared with the untreated control group and the treated control group, the content of TNF-α was higher in the experimental group on 30th, 60th, 90th and 120th day (all P<0.05). The contents of MMP-9 and MMP-2 in the experimental group on 60th and 90th day were significantly higher than those in the untreated group and the treated control group, respectively (all P<0.05). On the 30th, 60th, 90th, and 120th day, the content of TGF-β1 in the experimental group was significantly higher compared with the two control groups (all P<0.05). The contents of lung collagen type Ⅰ and type Ⅲ were higher in the experimental group on 60th, 90th and 120th day, respectively, compared with the two control groups (all P<0.05).ConclusionsThe strong sandstorm environmental exposure to a certain period of time can promote lung interstitial collagen deposition in rat. With the prolonged exposure time, the deposition of collagen increases. TNF-α, MMP-2, MMP-9 and TGF-β1 may all participate and induce the process of pulmonary fibrosis.
Riboflavin-ultraviolet A (UVA) collagen cross-linking has not only achieved good clinical efficacy in the treatment of corneal diseases such as dilatation keratopathy, bullae keratopathy, infectious keratopathy, and in the combined treatment of corneal refractive surgeries, but also its efficacy and safety in scleral collagen cross-linking have been initially confirmed. To better promote the application of cross-linking in the clinical treatment of corneal and scleral diseases, exploring controllability and predictability of the surgical efficacy are both important for evaluating the surgical efficacy and personalized precision treatment. In this paper, the progress on the cross-linking depth of riboflavin-UVA collagen cross-linking, and its relationship with the cross-linking effect will be reviewed. It will provide the reference for further application of this procedure in ophthalmology clinics.
Natural collagen peptides are collagen hydrolysates. Because of their unique physicochemical properties and excellent biological activities, collagen peptides have been a research hotspot of cosmetic raw materials development and skincare efficacy improvement. Combined with the needs of the skincare efficacy and the development trends of cosmetics, the extraction methods and their structural characteristics of natural collagen peptides were summarized in detail. The applications and its research progress in skincare efficacy of collagen peptides, such as moisturizing and anti-wrinkle, trophism and anti-aging, filling and skin regeneration were expressed with emphasis. Finally, the development and practical applications in cosmetics of natural collagen peptides were adequately prospected.
ObjectiveTo analyze the phasic changes of bone mass, bone turnover markers, and estrogen levels at different time points after glucocorticoid (GC) intervention in rat and their correlation. MethodsThirty-four female 3-month-old Sprague Dawley rats were randomly divided into the following 3 groups:baseline group (n=6), dexamethasone (DXM) group (n=14), and control group (n=14). Rats were injected with DXM at the dose of 0.75 mg/kg, twice a week for 12 weeks in DXM group, with salt solution lavage in control group, and no treatment was given in baseline group. The body mass, adrenal weight, and uterus weight were measured. Bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) of lumbar vertebral and femurs were detected by dual energy X-ray absorptiometry. Meanwhile, the serum levels of N-terminal propeptide of type I procollagen (PINP), C-terminal cross-linking telopeptide of type I collagen (β-CTX), and estrogen levels were determined by ELISA before experiment in baseline group and at 4, 8, and 12 weeks after experiment in control and DXM groups. At last, the correlation was analyzed among body weight, BMD, PINP, β-CTX, estrogen levels, and GC intervention duration of DXM group. ResultsThe body mass, adrenal weight, and uterus weight in DXM group were significantly lower than those in baseline group and control group at all the time points (P<0.05). The levels of PINP and β-CTX elevated slowly in DXM group, significant difference was found at 12 weeks (P<0.05), but no significant difference at the 4 and 8 weeks (P>0.05) when compared with those in baseline group and control group. The estrogen level in DXM group was significantly lower than that in baseline group and control group at all the time points (P<0.05). BMD, BMC, and BA of lumbar vertebral and femurs in DXM group were significantly lower than those in control group at all the time points after GC intervention (P<0.05). Loss of bone mass of L2 and femoral trochanteric region in DXM group was the lowest of all ranges of interest (ROIs). BMC and BA of lumbar vertebrae and BA of femoral shaft in DXM group at 4 weeks were significantly lower than those in baseline group (P<0.05). But there was no significant difference in BMD, BMC, and BA of other lumbar vertebrae and femurs' ROIs between DXM group and baseline group at all the time points (P>0.05). After GC intervention, BMD of lumbar vertebrae and femurs had negative correlation with PINP and β-CTX (P<0.05) and positive correlation with estrogen level (P<0.05). ConclusionThe bone mass decreases rapidly at the early stage after GC intervention and then maintains a low level with time, the levels of bone turnover markers show a progressive increase, and the estrogen levels show a decrease trend. In addition, body weight, the levels of bone turnover markers and estrogen are associated with the change of bone mass.