Abstract To look for a substitute material of microvessel, 30 rabbits were divided into 2 groups. A segment of 5mm of rabbit femoral artery was resected and a segment of 10mm of human placental artery was placed in the defect with both ends anastomosed. Twenty experimental rabbits received freezedried human placental vessel and 10 rabbits received fresh as control. After 24 hours, 2 weeks, 3 months, the arteries were explored. If the artery was found to be obstructed, the segment was removed for histologic examination. The results showed: in the experimental group, 2 weeks after operation, the rateof patency was 85%, and it decreased to 50% 3 months after the operation. Under the light and scanning electronic microscope, the transplanted vessels were decomposed and inside the unobstructed transplanted vessels in both groups a layer of fibrous tissue was formed as the new wall of vessel. It was concluded thatthe immunologic reaction could not be prevented but would only be put off for aperiod of time by cryochem. Further more study should be done in using placental atery as a substitute material in repairing vascular defect.
【Abstract】 Objective To develop a novel cartilage acellular matrix (CACM) scaffold and to investigate its performance for cartilage tissue engineering. Methods Human cartilage microfilaments about 100 nm-5 μm were prepared after pulverization and gradient centrifugation and made into 3% suspension after acellularization treatment. After placing the suspension into moulds, 3-D porous CACM scaffolds were fabricated using a simple freeze-drying method. The scaffolds were cross-l inked by exposure to ultraviolet radiation and immersion in a carbodiimide solution 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysucinimide. The scaffolds were investigated by histological staining, SEM observation and porosity measurement, water absorption rate analysis. MTT test was also done to assess cytotoxicity of the scaffolds. After induced by conditioned medium including TGF-β1, canine BMSCs were seeded into the scaffold. Cell prol iferation and differentiation were analyzed using inverted microscope and SEM. Results The histological staining showed that there are no chondrocytefragments in the scaffolds and that toluidine blue, safranin O and anti-collagen II immunohistochemistry staining werepositive. The novel 3-D porous CACM scaffold had good pore interconnectivity with pore diameter (155 ± 34) μm, 91.3% ± 2.0% porosity and 2 451% ± 155% water absorption rate. The intrinsic cytotoxicity assessment of novel scaffolds using MTT test showed that the scaffolds had no cytotoxic effect on BMSCs. Inverted microscope showed that most of the cells attached to the scaffold. SEM micrographs indicated that cells covered the scaffolds uniformly and majority of the cells showed the round or ell iptic morphology with much matrix secretion. Conclusion The 3-D porous CACM scaffold reserved most of extracellular matrix after thoroughly decellularization, has good pore diameter and porosity, non-toxicity and good biocompatibil ity, which make it a suitable candidate as an alternative cell-carrier for cartilage tissue engineering.
ObjectiveTo study the preparation and cytocompatibility of bone tissue engineering scaffolds by combining low temperature three dimensional (3D) printing and vacuum freeze-drying techniques. MethodsCollagen (COL)and silk fibroin (SF) were manufactured from fresh bovine tendon and silkworm silk. SolidWorks2014 was adopted to design bone tissue engineering scaffold models with the size of 9 mm×9 mm×3 mm and pore diameter of 500μm. According to the behavior of composite materials that low temperature 3D printing equipment required, COL, SF, and nano-hydroxyapatite (nHA)at a ratio of 9:3:2 and low temperature 3D printing in combination with vacuum freeze-drying techniques were accepted to build COL/SF/nHA composite scaffolds. Gross observation and scanning electron microscope (SEM) were applied to observe the morphology and surface structures of composite scaffolds. Meanwhile, compression displacement, compression stress, and elasticity modulus were measured by mechanics machine to analyze mechanical properties of composite scaffolds. The growth and proliferation of MC3T3-E1 cells were evaluated using SEM, inverted microscope, and MTT assay after cultured for 1, 7, 14, and 21 days on the composite scaffolds. The RT-PCR and Western blot techniques were adopted to detect the gene and protein expressions of COL I, alkaline phosphatase (ALP), and osteocalcin (OCN) in MC3T3-E1 cells after 21 days. ResultsCOL/SF/nHA composite scaffolds were successfully prepared by low temperature 3D printing technology and vacuum freeze-drying techniques; the SEM results showed that the bionic bone scaffolds were 3D polyporous structures with macropores and micropores. The mechanical performance showed that the elasticity modulus was (344.783 07±40.728 55) kPa; compression displacement was (0.958 41±0.000 84) mm; and compression stress was (0.062 15±0.007 15) MPa. The results of inverted microscope, SEM, and MTT method showed that a large number of cells adhered to the surface with full extension and good cells growth inside the macropores, which demonstrated a satisfactory proliferation rate of the MC3T3-E1 cells on the composite scaffolds. The RT-PCR and Western blot electrophoresis revealed gene expressions and protein synthesis of COL I, ALP, and OCN in MC3T3-E1 cells. ConclusionLow temperature 3D printing in combination with vacuum freeze-drying techniques could realize multi-aperture coexisted bionic bone tissue engineering scaffolds and control the microstructures of composite scaffolds precisely that possess good cytocompatibility. It was expected to be a bone defect repair material, which lays a foundation for further research of bone defect.
The freeze-drying is a technology that preserves biological samples in a dry state, which is beneficial for storage, transportation, and cost saving. In this study, the bovine pericardium was treated with a freeze-drying protectant composed of polyethylene glycol (PEG) and trehalose (Tre), and then freeze-dried. The results demonstrated that the mechanical properties of the pericardium treated with PEG + 10% w/v Tre were superior to those of the pericardium fixed with glutaraldehyde (GA). The wet state water content of the rehydrated pericardium, determined using the Karl Fischer method, was (74.81 ± 1.44)%, which was comparable to that of the GA-fixed pericardium. The dry state water content was significantly reduced to (8.64 ± 1.52)%, indicating effective dehydration during the freeze-drying process. Differential scanning calorimetry (DSC) testing revealed that the thermal shrinkage temperature of the pericardium was (84.96 ± 0.49) ℃, higher than that of the GA-fixed pericardium (83.14 ± 0.11) ℃, indicating greater thermal stability. Fourier transform infrared spectroscopy (FTIR) results showed no damage to the protein structure during freeze-drying. Hematoxylin and eosin (HE) staining demonstrated that the freeze-drying process reduced pore formation, prevented ice crystal growth, and resulted in a tighter arrangement of tissue fibers. The frozen-dried bovine pericardium was subjected to tests for cell viability and hemolysis rate. The results revealed a cell proliferation rate of (77.87 ± 0.49)%, corresponding to a toxicity grade of 1. Additionally, the hemolysis rate was (0.17 ± 0.02)%, which is below the standard of 5%. These findings indicated that the frozen-dried bovine pericardium exhibited satisfactory performance in terms of cytotoxicity and hemolysis, thus meeting the relevant standards. In summary, the performance of the bovine pericardium treated with PEG + 10% w/v Tre and subjected to freeze-drying could meet the required standards.
Cell freeze-drying can be divided into the freezing and drying processes. Mechanical damage caused by ice crystals and damage from solute during freezing shall not be ignored and lyoprotectants are commonly used to reduce those damages on cells. In order to study the mechanism of lyoprotectants to protect cells and determine an optimal lyoprotectant formula, the thermophysical properties and percentage of unfrozen water of different lyoprotectants in freezing were investigated with differential scanning calorimeter (DSC). The survival rate indicated by trypan blue exclusion test and cell-attachment rate after 24 h using different lyoprotectants to freeze hepatoma Hep-G2 cells were measured after cell cryopreservation. The results show that 40% (W/V) PVP + 10% (V/V) glycerol + 15% (V/V) fetal bovine serum + 20% (W/V) trehalose formula of lyoprotectant demonstrate the best effect in protecting cells during freezing, for cell-attachment rate after 24 h is 44.56% ± 2.73%. In conclusion, the formula of lyoprotectant mentioned above can effectively protect cells.
ObjectiveTo investigate the problems in the use of quick-drying hand disinfectants and formulate intervention measures to improve the hand hygiene compliance of nursing staff.MethodsFrom February 2014 to June 2016, the hand hygiene compliance of nursing staff was continuously observed according to the hand hygiene observation table recommended by the World Health Organization. The questionnaire on the use of quick-drying hand disinfectants, which passed the reliability and validity test, was used to find out the reasons leading to the low compliance rate of hand hygiene among nurses, and pertinent interventions were formulated. From November 2016 to December 2017, intervention measures were gradually implemented throughout the hospital, and the hand hygiene compliance of nursing staff was continuously observed again. Then we compared the compliance rate of hand hygiene and the compliance rate of hygienic hand disinfection among nurses in the second quarter of 2016 (before intervention) with those in the last quarter of 2017 (after intervention).ResultsThe compliance rates of hand hygiene and hygienic hand disinfection among nurses before intervention were 62.15% and 49.77%, respectively, and those after intervention were 91.64% and 90.80%, respectively. The differences were statistically significant (P<0.05).ConclusionThe factors affecting the hand hygiene compliance of nursing staff are identified through questionnaires and targeted intervention measures have effectively improved the hand hygiene compliance rate of nursing staff.
Objective To investigate the impact of different final rinsing parameters of automated endoscopic reprocessors on peracetic acid (PAA) residuals in gastrointestinal endoscope channels, and to provide scientific evidence for optimizing endoscope cleaning and disinfection processes in clinical settings and reducing patient exposure risks. Methods From January to March 2025, 86 gastroscopes and 6 automated endoscopic reprocessors regularly used in the Endoscopy Center, Zhongshan Hospital, Fudan University were selected as the research subjects. They were divided into 3 groups based on the duration and frequency of final rinsing (group A: final rinsing for 2 times, with each rinsing lasting for 2.5 minutes, and a total rinsing time of 5 minutes; group B: final rinsing for 3 times, with each rinsing lasting for 2 minutes, and a total rinsing time of 6 minutes; group C: final rinsing for 3 times, with each rinsing lasting for 2.5 minutes, and a total rinsing time of 7.5 minutes). The PAA residuals in the endoscope channels of each group before and after drying were detected, and the compliance rates of PAA residues with standards were calculated. Results During the study period, groups A, B, and C underwent 40, 52, and 43 endoscopic disinfection procedures, respectively. Before drying, there was a significant difference in the residual PAA levels among the three groups (median PAA residual levels in groups A, B, and C were 5.34, 2.51, and 0.94 mg/L, respectively; P<0.05). Further pairwise comparisons also showed statistically significant differences (P<0.05). After drying, there was a significant difference in the residual PAA levels among the three groups (median PAA residual levels in groups A, B, and C were 3.37, 0.90, and 0.75 mg/L, respectively; P<0.05). However, further pairwise comparisons revealed no significant difference in PAA residual levels between group B and group C (P>0.05), while the remaining pairwise comparisons showed statistically significant differences (P<0.05). Within-group comparisons of PAA residual levels before and after drying showed significant differences in PAA residual levels in groups A and B before and after drying (P<0.05), while there was no significant difference in PAA residual levels in group C before and after drying (P>0.05). The PAA residual compliance rates in groups A and B after drying were significantly higher than those before drying (group A: 5.00% before drying and 27.50% after drying; group B: 1.92% before drying and 57.69% after drying; P<0.05), while there was no significant difference in the PAA residual compliance rates in group C before and after drying (P>0.05). Conclusions Increasing the number of final rinsing, extending the rinsing duration, and intensifying the drying process can effectively reduce PAA residues. Clinically, it is recommended to optimize the final rinsing parameters of the automated endoscopic reprocessor, combined with intensified drying, to reduce PAA residues and ensure patient safety.