The digestive tract is designed for the optimal processing of food that nourishes all organ systems.The esophagus,stomach,small bowel,and colon are sophisticated neuromuscular tubes with specialized sphincters that tr...The digestive tract is designed for the optimal processing of food that nourishes all organ systems.The esophagus,stomach,small bowel,and colon are sophisticated neuromuscular tubes with specialized sphincters that transport ingested food-stuffs from one region to another.Peristaltic contractions move ingested solids and liquids from the esophagus into the stomach;the stomach mixes the ingested nutrients into chyme and empties chyme from the stomach into the duodenum.The to-and-fro movement of the small bowel maximizes absorption of fat,protein,and carbohydrates.Peristaltic contractions are necessary for colon function and defecation.展开更多
Objective To investigate the feasibility of tendon engineering in vitro using tenocyws and polyglycolic acids （ PGA ）. Methods Tenocytes were isolated by tissue explant method and expanded in vitro. Cells of the sec...Objective To investigate the feasibility of tendon engineering in vitro using tenocyws and polyglycolic acids （ PGA ）. Methods Tenocytes were isolated by tissue explant method and expanded in vitro. Cells of the second passage were collected and seeded onto PGA scaffolds made from PGA unwoven fibers at the density of 20 × 10^6 cells/ml. At 1 week postseeding ,the constructs were divided into three groups as follows： cell-scaffold constructs under constant tension generated by a U-shaped spring as the experimental group （ n = 5 ）, cell-scaffold constructs under no tension as control group 1 （ n = 4 ）, cell-free scaffolds under constant tension as control group 2 （n =3）. Samples were harvested at 2, 4 and 6 weeks for histological and immunohistochemical （ IHC ） examinations. Transmission electron microscopy （TEM） and mechanical test were performed to evaluate the constructs of 6 weeks. Results At 2 weeks, the constructs were mainly composed of undegraded PGA fibers. Gross and histological examination revealed no difference between the groups. At 4 weeks, neo-tendon was visible through gross observation in experimental group and control group 1. Histology and immunohistochemistry revealed the formation of collagen fibers. While in control group 2, PGA fibers were mostly degraded. At 6 weeks, the constructs were much thinner in experimental group than those in control group 1 （ 1.44 ± 0.13mm vs 2.55 ± 0. 18mm in diameter ）. TEM showed periodical strata of collagen fibers in the constructs from experimental group and control group 1. However, histology in experimental group revealed longitudinal alignment of collagen fibers, which more resembled natural tendon than neotendon formed in control group 1. Besides, the maximum load to failure（ Newton/mm^2 ） was greater in experimental group than that in control group 1 （1. 107 ±0. 327 vs 0. 294 ± 0. 138, P 〈0.05）. Conclusion It＇ s possible to engineer tendon substitutes in vitro. Cyclic strain generated by a bioreactor may be the optimal mechanical stimulation and is currently under investigation.展开更多
Objective: To repair rabbit tendon defects with tissue engineering method. Methods: The third passage of fetal skin fibroblast cells was labeled with 5 bromo 2 deoxyuridine (Brdu) and then seeded on human amnion extra...Objective: To repair rabbit tendon defects with tissue engineering method. Methods: The third passage of fetal skin fibroblast cells was labeled with 5 bromo 2 deoxyuridine (Brdu) and then seeded on human amnion extracellular matrix ( HA ECM ). Using 1 cm long Achilles tendon defects as repairing models in the experimental group, tendon defects were core bridged with polydioxanone (PDS) and then capsulated with the complex of fibroblasts HA ECM . In the control group I, defective tendons were sutured with PDS following the former procedure and capsulated with HA ECM (without fibroblasts). In the control group II, only PDS was applied to connect the defective tendons. Gross examination, light microscopy, scanning electronmicroscopy and biomechanical measurement of the repaired tendons were respectively performed at postoperative 1, 2, 3 month as well as immunohistochemical examination. Results: The optimal cell concentration for seeding fibroblasts was 3.5 ×10 6 cells/ml. Cells grew well and radiated or paralleled on HA ECM . Immunohistochemistry showed that the labeled seed fibroblasts played an important role in tendonization. The results of light microscopy, electron microscopy, and biomechanical assessment suggested that the rate and quality of tendonization in the experimental group was superior to those of the control group I and II. The tensile strength in the experimental group was the greatest, the next was in the control group I, and the worst in the control group II (P< 0.05 ). Conclusions: HA ECM is the excellent carrier for fibroblasts. Fibroblasts HA ECM complex has the capability to repair tendon defect and to tendonize with rapid rate and good performance three months after operation. Its tensile strength is 81.8 % of that of normal tendon.展开更多
基金Supported by NIH Research Grants R01DK071614,1RC1DK 087151,and U01 DK073975-01
文摘The digestive tract is designed for the optimal processing of food that nourishes all organ systems.The esophagus,stomach,small bowel,and colon are sophisticated neuromuscular tubes with specialized sphincters that transport ingested food-stuffs from one region to another.Peristaltic contractions move ingested solids and liquids from the esophagus into the stomach;the stomach mixes the ingested nutrients into chyme and empties chyme from the stomach into the duodenum.The to-and-fro movement of the small bowel maximizes absorption of fat,protein,and carbohydrates.Peristaltic contractions are necessary for colon function and defecation.
文摘Objective To investigate the feasibility of tendon engineering in vitro using tenocyws and polyglycolic acids （ PGA ）. Methods Tenocytes were isolated by tissue explant method and expanded in vitro. Cells of the second passage were collected and seeded onto PGA scaffolds made from PGA unwoven fibers at the density of 20 × 10^6 cells/ml. At 1 week postseeding ,the constructs were divided into three groups as follows： cell-scaffold constructs under constant tension generated by a U-shaped spring as the experimental group （ n = 5 ）, cell-scaffold constructs under no tension as control group 1 （ n = 4 ）, cell-free scaffolds under constant tension as control group 2 （n =3）. Samples were harvested at 2, 4 and 6 weeks for histological and immunohistochemical （ IHC ） examinations. Transmission electron microscopy （TEM） and mechanical test were performed to evaluate the constructs of 6 weeks. Results At 2 weeks, the constructs were mainly composed of undegraded PGA fibers. Gross and histological examination revealed no difference between the groups. At 4 weeks, neo-tendon was visible through gross observation in experimental group and control group 1. Histology and immunohistochemistry revealed the formation of collagen fibers. While in control group 2, PGA fibers were mostly degraded. At 6 weeks, the constructs were much thinner in experimental group than those in control group 1 （ 1.44 ± 0.13mm vs 2.55 ± 0. 18mm in diameter ）. TEM showed periodical strata of collagen fibers in the constructs from experimental group and control group 1. However, histology in experimental group revealed longitudinal alignment of collagen fibers, which more resembled natural tendon than neotendon formed in control group 1. Besides, the maximum load to failure（ Newton/mm^2 ） was greater in experimental group than that in control group 1 （1. 107 ±0. 327 vs 0. 294 ± 0. 138, P 〈0.05）. Conclusion It＇ s possible to engineer tendon substitutes in vitro. Cyclic strain generated by a bioreactor may be the optimal mechanical stimulation and is currently under investigation.
基金Supported by National Natural Science Foundation ofChina (No:39830 10 0 )
文摘Objective: To repair rabbit tendon defects with tissue engineering method. Methods: The third passage of fetal skin fibroblast cells was labeled with 5 bromo 2 deoxyuridine (Brdu) and then seeded on human amnion extracellular matrix ( HA ECM ). Using 1 cm long Achilles tendon defects as repairing models in the experimental group, tendon defects were core bridged with polydioxanone (PDS) and then capsulated with the complex of fibroblasts HA ECM . In the control group I, defective tendons were sutured with PDS following the former procedure and capsulated with HA ECM (without fibroblasts). In the control group II, only PDS was applied to connect the defective tendons. Gross examination, light microscopy, scanning electronmicroscopy and biomechanical measurement of the repaired tendons were respectively performed at postoperative 1, 2, 3 month as well as immunohistochemical examination. Results: The optimal cell concentration for seeding fibroblasts was 3.5 ×10 6 cells/ml. Cells grew well and radiated or paralleled on HA ECM . Immunohistochemistry showed that the labeled seed fibroblasts played an important role in tendonization. The results of light microscopy, electron microscopy, and biomechanical assessment suggested that the rate and quality of tendonization in the experimental group was superior to those of the control group I and II. The tensile strength in the experimental group was the greatest, the next was in the control group I, and the worst in the control group II (P< 0.05 ). Conclusions: HA ECM is the excellent carrier for fibroblasts. Fibroblasts HA ECM complex has the capability to repair tendon defect and to tendonize with rapid rate and good performance three months after operation. Its tensile strength is 81.8 % of that of normal tendon.
