ABSTRACT
Background: The incidence of placement of osteosynthetic materials has grown worldwide. Bioabsorbable materials are more commonly used now days in Orthopedic surgeries. Implants modify the risk of infection by bacterial adhesion, tissue integration, and immunomodulation. Bacterial adhesion to implant leads to interaction between bacteria and implant. Aim: To evaluate the incidence of infections associated with use of bioabsorbable implants in Orthopedic surgeries. Materials and methods: The infection rates among 1057 patients were treated with bioabsorbable osteosynthesis devices was investigated. The implant material used was PGA in approximately three fourths of the patients. Results: Depending on the bioabsorbable material used, the infection rates varied from 0.7% (SRPLLA) to 6.5% (SR-PGA and SR-PLLA together). In a comparison with metallic osteosynthesis devices, a total 522 ankle fracture patients were studied. There was no significant difference between the infection rates of the bioabsorbable fixation group (3.2%) and metallic fixation group (4.1%). The effect of bioabsorbable implants volume on wound infections showing a significant positive correlation between the incidence of infection and the implant volume when non-stained SR-PGA or SR-PLLA implants were used. In fracture patients the raising of the implant-bone volume ratio correlated with the rising incidence of infection. Conclusion: Increasing the implant volume causes a higher incidence of wound infection when modern, non-stained implants are used. The increase in the incidence of infection is most prominent when SR-PLLA implants are used. Increasing the implant-bone volume ratio causes a higher incidence of wound infection on the tibial side.
ABSTRACT
Human hepatocarcinoma cells, HepG2 were cultured onto biodegradable polyglycolic acid (PGA) polymer scaffolds, which were cultured in a rotating cell culture system (RCCS) to form a three-dimensional (3D) multicellular culture in vitro. The RCCS can simulate microgravity effects with low shear stress and well exchanging for gas. Then the growth characteristics and some mechanism of the cells in RCCS were detected by scanning electron microscopy (SEM), transmission electron microscopy (TEM), RT-PCR and flow cytometry (FCM). The results indicate that the cells grew well with polyhedron morphology and lots of microvilli, mitochondria and tight junctions in this system, which means that this system is useful for cells to form 3D structure to mimic cell status in vivo. The expression of some cell adhesion molecules (CAMs) were changed markedly, which are closely associated with cancer invasion and metastasis. The characters of increased expression of integrin ?1(CD29), CD44, intercellular adhesion molecule-1(CD54) and depressed expression of E-cadherin presumably show that the HepG2 cells cultured in RCCS could recur some characters of primary liver cancer in vivo, the capacity of invasion and metastasis. It is necessary for acquiring perfect and external results to select an appropriate research model for studying in vitro. This 3D culture in vitro under simulated microgravity can provide a useful and reasonable model for oncology, anticancer drugs research and other research.
ABSTRACT
Objective To observe whether the full-thickness defects of articular cartilage at the knee joint of rabbits could be repaired by implantation of polyglycolic-acid(PGA) composites adhered with bone marrow stromal cells (BMSCs). Methods Culture-expanded rabbits’BMSCs were seeded onto porous PGA scaffolds. After a 72-hour co-culturing, the cell-adhered PGA was implanted into the articular cartilage defect at the intercondylar fossa of the femur. The rabbits were sacrificed 12 weeks later after the operation and the specimens were examined histologically for morphologic features, and stained immunohistochemically for type Ⅱcollagen. Results The specimens harvested from BMSCs-PGA composite demonstrated a hyaline cartilage formation. No obvious progressive degeneration sign was found in the newly formed tissue. The control groups showed no hyaline-like cartilage formation. Conclusion PGA composites adhered with in vitro culture-expanded autologous BMSCs can facilitate formation of hyaline-like cartilage in rabbits.
ABSTRACT
Neomorphogenesis using tissue engineering technique by cell transplantation with biodegradable polymer has been introduced as a new method to achieve organ replacement or to create new tissues. Using this tissue engineering technique, neocartilage formation can be possible when isolated chondrocyte is combined with biocompatible and biodegradable polymer scaffolds. The purposes of this study are to investigate whether chondrocyte-polyglycolic acid(PGA) polymer can be designed to induce cartilage formation in a predetermined shape, to analyze the properties of neocartilage by histologic and immunohistochemical study. Chondrocytes were isolated from the articular cartilage of swine shoulder joint and seeded onto four PGA polymers(disc shape, diameter;1cm, thickness; 0.3 cm) at a concentration of 5 x 107 chondrocytes per cm3. Chondrocyte-PGA polymers were implanted into left side of subcutaneous pockets on the dorsa of 4 athymic mice. PGA polymers without chondrocyte were implanted into the right side of subcutaneous pockets of the same animals as a control study. The chondrocyte-PGA polymers were harvested 2, 4, 6 and 8 weeks after implantation and investigated grossly, histologically and immunohistochemically. Chondrocytes were also cultured in Ham's F-12 medium under 5% CO2 incubator at 37degrees C and analyzed by histologic and immunohistologic study. The analysis confirmed the following results: 1. In vitro study, it was confirmed by Hematoxylin-Eosin (H-E) stain and toluidine blue stain that histologic findings of cultured chondrocyte corresponded to normal chondrocyte. 2. After 4 weeks of implantation of chondrocyte-PGA polymer, specimens changed in gross finding to pearly white opalescence and firm on palpation and this findings were accentuated progressively. But PGA polymers without chondrocyte could not maintain its shape and were resolved gradually. 3. The appearance of normal immature cartilage was detected at 2 weeks of implantation of chondrocyte-PGA polymer in H-E stain and toluidine blue stain. Maturation process of cultured chondrocyte was observed by steps in the 4th, 6th and 8th week. 4. Using the immunohistochemistric study, the presences of Type II collagen and CD44 were confirmed in cultured chondrocytes. This finding meant that neocartilage could inherit the original properties of chondrocyte. 5. Nipple-shaped cartilage discs which could assure the mechanical and histologic properties of normal cartilage were successfully created. It seems to be possible to apply this method to other kinds of manufacture with various shaped-PGA polymer. This study showed not only new cartilage formation could be possible using chondrocyte and PGA polymer but also engineered tissue could be one of the modalities to treat the patients suffering from the shortage of tissue in the future. With further prudent researches, tissue engineering technique can be a distinguished armament in reconstruction of human body including cartilage.