Objective To explore the medical ethical problens in the research of tissue engineering and their clinical application.Methods According to the technical route of tissue engineering ,including seeding cells.scaffold materials,implantation in body,ethical problems and their disposal were dissussed.Results Patient's rights to know the facts of test,efficacy and security of clinical application must be fully ensured during implantation of seeding cells and scaffold materials to human body.Conclusion In needs to formulate related standard of tissue engineered products and perfect politics and regulations.

BACKGROUND:The low output of seed cells and long cycle of traditional ceils culture methods in tendon animal models(rabbits and chicken) restrict the researches of tendon tissue engineering study.OBJECTIVE:To establish an ideal culture protocol of tail tendon in SD rats,to get more seed cells within less time for subsequent engineered tendon construction research.DESIGN,TIME AND SETTING:Controlled observation was performed in the National Key Laboratory of Biotherapy,Department of Stem Cells and Tissue Engineering,Sichuan University between February and November in 2006.MATERIALS:Rat tail tendon cells were harvested from 2 SD rats,aged 7-10 days;human prepuce fibroblasts were offered by National Key Laboratory of Biotherapy,Department of Stem Cells and Tissue Engineering,Sichuan University.METHODS:Tail tendon of SD rats was draw off and cut into pieces,which were then cultured in 10% fetal bovine serum+DFculture medium for getting primary tendoncyte by using suspension tissue culture method. The third generation cells were processed into immuocytochemistry stain with collagen type Ⅰ and Ⅲ,while human prepuce fibroblasts served as controls.Absorbance of stain result was measured by image-pro plus 5.02 for statistical analysis.MAIN OUTCOME MEASURES:Immuocytochemistry stain and absorbance measurement of SD rat tail tendon cells.RESULTS:The second generation of SD rat tail tendon cells were positive for type Ⅰ collagen stain,and negative for type Ⅲ collagen stain;human fibroblast were positive for both Ⅰ and Ⅲ collagen. In the rat tail tendon cells and human flbroblasts,the absorbance value of type Ⅰ collagen expression was dramatically higher than of type Ⅲ collagen(P＜0.05). There was no significant differences addressing the absorbance of type Ⅲ collagen expression between type Ⅰ and Ⅲ collagen of SD rat tail tendon cells and blank control group (P＞0.05).CONCLUSION:Cells cultured from SD rat tail tendon have biological characteristic of tendon cells. Tissue piece suspensionculture can obtain a quantity of primary or subcuitured cells of rat tail tendon within a short time.

Using tissue-engineered tendons to repair tendons and ligaments as well as functional reconstruction is the focus of nowadays researches. The scaffolds must be not only unharmful to health, but also easy for cells attachment, and be able to induce collagen deposition to form a neotendon with mechanic properties similar to those of normal tendon. In recent researches, it has been found that the mechanic properties of the implants change with the degrading and femdonizing of scaffolds. The relationships between collagen deposition, scaffolds degradation and mechanic properties of neotendon need to be defined more clearly.
Animals ; Biocompatible Materials ; metabolism ; Biodegradation, Environmental ; Bioprosthesis ; Collagen ; metabolism ; Dogs ; Mice ; Rats ; Sheep ; Tendons ; Tissue Engineering

BACKGROUND:Accumulative evidence supports that vitreous cryopreservation can improve the cel survival rate. OBJECTIVE:To investigate the effect of vitreous cryopreservation on the tenocytes co-cultured with the porous polydimethylsiloxane (PDMS) scaffold. METHODS:Tenocytes were co-cultured with the porous PDMS scaffold for 9-14 days, and then preserved and resuscitated in the 10%dimethyl sulfoxide (DMSO), 21%DMSO and VS55, respectively. One hour later, the survival rate of post-resuscitated tenocytes versus pre-resusciated tenocytes was analyzed by live/dead double color fluorescent staining and flow cytometry. RESULTS AND CONCLUSION:Live/dead double color fluorescent staining revealed that tenocytes in the 10%DMSO group appeared to be irregular and double stained, and a large number of cel s shedding from the scaffold. The VS55 and 21%DMSO groups showed some spindle and hemispherical cel s single stained for green fluorescence and few double stained irregular cel s. Additional y, the cel density in the two groups was significantly lower than that in the control group. Flow cytometry results found that there were homogenous cel s in the control group;the number of cel s in the 10%DMSO group was too low to undergo flow cytometry;smal cel particles were visible in the VS55 group;in the 21%DMSO group, the cel volume was similar with the control group, and smal particles also existed. The survival rate in the VS55 group (64.9%) was significantly lower than that in the 21%DMSO group (76.2%;P<0.05). Conversely, the survived cel s were rare in the 10%DMSO group. To conclude, 21%DMSO vitreous cryopreservation improves the cel survival rate and is beneficial for tenocyte adherence to the scaffold.

In this brief review, some key issues related to cryopreservation of seeding cells, scaffolds, and engineered tissues are outlined. The importance of cryopreservation technology to the research and development of tissue engineered products is demonstrated. The biological or biochemical reaction rate must be reduced or completely shut off in order to preserve the tissue engineered products for a long period of time. Cryopreservation may be one of the possible approaches to the fulfillment of this requirement. Seeding cells are stored at low temperature. Tissue engineered scaffold products are usually lyophilized. Engineered tissues are preserved by vitreous cryopreservation technology.
Cell Count ; Cell Survival ; Cryopreservation ; methods ; Humans ; Tissue Engineering ; Tissue Preservation ; Tissue Survival

Recently, in vitro dynamical cell-culture has been drawing more and more attention from researchers in the areas of tissue engineer, and a series of researches have demonstrated that cyclic mechanical stretching has significant effects on the cell proliferation, differentiation, and on the cell alignment on scaffold, as well as on the synthesis of extracellular matrix, cytokines, and matrix metalloproteinases (MMPs). By focusing on reviewing the culture of several kinds of fibroblasts in vitro, we learned that these cellular responses mentioned above induced by cyclic mechanical stretching were tested by many precisely designed experiments, and assumed that cyclic mechanical stretching, if applied properly, would contribute significantly to our purpose of constructing more sophisticated tissue-engineered tendon and ligament.
Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Fibroblasts ; cytology ; Humans ; Matrix Metalloproteinases ; metabolism ; Periodicity ; Shear Strength ; Stress, Mechanical ; Tissue Engineering

To detect the properties of natural xenogeneic bone derived materials which were processed with different physical and chemical treatments, we made fully deproteinized bone(FDB), partially deproteinized bone (PDPB), partially decalcified bone(PDCB) from pig ribs. Their morphological features, constitute components and mechanical properties were examined by scanning electron microscopy, x-rays diffraction analysis, mechanical assay and so on. The results showed that FDB, PDPB and PDCB maintained natural network pore system. The ratios of calcium to phosphorus were 1.81, 1.74 and 1.50, and the protein contents were 0.01% +/- 0.02%, 22.41% +/- 0.83% and 35.75% +/- 2.12% respectively. The sequence of their mechanic strength was PDCB > PDPB > FDB. These data indicate that FDB, PDPB and PDCB possess natural network pore system. Their organic and inorganic component ratios and contents are different, so their mechanic properties are not alike. Additionally, more investigations will be necessary to detect the biocompatibility of the three different scaffold materials of natural derived bone.
Animals ; Biocompatible Materials ; chemistry ; Biomechanical Phenomena ; Bone and Bones ; chemistry ; Materials Testing ; Swine ; Tissue Engineering

Cell adhesion is a basic and very important tissue in the field of tissue engineering. Fibronectin and integrins are the most important elements to cell adhesion. Some surface receptors of fibroblast can also conjugate with type I collagen in extracellular matrix (ECM) directly. Laminin receptors on the surface of fibroblast bound to laminin also play a role in cell adhesion. In this paper are reviewed a number of related articles. The structures and function of fibronectin and integrins are discussed in detail; the tendon cell's adhesion structures are also discussed. Yet, there was scarcely any paper on the effects which the preservation of tissue engineered products may have on cells' adhesion fo ECM. Therefore, researching on cell adhesion and finding a way of preservation that has no or very little adverse effect on cell adhesion is an important topic. Results from expected advanced researches on cell adhesion may probably find promising applications in the field of tissue engineering.
Cell Adhesion ; Extracellular Matrix ; metabolism ; Fibroblasts ; cytology ; Fibronectins ; metabolism ; Humans ; Integrins ; metabolism ; Laminin ; metabolism ; Tendons ; metabolism ; Tissue Engineering

In this study we examined the in vitro characteristics of tenocyte adhesion to biologically-modified surface of polymer. Polylactic-co-glycolic acid (PLGA) 85/15 films were prepared by a solvent-casting technique. Each film was adhered onto the bottom of a chamber. The film was precoated with poly-D-lysine (PDL), and then coated with serum-free F12 medium containing various concentrations of fibronectin (FN), type I collagen (CN I), and insulin-like growth factor1 (IGF-1). The monoclonal antibodies (to FN and to CN I) with various dilutions were used to inhibit attachment of tenocytes to surface precoated with FN or CN I. Human embryonic tendon cells (HETCs) and transformed human embryonic tendon cells (THETCs) were used as the seeding cells. The system used for the measurement of adhesion force was the micropipette aspiration experiment system. The micropipette was manipulated to aspirate a small portion of the tenocyte body by using a small aspiration pressure. Then the pipette was pulled away from the adhesion area by micromanipulation. The minimum force required to detach the tenocyte from the substrate was defined as the adhesion force. The results showed that modification of FN or CN I by precoating significantly enhanced attachment of tenocytes to surface of polymer (P < 0.05). As antibodies to FN or CN I were added to a polymer film precoated with FN or CN I, the adhesion force decreased significantly (P < 0.05). We concluded that the specific adhesion forces of tenocytes to extracellular matrix adhesion proteins (FN and CN I) had coordinated action and showed good dependence on their precoating concentrations, and were inhibited by the antibodies to these adhesion proteins. Films precoated with IGF-1 strongly accelerated the adhesion of tenocytes to polymer. These results indicate that the specific adhesion of tenocytes to polymer can be promoted by coating extracellular matrix adhesive proteins and insulin-like growth factor1. It is of great importance to construct tissue-engineered tendon.
Biocompatible Materials ; chemistry ; Cell Adhesion ; drug effects ; physiology ; Cells, Cultured ; Extracellular Matrix Proteins ; pharmacology ; Growth Substances ; pharmacology ; Humans ; Lactic Acid ; chemistry ; Polyglycolic Acid ; chemistry ; Polylysine ; pharmacology ; Polymers ; chemistry ; Tendons ; cytology ; embryology ; physiology ; Tissue Engineering

By observations of the features of ultrastructure changes in the tissue engineered artificial tendon of vitreous cryopreservation, we investigated the repairing effect of tendon after an in-vivo implantation and hence we provided an important theoretical and experimental basis for the vitreous cryopreservation and application of tissue engineered artificial tendon. After vitreous cryopreservation, the implantation materials of tissue engineered artificial tendon dynamically constructed in vitro were implanted in rats for reparation of the tendon defect. A scanning electron microscope was used. At the 2nd week, the materials presented a reticular formation and there were juvenile tendon cells among materials. At the 6th week, materials were already degraded and absorbed, and then were substituted by neonatal tendon cells and collagen fibers. At the 8th week, dense tendon tissues containing uniform tendon cells and collagen fibers were found already formed; the density of collagen fibers significantly increased with time. Using a transmission electron microscope at the 2nd week, we found active proliferation of tendon cells; most of them were immature cells with a complete nuclear membrane, clear nucleolus and little collagen fibers. At the 6th week, tendon cells were more mature with a little-sized, deep-stained nucleolus surrounded by plenty of collagen fibers with complete fiber structure and clear cross striation. There was no significant difference between the two groups. Using an electron microscope, we found a very good agreement in observation of the tissue engineered artificial tendon after the in-vivo implantation in two groups. Neonatal tendon cells and collagen fiber tissues grew well and are in a similar form and order when compared versus normal tendon tissues. This proved that vitreous cryopreservation has no significant influence on the function of tendon cells. The neonatal tissue-engineered tendon exerts good function of growth and repair.
Achilles Tendon ; injuries ; surgery ; ultrastructure ; Animals ; Cryopreservation ; Female ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Tendons ; cytology ; transplantation ; Tissue Engineering ; methods ; Tissue Preservation ; methods ; Tissue Scaffolds ; Vitrification