OBJECTIVE This paper aims to investigate the suitable cell density and the best formation time of tissue engineered autologous cartilage and to provide theoretical basis and parameters for clinical application. METHODS The chondrocytes isolated from mini swines’ ears were mixed with injectable biocompatible matrix (Pluronic), and the density of cell suspensions were 10, 20, 30, 40, 50, 60, 70 x 10(4)/ml. The chondrocyte-polymer constructs were subcutaneously injected into the abdomen of autologous swine. The specimens were observed grossly and histologically after 6 weeks, and investigated the suitable cell density. Then the chondrocyte-polymer constructs with suitable cell density were transplanted into the abdomen of autologous swine and evaluated grossly and histologically in 1, 3, 6, 9, 15 weeks after transplantation to investigate the best formation time of tissue engineered cartilage. RESULTS The experiments demonstrated that the tissue engineered autologous cartilage was similar to the natural cartilage on animals with normal immune system in histological characteristics. The optimal chondrocyte density is 50 x 10(6)/ml, and the proper harvest time is the sixth week. CONCLUSION With tissue engineering skills, we have identified the optimal chondrocyte density and the proper harvest time.
Objective To review the recent progress of the researches in the field of cartilage tissue engineering, and to discuss the challenges in construction of tissue engineered cartilage. Methods Literature related with cartilage tissue engineering was reviewed and analyzed. Results Some techniques have been appl ied in cl inical. As far as the seeding cells, induced pluripotent stem cells have attracted much more attention. Current strategies of scaffold designing are trying to imitate both component and structure of natural extracellular matrix. Cartilage regeneration through the autologous cell homing technique el iminate the transplantation of exotic cells and has become the hot topic. Conclusion Successful treatment of the damaged cartilage using tissue engineering method will depend on the advances of stem cell technology development, biomimetic scaffolds fabrication and proper appl ication of growth factors.
Objective To construct the recombinant adenovirus bearing human transforming growth factor β1(TGF-β1) and bone morphogenetic protein 7 (BMP-7) genes, and investigate its co-expression in the marrow stromalstemcells (MSCs) and bioactivity effect. Methods Using the replication defective adenovirus AdEasy as a carrier, MSCs were infected by the high-titer-level recombinant adenovirus taking TGF-β1 and BMP-7 genes. Immunocytochemistry, in situ hybridization，reverse transcription-polymerase chain reaction (RT-PCR), and hexuronic acid level test were used to detect the coexpression of the exogenous genes and to analyze their effect transfection on directive differentiation of MSCs. Results The immunocytochemistry staining showed that the brown coarse grains were situated in the cytoplasm of the most MSCs 72 h after infection. Procollagen ⅡmRNA in the cells was detected by the in situ hybridization, and the content of hexuronic acid in the culture mediumwas significantly increased 10 days after infection compared with the level before infecton (Plt;0.01). Conclusion The recombinant adenovirus bearing human TGF-β1 and BMP-7 genes can be constructed, and the exogenous gene can be coexpressed in MSCs, which may offer a novel approach to thelocal combination gene therapy for repairing joint cartilage defects.
Objective To explore the relationship of the limited resource of the autologous bone marrow mesenchymal stem cells (MSCs) in articularcavity to the treatment results of full-thickness articular cartilage defect, and to investigate whether the extrogenous sodium hyaluronate(SH) promotes the migration of MSCs cultured in vitro tothe articular defect in vivo. Methods Sixty-six Japan rabbits were made the model of the full-thickness articular cartilage defect (5 mm width and 4 mm depth).The autologous MSCs were extracted from the rabbit femur, cultured in vitro, labeledby Brdu, and injected into the injured articular cavity with or without SH. Theexperiment was divided into 4 groups; group A (MSCs and SH, n=15); group B (MSCs, n=15); group C (SH, n=18); and group D (non-treatment, n=18). The morphologic observation was made by HE staining, Mallory staining and immunohistochemical staining after 5 weeks, 8 weeks and 12 weeks of operation. Results There were significant differences in the thickness of repairing tissue between group A and group B(Plt;0.01); but there were no significant differences between group A and group C, and between group B and group D(P＞0.05). Thehistological observation showed that the main repairing tissue was fibrocartilage in group A and fiber tissue in group B. Conclusion MSCs cultured in vitro and injected into the articular cavity can not improve the treatment results of the articular cartilage defect. Extrogenous SH has effect on repairing cartilage defect. The extrogenous SH has no effect on the chemotaxis of the MSCs, and on the collection of MSCs into the joint defect.
Objective To study the biological characteristic and potential of chondrocytes grafting cultured on fascia in repairing large defect of articular cartilage in rabbits. Methods Chondrocytes of young rabbits were isolated and subcultured on fascia. The large defect of articular cartilage was repaired by grafts of freeze-preserved and fresh chondrocytes cultured on fascia, and free chondrocytes respectively; the biological characteristic and metabolism were evaluated bymacroscopic, histological and immunohistochemical observations, autoradiography method and the measurement of nitric oxide content 6, 12, 24 weeks after grafting. Results The chondrocytes cultured on fascia maintained normal growth feature and metabolism, and there was no damage to chondrocytes after cryopreservation; the repaired cartilage was similar to the normal cartilage in cellular morphology and biological characteristics. Conclusion Chondrocytes could be cultured normally on fascia, which could be used as an ideal carrier of chondrocytes.
OBJECTIVE: To study the feasibility of the formation of allogeneic tissue-engineered cartilage of certain shape in immunocompetent animal using the injectable biomaterial. METHODS: Fresh newborn rabbits’ articular cartilages were obtained under sterile condition (lt; 6 hours after death) and incubated in the sterile 0.3% type II collagenase solution. After digestion of 8 to 12 hours, the solution was filtered through a 150 micron nylon mesh and centrifuged, then the chondrocytes were washed twice with phosphate buffered saline (PBS) and mixed with the biomaterial to create a final cell density of 5 x 107/ml. The cell-biomaterial admixture was injected into rabbits subcutaneously 0.3 ml each point while we drew the needle back in order to form the neocartilage in the shape of cudgel, and the control groups were injected with only the biomaterial or the suspension of chondrocytes with the density of 5 x 10(7)/ml. After 4, 6, 8 and 12 weeks, the neocartilages were harvested to analyze. RESULTS: The new nodes could be touched subcutaneously after 2 weeks. In the sections of the samples harvested after 4 weeks, it was found that the matrix secreted and the collagen formed. After 6 weeks and later than that, the neocartilages were mature and the biomaterial was almost completely degraded. The cudgel-shaped samples of neocartilage could be formed by injection. In the experiment group, there was no obvious immune rejection response. On the contrary, there were no neocartilage formed in the control group. CONCLUSION: The injectable biomaterial is a relatively ideal biomaterial for tissue engineering, and it is feasible to form allogeneic tissue engineered cartilage of certain shape by injection in an immunocompetent animal.
In order to observe the effects of different facing directions of the germinal layer of periosteum on the cartilage regeneration, the human fibrin adhesive agent was used to adhere autogenous periosteum to repair the articular cartilage defect of rabbits. Twentyfour rabbits with 48 knee joints were divided randomly into two groups. A 0.6cm×1.2cm articular cartilage defect was created on the femoral trochlea until there was bleeding from the subchondral bone. A piece of periosteum, sized 0.75cm×1.5cm, was removed from the medial aspect of upper tibia. The periosteum was adhered to the defect by human fibrin adhesive agent. In Group 1 the germinal layer faced the subchondral bone and in Group 2 the germinal layer faced the joint cavity. The cartilage regeneration in both groups was observed by naked eyes and light microscope in 2nd and 6th weeks and by electron microscope after Safronin Ostained in 12th and 20th weeks. The results showed that before the 6th week, the cartilage regeneration was faster in Group 2 than that in Group 1. After that there was no significant difference in regeneration between the two groups. This suggested that the facing direction of the germinal layer was not a critical factor on cartilage regeneration. It was also found that the strength of the adhesive agent was not enough. The regenerated cartilage was proved to be hyaline cartilage.
ObjectiveTo investigate the effect of inhibiting autotaxin (ATX)-lysophosphatidic acid (LPA) pathway on the cartilage of knee osteoarthritis in rats.MethodsPrimary chondrocytes within three generations of Sprague-Dawley rats (8 weeks old, male) were randomly divided into 6 groups, including blank control group, model group, 1 μmol/L PF-8380 group, 10 μmol/L PF-8380 group, 1 μmol/L Ki16425 group, and 10 μmol/L Ki16425 group. Except for the blank control group, the other groups were modeled with osteoarthritis using interleukin-1β (10 ng/mL, 24 h), and then the experimental groups, i.e., 1 μmol/L PF-8380 group, 10 μmol/L PF-8380 group, 1 μmol/L Ki16425 group, and 10 μmol/L Ki16425 group, were intervened with 1, 10 μmol/L PF-8380 (ATX inhibitor) and 1, 10 μmol/L Ki16425 (LPA receptor antagonist) for 24 h, respectively. immunocytochemistry staining was used to determine the expression of type Ⅱ collagen (Col Ⅱ) in cytoplasm, and Western Blot was used to determine the expression of ATX, LPA, and matrix metalloproteinase-13 (MMP-13) in chondrocytes.ResultsCompared with the blank control group, the average absorbance of Col Ⅱ in chondrocytes in the model group was significantly reduced (0.003 9±0.000 8 vs. 0.110 0± 0.009 0, P<0.05). The expression levels of ATX, LPA, and MMP-13 in chondrocytes in the model group, 1 μmol/L PF-8380 group, 10 μmol/L PF-8380 group, and 1 μmol/L Ki16425 group were significantly higher than those in the blank control group, while the expression levels of ATX, LPA, and MMP-13 in the 10 μmol/L Ki16425 group had no significant difference with those in the blank control group; the expression levels of ATX, LPA, and MMP-13 in the model group, 10 μmol/L PF-8380 group, and 1 μmol/L PF-8380 group decreased in order; the expression levels of ATX, LPA, and MMP-13 in the model group, 1 μmol/L Ki16425 group, and 10 μmol/L Ki16425 group decreased in order.ConclusionInhibiting ATX-LPA pathway may inhibit the up-regulation of MMP-13 levels in articular cartilage of osteoarthritis in rats to reduce the damage of cartilage.
ObjectiveTo study the hydrophilicity and the cell biocompatibility of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) coated with a fusion protein polyhydroxyalkanoates granule binding protein (PhaP) fused with Arg-Gly-Asp (RGD) peptide (PhaP-RGD). MethodsPHBV and PHBHHx films were fabricated by solvent evaporation.Scanning electronic microscope (SEM) was used to study the morphology of the films.PhaP-RGD fusion proteins were expressed and purified by the technology of protein engineering; PHBV and PHBHHx films were immersed in the PhaP-RGD with an amount of 3.5 mg/mL protein/per sample respectively.The hydrophilicity of the surface were detected by the contact angle measurements.Septal cartilage cells obtained from human septal cartilage were cultured in vitro.The 2nd passage chondrocytes were incubated on PHBV unmodified with PhaP-RGD in group A1,PHBV modified with PhaP-RGD in group A2,PHBHHx unmodified with PhaP-RGD in group B1,PHBHHx modified with PhaP-RGD in group B2,and on the cell culture plates in group C.After cultured for 3 days,the proliferation of cells was detected by the DAPI staining; the proliferation viability of cells was detected by the MTT assay after cultured for 3 and 7 days; after cultured for 7 days,the adhesion and morphology of the cells on the surface of the biomaterial films were observed by SEM and the matrix of the cells was detected through the toluidine blue staining. ResultsSEM observation showed that PHBV and PHBHHx films had porous structures.The contact angle of the surface of the PHBV and PHBHHx films modified with PhaP-RGD fusion proteins were significantly reduced when compared with the films unmodified with PhaP-RGD fusion proteins (P<0.05).Chondrocytes of human nasal septal cartilage incubated on the films could grow in all groups.After 3 days of cultivation in vitro,the cell proliferation and viability of group B2 were the strongest among all groups (P<0.05); the cell proliferation after cultured for 7 days was significantly stronger than that after cultured for 3 days in groups A1,A2,B1,and B2 (P<0.05); and the cell proliferation was significantly stronger in groups B1 and B2 than groups A1,A2 and C,in group B2 than group B1,and in group A1 than group A2 (P<0.05).The results of toluidine blue staining showed that blue metachromasia matrixes were observed in groups A1,A2,B1,and B2; group A1 and group A2 had similar staining degree,and the staining of group B2 was deeper than that of group B1.The adhesion of cells in all groups was good through SEM observation; and the connection of cells formed and stretched into the pores of the materials. ConclusionThe biomaterial films of PHBHHx modified with PhaP-RGD fusion protein can promote its biocompatibility with chondrocytes.
Objective To develop a scaffold material containing collagen Ⅰ and sodium hyaluronate for the cartilage tissue engineering and to evaluate its biocompatibility by using the rabbit chondrocytes derived from amandibular condylar process. Methods The porous matrices containing collagen Ⅰ and sodium hyaluronate were fabricated by the freezedrying technique and were crosslinked by using 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide (EDC). The microstructure of the scaffold was observed under thescanning electron microscope (SEM), and the enzymatic degradation test was performed to compare the ability of the scaffold resistance to collagenase before and after the crosslinking. The chondrocytes from the rabbits’ condylar process were isolated and cultured before they were seeded into the scaffold, and cell attachment and proliferation were measured by the cell count 1, 3, 5, 7 and 10 daysafter the cell being seeded; then, the biocompatibility of the scaffold was evaluated by the light microscopic examination, histological examination, and the SEM exmination. Results The porous structure of the scaffold facilitated the penetration and attachment of the seeded cells. The porosity was 83.7% and the pore size was 100-120 μm. The cell number increased from 3.7×104 per scaffold 1 day after the cell being seeded to 8.2×104 per scaffold 10 days after the cell being seeded. The crosslinking treatment could significantly enhance the scaffold resistance to the collagenase activity. The examinations under the light microscope and SEM indicated that the chondrocyte adhered and spread well on the scaffold, and the extracellular matrices were also observed around the chondrocytes. Conclusion The porous scaffold composed of collagen Ⅰ and hyaluronan has anappropriate structure and a good biocompatibility for the attachment and proliferation of the chondrocytes, which can facilitate it to become a useful scaffold in the cartilage tissue engineering.