Objective To explore the possibility of constructing tissue engineered cartilage complex three-dimensional nano-scaffold with collagen type II and hyaluronic acid (HA) by electrospinning. Methods The three-dimensional porous nano-scaffolds were prepared by electrospinning techniques with collagen type II and HA (8 ∶ 1, W ∶ W), which was dissolved in mixed solvent of 3-trifluoroethanol and water (1 ∶ 1, V ∶ V). The morphology were observed by light microscope and scanning electron microscope (SEM). And the porosity, water absorption rate, contact angle, and degradation rate were detected. Chondrocytes were harvested from 1-week-old Japanese white rabbit, which was disgested by 0.25% trypsin 30 minutes and 1% collagenase overlight. The passage 2 chondrocytes were seeded on the nano-scaffold. The cell adhesion and proliferation were evaluated by cell counting kit 8 (CCK-8). The cell-scaffold composites were cultured for 2 weeks in vitro, and the biological morphology and extracelluar matrix (ECM) secretion were observed by histological analysis. Results The optimal electrospinning condition of nano-scaffold was 10% electrospinning solution concentration, 10 cm receiver distance, 5 mL/ h spinning injection speed. The scaffold had uniform diameter and good porosity through the light microscope and SEM. The diameter was 300-600 nm, and the porosity was 89.5% ± 25.0%. The contact angle was (35.6 ± 3.4)°, and the water absorption was 1 120% ± 34% at 24 hours, which indicated excellent hydrophilicity. The degradation rate was 42.24% ± 1.51% at 48 days. CCK-8 results showed that the adhesive rate of cells with scaffold was 169.14% ± 11.26% at 12 hours, and the cell survival rate was 126.03% ± 4.54% at 7 days. The histological and immunohistochemical staining results showed that the chondrocytes could grow well on the scaffold and secreted ECM. And the similar cartilage lacuma structure could be found at 2 weeks after co-culture, which suggested that hyaline cartilage formed. Conclusion The collage type II and HA complex three-dimensional nano-scaffold has good physicochemical properties and excellent biocompatibility, so it can be used as a tissue engineered cartilage scaffold.
Objective To explore heterotopic chondrogenesis of canine myoblasts induced by cartilage-derived morphogenetic protein 2 (CDMP-2) and transforming growth factor β1 (TGF-β1) which were seeded on poly (lactide-co-glycolide) (PLGA) scaffolds after implantation in a subcutaneous pocket of nude mice. Methods Myoblasts from rectus femoris of 1-year-old Beagle were seeded on PLGA scaffolds and cultured in medium containing CDMP-2 and TGF-β1 for 2 weeks in vitro. Then induced myoblasts-PLGA scaffold, uninduced myoblasts-PLGA scaffold, CDMP-2 and TGF-β1-PLGA scaffold, and simple PLGA scaffold were implanted into 4 zygomorphic back subcutaneous pockets of 24 nude mice in groups A, B, C, and D, respectively. At 8 and 12 weeks, the samples were harvested for general observation, HE staining and toluidine blue staining, immunohistochemical staining for collagen type I and collagen type II; the mRNA expressions of collagen type I, collagen type II, Aggrecan, and Sox9 were determined by RT-PCR, the glycosaminoglycans (GAG) content by Alician blue staining, and the compressive elastic modulus by biomechanics. Results In group A, cartilaginoid tissue was milky white with smooth surface and slight elasticity at 8 weeks, and had similar appearance and elasticity to normal cartilage tissue at 12 weeks. In group B, few residual tissue remained at 8 weeks, and was completely degraded at 12 weeks. In groups C and D, the implants disappeared at 8 weeks. HE staining showed that mature cartilage lacuna formed of group A at 8 and 12 weeks; no cartilage lacuna formed in group B at 8 weeks. Toluidine blue staining confirmed that new cartilage cells were oval and arranged in line, with lacuna and blue-staining positive cytoplasm and extracellular matrix in group A at 8 and 12 weeks; no blue metachromatic extracellular matrix was seen in group B at 8 weeks. Collagen type I and collagen type II expressed positively in group A, did not expressed in group B by immunohistochemical staining. At 8 weeks, the mRNA expressions of collagen type I, collagen type II, Aggrecan, and Sox9 were detected by RT-PCR in group A at 8 and 12 weeks, but negative results were shown in group B. The compressive elastic modulus and GAG content of group A were (90.79 ± 1.78) MPa and (10.20 ± 1.07) μg/mL respectively at 12 weeks, showing significant differences when compared with normal meniscus (P lt; 0.05). Conclusion Induced myoblasts-PLGA scaffolds can stably express chondrogenic phenotype in a heterotopic model of cartilage transplantation and represent a suitable tool for tissue engineering of menisci.
Objective To investigate the effect of allogeneic chondrocytes-calcium alginate gel composite under the intervention of low intensive pulsed ultrasound (LIPUS) for repairing rabbit articular cartilage defects. Methods Bilateral knee articular cartilage were harvested from 8 2-week-old New Zealand white rabbits to separate the chondrocytes by mechanical-collagen type II enzyme digestion. The 3rd passage chondrocytes were diluted by 1.2% sodium alginate to 5 × 106 cells/mL, then mixed with CaCl2 solution to prepare chondrocytes-calcium alginate gel composite, which was treated with LIPUS for 3 days (F0: 1 MHz; PRF: 1 kHz; Amp: 60 mW/cm2; Cycle: 50; Time: 20 minutes). An articular cartilage defect of 3 mm in diameter and 3 mm in thickness was established in both knees of 18 New Zealand white rabbits (aged 28-35 weeks; weighing, 2.1-2.8 kg), and divided into 3 groups randomly, 6 rabbits in each group: LIPUS group, common group, and model group. Defect was repaired with LIPUS-intervention gel composite, non LIPUS-intervention gel composite in LIPUS group and common group, respectively; defect was not treated in the model group. The general condition of rabbits was observed after operation. The repair effect was evaluated by gross and histological observations, immunohistochemical staining, and Wakitani score at 8 and 12 weeks after operation. Results Defect was filled with hyaline chondroid tissue and white chondroid tissue in LIPUS and common groups, respectively. LIPUS group was better than common group in the surface smooth degree and the degree of integration with surrounding tissue. Defect was repaired slowly, and the new tissue had poor elasticity in model group. Histological observation and Wakitani score showed that LIPUS group had better repair than common group at 8 and 12 weeks after operation; the repair effect of the 2 groups was significantly better than that of model group (P lt; 0.05); and significant differences in repair effect were found between at 8 and 12 weeks in LIPUS and common groups (P lt; 0.05). The collagen type II positive expression area and absorbance (A) value of LIPUS and common groups were significantly higher than those of model group (P lt; 0.05) at 8 and 12 weeks after operation, and the expression of LIPUS group was superior to that of common group at 12 weeks (P lt; 0.05); and significant differences were found between at 8 and 12 weeks in LIPUS group (P lt; 0.05), but no significant difference between 2 time points in common and model groups (P gt; 0.05). Conclusion Allogeneic chondrocytes-calcium alginate gel composite can effectively repair articular cartilage defect. The effect of LIPUS optimized allogeneic chondrocytes-calcium alginate gel composite is better.
【Abstract】 Objective The seed cells source is a research focus in tissue engineered cartilage. To observe whether the post-RNA interference (RNAi) chondrocytes could be used as the seed cells of tissue engineered cartilage. Methods Chondrocytes were separated from Sprague Dawley rats. The first passage chondrocytes were used and divided into 2 groups: normal chondrocytes (control group) and post-RNAi (experimental group). Normal and post-RNAi chondrocytes were seeded into chitosan/gelatin material and cultured in vitro to prepare tissue engineered cartilage. The contents of Aggrecan and Aggrecanase-1, 2 were measured by HE and Masson staining, scanning electron microscope (SEM), and RT-PCR. Results The histological results: no obvious difference was observed in cell number and extracellular matrix (ECM) between 2 groups at 2 weeks; when compared with control group, the secretion of ECM and the cell number increased in experimental group with time. The RT-PCR results: the expression of Aggrecan mRNA in experimental group was significantly higher than that in control group (P lt; 0.05); but the expressions of Aggrecanase-1, 2 mRNA in experimental group were significantly lower than those in control group (P lt; 0.05). The SEM results: the cell number in experimental group was obviously more than that in control group, and the cells in experimental group were conjugated closely. Conclusion The post-RNAi chondrocytes can be used as the seed cells for tissue engineered cartilage, which can secrete more Aggrecan than normal chondrocytes. But their biological activities need studying further.
Objective To study the effect of platelet lysate (PL) on chondrogenic differentiation of human umbil ical cord derived mesenchymal stem cells (hUCMSCs) in vitro. Methods Umbil ical cords were voluntarily donated by healthy mothers. The hUCMSCs were isolated by collagenase digestion and cultured in vitro. The surface markers of the cells were detected by flow cytometer. According to different components of inductive medium, the cultured hUCMSCs were divided into 3 groups: group A [H-DMEM medium, 10% fetal bovine serum (FBS), and 10%PL]; group B [H-DMEM medium, 10%FBS,10 ng/mL transforming growth factor β1 (TGF-β1), 1 × 10-7 mol/L dexamethasone, 50 μg/mL Vitamin C, and 1% insul intransferrin- selenium (ITS)]; and group C (H-DMEM medium, 10%FBS, 10 ng/mL TGF-β1, 1 × 10-7mol/L dexamethasone, 50 μg/ mL vitamin C, 1%ITS, and 10%PL). The hUCMSCs were induced in the mediums for 2 weeks. Toluidine blue staining was used to detect the secretion of chondrocyte matrix. Immunofluorescence method was used to identify the existence of collagen trpe II. The expressions of Aggrecan and collagen type II were detected by semiquantitative RT-PCR. Results Flow cytometer results showed that the hUCMSCs did not express the surface markers of hematopoietic cell CD34, CD45, and human leukocyte antigen DR, but expressed the surface markers of adhesion molecule and mesenchymal stem cells CD44, CD105, and CD146. Toluidine blue staining and immunofluorescence showed positive results in group C, weak positive results in group B, and negative results in group A. Semiquantitative RT-PCR showed the expressions of Aggrecan and collagen type II at mRNA level in groups B and C, but no expression in group A. The mRNA expressions of Aggrecan and collagen type II were higher in group C than in group B (P lt; 0.05). Conclusion Only 10%PL can not induce differentiation of hUCMSCs into chondrocytes, but it can be a supplement to the induced mediums. PL can improve hUCMSCs differentiating into chondrocytes obviously in vitro. This study provides new available conditions for constructing tissue engineered cartilage.
Objective Mechanical stimulation and inductive factors are both crucial aspects in tissue engineered cartilage. To evaluate the effects of mechanical stimulation combined with inductive factors on the differentiation of tissue engineered cartilage. Methods Bone marrow mesenchymal stem cells (BMSCs) were isolated from newborn porcine (aged7 days and weighing 3-6 kg) and expanded in vitro. The BMSCs at passage 2 were seeded onto a scaffold of poly (lactic-coglycol ic acid) (PLGA) in the concentration of 5 × 107/mL to prepare cell-scaffold composite. Cell-scaffold composites were cultivated in a medium with chondrocyte-inducted factors (group A), in a vessel with mechanic stimulating only (group B), or mechanic stimulating combined with chondrocyte-inducted factors (group C) (parameters of mechanics: 1 Hz, 0.5 MPa, and 4 hours/day). Cell-scaffold composite and auto-cartilage served as positive control (group D) and negative control (group E), respectively. After 4 weeks of cultivation, the thickness, elastic modulus, and glycosaminoglycan (GAG) content of composites were measured. Additionally, BMSCs chondrogenic differentiation was assessed via real-time fluorescent quantitative PCR, immunohistochemistry, and histological staining. Results The thickness, elastic modulus, and maximum load in group C were significantly higher than those in groups A and B (P lt; 0.05). In groups A, B, and C, cartilage lacuna formation, GAG expression, and positive results for collagen type II were obsersed through HE staining, Safranin-O staining, and immunohistochemistry staining. The dyeing depth was deeper in group A than in group B, and in group C than in groups A and B; group C was close to group E. The GAG content in group C was significantly higher than that in groups A and B (P lt; 0.05). Real-time fluorescent quantitative PCR revealed that mRNA expressions of collagen type I, collagen type II, and GAG in group C were significantly higher than those in groups A and B (P lt; 0.05), and in group A than in group B (P lt; 0.05). Conclusion Mechanical stimulation combined with chondrocyte inductive factors can enhance the mechanical properties of the composite and induce higher expression of collagen and GAG of BMSCs.
Objective To explore the effect of tissue engineered cartilage reconstructed by using sodium alginate hydrogel and SIS complex as scaffold material and chondrocyte as seed cell on the repair of full-thickness articular cartilage defects. Methods SIS was prepared by custom-made machine and detergent-enzyme treatment. Full-thickness articularcartilage of loading surface of the humeral head and the femoral condyle obtained from 8 New Zealand white rabbits (2-3weeks old) was used to culture chondrocytes in vitro. Rabbit chondrocytes at passage 4 cultured by conventional multipl ication method were diluted by sodium alginate to (5-7) × 107 cells/mL, and then were coated on SIS to prepare chondrocyte-sodium alginate hydrogel-SIS complex. Forty 6-month-old clean grade New Zealand white rabbits weighing 3.0-3.5 kg were randomized into two groups according to different operative methods (n=20 rabbits per group), and full-thickness cartilage defect model of the unilateral knee joint (right or left) was establ ished in every rabbit. In experimental group, the complex was implanted into the defect layer by layer to construct tissue engineered cartilage, and SIS membrane was coated on the surface to fill the defect completely. While in control group, the cartilage defect was filled by sodium alginate hydrogel and was sutured after being coated with SIS membrane without seeding of chondrocyte. General condition of the rabbits after operation was observed. The rabbits in two groups were killed 1, 3, 5, 7, and 9 months after operation, and underwent gross and histology observation. Results Eight rabbits were excluded due to anesthesia death, wound infection and diarrhea death. Sixteen rabbits per group were included in the experiment, and 3, 3, 3, 3, and 4 rabbits from each group were randomly selected and killed 1, 3, 5, 7, and 9 months after operation, respectively. Gross observation and histology Masson trichrome staining: in the experimental group, SIS on the surface of the implant was fused with the host tissue, and the inferface between them disappeared 1 month after operation; part of the implant was chondrified and the interface between the implant and the host tissue was fused 3 months after operation; the implant turned into fibrocartilage 5 months after operation; fiber arrangement of the cartilage in theimplant was close to that of the host tissue 7 months after operation; cartilage fiber in the implant arranged disorderly andactive cell metabol ism and prol iferation were evident 9 months after operation. While in the control group, no repair of thedefect was observed 9 months after operation. No obvious repair was evident in the defects of the control group within 9months after operation. Histomorphometric evaluation demonstrated that the staining intensity per unit area of the reparative tissue in the defect of the experimental group was significant higher than that of the control group at each time point (P lt; 0.05), the chondrification in the experimental group was increased gradually within 3, 5, and 7 months after operation (P lt; 0.05), and it was decreased 9 months after operation comparing with the value at 7 months after operation (P lt; 0.05). Conclusion Constructed by chondrocyte-sodium alginate hydrogel-SIS in complex with surficial suturing of SIS membrane, the tissue engineered cartilage can in-situ repair cartilage defect, promote the regeneration of cartilage tissue, and is in l ine with physiological repair process of articular cartilage.
【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.
【Abstract】 Objective To investigate the possibil ity of BMSCs seeded into collagen Ⅰ -glycosaminoglycan (CG)matrices to form the tissue engineered cartilage through chondrocyte inducing culture. Methods Bone marrow aspirate of dogs was cultured and expanded to the 3rd passage. BMSCs were harvested and seeded into the dehydrothemal treatment (DHT)cross-l inked CG matrices at 1×106 cells per 9 mm diameter sample. The samples were divided into experimental group and control group. In the experimental group, chondrogenic differentiation was achieved by the induction media for 2 weeks. Medium was changed every other day in both experimental group and control group. The formation of cartilage was assessed by HE staining and collagen Ⅱ immunohistochemical staining. Results The examinations under the inverted phase contrast microscopeindicated the 2nd and 3nd passage BMSCs had the similar morphology. HE staining showed the BMSCs in the experimental group appeared polygon or irregular morphology in the CG matrices, while BMSCs in the control group appeared fibroblast-l ike spindle or round morphology in the CG matrices. Extracellular matrix could be found around cells in the experimental group. Two weeks after seeded, the cells grew in the CG matrices, and positive collagen Ⅱ staining appeared around the cells in the experimentalgroup. There was no positive collagen Ⅱ staining appeared in the control group. Conclusion It is demonstrated that BMSCs seeded CG matrices can be induced toward cartilage by induction media.
To study how to repair the cartilage defect according to the principles of tissue engineering with acellular cartilage matrix as scaffold material. Methods The ear cartilage was obtained from a New Zealand white rabbit(weighing 2.4 kg )and then treated by a modified Courtman’s four-step method to produce the acellular cartilage matrix. Eighteen New Zealand white rabbits (aged 6 months, weighing 2.4-2.6 kg) with no sex l imit were divided into three groups. Forevery rabbit, two pieces of ear cartilage measured 1 cm × 1 cm were excised in each ear. Defects were repaired as follows: group A with the combined graft of acellular cartilage matrix and perichondium, group B with acellular cartilage matrix and group C with perichondium. Three animals in each group were killed 4 and 12 weeks postoperatively, respectively. Tissue samples obtained were analyzed with gross observation, hematoxyl in-eosin stain, Safranine O-alcian blue stain and type II collagen messenger RNA in situ hybridization respectively. Results In gross observation, the repaired sites in groups A and B were not change meaningfully in their shape 4 weeks postoperatively; but they felt a bit of thicker and harder 12 weeks postoperatively. In group C two repaired sites formed scabs at 2 weeks and perforated at 5 weeks. In histological observation, there was a sl ight inflammatory reaction surrounding the acellular cartilage matrix 4 weeks after it was implanted in groups A and B. The inflammatory cells were mainly lymphocytes. The perichondrium graft in group C was collapsed in the defects in HE stain. The defect sites were negative for Safranine O-alcian blue stain and type II collagen mRNA in situ hybridization in all groups. At 12 weeks cells were found in the acellular matrix which arranged in irregular manner in group A in HE stain and was positive for Safranine O-alcian blue stain and type II collagen mRNA in site hybridization. In groups B and C, no new cell was found in HE stain and the repaired sites were negative for Safranine O-alcian blue stain and type II collagen mRNA in situ hybridization. Conclusion Acellular