Objective To explore the preparing methods in vitro and test the cl inical appl icabil ity of implantation in vivo of bone marrow stromal stem cells (BMSCs)-biphasic scaffold to repair defects of cartilage and subchondral bone and tocompare the differences in repaired outcomes of composite, single biphasic scaffold and rabbits themselves. Methods The upper chondral phase and the lower osseous phase of the plugs, using poly-lactic-co-glycol ic acid (PLGA), hydroxyapatite (HA), and other biomaterials, were fused into carrier scaffold, on which collagen type I (Col I) was coated. The surface and inner structure of bi phasic scaffold were observed under scanning electron microscope (SEM). BMSCs was isolated from the bone marrow of tibia and femurs of young New Zealand rabbits using centrifuging and washing, and their morphologies and adherences were observed everyday. Then BMSCs were inoculated on the surface of scaffold to form BMSCs-scaffold composites. Osteochondral defects were surgically created on articular surface of femoral intercondyles of 30 New Zealand rabbits, which were divided into groups A, B and C. In group A, a bi phasic osteochondral composite were implanted into defect, BMSCs and biphasic cyl indrical porous plug of PLGA-HA-Col I in group B, and group C was used as a control without implant. Specimens were harvested to make macroscopic and histological observations at the 1st, 3rd, 6th, and 9th months after operation respectively; meanwhile immunohistological and micro-computed tomography (micro CT) examinations were performed and graded at the 9th month after operation. Results SEM showed an excellent connection of holes in the biphasic scaffold infiltrated by Col I. Optical microscopy and SEM showed a good growth of BMSCs in scaffold without obvious cellular morphological changes and an accumulation in the holes. Macroscopic samples showed a resistant existence of defects of group C within 9 months; the scaffold completely degenerated and chondral-l ike tissue formed on articular surface with partly collapses and irregular defects in group A; and smoother surface without collapses and approach to normal with texture of new regeneration in group B. There were statistically significant differences in macroscopic results (P lt; 0.001), group B was superior to group A, and group C was the worst. The micro CT showed good repairs and reconstruction of subchondral bone, with a acceptable integration with newborn chondral-l ike tissue and host bone in group B. Quantificational analysis of relevantparameters showed no significant differences. Histological results showed inflammations located in defects at the 1st month, new tissue grew into scaffold at the 3rd month; new chondral-l ike tissue crept on the margin of defects and biphasic scaffold degenerated completely at the 6th month, and lots of collagen formed in subchondral bone with major fibrocartilage on chondralarea at the 9th month after surgery in groups A and B. In groups A and B, immunohistological observations were weak positive for Col II and positive for Col I. Conclusion Biphasic scaffold implanted in body can induce and accelerate repair of defects of articular cartilages which are mainly filled with fibrocartilage, especially for subchondral bone. Scaffold combined with BMSCs has the best repairing effects 9 months after implantation.
Objective To study repair of osteochondral defects by using composite of autologous BMSCs and chitosan/HAP (CS/HAP) bilayered scaffold in rabbits and its feasibil ity as osteochondral tissue engineering scaffolds. Methods CS/HAP bilayered scaffolds were produced with CS and HAP using a lyophil ization and sintering method. The pore size of the scaffold was observed by scanning electron microscopy (SEM). Anhydrous ethanol substitution method determined its porosity. BMSCs were isolated from bone marrow and cultured by general bone marrow methods. Both CD44 and CD45 on the BMSCs surface were detected with immunocytochemistry to identify BMSCs. Cell-scaffold complex was made with BMSCs as seed cells and CS/HAP bilayered scaffold as carrier by fibrin glue planting technique. The distribution ofBMSCs in CS/HAP scaffold was tested by SEM. The osteochondral defect (4 mm in diameter and 3 mm in height) model was made in the right knee joint of 36 Japanese white rabbits, which were randomly divided into 3 groups. Defects were repaired with CS/HAP and BMSCs composite ( group A, n=12) and with CS/HAP implants (group B, n=12); defects were not treated as a control (group C, n=12). Histological evaluation and gross observation were carried out at 6 weeks (n=6 in each group) and 12 weeks (n=6 in each group) postoperatively. Semi-quantitative histomorphological analysis was done to evaluate the repair cartilage tissue according to the modified Wakitani grading scale. Results CS/HAP bilayered scaffold possessed a porosity of 76.00% ± 5.01% and pore size of 200-400 μm (mean 300 μm ) in CS layer, and 72.00% ± 4.23% and 200-500 μm (mean 350 μm) in HAP layer, respectively. BMSCs formed colonies within 10-14 days. Immunocytochemistry results showed BMSCs had positive CD44 expression and negative CD45 expression. At 6 and 12 weeks after operation, gross and histological observation showed that the cartilage defects were fully filled with regenerated tissue, but bone defects were partially repaired in group A; the cartilage and bone defects were partially filled with regenerated tissue in group B and group C. The modified Wakitani grading scale were 5.17 ± 1.17 and 3.20 ± 0.75 in group A, 9.00 ± 0.63 and 6.00 ± 0.89 in group B, and 10.00 ± 0.89 and 9.60 ± 0.82 in group C at 6 weeks and 12 weeks postoperatively, respectively; showing significant differences between group A and groups B, C (P lt; 0.05). Conclusion The novel CS/HAP bilayered scaffold possesses porous structure and will possibly become a newbiomaterial of osteochondral tissue engineering.
ccording to the characteristics of periosteum which have a copacity for regrowth of cartilage,free autogenous osteoperiosteal grafts taken from the medial side of the metaphsis of the tibia had beenused to reconstruct the osteochondral defects of the articular surface of the knee joint. The mothod wasillustrated by five cases which included of osteochondritis dissecans, subchondral osteonecrosis and oldfracture of the patella. By the period of 16-26 monthes follow up, using knee function...
ObjectiveTo review the current treatment status of osteochondral defects (OCD) of the knee joint. MethodsRecent literature concerning treatment of OCD of the knee joint was extensively reviewed and summarized. ResultsOCD affect both the articular cartilage and the underlying subchondral bone, whereas OCD caused by different etiologies require various treatments. OCD repair is available by conventional clinical methods or the advanced tissue engineering strategies. Current clinical treatment outcomes remain uncertain; tissue engineering has emerged as a potential option as it can be efficiently applied to regenerate bone, cartilage, and the bone-cartilage interface, as well as effectively restore normal function and mechanical properties of the cartilage and subchondral bone. ConclusionOCD management and repair remain a great challenge in orthopedic surgery, thus cartilage and subchondral bone should be promoted as an interdependent functional unit considering treatment strategies to provide the best solution for the treatment of osteochondral defects.
ObjectiveTo explore the relationship between subchondral bone reconstruction and articular cartilage regeneration in a rabbit model of spontaneous osteochondral repair. MethodsTwenty-four 6-month-old New Zealand white rabbits were included. The osteochondral defects (4 mm in diameter and 3 mm in depth) were created in the trochlear groove of the unilateral femur, which penetrated the subchondral bone without any treatment. The rabbits were sacrificed at 1, 4, 12, and 24 weeks after operation, respectively. The specimens were obtained for macroscopic, histological, and immunohistochemical observations. According to the International Cartilage Repair Society (ICRS) histological scoring, the effect of cartilage repair was assessed. The histomorphometrical parameters of subchondral bone were analyzed by micro-CT scan and reconstruction, and the relationship between cartilage repair and the histomorphometrical parameters of the subchondral bone were also analyzed. ResultsOsteochondral defects could be repaired spontaneously in rabbit model. With time, defect was gradually filled with repaired tissue, subchondral bone plate under the defect region gradually migrated upward. Bone mineral density, bone volume fraction, tissue mineralized density, trabecula number, and trabecula thickness were increased, while trabecula spacing was decreased. Significant difference was found in the other parameters between different time points (P<0.05) except for trabecula thickness between at 4 and 12 weeks after operation (P>0.05). Histological examination showed that fibrous repair was predominant with rare hyaline cartilage. With time, ICRS scores increased gradually, showing significant differences between other time points (P<0.05) except for between at 4 and 12 weeks after operation (P>0.05). Among the histomorphometrical parameters of subchondral bone, the trabecula spacing was negatively correlated with ICRS score (r=-0.584, P=0.039), and the other histomorphometrical parameters were positively correlated with ICRS score (r=0.680-0.891). ConclusionThere is relevant correlation as well as independent process between cartilage regeneration and subchondral bone reconstruction in the rabbit model of spontaneous osteochondral repair, and fast subchondral bone remodeling may adversely affect articular cartilage repair.