Scaffold With Natural Calcified Cartilage Zone for Osteochondral Defect Repair in Minipigs

Abstract

Background: Long-term outcomes of current clinical interventions for osteochondral defect are less than satisfactory. One possible reason is an ignorance of the interface structure between cartilage and subchondral bone, the calcified cartilage zone (CCZ). However, the importance of natural CCZ in osteochondral defects has not been directly described. Purpose: To explore the feasibility of fabricating trilayer scaffold containing natural CCZ for osteochondral defects and the role of CCZ in the repair process. Study Design: Controlled laboratory study. Methods: The scaffold was prepared by cross-linking lyophilized type II collagen sponge and acellular normal pig subchondral bone with or without natural CCZ. Autologous bone marrow stem cells (BMSCs) of minipig were mixed with type II collagen gel and injected into the cartilage layer of the scaffold before operation. Thirty minipigs were randomly divided into CCZ (n = 10), non-CCZ (n = 10), and blank control (n = 10) groups. An 8 mm–diameter full-thickness osteochondral defect was created on the trochlear surface, and scaffold containing BMSCs was transplanted into the defect according to grouping requirements. At 12 and 24 weeks postoperatively, specimens were assessed by macroscopic observation, magnetic resonance imaging examination, and histological observations (hematoxylin and eosin, Safranin O–fast green, type II collagen immunohistochemical, and Sirius red staining). Semiquantitative cartilage repair scoring was conducted using the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) system and the O’Driscoll repaired cartilage value system. Results: The defects in the blank control and non-CCZ groups were filled with fibrous tissue, while the cartilage layer of the CCZ group was mainly repaired by hyaline cartilage at 24 weeks postoperatively. The superior repair outcome of the CCZ group was confirmed by MOCART and O’Driscoll score. Conclusion: The trilayer scaffold containing natural CCZ obtained the best repair effect compared with the non-CCZ scaffold and the blank control, indicating the importance of the CCZ in osteochondral tissue engineering. Clinical Relevance: This study demonstrates the necessity to reconstruct CCZ in clinical osteochondral defect repair and provides a possible strategy for osteochondral tissue engineering.

Strategy of a cell-derived extracellular matrix for the construction of an osteochondral interlayer

“…[54][55][56] It has been known that the CCL is a transition zone connecting the cartilage and bone parts, mainly containing hypertrophic chondrocytes that transform from chondrocytes and then are calcified to form osteoblasts. 57,58 It is suggested that the D-ECMs derived from osteoblasts, Cho, and HCho should all have a large or small effect on BMSC hypertrophy. Herein, we explored this issue using the D-ECMs derived from these cell origins by culturing a cell sheet on PLLA/Gel fibrous mesh and subsequent decellularization, followed by re-seeding BMSCs onto the D-ECMs to evaluate the extent of BMSC hypertrophy.…”

The Dynamic Feature of Macrophage M1/M2 Imbalance Facilitates the Progression of Non-Traumatic Osteonecrosis of the Femoral Head

“…Slides were allowed to warm to room temperature, then stained with hematoxylin-eosin (HE) and Sirius Red as previously described ( Liu et al, 2017 ; Huang et al, 2021 ). Sections were examined using a BX40 light microscope (Olympus, Feasterville, PA, United States) and photographed at magnifications of ×0.5–20.…”

Recent development in multizonal scaffolds for osteochondral regeneration

“…On the other hand, scaffold-based strategies have been made with their structure, composition, and mechanical and biological properties exquisitely tailored through various chemical modifications such as by incorporating inorganic bioceramics or bioglasses [ 102 , 103 ]. More importantly, a CCL barrier allowing the transportations of oxygen and nutrition while minimizing cell passage can be obtained by both densifying the layer and reducing the pore size [ 98 ].Recent studies on trilayered scaffolds with an intermediate dense layer exhibited not only superior regeneration of hyaline-like cartilage and subchondral bone tissue in vivo [ [104] , [105] , [106] ], but also improved mechanical properties of the neo-formed tissues compared to bilayered scaffolds [ 64 , 104 ].…”

“…Besides these examples of multilayer lyophilization process, lyophilization is often used in combination with other techniques to fabricate MZSs. Huang et al [ 105 ] recently used lyophilization to bond type II collagen sponge and acellular normal pig subchondral bone, where a natural CCZ was included by removing the hyaline cartilage above the CCZ of pig knee. Such prepared scaffold showed a well-integrated morphology with a trilayered structure and exhibited excellent in vivo OC repair in a minipig knee joint defect model.…”