2015 ISAKOS Biennial Congress ePoster #409

Comparison of Hydroxyapatite and Beta-Tricalcium Phosphate for Osteochondral Repair Using the Hybrid Implant of Artificial Bone With a Scaffold-Free Tissue Engineered Construct Derived From Mesenchymal Stem Cells

Kazunori Shimomura, MD, PhD, Suita, Osaka JAPAN
Yu Moriguchi, MD, PhD, Suita City, Osaka JAPAN
Wataru Ando, MD, PhD, Suita City, Osaka JAPAN
Kota Koizumi, MD, Suita, Osaka JAPAN
Yukihiko Yasui, MD, Suita, Osaka JAPAN
Ryosuke Nansai, MS, Tokyo JAPAN
Hiromichi Fujie, Hachi-oji, Tokyo JAPAN
Shuji Horibe, MD, PhD, Habikino, Osaka JAPAN
Konsei Shino, MD, PhD, Osaka, Osaka JAPAN
Hideki Yoshikawa, MD, PhD, Suita, Osaka JAPAN
Norimasa Nakamura, MD, PhD, Osaka, Osaka JAPAN

Department of Orthopaedics, Osaka University Graduate School of Medicine, Suita City, Osaka, JAPAN

FDA Status Not Applicable

Summary: A hydroxyapatite-based hybrid implant coupled with a scaffold-free tissue engineered construct derived from synovial mesenchymal stem cells showed a superior osteochondral repair, longer-term durability of subchondral bone and prevention of the degeneration of repair cartilage, compared with a beta-tricalcium phosphate-based hybrid implant.

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Abstract:

For an ideal osteochondral repair, it is important to restore subchondral bone and cartilage layer-by-layer. We have developed a novel hybrid implant made of hydroxyapatite (HA)-based artificial bone coupled with a scaffold-free tissue engineered construct (TEC) derived from synovial mesenchymal stem cells (MSCs), and demonstrated that the hybrid implant significantly improved osteochondral repair in a rabbit osteochondral defect model, which exhibited the formation of hyaline-line cartilage, secure good tissue integration to adjacent host tissue, and advanced repair of subchndral bone. On the other hand, beta-tricalcium phosphate (ßTCP) is highly biocompatible material and is resorbed more rapidly than HA in vivo. Therefore, the use of ßTCP might be advantageous in more efficient subchondral bone remodeling. We hypothesized that a ßTCP-based hybrid implant coupled with synovial MSC derived TEC would show a superior osteochondral repair, compared with a HA-based hybrid implant, and tested this hypothesis using a rabbit osteochondral defect model.

All animals were handled in accordance with a protocol approved by the institutional ethical committee. MSCs were isolated enzymatically from rabbit synovial membranes. The MSCs were cultured at a high density to develop a complex of the cultured cells and the extracellular matrix synthesized by the cells (TEC). TEC was detached from culture dishes just before implanted surgery, and bind to artificial bone (5mm diameter, 4mm deep) of HA or ßTCP without any glue to create the osteochondral hybrid. Under anesthesia, 5mm diameter, 6mm deep osteochondral defect was created on the femoral groove of skeletally mature rabbits. The hybrid implant was then implanted in the defect without suture for 29 right knees (TEC/HA; 18 knees, TEC/ßTCP; 11 knees). Histology was stained with H&E and Toluidine Blue staining, and then histological scores were evaluated by modified O’Driscoll score at 1, 2 and 6 months after surgery.

The osteochodral defect treated with TEC/ßTCP showed rapid subchondral bone repair at 1 month, but the degeneration of repair cartilage was progressed at 6 months. The osteochodral defect treated with TEC/HA showed the delayed subchondral bone repair at 1 month, but similar quality of subchondral bone repair to TEC/ßTCP at 2 months. Notably, the repair osteochondral bone tissue maintained good quality until 6 months. Also, the repaired tissue exhibited good tissue integration to adjacent host tissue in both groups. In the histological scores for cartilage layer, there were no significant differences detected between both groups. The histological scores for subchondral bone layer in TEC/ßTCP group at 1 month showed significantly higher than that in TEC/HA group.

In the present study, the TEC/HA hybrid implant exhibited better histological findings in osteochondral repair than the TEC/ßTCP hybrid implant, contrary to our hypothesis. We demonstrated that the TEC/HA hybrid implant could warrant longer-term durability of subchondral bone and prevent the degeneration of repair cartilage, although the TEC/ßTCP hybrid implant showed an advanced subchondral bone repair at 1 month.