Narikazu Toyokawa

Electrospun Synthetic Polymer Scaffold for Cartilage Repair Without Cultured Cells in an Animal Model

PURPOSE The purpose of our study was to explore the possibility that an electrospun bioabsorbable scaffold could be used in the treatment of a full-thickness articular defect without the addition of exogenous cells in a rabbit model. METHODS Two types of poly(D,L-lactide-co-glycolide) (PLG) scaffolds, a solid cylindrical type and a cannulated tubular type, were made with the electrospinning method. Osteochondral defects, 5 mm in diameter and 5 mm in depth, made on the femoral condyles of rabbits were filled with these scaffolds, and the repair process was investigated histologically. RESULTS In the groups in which the defect was filled with the scaffold, fibrous tissue at the articular surface of the scaffold was observed at postoperative week 2. Thereafter cartilage at the articular surface and bone at the subchondral zone were regenerated, and the repaired cartilage was maintained through postoperative week 24. By contrast, the untreated defect was filled with hematoma at postoperative week 2; thereafter regenerated cartilage and bone were observed. However, the surface of the articular cartilage was not regular, and regenerated cartilage was not well organized. The histologic scores of the groups in which the defect was filled with cannulated tubular electrospun PLG scaffolds were significantly higher than those of the untreated defect group at postoperative weeks 12 and 24 (P < .01). CONCLUSIONS The electrospun PLG scaffold could repair a 5-mm osteochondral defect created in the rabbit model without exogenous cultured cells. CLINICAL RELEVANCE The electrospun PLG scaffold could repair full-thickness osteochondral defects. The cannulated type of PLG scaffold has the possibility to lead not only to good regeneration of cartilage but also to easy transplantation by use of a guidewire through the cannulas in the scaffold.

Localization of vascular endothelial growth factor during the early stages of osteochondral regeneration using a bioabsorbable synthetic polymer scaffold.

Vascular endothelial growth factor (VEGF) plays a critical role in chondrogenic differentiation in the growth plate of the epiphysis. This function is necessary for chondrocyte survival in cartilage development. We investigated the localization of VEGF in the osteochondral regeneration process using a bioabsorbable polymer scaffold. Osteochondral defects (5 mm in diameter and 5 mm in depth) were made on the femoral condyle of forty‐eight skeletally mature female Japanese white rabbits. In total, twenty‐four defects were filled with poly(DL‐lactide‐co‐glycolide) scaffolds and the others were left untreated. The regeneration process was investigated macroscopically, histologically, immunohistochemically, and by gene expression analysis. In the early stages of osteochondral regeneration, bone ingrowth was observed in the deep zone of the scaffold with continuous VEGF expression; cartilage regeneration was observed in the superficial zone of the scaffold with decreased VEGF expression. In contrast, when the defect was left untreated, VEGF localization was observed throughout the entire defect area, and cartilage regeneration at the articular surface was delayed. We conclude that decrease in localization of VEGF at the articular surface in the postoperative early stage is closely related to the progression of cartilage regeneration in osteochondral defects.

MYCOBACTERIAL TUBERCULOUS TENOSYNOVITIS OF THE EXTENSOR TENDON OCCURRING AFTER LIVER TRANSPLANTATION: A CASE REPORT

Mycobacterial tuberculous tenosynovitis of the hand is a rare manifestation of extrapulmonary tuberculosis, while mycobacterial tuberculous tenosynovitis of the extensor tendon sheath is extremely rare. We report a case of tuberculous tenosynovitis of the extensor tendon of the finger, occurring in a man receiving immunosuppression following a liver transplantation. Symptoms improved clinically after conservative treatment with anti-tuberculous drugs.

Reconstruction of the elbow joint with extracorporeal irradiated bone graft associated with low intensity pulsed ultrasound in malignant soft tissue tumor

Reconstruction of the joint after curative resection of a malignant tumor, total joint replacement, free-vascularized bone graft, allograft, and extracorporeal irradiated bone autograft have been developed. We report a case in which reconstruction of the elbow joint with extracorporeal irradiated bone graft was carried out and the osteosynthesis site of the graft was treated with low intensity pulsed ultra sound after the operation.