Atsuyuki Inui

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.

Regeneration of rotator cuff tear using electrospun poly(d,l-Lactide-Co-Glycolide) scaffolds in a rabbit model.

PURPOSE The purpose of this study was to evaluate an application of poly(d,l-lactide-co-glycolide) (PLG) scaffold created by electrospinning in a rabbit rotator cuff defect model. METHODS Forty-two Japanese white rabbits were used in this study. Defects of the infraspinatus tendon were created, and the PLG scaffolds were implanted. Contralateral infraspinatus tendons were reattached without creating defects. Histologic analyses were performed 4, 8, and 16 weeks after the operation, and mechanical evaluations were performed 0, 4, 8, and 16 weeks after the operation. RESULTS Scaffold fibers remained without dissolution and spindle-shaped cells were observed inside of the scaffold at 4 weeks postoperatively. At 8 weeks, the PLG scaffold had dissolved and bone formation was observed at the scaffold-bone interface. At 16 weeks, the scaffold-bone interface matured and expression of type II collagen was observed. A statistical difference in ultimate failure load was not seen between the scaffold group and reattachment group or normal tendon after 8 weeks postoperatively. The stiffness in the scaffold group was not significantly different from that in the reattachment group at each time point. However, it was significantly weaker than normal tendon at each time point. CONCLUSIONS Transplantation of cell-free PLG scaffold showed cell migration and type II collagen and proteoglycan expression at the scaffold-bone junction by 16 weeks postoperatively with a sufficient ultimate failure load in a rabbit rotator cuff defect model. CLINICAL RELEVANCE The PLG scaffold could be applied to bridge rotator cuff defects. The results showed that bridging with scaffold can be equivalent to reattachment.

Temporary inductions of matrix metalloprotease‐3 (MMP‐3) expression and cell apoptosis are associated with tendon degeneration or rupture after corticosteroid injection

Corticosteroid injections are widely used to treat enthesopathy and tendinitis, but are also associated with possible side effects, such as tendon degeneration or rupture. However, the mechanism of tendon degeneration or rupture after corticosteroid injection remains controversial. The purpose of this study was to reveal the mechanism of tendon degeneration or rupture after injection of triamcinolone acetonide (TA) or prednisolone (PSL). Forty‐two rats were divided into 3 groups: A normal saline injection group (control group), a TA injection group, and a PSL injection group; the normal saline or corticosteroid was injected around the Achilles tendon. One or 3 weeks after injection, the tendons were subjected to biomechanical testing and histological analysis. At 1 week, the biomechanical strength was significantly lower in the corticosteroid groups. Histological analysis, at 1‐week post‐injection, showed collagen attenuation, increased expression of MMP‐3 and apoptotic cells in the corticosteroid groups. The histological changes and biomechanical weaknesses of the tendon were not seen at 3 weeks. These alterations appeared to be involved in tendon degeneration or rupture after corticosteroid injection.

Application of layered poly (L-lactic acid) cell free scaffold in a rabbit rotator cuff defect model

BackgroundThis study evaluated the application of a layered cell free poly (L-lactic acid) (PLLA) scaffold to regenerate an infraspinatus tendon defect in a rabbit model. We hypothesized that PLLA scaffold without cultivated cells would lead to regeneration of tissue with mechanical properties similar to reattached infraspinatus without tendon defects.MethodsLayered PLLA fabric with a smooth surface on one side and a pile-finished surface on the other side was used. Novel form of layered PLLA scaffold was created by superimposing 2 PLLA fabrics. Defects of the infraspinatus tendon were created in 32 rabbits and the PLLA scaffolds were transplanted, four rabbits were used as normal control. Contralateral infraspinatus tendons were reattached to humeral head without scaffold implantation. Histological and mechanical evaluations were performed at 4, 8, and 16 weeks after operation.ResultsAt 4 weeks postoperatively, cell migration was observed in the interstice of the PLLA fibers. Regenerated tissue was directly connected to the bone composed mainly of type III collagen, at 16 weeks postoperatively. The ultimate failure load increased in a time-dependent manner and no statistical difference was seen between normal infraspinatus tendon and scaffold group at 8 and 16 weeks postoperatively. There were no differences between scaffold group and reattach group at each time of point. The stiffness did not improve significantly in both groups.ConclusionsA novel form of layered PLLA scaffold has the potential to induce cell migration into the scaffold and to bridge the tendon defect with mechanical properties similar to reattached infraspinatus tendon model.

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.

Concurrent Rotator Cuff Tear and Axillary Nerve Palsy Associated with Anterior Dislocation of the Shoulder and Large Glenoid Rim Fracture: A “Terrible Tetrad”

We present a case of concurrent rotator cuff tear and axillary nerve palsy resulting from anterior dislocation of the shoulder and a large glenoid rim fracture—a “terrible tetrad.” A 61-year-old woman fell on her right shoulder. Radiographs showed anterior dislocation of the shoulder with a glenoid rim fracture, and an MRI two months after injury revealed a rotator cuff tear. Upon referral to our hospital, physical and electrophysiological examinations revealed axillary nerve palsy. The axillary nerve palsy was incomplete and recovering, and displacement of the glenoid rim fracture was minimal and already united; therefore, we surgically repaired only the rotator cuff tear three months after injury. The patient recovered satisfactorily following the operation. In patients whose axillary nerve palsy is recovering, surgeons should consider operating on rotator cuff tears in an attempt to prevent rotator cuff degeneration.

Rotator cuff repair using cell sheets derived from human rotator cuff in a rat model

To achieve biological regeneration of tendon‐bone junctions, cell sheets of human rotator‐cuff derived cells were used in a rat rotator cuff injury model. Human rotator‐cuff derived cells were isolated, and cell sheets were made using temperature‐responsive culture plates. Infraspinatus tendons in immunodeficient rats were resected bilaterally at the enthesis. In right shoulders, infraspinatus tendons were repaired by the transosseous method and covered with the cell sheet (sheet group), whereas the left infraspinatus tendons were repaired in the same way without the cell sheet (control group). Histological examinations (safranin‐O and fast green staining, isolectin B4, type II collagen, and human‐specific CD31) and mRNA expression (vascular endothelial growth factor; VEGF, type II collagen; Col2, and tenomodulin; TeM) were analyzed 4 weeks after surgery. Biomechanical tests were performed at 8 weeks. In the sheet group, proteoglycan at the enthesis with more type II collagen and isolectin B4 positive cells were seen compared with in the control group. Human specific CD31‐positive cells were detected only in the sheet group. VEGF and Col2 gene expressions were higher and TeM gene expression was lower in the sheet group than in the control group. In mechanical testing, the sheet group showed a significantly higher ultimate failure load than the control group at 8 weeks. Our results indicated that the rotator‐cuff derived cell sheet could promote cartilage regeneration and angiogenesis at the enthesis, with superior mechanical strength compared with the control. Treatment for rotator cuff injury using cell sheets could be a promising strategy for enthesis of tendon tissue engineering.

Dose- and time-dependent effects of triamcinolone acetonide on human rotator cuff-derived cells

Objectives To investigate the appropriate dose and interval for the administration of triamcinolone acetonide (TA) in treating tendinopathy to avoid adverse effects such as tendon degeneration and rupture. Methods Human rotator cuff-derived cells were cultured using three media: regular medium (control), regular medium with 0.1 mg/mL of TA (low TA group), and with 1.0 mg/mL of TA (high TA group). The cell morphology, apoptosis, and viability were assessed at designated time points. Results In the low TA group, the cells became flattened and polygonal at seven days then returned to normal at 21 days. The cell apoptosis ratio and messenger ribonucleic acid expression of caspase-3, 7, 8, and 9 increased, and viability was reduced in the low and high groups at seven days. In the low TA group, apoptosis and viability returned to normal at 21 days, however, in the high TA group, the cell morphology, apoptosis ratio, caspase-3, 7, 8, and 9 and viability did not return by day 21. Re-administration was performed in the low TA group at 7-, 14-, and 21-day intervals, and cell viability did not return to the control level at the 7- and 14-day intervals. Conclusion A 0.1 mg/mL dose of TA temporarily decreased cell viability and increased cell apoptosis, which was recovered at 21 days, however, 1 mg/mL of TA caused irreversible damage to cell morphology and viability. An interval > three weeks was needed to safely re-administer TA. These findings may help determine the appropriate dose and interval for TA injection therapy. Cite this article: Bone Joint Res 2014;3:328–34.

The effect of platelet-rich plasma on degeneration change of rotator cuff muscles: In vitro and in vivo evaluations†

Atrophy with fatty degeneration is often seen in rotator cuff muscles with torn tendons. PRP has been reported to enhance tissue repair processes after tendon ruptures. However, the effect of PRP on atrophy and fatty degeneration of the muscle is not yet known. The aim of this study is to examine the effect of PRP on degeneration change of rotator cuff muscles in vitro and in vivo. A murine myogenic cell line and a rat rotator cuff tear model were used in this study and PRP was administrated into subacromial space which is widely used in clinical practice. In in vitro study, administration of PRP to C2C12 cells stimulated cell proliferation while inhibited both myogenic and adipogenic differentiation. In in vivo study, administration of PRP suppressed Oil Red‐O positive lipid droplet formation. The expression of adipogenic genes was also decreased by PRP administration. In conclusion, PRP promoted proliferation of myoblast cells, while inhibiting adipogenic differentiation of myoblast cells and suppressing fatty degeneration change in rat torn rotator cuff muscles. Further investigations are needed to determine the clinical applicability of the PRP.

Arthroscopic Rotator Cuff Repair With Graft Augmentation of Fascia Lata for Large and Massive Tears

Excellent clinical results of arthroscopic repair of rotator cuff tears have been reported. However, retears after surgical repair of large and massive rotator cuff tears are one of the most common complications. We present single-row repair with graft augmentation of the fascia lata for large and massive rotator cuff tears to reduce tension at the tendon-bone repair site, and this technique may prevent retears of the repaired rotator cuff. A candidate for this technique is a patient who has a large or massive rotator cuff tear in which the torn edge cannot reach the footprint after mobilization of the torn rotator cuff. This technique could provide an excellent option for irreparable large and massive rotator cuff tears.