Naohiro Sawaguchi

Application of Tissue Engineering Techniques for Rotator Cuff Regeneration Using a Chitosan-Based Hyaluronan Hybrid Fiber Scaffold

Background The current surgical procedures for irreparable rotator cuff tears have considerable limitations. Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing these conditions. Hypothesis A chitosan-based hyaluronan hybrid scaffold could enhance type I collagen products with seeded fibroblasts and thereby increase the mechanical strength of regenerated tendon in vivo. Study Design Controlled laboratory study. Methods The scaffolds were created from chitosan-based hyaluronan hybrid polymer fibers. Forty-eight rabbit infraspinatus tendons and their humeral insertions were removed to create defects. Each defect was covered with a fibroblast-seeded scaffold (n = 16) or a non-fibroblast-seeded scaffold (n = 16). In the other 16 shoulders, the rotator cuff defect was left free as the control. At 4 and 12 weeks after surgery, the engineered tendons were assessed by histological, immunohistochemical (n = 2), and biomechanical (n = 6) analyses. Results Type I collagen was only seen in the fibroblast-seeded scaffold and increased in the regenerated tissue. The tensile strength and tangent modulus in the fibroblast-seeded scaffold were significantly improved from 4 to 12 weeks postoperatively. The fibroblast-seeded scaffold had a significantly greater tangent modulus than did the non-fibroblast-seeded scaffold and the control at 12 weeks. Conclusion This scaffold material enhanced the production of type I collagen and led to improved mechanical strength in the regenerated tissues of the rotator cuff in vivo. Clinical Relevance Rotator cuff regeneration is feasible using this tissue engineering technique.

Mobile-bearing total knee arthroplasty improves patellar tracking and patellofemoral contact stress: in vivo measurements in the same patients.

Controversies exist in clinical study concerning the effect of rotating platform on patellar tracking. The aim of this in vivo study was to compare tibial rotation, patellar tracking, and patellofemoral contact stress in mobile and fixed-bearing platform intraoperatively in the same knee. Sixty-six knees of posterior-stabilized total knee prostheses were evaluated using a computed tomography-guided navigation system. Medial shift and lateral tilt of patella were significantly smaller in mobile knee. Averaged maximum contact stress was significantly smaller in mobile knee than fixed knee. However, tibial rotation during flexion has no significant difference. This study showed that mobile platform total knee arthroplasty significantly improved patellar tracking and decreased patellofemoral contact stress.

Risk of Deep Venous Thrombosis in Drain Clamping With Tranexamic Acid and Carbazochrome Sodium Sulfonate Hydrate in Total Knee Arthroplasty

The aim of this randomized prospective study was to clarify risks associated with a drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate after total knee arthroplasty (TKA). Subjects comprised 100 patients scheduled to undergo TKA, randomized into 2 groups: 50 patients received the drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate and 50 patients received drain-clamping with saline. Although bleeding volume was significantly lower in the group with tranexamic acid and carbazochrome sodium sulfonate hydrate, risk of asymptomatic deep venous thrombosis as detected by ultrasonography was comparable between groups. Tranexamic acid and carbazochrome sodium sulfonate hydrate in the drain-clamping method help reduce bleeding after TKA without increasing the risk of deep venous thrombosis.

Effect of cyclic three-dimensional strain on cell proliferation and collagen synthesis of fibroblast-seeded chitosan-hyaluronan hybrid polymer fiber

BackgroundTissue engineering techniques using biodegradable three-dimensional (3D) scaffolds with cultured cells offer more potential alternatives for the treatment of severe ligament and tendon injuries. In tissue engineering, one of the crucial roles of 3D scaffolds is to provide a temporary template with the biomechanical characteristics of the native extracellular matrix (ECM) until the regenerated tissue matures. The purpose of the present study was to assess the effect of various cyclic mechanical stresses on cell proliferation and ECM production in a 3D scaffold made from chitosan and hyaluronan for ligament and tendon tissue engineering.MethodsThree-dimensional scaffolds seeded with rabbit patella tendon fibroblasts were attached to a bioreactor under various conditions: static group, no strain; stretch group, tensile strain; rotational group, rotational strain; combined group, rotational and tensile strain. In the Static group, 3 weeks of stationary culture was performed. In the remaining three groups, a loading regimen of 0.5 Hz for 18 h and then 6 h rest was carried out for 2 weeks after 1 week of static culture. The DNA content was determined to quantify cell proliferation. Real-time reverse transcription polymerase chain reaction analysis was performed to assess the mRNA levels of the ECM products.ResultsDNA content of the combined group was significantly higher than that of the static and stretch groups, and that of the rotational group was significant higher than that of the static and stretch groups at 21 days after cultivation. The mRNA level of types I and III collagen and fibromodulin in the combined group was significantly higher than that in the other three groups. The amount of collagen synthesis in the combined group was higher than that in the static group, but the difference was not significant.ConclusionsMultidimensional cyclic mechanical strain to mimic the physiological condition in vivo has the potential to improve or accelerate tissue regeneration in ligament and tendon tissue engineering using 3D scaffolds in vitro.

Biomechanical and histologic evaluation of tissue engineered ligaments using chitosan and hyaluronan hybrid polymer fibers: a rabbit medial collateral ligament reconstruction model.

In this study, we used a rabbit medial collateral ligament reconstruction model to evaluate a novel chitosan-based hyaluronan hybrid polymer fiber scaffold for ligament tissue engineering and to examine whether mechanical forces exerted in an in vivo model increased extracellular matrix production by seeded fibroblasts. Scaffolds were used 2 weeks after incubation with fibroblasts obtained from the same rabbit in a cell-seeded scaffold (CSS) group and without cells in a noncell-seeded scaffold (NCSS) group. At 3, 6, and 12 weeks after surgery, the failure loads of the engineered ligaments in the CSS groups were significantly greater than those in the NCSS groups. At 6 weeks after surgery, the reconstructed tissue of the CSS group was positive for type I collagen, whereas that in the NCSS group was negative for type I collagen. At 12 weeks after surgery, the reconstructed tissue stained positive for type I collagen in the CSS group, but negative in the NCSS group. Our results indicate that the scaffold material enhanced the production of type I collagen and led to improved mechanical strength in the engineered ligament in vivo.

Local Upregulation of Stromal Cell–Derived Factor-1 After Ligament Injuries Enhances Homing Rate of Bone Marrow Stromal Cells in Rats

In the present study the local expression of stromal cell-derived factor-1 (SDF-1) after ligament injury and correlated change in the homing rate of systemically induced bone marrow stromal cells (BMSCs) to the injured site were clarified using a rat medial collateral ligament (MCL) injury model. SDF-1 was temporarily upregulated peaking at 2 weeks after injury. Correlated with the alteration in SDF-1 expression, the homing rate of systemically induced BMSCs was temporarily upregulated peaking at 2-4 weeks after injury. The SDF-1 expression in the MCL seems to play a crucial role in cell homing. In addition, SDF-1 did not influence the BMSCs behavior in vitro in terms of the proliferation, adhesivity, and expression of ligament fibroblast markers. The cell-based therapy for ligament and tendon injury with reference to local expression of SDF-1 may be one of the available applications.

Extracellular Matrix Modulates Expression of Cell-Surface Proteoglycan Genes in Fibroblasts

Cell-surface proteoglycans are involved in many functions, including interactions with components of the extracellular microenvironment. They also act as coreceptors that bind and modify the actions of various growth factors, cytokines, and the extracellular matrix (ECM). This study investigated the regulation by the ECM of the expression of cell-surface proteoglycans (CD44, syndecan-1–4, betaglycan, glypican-1). We examined the changes in the expression levels of cell-surface proteoglycan genes in intact tendon, monolayer culture, and under various culture conditions. There was a significant increase in the expression of CD44 and syndecan-4 mRNAs during cell isolation from the tendon. With the switch to a 3D culture environment, there was a significant increase in the expression of CD44 at each passage point relative to its expression in 2D at those passage points. Syndecan-4 mRNA also increased steadily at each passage point in 3D culture environment. This influence on cell surface proteoglycans gene expression may indicate that collagen gel culture mimics in vivo tendon environment. This study provides further insight into the regulation of cell-surface proteoglycans in ligament and tendon fibroblasts by the ECM and 3D culture conditions.

Patella Eversion Reduces Early Knee Range of Motion and Muscle Torque Recovery after Total Knee Arthroplasty: Comparison between Minimally Invasive Total Knee Arthroplasty and Conventional Total Knee Arthroplasty

We hypothesized that patella eversion during total knee arthroplasty (TKA) reduces early return of active knee extension and flexion, quadriceps muscle strength, and postoperative pain. In 100 conventional TKA knees and 100 minimally invasive TKA (MIS TKA) knees, we compared knee range of motion (ROM), postoperative pain, and quadriceps muscle strength at 1 day, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 12 weeks, 1 year, and 5 years after surgery. The differences of surgical approach between MIS TKA and conventional TKA of this study are length of skin incision with subcutaneal flap and patella eversion. In MIS TKA, skin incision is shorter than conventional TKA. Furthermore, patella is not everted in MIS TKA procedure. There were no significant differences in preoperative factors. Postoperative improvement of ROM, postoperative muscle strength recovery, and postoperative improvement of visual analog scale were faster in patients with MIS TKA when compared to that in patients with conventional TKA. On the other hand, no significant difference was observed in complication, 5-year clinical results of subjective knee function score, and the postoperative component angle and lower leg alignment. These results indicate that patella eversion may affect muscle strength recovery and postoperative pain.