Biomedical subjects

Takuma Yamasaki

Publications and source records attributed to Takuma Yamasaki.

8 recordsLinked to original sources

PubMed2006

Mobilization of bone marrow-derived mesenchymal stem cells into the injured tissues after intraarticular injection and their contribution to tissue regeneration.

The purpose of present study was to evaluate active mobilization effect of mesenchymal stem cells (MSCs) into injured tissues after intraarticular injection of MSCs, and to evaluate their contribution to tissue regeneration. MSCs, which were obtained from green fluorescent protein (GFP) transgenic Sprague-Dawley (SD) rat and cultivated, were injected into normal SD rats in which multiple tissues had been injured including anterior cruciate ligament (ACL), medial meniscus, and articular cartilage of the femoral condyles. At 4 weeks after injection of MSCs, fluorescent microscopic observation, immunohistochemical or histological examinations were performed to evaluate mobilization of MSCs into injured tissue and their contribution to tissue regeneration. In the group of 1 x 10(6) MSCs injection, GFP positive cells could mobilize into the injured ACL alone in all 8 knees. In the group of 1 x 10(7) MSCs injection, GFP positive cells were observed in the injured site of ACL in all 8 knees and in the injured site of medial meniscus and cartilage of femoral condyles in 6 of 8 knees. More interestingly, extracellular matrix stained by toluidine blue was present around GFP positive cells in the injured femoral condyles cartilage and medial meniscus, indicating tissue regeneration. Intraarticularly injected MSCs could mobilize into the injured tissues, and probably contributed to tissue regeneration. This study demonstrated the possibility of intraarticular injection of MSCs for the treatment of intraarticular tissue injuries including ACL, meniscus, or cartilage. If this treatment option is established, it can be minimally invasive compared to conventional surgeries for these tissues.

Animals↗

PubMed2006

Rotational acetabular osteotomy for advanced osteoarthritis secondary to dysplasia of the hip.

BACKGROUND: Satisfactory intermediate and long-term results of rotational acetabular osteotomy for the treatment of early osteoarthritis secondary to developmental dysplasia of the hip have been reported. The purpose of this study was to examine the results of rotational acetabular osteotomy in patients with advanced osteoarthritis secondary to developmental dysplasia of the hip. METHODS: We performed a retrospective review of the results of rotational acetabular osteotomy in forty-three patients (forty-three hips). All of the patients had radiographic evidence of advanced-stage osteoarthritis, defined as narrowing of the joint space with cystic radiolucencies and small osteophytes according to the staging system of the Japanese Orthopaedic Association. Forty-one patients were female, and two were male. The mean age was 43.8 years at the time of surgery, and the mean duration of follow-up was 8.5 years. Clinical follow-up was performed with use of the system of Merle d'Aubigné and Postel. The center-edge angle, acetabular roof angle, head lateralization index, and minimum width of the joint space were measured on radiographs made preoperatively, postoperatively, and at the time of final follow-up. Postoperative joint congruency was classified into four grades. RESULTS: The mean preoperative Merle d'Aubigné clinical score was 13.3 points, which improved to a mean of 15.4 points at the time of the latest follow-up (p < 0.0001). The mean center-edge angle improved from 0.7 degrees preoperatively to 29 degrees at three months postoperatively (p < 0.0001), the mean acetabular roof angle improved from 30 degrees to 11 degrees (p < 0.0001), the mean head lateralization index improved from 0.69 to 0.65 (p < 0.01), and the mean minimum width of the joint space improved from 2.2 to 2.5 mm (p < 0.0003). Ten hips had radiographic evidence of progression of osteoarthritis. Kaplan-Meier survivorship analysis, with radiographic signs of progression of osteoarthritis as the end point, predicted a ten-year survival rate of 72.2%. CONCLUSIONS: Rotational acetabular osteotomy for advanced osteoarthritis secondary to dysplasia of the hip in properly selected patients can improve clinical scores and is associated with a lack of radiographic signs of progression of osteoarthritis in most patients. LEVEL OF EVIDENCE: Therapeutic Level IV.

Acetabulum↗

PubMed2005

Meniscal regeneration using tissue engineering with a scaffold derived from a rat meniscus and mesenchymal stromal cells derived from rat bone marrow.

The purpose of this study was to regenerate a meniscus using a scaffold from a normal meniscus and mesenchymal stromal cells derived from bone marrow (BM-MSCs). Thirty Sprague-Dawley rat menisci were excised and freeze-thawed three times with liquid nitrogen to kill the original meniscal cells. Bone marrow was aspirated from enhanced green fluorescent protein transgenic Sprague-Dawley rats. BM-MSCs were isolated, cultured for 2 weeks, and 2 x 10(5) cells were then seeded onto the meniscal scaffolds. Using a fluorescent microscope and immunohistochemical staining, repopulation of enhanced green fluorescent protein positive cells was observed in the superficial zone of the scaffold after 1 week of culture, and then in the deep zone after 2 weeks. At 4 weeks, expression of extracellular matrices was detected histologically and expression of mRNA for aggrecan and type X collagen was detected. Stiffness of the cultured tissue, assessed by the indentation stiffness test, had increased significantly after 2 weeks in culture, and approximated the stiffness of a normal meniscus. From this study, we conclude that a scaffold derived from a normal meniscus seeded with BM-MSCs can form a meniscus approximating a normal meniscus.

Animals↗

PubMed2005

Meniscal repair using bone marrow-derived mesenchymal stem cells: experimental study using green fluorescent protein transgenic rats.

Meniscal tears in the avascular zone have very limited potential to heal because of a poor blood supply. Although there have been many attempts to promote the healing potential of the torn meniscus, no established treatments have achieved sufficient meniscal healing. In this study, we evaluated the efficacy of mesenchymal stem cell transplantation as a cell source to promote meniscal healing, using cells from the green fluorescent protein (GFP) transgenic rat and organ culture model. Mesenchymal stem cells from bone marrow were isolated and expanded in monolayer culture. They were embedded in fibrin glue and were transplanted into the meniscal defects of Sprague-Dawley rats. In the control groups, the defects remained untreated, or only fibrin glue without cells was transplanted. The GFP-positive cells enabled us to detect the transplanted cells from recipient cells easily. As a result, transplanted mesenchymal stem cells could survive and proliferate in the meniscal defects in the organ culture model. They also could produce an abundant extracellular matrix stained by toluidine blue around the cells which contributed to meniscal healing in the avascular status. We could detect transplanted GFP cells under a fluorescent microscope until 8 weeks after transplantation. In a clinical situation, mesenchymal stem cell transplantation is a promising new clinical strategy for the treatment of meniscal tears in the avascular zone.

Animals↗

PubMed2005

Bone remodeling of a femoral head after transtrochanteric rotational osteotomy for osteonecrosis associated with slipped capital femoral epiphysis: a case report.

A rare case of a 12-year-old boy on whom a joint-preserving operation for osteonecrosis after slipped capital femoral epiphysis (SCFE) was performed, is described. Firstly, in situ pinning was performed for acute-on-chronic SCFE. However, osteonecrosis and collapse of the femoral head occurred at 7 months after surgery. Secondly, transtrochanteric rotational osteotomy (TRO) was performed against progression of the collapse of the femoral head. Eight years of X-ray observation revealed bone remodeling at the osteonecrotic region. No documentation has been reported about the potential of bone remodeling of a femoral head with osteonecrosis after SCFE. This case indicates that a joint-preserving operation such as TRO is capable of promoting bone remodeling in such circumstances.

Bone Remodeling↗

PubMed2005

Natural course of the minimally symptomatic nonoperated hip in patients with bilateral hip dysplasia treated with contralateral rotational acetabular osteotomy.

BACKGROUND: The purpose of this study was to investigate the natural course of the minimally symptomatic nonoperated hip in patients with pre-osteoarthritis or early osteoarthritis in bilaterally dysplastic hips. METHODS: The material consisted of 61 patients with bilaterally dysplastic hips who underwent rotational acetabular osteotomy in their symptomatic hip and nonoperative treatment in their asymptomatic or minimally symptomatic hip. The average follow-up was 10.1 years (range 7.0-15.6 years), and the average age at the time of surgery was 38.2 years (range 20-58 years). All patients were divided into two groups by joint congruity of the nonoperated hip at surgery with rotational acetabular osteotomy. RESULTS: On radiographic assessment, 1 of the 35 pre-osteoarthritis hips had developed early osteoarthritis, and 6 of the 26 early osteoarthritis hips had progressed to advanced osteoarthritis. The Kaplan-Meier survivorship analysis for the whole group of nonoperated hips, with radiographic progression of osteoarthritis as the endpoint, predicted a 10-year survival rate of 83.7% (95% confidence interval 70%-98%). Significant differences were observed in the radiographic stage (pre- and early osteoarthritis group, P=0.015) and joint congruity (good and fair group, P=0.005). CONCLUSIONS: If the contralateral nonoperated hip has good joint congruity, minimal symptoms, and no or little radiographic change in patients with pre- or early osteoarthritis and bilateral acetabular dysplasia, the probability of radiographic progression is low.

Adult↗

PubMed2005

Serum interleukin 8 levels correlate with synovial fluid levels in patients with aseptic loosening of hip prosthesis.

Levels of inflammatory cytokines (tumor necrosis factor alpha, interleukin [IL] 6, and IL-8) in serum from patients with osteolysis on radiographs after hip arthroplasty [osteolysis(+), n = 28], patients without osteolysis after hip arthroplasty [osteolysis(-), n = 24], and nonoperated healthy subjects [controls, n = 20] were determined. In addition, cytokine levels in synovial fluid from patients undergoing revision total hip arthroplasty (n = 14) for loosening were measured and compared with each other and with the area of osteolysis on radiographs. Serum IL-6 and IL-8 levels were significantly higher in the osteolysis(+) group than in the osteolysis(-) or the control groups. Furthermore, a significant correlation was found between the serum and synovial fluid IL-8 levels and between synovial fluid IL-8 levels and the area of osteolysis in patients undergoing revision total hip arthroplasty. Therefore, serum IL-8 levels could be a useful periprosthetic osteolysis marker.

Female↗

PubMed2003

Bone-preserving prosthesis with a single axis for treating osteonecrosis of the femoral head: midterm results for the thrust plate hip prosthesis.

We studied 27 patients (31 joints) who underwent total hip arthroplasty (THA) using the thrust plate hip prosthesis (TPP) for osteonecrosis of the femoral head. The mean follow-up period was 56 months (range 38-72 months). Clinical evaluation by the Merle d'Aubigne and Postel system showed a significant improvement from a preoperative mean score of 8.1 to a final mean follow-up score of 16.6. Mechanical loosening developed about 1 year postoperatively in one joint with a bone defect. Grade 1 stress shielding was observed in four joints. Although indications for the TPP are restricted to certain cases, unlike the conventional intramedullary stem, much can be expected of TPP. It is an outstanding prosthesis for osteonecrosis of the femoral head of young patients in terms of bone preservation and physiological load transfer.

Adult↗