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| 2. |
- Långsjö, Teemu, et al.
(författare)
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Quantitative analysis of collagen network structure and fibril dimensions in cartilage repair with autologous chondrocyte transplantation.
- 2010
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Ingår i: Cells Tissues Organs. - : S. Karger AG. - 1422-6405 .- 1422-6421. ; 192:6, s. 351-360
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of this study was to undertake a stereological analysis to quantify the dimensions of the collagen network in the repair tissue of porcine joints after they had been subjected to autologous chondrocyte transplantation (ACT).METHOD: ACT was used to repair cartilage lesions in knee joints of pigs. Electron-microscopic stereology, immunostaining for type II collagen, and quantitative polarized-light microscopy were utilized to study the collagen fibrils in the repair tissue 3 and 12 months after the operation.RESULTS: The collagen volume density (V(V)) was lower in the repair tissue than in normal cartilage at 3 months (20.4 vs. 23.7%) after the operation. The collagen surface density (S(V), 1.5·10(-2) vs. 3.1·10(-2) nm(2)/nm(3)) and V(V) increased with time in the repair tissue (20.4 vs. 44.7%). Quantitative polarized-light microscopy detected a higher degree of collagen parallelism in the repair tissue at 3 months after the operation (55.7 vs. 49.7%). In contrast, 1 year after the operation, fibril parallelism was lower in the repair tissue than in the control cartilage (47.5 vs. 69.8%).CONCLUSION: Following ACT, V(V) and S(V) increased in the repair tissue with time, reflecting maturation of the tissue. One year after the operation, there was a lower level of fibril organization in the repair tissue than in the control cartilage. Thus, the newly synthesized collagen fibrils in the repair tissue appeared to form a denser network than in the control cartilage, but the fibrils remained more randomly oriented.
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| 3. |
- Pulliainen, Outi, et al.
(författare)
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Poly-L-D-lactic acid scaffold in the repair of porcine knee cartilage lesions.
- 2007
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Ingår i: Tissue engineering. - : Mary Ann Liebert Inc. - 1076-3279 .- 1557-8690. ; 13:6, s. 1347-55
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Tidskriftsartikel (refereegranskat)abstract
- Articular cartilage injuries cause a major clinical problem because of the negligible repair capacity of cartilage. Autologous chondrocyte transplantation is a surgical method developed to repair cartilage lesions. In the operation, cartilage defect is covered with a periosteal patch and the suspension of cultured autologous chondrocytes is injected into the lesion site. The method can form good repair tissue, but new techniques are needed to make the operation easier and to increase the postoperative biomechanical properties of the repair tissue. In this study, we investigated poly-L,D-lactic acid (PLDLA) scaffolds alone or seeded with autologous chondrocytes in the repair of circular 6-mm cartilage lesions in immature porcine knee joints. Spontaneous repair was used as a reference. Histologic evaluation of the repair tissue showed that spontaneous repair exhibited higher scores than either PLDLA scaffold group (with or without seeded chondrocytes). The scaffold material was most often seen embedded in the subchondral bone underneath the defect area, probably because of the hardness of the PLDLA material. However, some of the cell-seeded and nonseeded scaffolds contained cartilaginous tissue, suggesting that invasion of mesenchymal cells inside nonseeded scaffolds had occurred. Hyaluronan deposited in the scaffold had possibly acted as a chemoattractant for the cell recruitment. In conclusion, the PLDLA scaffold material used in this study was obviously mechanically too hard to be used for cartilage repair in immature animals.
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| 4. |
- Vasara, Anna I., et al.
(författare)
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Arthroscopic cartilage indentation and cartilage lesions of anterior cruciate ligament-deficient knees
- 2005
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Ingår i: AMERICAN JOURNAL OF SPORTS MEDICINE. - : SAGE Publications. - 0363-5465 .- 1552-3365. ; 33:3, s. 408-414
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Tidskriftsartikel (refereegranskat)abstract
- The anterior cruciate ligament-deficient knee is prone to osteoarthritis and meniscus lesions. Very little, however, is known about the biomechanical properties of articular cartilage in anterior cruciate ligament-deficient knees. Purpose To evaluate biomechanical and macroscopical cartilage changes in the knee joint with respect to the time after anterior cruciate ligament rupture. Hypothesis Chronic anterior cruciate ligament deficiency induces cartilage softening. Study Design Cross-sectional study; Level of evidence, 3. Methods Cartilage stiffness of 50 patients undergoing anterior cruciate ligament reconstructive surgery because of symptomatic knee instability after chronic anterior cruciate ligament rupture was measured with an arthroscopic indenter device, and the number and size of cartilage lesions were evaluated. Results The cartilage stiffness did not correlate with time from trauma to surgery (r = 0.002, P =. 99), but the number of cartilage lesions in the knee increased when the time from the initial trauma to reconstructive surgery increased (r = 0.356, P =. 011). Indentation values measured on healthy-looking cartilage on damaged joint surfaces were lower than the values measured on healthy joint surfaces (P <. 01 on lateral femoral condyle and on tibial plateaus). Conclusions The number of cartilage lesions increases with increased time after initial trauma. The arthroscopic indenter device is able to detect cartilage softening as the early mechanical sign of degradation not yet visible to the eye.
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| 5. |
- Vasara, Anna I, et al.
(författare)
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Immature porcine knee cartilage lesions show good healing with or without autologous chondrocyte transplantation.
- 2006
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Ingår i: Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society. - : Elsevier BV. - 1063-4584 .- 1522-9653. ; 14:10, s. 1066-74
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The purpose of this study was to find out how deep chondral lesions heal in growing animals spontaneously and after autologous chondrocyte transplantation. METHODS: A 6mm deep chondral lesion was created in the knee joints of 57 immature pigs and repaired with autologous chondrocyte transplantation covered with periosteum or muscle fascia, with periosteum only, or left untreated. After 3 and 12 months, the repair tissue was evaluated with International Cartilage Repair Society (ICRS) macroscopic grading, modified O'Driscoll histological scoring, and staining for collagen type II and hyaluronan, and with toluidine blue and safranin-O staining for glycosaminoglycans. The repair tissue structure was also examined with quantitative polarized light microscopy and indentation analysis of the cartilage stiffness. RESULTS: The ICRS grading indicated nearly normal repair tissue in 65% (10/17) after the autologous chondrocyte transplantation and 86% (7/8) after no repair at 3 months. At 1 year, the repair tissue was nearly normal in all cases in the spontaneous repair group and in 38% (3/8) in the chondrocyte transplantation group. In most cases, the cartilage repair tissue stained intensely for glycosaminoglycans and collagen type II indicating repair tissue with true constituents of articular cartilage. There was a statistical difference in the total histological scores at 3 months (P=0.028) with the best repair in the spontaneous repair group. A marked subchondral bone reaction, staining with toluidine blue and collagen type II, was seen in 65% of all animals. CONCLUSIONS: The spontaneous repair ability of full thickness cartilage defects of immature pigs is significant and periosteum or autologous chondrocytes do not bring any additional benefits to the repair.
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| 6. |
- Vasara, Anna I, et al.
(författare)
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Indentation stiffness of repair tissue after autologous chondrocyte transplantation.
- 2005
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Ingår i: Clinical orthopaedics and related research. - 0009-921X. ; :433, s. 233-42
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Tidskriftsartikel (refereegranskat)abstract
- Our main hypothesis was that indentation stiffness of the repair tissue approaches the values of adjacent cartilage 1 year after autologous chondrocyte transplantation. We also wanted to investigate the differences between osteochondritic lesions and full-thickness lesions. Thirty patients with cartilage lesions were operated on with autologous chondrocyte transplantation. The repair was evaluated arthroscopically, indentation stiffness was measured, and clinical evaluations were done. The stiffness of the repair tissue improved to 62% (mean 2.04 +/- 0.83 N, mean +/- SD) of adjacent cartilage (3.58 +/- 1.04 N). Fifty-three percent of the patients graded their knee as excellent or good and 47% of the patients graded their knee as fair at the followup. In six patients the normalized stiffness was at least 80%, suggesting hyaline-like repair. The indentation stiffness of the osteochondritis dissecans lesion repairs (1.45 +/- 0.46 N; n = 7) was less than that of the nonosteochondritis dissecans lesion repair sites (2.37 +/- 0.72 N; n = 19). Gadolinium-enhanced magnetic resonance imaging of the cartilage (dGEMRIC) during followup of four patients suggested proteoglycan replenishment, although all grafts showed low indentation values. Low stiffness values may indicate incomplete maturation or predominantly fibrous repair. The indentation analysis showed that the repair tissue stiffness could, in some cases, reach the same level as the adjacent cartilage, but there was a large variation among the grafts.
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| 7. |
- Vasara, Anna I, et al.
(författare)
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Persisting high levels of synovial fluid markers after cartilage repair: a pilot study.
- 2009
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Ingår i: Clinical orthopaedics and related research. - : Ovid Technologies (Wolters Kluwer Health). - 1528-1132 .- 0009-921X. ; 467:1, s. 267-72
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Tidskriftsartikel (refereegranskat)abstract
- Local attempts to repair a cartilage lesion could cause increased levels of anabolic and catabolic factors in the synovial fluid. After repair with regenerated cartilage, the homeostasis of the cartilage ideally would return to normal. In this pilot study, we first hypothesized levels of synovial fluid markers would be higher in patients with cartilage lesions than in patients with no cartilage lesions, and then we hypothesized the levels of synovial fluid markers would decrease after cartilage repair. We collected synovial fluid samples from 10 patients before autologous chondrocyte transplantation of the knee. One year later, a second set of samples was collected and arthroscopic evaluation of the repair site was performed. Fifteen patients undergoing knee arthroscopy for various symptoms but with no apparent cartilage lesions served as control subjects. We measured synovial fluid matrix metalloproteinase-3 (MMP-3) and insulinlike growth factor-I (IGF-I) concentrations with specific activity and enzyme-linked immunosorbent assays, respectively. The levels of MMP-3 and IGF-I were higher in patients having cartilage lesions than in control subjects with no cartilage lesions. One year after cartilage repair, the lesions were filled with repair tissue, but the levels of MMP-3 and IGF-I remained elevated, indicating either graft remodeling or early degeneration. Level of Evidence: Level III, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
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| 8. |
- Vasara, Anna I, et al.
(författare)
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Subchondral bone reaction associated with chondral defect and attempted cartilage repair in goats.
- 2004
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Ingår i: Calcified tissue international. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 74:1, s. 107-14
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Tidskriftsartikel (refereegranskat)abstract
- Repair of cartilage damage with autologous chondrocyte transplantation (ACT) has become popular in clinical use during the past few years. Although clinical results have mostly been successful, several unanswered questions remain regarding the biological mechanism of the repair process. The aim of this study was to develop a goat model for ACT. The repair was not successful due to the graft delamination, but we characterize the subchondral changes seen after the procedure. A chondral lesion was created in 14 goat knees, operated on 1 month later with ACT, and covered with periosteum or a bioabsorbable poly-L/D-lactide scaffold. After 3 months, only two of the five lesions repaired with ACT showed partly hyaline-like repair tissue, and all lesions (n = 4) with the scaffold failed. Even though the lesions did not extend through the calcified cartilage, the bone volume and collagen organization of bone structure were decreased when assessed by quantitative polarized light microscopy. There was a significant loss of bone matrix and distortion of the trabecular structure of subchondral bone, which extended several millimeters into the bone. The subchondral bone demonstrated strong hyaluronan staining in the bone marrow and cartilaginous areas with signs of endochondral ossification, suggesting structural remodeling of the bone. The goat model used here proved not to be an optimal model for ACT. The changes in subchondral bone may alter the biomechanical properties of the subchondral plate and thus the long-term survival of the repair tissue after ACT.
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