| 1. |
- Bigdeli, Narmin, 1974, et al.
(author)
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Coculture of human embryonic stem cells and human articular chondrocytes results in significantly altered phenotype and improved chondrogenic differentiation.
- 2009
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In: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 27:8, s. 1812-21
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Journal article (peer-reviewed)abstract
- Human embryonic stem (hES) cells have been suggested as a cell source for the repair of cartilage lesions. Here we studied how coculture with human articular chondrocytes affects the expansion potential, morphology, expression of surface markers, and differentiation abilities of hES cells, with special regard to chondrogenic differentiation. Undifferentiated hES cells were cocultured with irradiated neonatal or adult articular chondrocytes in high-density pellet mass cultures for 14 days. Cocultured hES cells were then expanded on plastic and their differentiation potential toward the adipogenic, osteogenic, and chondrogenic lineages was compared with that of undifferentiated hES cells. The expression of different surface markers was investigated using flow cytometry and teratoma formation was studied using injection of the cells under the kidney capsule. Our results demonstrate that although hES cells have to be grown on Matrigel, the cocultured hES cells could be massively expanded on plastic with a morphology and expression of surface markers similar to mesenchymal stem cells. Coculture further resulted in a more homogenous pellet and significantly increased cartilage matrix production, both in high-density pellet mass cultures and hyaluronan-based scaffolds. Moreover, cocultured cells formed colonies in agarose suspension culture, also demonstrating differentiation toward chondroprogenitor cells, whereas no colonies were detected in the hES cell cultures. Coculture further resulted in a significantly decreased osteogenic potential. No teratoma formation was detected. Our results confirm the potential of the culture microenvironment to influence hES cell morphology, expansion potential, and differentiation abilities over several population doublings.
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| 2. |
- Bodin, Aase Katarina, 1977, et al.
(author)
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Bacterial cellulose as a potential meniscus implant
- 2007
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In: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 1:5, s. 406-8
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Journal article (peer-reviewed)abstract
- Traumatic or degenerative meniscal lesions are a frequent problem. The meniscus cannot regenerate after resection. These lesions often progress and lead to osteoarthritis. Collagen meniscal implants have been used in clinical practice to regenerate meniscal tissue after partial meniscectomy. The mechanical properties of bacterial cellulose (BC) gel were compared with a collagen material and the pig meniscus. BC was grown statically in corn steep liquid medium, as described elsewhere. Pig meniscus was harvested from pigs. The collagen implant was packed in sterile conditions until use. The different materials were evaluated under tensile and compression load, using an Instron 5542 with a 500 N load cell. The feasibility for implantation was explored using a pig model. The Young's modulus of bacterial cellulose was measured to be 1 MPa, 100 times less for the collagen material, 0.01 MPa in tensile load. The Young's modulus of bacterial cellulose and meniscus are similar in magnitude under a compression load of 2 kPa and with five times better mechanical properties than the collagen material. At higher compression strain, however, the pig meniscus is clearly stronger. These differences are clearly due to a more ordered and arranged structure of the collagen fibrils in the meniscus. The combination of the facts that BC is inexpensive, can be produced in a meniscus shape, and promotes cell migration makes it an attractive material for consideration as a meniscus implant. Copyright (c) 2007 John Wiley & Sons, Ltd.
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| 3. |
- Concaro, Sebastian, et al.
(author)
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Bioreactors for Tissue Engineering of Cartilage
- 2009
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In: Advances in Biochemical Engineering/Biotechnology. - 0724-6145 .- 1616-8542. - 9783540693574 ; 112, s. 125-143
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Book chapter (other academic/artistic)abstract
- The cartilage regenerative medicine field has evolved during the last decades. The first-generation technology, autologous chondrocyte transplantation (ACT) involved the transplantation of in vitro expanded chondrocytes to cartilage defects. The second generation involves the seeding of chondrocytes in a three-dimensional scaffold. The technique has several potential advantages such as the ability of arthroscopic implantation, in vitro pre-differentiation of cells and implant stability among others (Brittberg M, Lindahl A, Nilsson A, Ohlsson C, Isaksson O, Peterson L, N Engl J Med 331(14):889-895, 1994; Henderson I, Francisco R, Oakes B, Cameron J, Knee 12(3):209-216, 2005; Peterson L, Minas T, Brittberg M, Nilsson A, Sjogren-Jansson E, Lindahl A, Clin Orthop (374):212-234, 2000; Nagel-Heyer S, Goepfert C, Feyerabend F, Petersen JP, Adamietz P, Meenen NM, et al. Bioprocess Biosyst Eng 27(4):273-280, 2005; Portner R, Nagel-Heyer S, Goepfert C, Adamietz P, Meenen NM, J Biosci Bioeng 100(3):235-245, 2005; Nagel-Heyer S, Goepfert C, Adamietz P, Meenen NM, Portner R, J Biotechnol 121(4):486-497, 2006; Heyland J, Wiegandt K, Goepfert C, Nagel-Heyer S, Ilinich E, Schumacher U, et al. Biotechnol Lett 28(20):1641-1648, 2006). The nutritional requirements of cells that are synthesizing extra-cellular matrix increase along the differentiation process. The mass transfer must be increased according to the tissue properties. Bioreactors represent an attractive tool to accelerate the biochemical and mechanical properties of the engineered tissues providing adequate mass transfer and physical stimuli. Different reactor systems have been [5] developed during the last decades based on different physical stimulation concepts. Static and dynamic compression, confined and nonconfined compression-based reactors have been described in this review. Perfusion systems represent an attractive way of culturing constructs under dynamic conditions. Several groups showed increased matrix production using confined and unconfined systems. Development of automatic culture systems and noninvasive monitoring of matrix production will take place during the next few years in order to improve the cost affectivity of tissue-engineered products. © 2009 Springer.
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| 4. |
- Concaro, Sebastian
(author)
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Cartilage Tissue Engineering. A study on how to improve cartilage repair.
- 2010
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Doctoral thesis (other academic/artistic)abstract
- One of the first examples of musculoskeletal tissue engineering is autologous chondrocyte implantation (ACI).The first patient with a cartilage lesion was operated with ACI in 1987 and at that time suspension implantation was used. Today, we use the third generation of ACI where scaffolds are employed to support redifferentiation and neocartilage formation in vitro and further maturation in vivo after implantation to treat the cartilage defects. A great deal of information is still needed to cl... merinically improve cartilage production. Variables such us the cell seeding density, the cell culture media formulation, the degree of redifferentiation and the material and biological properties of the scaffold used remain to be investigated further. In the work reported in paper I we aimed to elucidate whether mesenchymal stem cells (MSC:s) are better than committed chondrocytes in producing cartilage in vitro, whether the co-culture of MSC:s and chondrocytes play a role in enhancing cartilage production in vitro and if different biomaterials affect the differentiation capacity in vitro. The effect of the cell seeding concentration was evaluated in paper 2 by culturing human adult chondrocytes in chitosan scaffolds. After 14 and 28 days in a 3D culture, the constructs were assessed for collagen, glycosaminoglycans and DNA content. The mechanical properties of the constructs were determined using a dynamic oscillatory shear test. In paper III we studied whether the degree of redifferentiation of chondrocytes in in vitro cultured scaffolds had an effect on the neocartilage formation after implantation. It was studied whether redifferentiation of the chondrocytes was accomplished by recapitulating the signaling pattern used by chondrocytes during fetal development. In paper IV we tried to determine the effect of different culture conditions on the in vivo chondrogenic capacity and integration properties of human tissue engineered chondrocyte constructs. In paper V we evaluated the biomimetic properties of different materials. Materials with good biomimetic properties may influence the initial phases of tissue regeneration by inducing a strong migration of cells into the pores of the scaffold. Materials and Methods MSC:s and human adult and pig chondrocytes were cultured in different materials in order to prove the different hypotheses. The chondrocyte differentiation in vitro and in vivo was evaluated using real time PCR to asses the expression of different genes. The total amount of collagen and proteglycans was determined biochemically. Inmunohistochemistry and different histological scores were used to evaluate the presence of cartilage specific proteins and to semiquantify the histological aspect of tissue engineered constructs after in vitro or in vivo evaluation. A novel transmigration assay was designed to evaluate the biomimetic properties of different biomaterials. To evaluate the in vivo chondrogenic potential, tissue engineered constructs produced in vitro were subcutaneously implanted in nude mice or into cartilage defects in human osteochondral plugs. Results Related to the number of chondrocytes used, coculture with MSC:s led to a strong increase in collagen type IX mRNA expression, an indicator for long-term stability of cartilage. Chondrocytes had better redifferentiation potential as compared to MSC:s. Tissue glue Tisseel® provided slightly better chondrogenic conditions than Tissue Fleece®. We determined that concentrations of 12–25 million cells/cm3 are needed in a chitosan scaffold to increase the matrix production and mechanical properties of human adult chondrocytes under static conditions. We were able to determine that the in vitro chondrogenesis in scaffolds induce a signalling pattern similar to the one seen in fetal development. Furthermore the results indicates that redifferentiation of in vitro expanded articular chondrocytes is needed at the time of implantation for neocartilage formation. However, 14 days of preculture in vitro used clinically today might be reduced. Conclusion It is possible to significantly improve cartilage repair by using the right amount of cell concentration in seeded scaffolds, chondrogenic cells co-cultured and by choosing the right type of biomimetic scaffolding material. The future of cartilage repair lies in further development of suitable materials and good quality cells expanded under the most ideal conditions.
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| 5. |
- Concaro, Sebastian, et al.
(author)
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Effect of cell seeding concentration on the quality of tissue engineered constructs loaded with adult human articular chondrocytes.
- 2008
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In: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 2:1, s. 14-21
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Journal article (peer-reviewed)abstract
- Many aspects of the process of in vitro differentiation of chondrocytes in three-dimensional (3D) scaffolds need to be further investigated. Chitosan scaffolds were produced by freeze-drying 3% w/v 90% DDA chitosan gels. The effect of the cell seeding concentration was evaluated by culturing human adult chondrocytes in chitosan scaffolds After the first passage, cells were seeded into chitosan scaffolds with a diameter of 8 mm. The final cell seeding concentration per cm3 of chitosan scaffold was: Group A, 3 x 10(6); Group B, 6 x 10(6); Group C, 12 x 10(6); and Group D, 25 x 10(6) cells. After 14 and 28 days in 3D culture, the constructs were assesed for collagen, glucosaminoglycans and DNA content. The mechanical properties of the constructs were determined using a dynamic oscillatory shear test. The histological aspect of the constructs was evaluated using the Bern score. The collagen and GAG concentration increased, varying the cell seeding concentration. There was a significant increase in proteoglycan and hydroxyproline production between groups C and D. The sulphated GAG content increased significantly in the group D as compared to the other groups. The mechanical properties of the different constructs increased over time, from 9.6 G'/kPa at 14 days of 3D culture to 14.6 G'/kPa at 28 days under the same culture conditions. In this study we were able to determine that concentrations of 12-25 million cells/cm2 are needed to increase the matrix production and mechanical properties of human adult chondrocytes under static conditions.
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| 6. |
- de Windt, Tommy S, et al.
(author)
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Strategies for patient profiling in articular cartilage repair of the knee: a prospective cohort of patients treated by one experienced cartilage surgeon.
- 2012
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In: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. - : Springer Science and Business Media LLC. - 1433-7347. ; 20:11, s. 2225-32
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Journal article (peer-reviewed)abstract
- PURPOSE: The purpose of this study was to report on the clinical outcome of a large heterogenic cartilage repair population treated with the profiling strategies of one experienced cartilage surgeon to provide evidence based tools for treatment selection in a clinical environment. METHODS: A total of 216 patients were identified in this prospective single-surgeon study. For the primary and secondary treatment of smaller defects, microfracture (MF) was used. Hyalograft C was used for first and second line larger defects, while carbon-fiber rod and pad implantations were used as a salvage procedure. RESULTS: Three years after the initial procedure, the clinical improvement was excellent for MF and Hyalograft C (P<0.001) and good for carbon-fiber procedures (P<0.05). Hyalograft C patients with prior anterior cruciate ligament reconstruction had less clinical improvement (P<0.05), while MF patients with prior cartilage repair were more likely to fail (Odds Ratio 20.5, P<0.05). CONCLUSION: This is the first study that provides an assessment of the treatment strategies used by an experienced cartilage surgeon. A treatment algorithm for cartilage repair in a heterogenic population was created that based on the findings of this study could be implemented in a clinical environment. LEVEL OF EVIDENCE: Prospective clinical case series, Level IV.
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| 7. |
- Hildner, Florian, et al.
(author)
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Human adipose-derived stem cells contribute to chondrogenesis in coculture with human articular chondrocytes.
- 2009
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In: Tissue engineering. Part A. - : Mary Ann Liebert Inc. - 1937-335X .- 1937-3341. ; 15:12, s. 3961-9
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Journal article (peer-reviewed)abstract
- Adipose tissue is easily available and contains high numbers of stem cells that are capable for chondrogenic differentiation. We hypothesize that a partial substitution of chondrocytes with autologous adipose-derived stem cells (ASC) might be a possible strategy to reduce the number of chondrocytes needed in matrix-associated autologous chondrocyte transplantation. To lay the ground, in vitro coculture experiments were performed using human chondrocytes and human ASC. Chondrocytes were obtained from donors undergoing matrix-associated autologous chondrocyte transplantation. ASC were isolated from liposuction material. Chondrocytes and ASC were seeded either in fibrin (Tisseel; Baxter, Vienna, Austria) or collagen matrix (Tissue Fleece; Baxter, Unterschleissheim, Germany). RNA for quantitative reverse transcriptase (RT)-polymerase chain reaction was isolated after 2 weeks of culture in chondrogenic medium, and after 4 weeks samples were processed for histology. Related to the number of chondrocytes used, coculture with ASC led to strong increase in collagen type IX mRNA expression, which is an indicator for long-term stability of cartilage. Moderate upregulation was shown for SOX9, aggrecan, melanoma inhibitory activity, cartilage link protein 1, and cartilage oligomeric matrix protein mRNA. However, expression of collagen I and collagen II indicates the synthesis of fibrous tissue, which might be due to the use of dedifferentiated chondrocytes. Tisseel provided slightly better chondrogenic conditions than Tissue Fleece. These data support the possibility to take advantage of ASC in cartilage regeneration in conjunction with autologous chondrocytes.
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| 8. |
- Nilsson, Niklas, 1995, et al.
(author)
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Both gastrocnemius aponeurosis flaps and semitendinosus tendon grafts are effective in the treatment of chronic Achilles tendon ruptures - a systematic review.
- 2023
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In: BMC musculoskeletal disorders. - 1471-2474. ; 24:1
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Journal article (peer-reviewed)abstract
- A chronic Achilles tendon rupture (ATR) is defined as an ATR that has been left untreated for more than four weeks following rupture. This systematic review aims to summarize the outcomes of chronic ATR treated using either a gastrocnemius aponeurosis flap or semitendinosus tendon graft.A systematic search was conducted in three databases (PubMed, Scopus and Cochrane), for studies describing outcomes after surgical treatment of chronic ATR using gastrocnemius aponeurosis flaps or semitendinosus tendon grafts with more than 10 patients included. The studies were assessed for quality and risk of bias using the Methodological Items used to assess risk of bias in Non-Randomized Studies (MINORS).Out of the 818 studies identified with the initial search, a total of 36 studies with 763 individual patients were included in this systematic review. Gastrocnemius aponeurosis flap was used in 21 and semitendinosus tendon graft was used in 13 of the studies. The mean (SD) postoperative Achilles tendon Total Rupture Score (ATRS) for patients treated with a gastrocnemius aponeurosis flap was 83 (14) points and the mean (SD) American Orthopaedic Foot and Ankle Score (AOFAS) was 96 (1.7) points compared with ATRS 88 (6.9) points and AOFAS 92 (5.6) points for patients treated with a semitendinosus tendon graft. The included studies generally had low-quality according to MINORS, with a median of 8 (range 2-13) for all studies.Both gastrocnemius aponeurosis flaps and semitendinosus tendon grafts give acceptable results with minimal complications and are valid methods for treating chronic ATR. The main difference is more wound healing complications in patients treated with a gastrocnemius aponeurosis flap and more sural nerve injuries in patients treated with a semitendinosus grafts. The current literature on the subject is of mainly low quality and the absence of a patient-related outcome measure validated for chronic ATR makes comparisons between studies difficult.Level IV.
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| 9. |
- Nilsson, Niklas, 1995, et al.
(author)
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The Delayed Presentation of Achilles Tendon Ruptures Is Associated With Marked Alterations in the Gene Expression of COL1A1, MMPs, TIMPs, and IL-6
- 2024
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In: American Journal of Sports Medicine. - : SAGE PUBLICATIONS INC. - 0363-5465 .- 1552-3365. ; 52:1, s. 164-173
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Journal article (peer-reviewed)abstract
- Background: Both acute and chronic Achilles tendon ruptures are affected by alterations in the extracellular matrix during the healing process of the tendon. Yet, these alterations in gene expression patterns are not well characterized. Purpose: To characterize temporal and spatial differences in gene expression patterns after an Achilles tendon rupture and to evaluate if cells from chronic Achilles tendon ruptures have the same ability to form new tendon tissue (tendon constructs) as healthy tendon cells. Study Design: Controlled laboratory study. Methods: A total of 35 patients with surgically treated Achilles tendon ruptures were included in the study and divided into 3 groups: acute (<4 weeks), short-term chronic (1-6 months), and long-term chronic (>6 months). Biopsy specimens were collected during surgical repair and were used to analyze the gene expression within the different groups and to compare mRNA levels in the proximal and distal tendon ends. A complementary in vitro experiment was performed to evaluate if cells from chronic Achilles tendon ruptures can form tendon constructs. Results: The mRNA levels for COL1A1 and COL3A1 were significantly higher in the short-term chronic group compared with the acute group (P <.05). Both MMP-1 and MMP-13 had the highest mRNA levels in the acute group (P <.01) compared with the long-term chronic group, while MMP-2 had the highest mRNA level in the short-term chronic group. Significant differences between the proximal and distal tendon ends were only detected for the monocyte and macrophage marker CD163 (P <.05), which was more expressed proximally. Cells extracted from chronic Achilles tendon ruptures displayed a similar ability and effectiveness to form tendon constructs as healthy tendon cells. Conclusion: A high collagenase gene activity after an Achilles tendon rupture indicated possible rapid matrix degradation in the acute phase. Chronic ruptures appeared to initiate the healing process even before treatment, indicated by the higher expression of collagen in the short-term chronic group. Cells from chronic Achilles tendon ruptures also displayed an ability to form new tendon tissue in vitro. Clinical Relevance: The study shows a rapid increase in collagenase gene expression, which could lead to matrix degradation that continues for months after an Achilles tendon rupture.
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| 10. |
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