Matrix-associated Chondrocyte Transplantation Research Articles

Adjacent cartilage tissue structure after successful transplantation: a quantitative MRI study using T2 mapping and texture analysis

ObjectivesThe aim of this study was to assess the texture of repair tissue and tissue adjacent to the repair site after matrix-associated chondrocyte transplantation (MACT) of the knee using gray-level co-occurrence matrix (GLCM) texture analysis of T2 quantitative maps.MethodsTwenty patients derived from the MRI sub-study of multicenter, single-arm phase III study underwent examination on a 3 T MR scanner, including a T2 mapping sequence 12 and 24 months after MACT. Changes between the time points in mean T2 values and 20 GLCM features were assessed for repair tissue, adjacent tissue, and reference cartilage. Differences in T2 values and selected GLCM features between the three cartilage sites at two time points were analyzed using linear mixed-effect models.ResultsA significant decrease in T2 values after MACT, between time points, was observed only in repair cartilage (p < 0.001). Models showed significant differences in GLCM features between repair tissue and reference cartilage, namely, autocorrelation (p < 0.001), correlation (p = 0.015), homogeneity (p = 0.002), contrast (p < 0.001), and difference entropy (p = 0.047). The effect of time was significant in a majority of models with regard to GLCM features (except autocorrelation) (p ≤ 0.001). Values in repair and adjacent tissue became similar to reference tissue over time.ConclusionsGLCM is a useful add-on to T2 mapping in the evaluation of knee cartilage after MACT by increasing the sensitivity to changes in cartilage structure. The results suggest that cartilage tissue adjacent to the repair site heals along with the cartilage implant.Key Points• GLCM is a useful add-on to T2mapping in the evaluation of knee cartilage after MACT by increasing the sensitivity to changes in cartilage structure.• Repair and adjacent tissue became similar to reference tissue over time.• The results suggest that cartilage tissue adjacent to the repair site heals along with the cartilage implant.

Differentiation of Cartilage Repair Techniques Using Texture Analysis from T2 Maps.

ObjectiveThe aim of this study was to investigate texture features from T2 maps as a marker for distinguishing the maturation of repair tissue after 2 different cartilage repair procedures.DesignSeventy-nine patients, after either microfracture (MFX) or matrix-associated chondrocyte transplantation (MACT), were examined on a 3-T magnetic resonance (MR) scanner with morphological and quantitative (T2 mapping) MR sequences 2 years after surgery. Twenty-one texture features from a gray-level co-occurrence matrix (GLCM) were extracted. The texture feature difference between 2 repair types was assessed individually for the femoral condyle and trochlea/anterior condyle using linear regression models. The stability and reproducibility of texture features for focal cartilage were calculated using intra-observer variability and area under curve from receiver operating characteristics.ResultsThere was no statistical significance found between MFX and MACT for T2 values (P = 0.96). There was, however, found a statistical significance between MFX and MACT in femoral condyle in GLCM features autocorrelation (P < 0.001), sum of squares (P = 0.023), sum average (P = 0.005), sum variance (P = 0.0048), and sum entropy (P = 0.05); and in anterior condyle/trochlea homogeneity (P = 0.02) and dissimilarity (P < 0.001).ConclusionTexture analysis using GLCM provides a useful extension to T2 mapping for the characterization of cartilage repair tissue by increasing its sensitivity to tissue structure. Some texture features were able to distinguish between repair tissue after different cartilage repair procedures, as repair tissue texture (and hence, probably collagen organization) 24 months after MACT more closely resembled healthy cartilage than did MFX repair tissue.

Functional outcome in patients following cartilage regenerative treatement: outcome at minimum follow-up of 12 months

Aims and Objectives:Full thickness cartilage defects may be devastating for the patients. Even though, the surgical options have improved, only limited information for returning to sports. Aim of this study was therefore to compare the functional outcome and the return to sports rate of patients following cartilage regenerative treatment at a minimum follow up of 12 months.Materials and Methods:A total of 50 Patients (32 male, 18 female) undergoing cartilage regeneration using a Matrix-associated chondrocyte transplantation (MACT, Novocart, TETEC, Aesculap) (27 femorotibial, 23 patellofemoral) were evaluated at a minimum follow-up of 12 months. Follow-up was performed using a multifactorial functional analysis including isokinetic strength measurements (BTE-primus), proprioceptive tests (MTF tests), a tapping test and a 3d-motion analysis (myomotion, Noraxon) during single leg squats, bilateral drop jumps and single leg hop tests. Agility was assessed using a lateral speedchase (Globalspeed, Hemsbach). Clinical results were recorded using Tegner and Lysholm score.Results:Patients showed a Lysholm score of 86,3 +/-10,3 and 84,0 +/-13,9 for male and female, respectively. The tegner score was significantly reduced when compared to preoperatively (male 4,72 +/-1,6, female 4,75 +/-1,5). Thigh circumference was reduced by an average of 3,6 cm for male and 4,4 cm for female patients. The tapping test revealed no differences between male and female patients providing a leg symmetry index (LSI) of 102,0 (+/-8,4) with an overall average frequency of 10,14 (+/-1,27). During single leg squat male patients had a significantly lower knee flexion of 55,8 (+/-8,5) of the postoperative leg compared to the non-injured leg (62,2 +/-8,2) whereas the knee abduction was -6.8 (+/-15,1) and -11,8 -11,82 (+/-16,6) for the postoperatively and non-injured leg, respectively. Evaluating the single leg hop, the LSI of distance values was 90,8 (+/-11,9) and for height values 84,0 (+/-16,0) for the male patients. There was a trend towards reduced ROM with regard to knee flexion of the injured leg to the non-injured. Cutting time during lateral speedchase showed a LSI of 98,29 (+/-13,8) and 99,44 (+/-8,2) for male and female patients, respectively.Conclusion:This prospective analysis of patients following cartilage regeneration implicates that the use of a multifactorial “return-to-sports” analysis 12 months postoperatively provides a good correlation to the clinical outcome and scores. At this FU point, Patients following MACT show knee joint function that is close to normal.

Matrix-associated chondrocyte transplantation for reconstruction of articulating surfaces in the temporomandibular joint: a pilot study covering medium- and long-term outcomes of 6 patients

ObjectiveMatrix-associated chondrocyte transplantation is routinely used in joints of the extremities but not in the temporomandibular joint (TMJ).Study DesignWe report the first case series in 7 patients of a tissue engineering approach to regenerate severely degraded articulating surfaces in the TMJ by simultaneously completely resurfacing both the mandibular condyle and the articular eminence/glenoid fossa with a commercially available collagen sponge seeded with autologous cells stabilized within a fibrin matrix. To facilitate healing, we temporarily employed a silicone membrane to protect the engineered tissues. The indications for surgery were posttraumatic fibro-osseous ankylosis, ankylosing osteoarthritis, or late-stage osteoarthritis.ResultsSix of the patients were recalled for follow-up after 3 years 6 months to 12 years 1 month. The maximum incisal opening was 18.2 ± 9.2 mm (range, 9-33 mm) before and 31.2 ± 13.6 mm (range, 12-47 mm) at the latest follow-up. Histologic specimens taken at 4 months showed beginning differentiation of fibrocytes into chondrocytes, whereas at 3 and 11 years, mature hyaline cartilage—not typical for the TMJ—was present.ConclusionsWe conclude that the reconstruction of TMJ surfaces by matrix-associated chondrocyte transplantation may become a routine method for cartilage regeneration in the TMJ in the future.

Jellyfish collagen matrices conserve the chondrogenic phenotype in two- and three-dimensional collagen matrices.

Cartilage is a tissue with a very low capability of self-repair and the search for suitable materials supporting the chondrogenic phenotype and thus avoiding fibrotic dedifferentiation for matrix-associated chondrocyte transplantation (MACI) is ongoing. Jellyfish collagen was thought to be a suitable material mainly because of its good availability and easy handling. Collagen was extracted from jellyfish Rhopilema esculentum and the spreading of porcine chondrocytes on two (2D) and three dimensional (3D) collagen matrices examined in comparison with vertebrate collagens, placenta collagen and a commercially available matrix from porcine collagen type I (Optimaix®). In 2D, most chondrocytes kept their round shape on jellyfish collagen and vertebrate collagen type II compared with vertebrate collagen type I. This was also confirmed in 3D experiments, where chondrocytes preserved their phenotype on jellyfish collagen, as indicated by high collagen II/(II + I) ratios (≥54 % and ~92 % collagen type II in mRNA and protein, respectively) and no proliferation during 28 days of cultivation. These observations were discussed with a view to potential structural differences of jellyfish collagen, which might influence the integrin-mediated adhesion mechanisms of vertebrate cells on jellyfish collagen. This probably results from a lack of integrin-binding sites and the existence of an alternative binding mechanism such that cells kept their round shape on jellyfish collagen, preventing chondrocytes from dedifferentiation. Thus, collagen from R. esculentum is a very suitable and promising material for cartilage tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.

Arthroscopic Treatment of Isolated, Full Thickness Cartilage Defects of the Acetabulum Caused by CAM Impingement of the Hip Joint by Autologous Matrix Associated Chondrocyte Transplantation (ACT3D). Clinical Follow-up Study Over 2 Years

Arthroscopic Treatment of Isolated, Full Thickness Cartilage Defects of the Acetabulum Caused by CAM Impingement of the Hip Joint by Autologous Matrix Associated Chondrocyte Transplantation (ACT3D). Clinical Follow-up Study Over 2 Years

Influence of Cell Differentiation and IL-1β Expression on Clinical Outcomes After Matrix-Associated Chondrocyte Transplantation

Background: Several patient- and defect-specific factors influencing clinical outcomes after matrix-associated chondrocyte transplantation (MACT) have been identified, including the patient’s age, location of the defect, or duration of symptoms before surgery. Little is known, however, about the influence of cell-specific characteristics on clinical results after transplantation. Purpose: The aim of the present study was to investigate the influence of cell differentiation and interleukin-1 β (IL-1β) expression on clinical outcomes up to 5 years after MACT. Study Design: Case series; Level of evidence, 4. Methods: Twenty-seven patients who underwent MACT of the tibiofemoral joint area of the knee were included in this study. Clinical assessments were performed preoperatively as well as 6, 12, 24, and 60 months after transplantation by using the following scores: the Knee injury and Osteoarthritis Outcome Score (KOOS), the International Knee Documentation Committee (IKDC) Subjective Knee Form, the Noyes sports activity rating scale, the Brittberg clinical score, and a visual analog scale (VAS) for pain. The quality of repair tissue was assessed by magnetic resonance imaging using the magnetic resonance observation of cartilage repair tissue (MOCART) score at 1 and 5 years. Cell differentiation (defined as collagen type II:type I expression ratio), aggrecan, and IL-1β expression were determined by real-time polymerase chain reaction in transplant residuals and were correlated with clinical outcomes. Results: The largest improvements in clinical scores were found during the first year. Two years postoperatively, a stable improvement was reached until 5 years after transplantation, with a mean IKDC score of 34.4 ± 8.6 preoperatively to 77.9 ± 16 after 24 months (P < .001). Cell differentiation showed a significant positive correlation with nearly all clinical scores at different time points, especially after 12 months (P < .05). IL-1β expression negatively influenced clinical outcomes at 24 months (Brittberg score) and 60 months (Brittberg and VAS scores) after surgery (P < .05). No correlation was found between the MOCART score and clinical outcomes or gene expression. Conclusion: Our data demonstrate that cell differentiation and IL-1β expression influence clinical outcomes up to 5 years after MACT.

Gene expression and cell differentiation in matrix-associated chondrocyte transplantation grafts: a comparative study

Although scaffold composition and architecture are considered to be important parameters for tissue engineering, their influence on gene expression and cell differentiation is rarely investigated in scaffolds used for matrix-associated autologous chondrocyte transplantation (MACT). In this study we have therefore comparatively analyzed the gene expression of important chondrogenic markers in four clinical applied cell-graft systems with very different scaffold characteristics. Residuals (n=165) of four different transplant types (MACI®, Hyalograft®C, CaReS® and Novocart®3D) were collected during surgery and analyzed for Col1, Col2, aggrecan, versican, melanoma inhibitory activity (MIA) and IL-1β by real-time PCR. Scaffold and cell morphology were evaluated by histology and electron microscopy. Despite the cultivation on 3D scaffolds, the cell differentiation on all transplant types didn't reach the levels of native cartilage. Gene expression highly differed between the transplant types. The highest differentiation of cells (Col2/Col1 ratio) was found in CaReS®, followed by Novocart®3D, Hyalograft®C and MACI®. IL-1β expression also exhibited high differences between the scaffolds showing low expression levels in Novocart®3D and CaReS® and higher expression levels in MACI® and Hyalograft®C. Our data indicate that scaffold characteristics as well as culture conditions highly influence gene expression in cartilage transplants and that these parameters may have profound impact on the tissue regeneration after MACT.

The influence of scaffold architecture on chondrocyte distribution and behavior in matrix-associated chondrocyte transplantation grafts

Scaffold architecture and composition are important parameters in cartilage tissue engineering. In this in vitro study, we compared the morphology of four different cell-graft systems applied in clinical cartilage regeneration and analyzed the cell distribution (DAPI nuclei staining) and cell–scaffold interaction (SEM, TEM). Our investigations revealed major differences in cell distribution related to scaffold density, pore size and architecture. Material composition influenced the quantity of autogenous matrix used for cellular adhesion. Cell bonding was further influenced by the geometry of the scaffold subunits. On scaffolds with widely spaced fibers and a thickness less than the cell diameter, chondrocytes surrounded the scaffold fibers with cell extensions. On those fibers, chondrocytes were spherical, suggesting a differentiated phenotype. Fiber sizes smaller than chondrocyte size, and widely spaced, are therefore beneficial in terms of improved adhesion by cell shape adaptation. They also support the differentiated stage of chondrocytes by preventing the fibroblast-like and polygonal cell shape, at least briefly.

Regression error estimation significantly improves the region‐of‐interest statistics of noisy MR images

The region-of-interest (ROI) selection and evaluation is one of the key factors in the successful evaluation of radiological images. However, the presence of noise in images may lead to incorrect diagnosis. The aim of this study was to test the hypothesis that the weighting by error estimation in ROI assessment might significantly improve the validity of the results. As a model, the data maps of the transverse relaxation time constants (T2) from patients who underwent a matrix-associated chondrocyte transplantation procedure on the femoral condyle were analyzed. Artificial noise with a Rician density probability distribution was added to each TE image. ROIs were processed either as a regular arithmetic mean or as a weighted mean, in which weighted coefficients were calculated with regard to fitting error estimates [coefficient of determination (R2); root mean squared error (RMSE), mean absolute error (MSE), mean squared error (MAE), and chi-squared error (chi2)]. The global T2 values in repair tissue (mean +/- standard deviation, 62 +/- 7 ms; range 51-70 ms) and in healthy cartilage (mean +/- SD, 49 +/- 6 ms; range 40-60 ms) were significantly different (p < 0.001). With a 45% or greater decrease from the original SNR value (corresponding to a noise level of 35% of random value), the statistical significance was lost (P > 0.05); however, the use of the coefficient of determination (R2) as a correction factor was able to maintain the p-value of < 0.05 up to a 56% decrease from the original SNR value. The results of this study can prospectively be applied in a wide range of radiological imaging techniques in cases when error estimation is possible. Our analysis on MR images with artificially added noise showed that utilization of the correlation of determination (R2) as a weighting parameter in ROI evaluation may significantly improve the differentiation between native and transplanted cartilage tissue in noisy images. This could be an added benefit in the non-invasive monitoring of the post-operative status of patients with cartilage transplants if the MR images are not ideal (e.g., lower field strength or lower SNR).

Cell-Laden and Cell-Free Matrix-Induced Chondrogenesis versus Microfracture for the Treatment of Articular Cartilage Defects: A Histological and Biomechanical Study in Sheep.

Objective:The aim of this study was to evaluate the regenerative potential of cell-laden and cell-free collagen matrices in comparison to microfracture treatment applied to full-thickness chondral defects in an ovine model.Methods:Animals (n = 30) were randomized into 5 treatment groups, and 7-mm full-cartilage-thickness defects were set at the trochlea and medial condyle of both knee joints and treated as follows: 2 scaffolds in comparison (collagen I/III, Chondro-Gide®; collagen II, Chondrocell®) for covering microfractured defects (autologous matrix-induced chondrogenesis), both scaffolds colonized in vitro with autologous chondrocytes (matrix-associated chondrocyte transplantation), or scaffold-free microfracture technique. One year after surgery, cartilage lesions were biomechanically (indentation test), histologically (O’Driscoll score), and immunohistochemically (collagen type I and II staining) evaluated.Results:All treatment groups of the animal model induced more repair tissue and showed better histological scores and biomechanical properties compared to controls. The average thickness of the repair tissue was significantly greater when a scaffold was used, especially the collagen I/III membrane. However, none of the index procedures surpassed the others from a biomechanical point of view or based on the histological scoring. Collagen type II expression was better in condylar defects compared to the trochlea, especially in those treated with collagen I/III membranes.Conclusion:Covering of defects with suitable matrices promotes repair tissue formation and is suggested to be a promising treatment option for cartilage defects. However, it failed to improve the biomechanical and histological properties of regenerated articular cartilage compared to microfracture alone in an ovine model under the given circumstances.

Regulative Mechanisms of Chondrocyte Adhesion

Interaction between chondrocytes and extracellular matrix is considered a key factor in the generation of grafts for matrix-associated chondrocyte transplantation. Therefore, our objective was to study the influence of differentiation status on cellular attachment. Adhesion of chondrocytes to collagen type II increased after removal from native cartilage up to the third day in monolayer in a dose-dependent manner. Following dedifferentiation after the second passage, adhesion to collagen types I (-84%) and II (-46%) decreased, whereas adhesion to fibrinogen (+59%) and fibronectin (+43%) increased. A cartilage construct was developed based on a clinically established collagen type I scaffold. In this matrix, more than 80% of the cells could be immobilized by mechanisms of adhesion, filtration, and cell entrapment. Confocal laser microscopy revealed focal adhesion sites as points of cell-matrix interaction, as well as collagen type II expression in the cartilage graft after two weeks of in vitro cultivation. Basic fibroblast growth factor (bFGF) treated chondrocytes showed increased adhesion to collagen types I and II, fibronectin, and fibrinogen. Attachment to these investigated proteins significantly enhanced cell proliferation. Matrix design in cartilage engineering must meet the biological demands of amplified cells, because adhesion of chondrocytes depends on their differentiation status and is regulated by bFGF.