Population doublings and percentage of S100-positive cells as predictors of in vitro chondrogenicity of expanded human articular chondrocytes

The aim of this study was to investigate the interconnection between the processes of proliferation, dedifferentiation, and intrinsic redifferentiation (chondrogenic) capacities of human articular chondrocyte (HAC), and to identify markers linking HAC dedifferentiation status with their chondrogenic potential. Cumulative population doublings (PD) of HAC expanded in monolayer culture were determined, and a threshold range of 3.57-4.19 PD was identified as indicative of HAC loss of intrinsic chondrogenic capacity in pellets incubated without added chondrogenic factors. While several specific gene and surface markers defined early HAC dedifferentiation process, no clear correlation with the loss of intrinsic chondrogenic potential could be established. CD90 expression during HAC monolayer culture revealed two subpopulations, with sorted CD90-negative cells showing lower proliferative capacity and higher chondrogenic potential compared to CD90-positive cells. Although these data further validated PD as critical for in vitro chondrogenesis, due to the early shift in expression, CD90 could not be considered for predicting chondrogenic potential of HAC expanded for several weeks. In contrast, an excellent mathematically modeled correlation was established between PD and the decline of HAC expressing the intracellular marker S100, providing a direct link between the number of cell divisions and dedifferentiation/loss of intrinsic chondrogenic capacity. Based on the dynamics of S100-positive HAC during expansion, we propose asymmetric cell division as a potential mechanism of HAC dedifferentiation, and S100 as a marker to assess chondrogenicity of HAC during expansion, of potential value for cell-based cartilage repair treatments.

T1 assessment of hip joint cartilage following intra-articular gadolinium injection: a pilot study

This pilot study defines the feasibility of cartilage assessment in symptomatic femoroacetabular impingement patients using intra-articular delayed gadolinium-enhanced MRI of cartilage (ia-dGEMRIC). Nine patients were scanned preliminary to study the contrast infiltration process into hip joint cartilage. Twenty-seven patients with symptomatic femoroacetabular impingement were subsequently scanned with intra-articular delayed gadolinium-enhanced MRI of cartilage. These T(1) findings were correlated to morphological findings. Zonal variations were studied. This pilot study demonstrates a significant difference between the pre- and postcontrast T(1) values (P < 0.001) remaining constant for 45 min. We noted higher mean T(1) values in morphologically normal-appearing cartilage than in damaged cartilage, which was statistically significant for all zones except the anterior-superior zone. Intraobserver (0.972) and interobserver correlation coefficients (0.933) were statistically significant. This study outlines the feasibility of intra-articular delayed gadolinium-enhanced MRI of cartilage for assessment of cartilage changes in patients with femoroacetabular impingement. It can also define the topographic extent and differing severities of cartilage damage.

Intravenous versus intra-articular delayed gadolinium-enhanced magnetic resonance imaging in the hip joint: a comparative analysis

The purpose of this study was to investigate whether T1-mapping of hip joint with intra-articular delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (ia-dGEMRIC) is comparable to the already established intravenous (iv)-technique for assessing different grades of cartilage degeneration.

The in vivo effects of unloading and compression on T1-Gd (dGEMRIC) relaxation times in healthy articular knee cartilage at 3.0 Tesla

The purpose was to investigate the in vivo effects of unloading and compression on T1-Gd relaxation times in healthy articular knee cartilage.

Micromass co-culture of human articular chondrocytes and human bone marrow mesenchymal stem cells to investigate stable neocartilage tissue formation in vitro

Cell therapies for articular cartilage defects rely on expanded chondrocytes. Mesenchymal stem cells (MSC) represent an alternative cell source should their hypertrophic differentiation pathway be prevented. Possible cellular instruction between human articular chondrocytes (HAC) and human bone marrow MSC was investigated in micromass pellets. HAC and MSC were mixed in different percentages or incubated individually in pellets for 3 or 6 weeks with and without TGF-beta1 and dexamethasone (±T±D) as chondrogenic factors. Collagen II, collagen X and S100 protein expression were assessed using immunohistochemistry. Proteoglycan synthesis was evaluated applying the Bern score and quantified using dimethylmethylene blue dye binding assay. Alkaline phosphatase activity (ALP) was detected on cryosections and soluble ALP measured in pellet supernatants. HAC alone generated hyaline-like discs, while MSC formed spheroid pellets in ±T±D. Co-cultured pellets changed from disc to spheroid shape with decreasing number of HAC, and displayed random cell distribution. In -T-D, HAC expressed S100, produced GAG and collagen II, and formed lacunae, while MSC did not produce any cartilage-specific proteins. Based on GAG, collagen type II and S100 expression chondrogenic differentiation occurred in -T-D MSC co-cultures. However, quantitative experimental GAG and DNA values did not differ from predicted values, suggesting only HAC contribution to GAG production. MSC produced cartilage-specific matrix only in +T+D but underwent hypertrophy in all pellet cultures. In summary, influence of HAC on MSC was restricted to early signs of neochondrogenesis. However, MSC did not contribute to the proteoglycan deposition, and HAC could not prevent hypertrophy of MSC induced by chondrogenic stimuli.

T2 star relaxation times for assessment of articular cartilage at 3 T: a feasibility study

T2 mapping techniques use the relaxation constant as an indirect marker of cartilage structure, and the relaxation constant has also been shown to be a sensitive parameter for cartilage evaluation. As a possible additional robust biomarker, T2* relaxation time is a potential, clinically feasible parameter for the biochemical evaluation of articular cartilage.

The structure of articular cartilage

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A study of progress of labour using intrapartum translabial ultrasound, assessing head station, direction, and angle of descent

Intrapartum translabial ultrasound (ITU) has the potential to objectively and quantitatively assess the progress of labour. The relationships between the different ITU parameters and their development during normal term labour have not been studied.

Investigation of different apple cultivars by high resolution magic angle spinning NMR. A feasibility study

(1)H HR-MAS NMR spectroscopy was applied to apple tissue samples deriving from 3 different cultivars. The NMR data were statistically evaluated by analysis of variance (ANOVA), principal component analysis (PCA), and partial least-squares-discriminant analysis (PLS-DA). The intra-apple variability of the compounds was found to be significantly lower than the inter-apple variability within one cultivar. A clear separation of the three different apple cultivars could be obtained by multivariate analysis. Direct comparison of the NMR spectra obtained from apple tissue (with HR-MAS) and juice (with liquid-state HR NMR) showed distinct differences in some metabolites, which are probably due to changes induced by juice preparation. This preliminary study demonstrates the feasibility of (1)H HR-MAS NMR in combination with multivariate analysis as a tool for future chemometric studies applied to intact fruit tissues, e.g. for investigating compositional changes due to physiological disorders, specific growth or storage conditions.

Advanced morphological 3D magnetic resonance observation of cartilage repair tissue (MOCART) scoring using a new isotropic 3D proton-density, turbo spin echo sequence with variable flip angle distribution (PD-SPACE) compared to an isotropic 3D steady-state free precession sequence (True-FISP) and standard 2D sequences

To evaluate a new isotropic 3D proton-density, turbo-spin-echo sequence with variable flip-angle distribution (PD-SPACE) sequence compared to an isotropic 3D true-fast-imaging with steady-state-precession (True-FISP) sequence and 2D standard MR sequences with regard to the new 3D magnetic resonance observation of cartilage repair tissue (MOCART) score.

Evaluation of articular cartilage in patients with femoroacetabular impingement (FAI) using T2* mapping at different time points at 3.0 Tesla MRI: a feasibility study

To define the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration prior to surgery in patients with symptomatic femoroacetabular impingement (FAI), we compared cartilage of the hip joint in patients with FAI and healthy volunteers using T2* mapping at 3.0 Tesla over time.

Extra-articular fractures of the proximal phalanges of the fingers: a comparison of 2 methods of functional, conservative treatment

For nonsurgical treatment of fractures of the proximal phalanges of the triphalangeal fingers, different dynamic casts have been described. The main principle behind these casts is advancement and tightening of the extensor hood, caused by a combination of blocking the metacarpophalangeal joints in flexion and actively flexing the proximal interphalangeal joints. In contrast to established treatment protocols using functional forearm casts, the Lucerne cast allows for free mobilization of the wrist joint. The purpose of the current multicenter study was to compare the results of conservative, functional treatment using 2 different methods, either a forearm cast or a Lucerne cast.

Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.