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Knee osteoarthritis is the most prevalent joint disease worldwide and total knee arthroplasty (TKA) is often the only evidence-based treatment option left for patients with endstage osteoarthritis. The postoperative outcomes as well as the different rehabilitation procedures are most commonly evaluated by patient-reported outcome measurements (PROMs). However, in acute clinical-stage stages, performance-based measures were shown to yield greater responsiveness than PROMs, which failed to capture functional declines and may overestimate long-term functional improvements. Moreover, these tests represent a variety of daily life activities which helps to estimate whether a patient is functioning adequately prior to discharge from hospital and in the following rehabilitation. The ability to rise from a sitting position is one of those activities which is important for an elderly person to maintain an independent life. Also, it was shown that chair rising test performance is highly correlated with deviations in gait patterns. However, there is no data available yet if this test can be used at perioperative time-points in patients undergoing TKA and how reliable this test is. Therefore, this study investigates the reliability and the minimal detectable change and the development of the performance of the weight-balanced chair rising test in patients before and after TKA. This study was designed as a test-retest reliability study. Participants were recruited in an orthopedic hospital after they were scheduled for total knee arthroplasty. The participants performed two chair rising tests (five-times-sit-to-stand) on a ground reaction force plate at one-day preoperatively (M0), five days- (M1), ten days (M2)- and ten weeks postoperatively (M3). The test-retest reliability of the weight balanced asymmetry measured as ground reaction force in Newton was analyzed for each of the four time-points. Therefore, the minimal detectable change within a confidence interval of 95% (MDC95) and the ICC were calculated. 16 male and 8 female subjects (N=24) with a mean age of age 63,93 (±9,59) were included. The mean side-to-side difference in N was 138(±104) at M0, 319(±125) at M1, 254(±109) at M2 and 116(±74) at M3. The test-retest reliability ranged between ICC=.84-.96 at all four time points, indicating good to excellent reliability. The MDC95 ranges from 79–113 N. No adverse events were recorded after the performance of the test and no participants dropped out because of study-related reasons. The weight-balanced chair rising test shows good- to excellent reliability. After an initial decrease of loading symmetry at M1 and M2 preoperative levels are reached as early as at M3. The weight-balanced chair rising test provides objective data about loading symmetry during an activity of daily living. It is reliable and feasible to use in as well in-patient as out- patient rehabilitation of patients with TKA.
Human serum or FCS: Differentiation of human cartilage-like microtissues depends on serum selection
(2018)
Introduction: Regeneration of articular cartilage defects is limited. Hence, cell-based therapies for the treatment were developed using e.g. chondrocytes isolated from patient biopsies. For cell culture fetal calf serum (FCS) is often used as media supplement to establish engineering processes for transplants in regenerative medicine. However, the usage of xenogeneic serum could mask the intrinsic behavior of human cells in vitro. This could be particularly important for the dedifferentiation process during cell expansion and redifferentiation in 3D-culture. The aim of this study was to compare the development of microtissues derived from chondrocytes cultivated in presence of FCS with those cultivated in human serum (HS).
Material and Methods: Human articular chondrocytes isolated from knee joints were expanded in medium with HS or FCS. Scaffold-free microtissues were generated using the agar overlay technique. After four and eight weeks the macroscopic appearance (reflected-light microscopy) was documented and the size of the microtissues was determined. The differentiation degree was evaluated via histology to visualize typical glycosamino¬glycans (Safranin O, Alcian blue) and immunohisto¬chemistry (IH) to detect cartilage-specific markers (collagen type II, proteoglycans, COMP, Sox9) on cryosections.
Results and Conclusion: Cells from all donors in both medium compositions generated microtissues – but with distinct differences in the differentiation levels. Microtissues cultured in medium with FCS showed a higher differentiation level compared to microtissues in HS. This is evidenced by a higher amount of matrix resulting in bigger microtissues (diameter in FCS is 42% larger compared to HS) and a more cartilage-like composition of the matrix (not any/little colouring in HS versus intense staining in FCS). IH analysis showed the same pattern. Not any/less positivity for collagen type II, proteoglycan, COMP, and Sox9 in HS versus moderate-to-high positivity in FCS-cultured microtissues. Absolute values vary from donor to donor whereas an individualized expression profile only became visible in microtissues cultured in HS medium. HS should be preferred for the engineering of cartilage-like microtissues, as it rather enables a "human-based" situation in vitro.
Supported by „Gesundheitscampus Brandenburg“ and „Ministerium für Wissenschaft, Forschung und Kultur“, state of Brandenburg, Germany.
BACKGROUND: Tissue engineering has become a major field of research in biotechnology and biomedicine. As a consequence, cell-based therapeutic approaches are entering the hospitals, especially for skeletal regeneration. Traumatic injuries of cartilage are treated with autologous cell suspensions or in vitro generated cartilage tissues, but there is actually no therapy available for degenerative cartilage defects. However, Osteoarthritis (OA) is a major public health problem in the world affecting 240 million people globally.
OBJECTIVE: To develop suitable in vitro tissues, the properties of chondrogenic spheroids should be optimized via coculture with cells naturally occurring as joint neighbours.
METHODS: Human chondrocytes were isolated from condyles and propagated in monolayer culture. Scaffold-free spheroids were generated and co-cultured with joint-specific partner cells (osteoblast-like osteosarcoma cells, fibroblasts). Morphology and differentiation was analyzed using histochemistry (Alcian blue, Safranin O) and immunohistochemistry for cartilage markers (collagen type II, Sox9, proteoglycan), proliferation-associated protein (Ki67) and markers of connective tissue (collagen type I and actin).
RESULTS: The provision of a more natural microenvironment in vitro via co-culture of chondrocyte-based aggregates with osteoblast-like Saos-2 cells enhanced the differentiation potential of chondrogenic spheroids towards hyaline cartilage.
CONCLUSIONS: The study showed the positive influence of Saos-2 cells on the differentiation potential of human chondrocytes in co-culture.