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Purpose
Hypertrophic cartilage is an important characteristic of osteoarthritis and can often be found in patients suffering from osteoarthritis. Although the exact pathomechanism remains poorly understood, hypertrophic de-differentiation of chondrocytes also poses a major challenge in the cell-based repair of hyaline cartilage using mesenchymal stromal cells (MSCs). While different members of the transforming growth factor beta (TGF-β) family have been shown to promote chondrogenesis in MSCs, the transition into a hypertrophic phenotype remains a problem. To further examine this topic we compared the effects of the transcription growth and differentiation factor 5 (GDF-5) and the mutant R57A on in vitro chondrogenesis in MSCs.
Methods
Bone marrow-derived MSCs (BMSCs) were placed in pellet culture and in-cubated in chondrogenic differentiation medium containing R57A, GDF-5 and TGF-ß1 for 21 days. Chondrogenesis was examined histologically, immunohistochemically, through biochemical assays and by RT-qPCR regarding the expression of chondrogenic marker genes.
Results
Treatment of BMSCs with R57A led to a dose dependent induction of chondrogenesis in BMSCs. Biochemical assays also showed an elevated glycosaminoglycan (GAG) content and expression of chondrogenic marker genes in corresponding pellets. While treatment with R57A led to superior chondrogenic differentiation compared to treatment with the GDF-5 wild type and similar levels compared to incubation with TGF-ß1, levels of chondrogenic hypertrophy were lower after induction with R57A and the GDF-5 wild type.
Conclusions
R57A is a stronger inducer of chondrogenesis in BMSCs than the GDF-5 wild type while leading to lower levels of chondrogenic hypertrophy in comparison with TGF-ß1.
(1) Background: The mesenchymal stromal cells (MSCs) of different tissue origins are applied in cell-based chondrogenic regeneration. However, there is a lack of comparability determining the most suitable cell source for the tissue engineering (TE) of cartilage. The purpose of this study was to compare the in vitro chondrogenic potential of MSC-like cells from different tissue sources (bone marrow, meniscus, anterior cruciate ligament, synovial membrane, and the infrapatellar fat pad removed during total knee arthroplasty (TKA)) and define which cell source is best suited for cartilage regeneration. (2) Methods: MSC-like cells were isolated from five donors and expanded using adherent monolayer cultures. Differentiation was induced by culture media containing specific growth factors. Transforming growth factor (TGF)-ß1 was used as the growth factor for chondrogenic differentiation. Osteogenesis and adipogenesis were induced in monolayer cultures for 27 days, while pellet cell cultures were used for chondrogenesis for 21 days. Control cultures were maintained under the same conditions. After, the differentiation period samples were analyzed, using histological and immunohistochemical staining, as well as molecularbiological analysis by RT-PCR, to assess the expression of specific marker genes. (3) Results: Plastic-adherent growth and in vitro trilineage differentiation capacity of all isolated cells were proven. Flow cytometry revealed the clear co-expression of surface markers CD44, CD73, CD90, and CD105 on all isolated cells. Adipogenesis was validated through the formation of lipid droplets, while osteogenesis was proven by the formation of calcium deposits within differentiated cell cultures. The formation of proteoglycans was observed during chondrogenesis in pellet cultures, with immunohistochemical staining revealing an increased relative gene expression of collagen type II. RT-PCR proved an elevated expression of specific marker genes after successful differentiation, with no significant differences regarding different cell source of native tissue. (4) Conclusions: Irrespective of the cell source of native tissue, all MSC-like cells showed multipotent differentiation potential in vitro. The multipotent differentiation capacity did not differ significantly, and chondrogenic differentiation was proven in all pellet cultures. Therefore, cell suitability for cell-based cartilage therapies and tissue engineering is given for various tissue origins that are routinely removed during total knee arthroplasty (TKA). This study might provide essential information for the clinical tool of cell harvesting, leading to more flexibility in cell availability.
Objective
As native cartilage consists of different phenotypical zones, this study aims to fabricate different types of neocartilage constructs from collagen hydrogels and human mesenchymal stromal cells (MSCs) genetically modified to express different chondrogenic factors.
Design
Human MSCs derived from bone-marrow of osteoarthritis (OA) hips were genetically modified using adenoviral vectors encoding sex-determining region Y-type high-mobility-group-box (SOX)9,transforming growth factor beta (TGFB) 1or bone morphogenetic protein (BMP) 2cDNA, placed in type I collagen hydrogels and maintained in serum-free chondrogenic media for three weeks. Control constructs contained unmodified MSCs or MSCs expressing GFP. The respective constructs were analyzed histologically, immunohistochemically, biochemically, and by qRT-PCR for chondrogenesis and hypertrophy.
Results
Chondrogenesis in MSCs was consistently and strongly induced in collagen I hydrogels by the transgenesSOX9,TGFB1andBMP2as evidenced by positive staining for proteoglycans, chondroitin-4-sulfate (CS4) and collagen (COL) type II, increased levels of glycosaminoglycan (GAG) synthesis, and expression of mRNAs associated with chondrogenesis. The control groups were entirely non-chondrogenic. The levels of hypertrophy, as judged by expression of alkaline phosphatase (ALP) and COL X on both the protein and mRNA levels revealed different stages of hypertrophy within the chondrogenic groups (BMP2>TGFB1>SOX9).
Conclusions
Different types of neocartilage with varying levels of hypertrophy could be generated from human MSCs in collagen hydrogels by transfer of genes encoding the chondrogenic factorsSOX9,TGFB1andBMP2. This technology may be harnessed for regeneration of specific zones of native cartilage upon damage.
PMMA bone cement: antibiotic elution and mechanical properties in the context of clinical use
(2022)
This literature review discusses the use of antibiotic loaded polymethylmethacrylate bone cements in arthroplasty. The clinically relevant differences that have to be considered when antibiotic loaded bone cements (ALBC) are used either for long-term implant fixation or as spacers for the treatment of periprosthetic joint infections are outlined. In this context, in vitro findings for antibiotic elution and material properties are summarized and transferred to clinical use.
Background
While multiple in vitro studies examined mesenchymal stromal cells (MSCs) derived from bone marrow or hyaline cartilage, there is little to no data about the presence of MSCs in the joint capsule or the ligamentum capitis femoris (LCF) of the hip joint. Therefore, this in vitro study examined the presence and differentiation potential of MSCs isolated from the bone marrow, arthritic hyaline cartilage, the LCF and full-thickness samples of the anterior joint capsule of the hip joint.
Methods
MSCs were isolated and multiplied in adherent monolayer cell cultures. Osteogenesis and adipogenesis were induced in monolayer cell cultures for 21 days using a differentiation medium containing specific growth factors, while chondrogenesis in the presence of TGF-ss1 was performed using pellet-culture for 27 days. Control cultures were maintained for comparison over the same duration of time. The differentiation process was analyzed using histological and immunohistochemical stainings as well as semiquantitative RT-PCR for measuring the mean expression levels of tissue-specific genes.
Results
This in vitro research showed that the isolated cells from all four donor tissues grew plastic-adherent and showed similar adipogenic and osteogenic differentiation capacity as proven by the histological detection of lipid droplets or deposits of extracellular calcium and collagen type I. After 27 days of chondrogenesis proteoglycans accumulated in the differentiated MSC-pellets from all donor tissues. Immunohistochemical staining revealed vast amounts of collagen type II in all differentiated MSC-pellets, except for those from the LCF. Interestingly, all differentiated MSCs still showed a clear increase in mean expression of adipogenic, osteogenic and chondrogenic marker genes. In addition, the examination of an exemplary selected donor sample revealed that cells from all four donor tissues were clearly positive for the surface markers CD44, CD73, CD90 and CD105 by flow cytometric analysis.
Conclusions
This study proved the presence of MSC-like cells in all four examined donor tissues of the hip joint. No significant differences were observed during osteogenic or adipogenic differentiation depending on the source of MSCs used. Further research is necessary to fully determine the tripotent differentiation potential of cells isolated from the LCF and capsule tissue of the hip joint.
Objectives
The long head of the biceps (LHB) is often resected in shoulder surgery and could therefore serve as a cell source for tissue engineering approaches in the shoulder. However, whether it represents a suitable cell source for regenerative approaches, both in the inflamed and non-inflamed states, remains unclear. In the present study, inflamed and native human LHBs were comparatively characterized for features of regeneration.
Methods
In total, 22 resected LHB tendons were classified into inflamed samples (n = 11) and non-inflamed samples (n = 11). Proliferation potential and specific marker gene expression of primary LHB-derived cell cultures were analyzed. Multipotentiality, including osteogenic, adipogenic, chondrogenic, and tenogenic differentiation potential of both groups were compared under respective lineage-specific culture conditions.
Results
Inflammation does not seem to affect the proliferation rate of the isolated tendon-derived stem cells (TDSCs) and the tenogenic marker gene expression. Cells from both groups showed an equivalent osteogenic, adipogenic, chondrogenic and tenogenic differentiation potential in histology and real-time polymerase chain reaction (RT-PCR) analysis.
Conclusion
These results suggest that the LHB tendon might be a suitable cell source for regenerative approaches, both in inflamed and non-inflamed states. The LHB with and without tendinitis has been characterized as a novel source of TDSCs, which might facilitate treatment of degeneration and induction of regeneration in shoulder surgery.
Background
For improved outcomes in total knee arthroplasty (TKA) correct implant fitting and positioning are crucial. In order to facilitate a best possible implant fitting and positioning patient-specific systems have been developed. However, whether or not these systems allow for better implant fitting and positioning has yet to be elucidated. For this reason, the aim was to analyse the novel patient-specific cruciate retaining knee replacement system iTotal (TM) CR G2 that utilizes custom-made implants and instruments for its ability to facilitate accurate implant fitting and positioning including correction of the hip-knee-ankle angle (HKA).
Methods
We assessed radiographic results of 106 patients who were treated with the second generation of a patient-specific cruciate retaining knee arthroplasty using iTotal\(^{TM}\) CR G2 (ConforMIS Inc.) for tricompartmental knee osteoarthritis (OA) using custom-made implants and instruments. The implant fit and positioning as well as the correction of the mechanical axis (hip-knee-ankle angle, HKA) and restoration of the joint line were determined using pre- and postoperative radiographic analyses.
Results
On average, HKA was corrected from 174.4 degrees +/- 4.6 degrees preoperatively to 178.8 degrees +/- 2.2 degrees postoperatively and the coronal femoro-tibial angle was adjusted on average 4.4 degrees. The measured preoperative tibial slope was 5.3 degrees +/- 2.2 degrees (mean +/- SD) and the average postoperative tibial slope was 4.7 degrees +/- 1.1 degrees on lateral views. The joint line was well preserved with an average modified Insall-Salvati index of 1.66 +/- 0.16 pre- and 1.67 +/- 0.16 postoperatively. The overall accuracy of fit of implant components was decent with a measured medial overhang of more than 1 mm (1.33 mm +/- 0.32 mm) in 4 cases only. Further, a lateral overhang of more than 1 mm (1.8 mm +/- 0.63) (measured in the anterior-posterior radiographs) was observed in 11 cases, with none of the 106 patients showing femoral notching.
Conclusion
The patient-specific iTotal\(^{TM}\) CR G2 total knee replacement system facilitated a proper fitting and positioning of the implant components. Moreover, a good restoration of the leg axis towards neutral alignment was achieved as planned. Nonetheless, further clinical follow-up studies are necessary to validate our findings and to determine the long-term impact of using this patient- specific system.
Background:
To prevent bone loss in hip arthroplasty, several short stem systems have been developed, including the Mayo conservative hip system. While there is a plethora of data confirming inherent advantages of these systems, only little is known about potential complications, especially when surgeons start to use these systems.
Methods:
In this study, we present a retrospective analysis of the patients’ outcome, complications and the complication management of the first 41 Mayo conservative hips performed in 37 patients. For this reason, functional scores, radiographic analyses, peri- and postoperative complications were assessed at an average follow-up of 35 months.
Results:
The overall HHS improved from 61.2 pre-operatively to 85.6 post-operatively. The German Extra Short Musculoskeletal Function Assessment Questionnaire (XSFMA-D) improved from 30.3 pre-operatively to 12.2 post-operatively. The most common complication was an intraoperative non-displaced fracture of the proximal femur observed in 5 cases (12.1%). Diabetes, higher BMI and older ages were shown to be risk factors for these intra-operative periprosthetic fractures (p < 0.01). Radiographic analysis revealed a good offset reconstruction in all cases.
Conclusion:
In our series, a high complication rate with 12.1% of non-displaced proximal femoral fractures was observed using the Mayo conservative hip. This may be attributed to the flat learning curve of the system or the inherent patient characteristics of the presented cohort."
Purpose. Copal\(^®\) spacem is a new PMMA bone cement for fabricating spacers. This study compares elution of gentamicin, elution of vancomycin, and compressive strength of Copal\(^®\) spacem and of Palacos\(^®\) R+G at different vancomycin loadings in the powder of the cements. We hypothesized that antibiotic elution of Copal\(^®\) spacem is superior at comparable compressive strength. Methods. Compression test specimens were fabricated using Copal\(^®\) spacem manually loaded with 0.5 g gentamicin and additionally 2 g, 4 g, and 6 g of vancomycin per 40 g of cement powder (COP specimens) and using 0.5 g gentamicin premixed Palacos\(^®\) R+G manually loaded with 2 g, 4 g, and 6 g of vancomycin per 40 g of cement powder (PAL specimens). These specimens were used for determination of gentamicin and vancomycin elution (in fetal calf serum, at 22°C) and for determination of compressive strength both prior and following the elution tests. Results. Cumulative gentamicin concentrations (p < 0.005) and gentamicin concentration after 28 days (p ≤ 0.043) were significantly lower for COP specimens compared to PAL specimens. Cumulative vancomycin concentrations were significantly higher (p ≤ 0.043) for COP specimens after the second day. Vancomycin concentrations after 28 days were not significantly higher for the Copal specimens loaded with 2 g and 4 g of vancomycin. Compressive strength was not significantly different between COP specimens and PAL specimens before elution tests. Compressive strength after the elution tests was significantly lower (p = 0.005) for COP specimens loaded with 2 g of vancomycin. Conclusion. We could not demonstrate consistent superior antibiotic elution from Copal\(^®\) spacem compared to Palacos\(^®\) R+G for fabricating gentamicin and vancomycin loaded spacers. The results do not favor Copal\(^®\) spacem over Palacos\(^®\) R+G for the use as a gentamicin and vancomycin biantibiotic-loaded spacer.