Background:
Osteoarthritis (OA) is a degenerative joint disease leading to pain and disability for which no curative treatment exists. A promising biological treatment for OA is intra-articular ...administration of platelet-rich plasma (PRP). PRP injections in OA joints can relieve pain, although the exact working mechanism is unclear.
Purpose:
To examine the effects of PRP releasate (PRPr) on pain, cartilage damage, and synovial inflammation in a mouse OA model.
Study Design:
Controlled laboratory study.
Methods:
OA was induced unilaterally in the knees of male mice (n = 36) by 2 intra-articular injections of collagenase at days –7 and –5. At day 0, pain was measured by registering weight distribution on the hindlimbs, after which mice were randomly divided into 2 groups. Mice received 3 intra-articular injections of PRP or saline in the affected knee. Seven mice per group were euthanized at day 5 for assessment of early synovial inflammation and cartilage damage. Pain in the remaining mice was registered for a total of 3 weeks. These mice were euthanized at day 21 for assessment of cartilage damage and synovial inflammation on histological evaluation. Antibodies against iNOS, CD163, and CD206 were used to identify different subtypes of macrophages in the synovial membrane.
Results:
Mice in the PRPr group increased the distribution of weight on the affected joint in 2 consecutive weeks after the start of the treatment (P < .05), whereas mice in the saline group did not. At day 21, PRPr-injected knees had a thinner synovial membrane (P < .05) and a trend toward less cartilage damage in the lateral joint compartment (P = .053) than saline-injected knees. OA knees treated with saline showed less anti-inflammatory (CD206+ and CD163+) cells at day 5 than healthy knees, an observation that was not made in the PRPr-treated group. A higher level of pain at day 7 was associated with a thicker synovial membrane at day 21. The presence of CD206+ cells was negatively associated with synovial membrane thickness.
Conclusion:
In a murine OA model, multiple PRPr injections reduced pain and synovial thickness, possibly through modulation of macrophage subtypes.
Clinical Relevance:
PRPr injections in early OA or shortly after joint trauma can reduce pain and synovial inflammation and may inhibit OA development in patients.
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Introduction: the impaired repair capacity of cartilage and the beginning of cell therapy
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Autologous chondrocyte implantation
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Combination products
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Randomized controlled studies
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Choice ...of cell types
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Regulating cellular activities
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Influence of growth factors on chondrogenic differentiation
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Influence of growth factors on matrix deposition
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Supportive effect of biomaterials
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Interference of inflammation with cartilage repair
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Tracking of transplanted cells in vivo
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Conclusion and future directions
Since the first cell therapeutic study to repair articular cartilage defects in the knee in 1994, several clinical studies have been reported. An overview of the results of clinical studies did not conclusively show improvement over conventional methods, mainly because few studies reach level I of evidence for effects on middle or long term. However, these explorative trials have provided valuable information about study design, mechanisms of repair and clinical outcome and have revealed that much is still unknown and further improvements are required. Furthermore, cellular and molecular studies using new technologies such as cell tracking, gene arrays and proteomics have provided more insight in the cell biology and mechanisms of joint surface regeneration. Besides articular cartilage, cartilage of other anatomical locations as well as progenitor cells are now considered as alternative cell sources. Growth Factor research has revealed some information on optimal conditions to support cartilage repair. Thus, there is hope for improvement. In order to obtain more robust and reproducible results, more detailed information is needed on many aspects including the fate of the cells, choice of cell type and culture parameters. As for the clinical aspects, it becomes clear that careful selection of patient groups is an important input parameter that should be optimized for each application. In addition, the study outcome parameters should be improved. Although reduced pain and improved function are, from the patient's perspective, the most important outcomes, there is a need for more structure/tissue‐related outcome measures. Ideally, criteria and/or markers to identify patients at risk and responders to treatment are the ultimate goal for these more sophisticated regenerative approaches in joint surface repair in particular, and regenerative medicine in general.
Macrophages play an important role in the development and progression of osteoarthritis (OA). The aim of this study was to identify macrophage phenotypes in synovium and monocyte subsets in ...peripheral blood in C57BL/6 mice by destabilizing the medial meniscus (DMM), and the association of macrophage subsets with OA features. DMM, sham, and non‐operated knees were histologically assessed between 1 and 56 days for macrophage polarization states by immunohistochemistry (IHC), cartilage damage, synovial thickening, and osteophytes (n = 9 per timepoint). Naive knees (n = 6) were used as controls. Monocyte and polarized synovial macrophage subsets were evaluated by flow cytometry. CD64 and CD206 levels on IHC were higher at early timepoints in DMM and sham knees compared to naive knees. iNOS labeling intensity was higher in DMM and sham knees than in naive knees from d3 onwards. CD163 expression was unaltered at all timepoints. Even though macrophage polarization profiles were similar in DMM and sham knees, only in DMM knees the presence of iNOS and CD206 associated with synovial thickness, and CD163 staining inversely correlated with osteophyte presence. At day 14, monocyte subset distribution was different in peripheral blood of DMM mice compared with sham mice. In conclusion, monocyte subsets in blood and synovial macrophage phenotypes vary after joint surgery. High levels of iNOS+, CD163+, and CD206+ cells are found in both destabilized and sham‐operated knees, and coexistence with joint instability may be a requirement to initiate and exacerbate OA progression.
Background and purpose
Corticosteroids such as triamcinolone acetonide (TAA) are potent drugs administered intra‐articularly as an anti‐inflammatory therapy to relieve pain associated with ...osteoarthritis (OA). However, the ability of early TAA intervention to mitigate OA progression and modulate immune cell subsets remains unclear. Here, we sought to understand the effect of early intra‐articular injection of TAA on OA progression, local macrophages, and peripheral blood monocytes.
Experimental approach
Degenerative joint disease was induced by intra‐articular injection of collagenase into the knee joint of male C57BL/6 mice. After 1 week, TAA or saline was injected intra‐articularly. Blood was taken throughout the study to analyse monocyte subsets. Mice were killed at days 14 and 56 post‐induction of collagenase‐induced OA (CiOA) to examine synovial macrophages and structural OA features.
Key results
The percentage of macrophages relative to total live cells present within knee joints was increased in collagenase‐ compared with saline‐injected knees at day 14 and was not altered by TAA treatment. However, at day 56, post‐induction of CiOA, TAA‐treated knees had increased levels of macrophages compared with the knees of untreated CiOA‐mice. The distribution of monocyte subsets present in peripheral blood was not altered by TAA treatment during the development of CiOA. Osteophyte maturation was increased in TAA‐injected knees at day 56.
Conclusion and implications
Intra‐articular injection of TAA increases long‐term synovial macrophage numbers and osteophytosis. Our findings suggest that TAA accentuates the progression of osteoarthritis‐associated features when applied to an acutely inflamed knee.
Purpose
To evaluate in vivo T
2
mapping as quantitative, imaging-based biomarker for meniscal degeneration in humans, by studying the correlation between T
2
relaxation time and degree of ...histological degeneration as reference standard.
Methods
In this prospective validation study, 13 menisci from seven patients with radiographic knee osteoarthritis (median age 67 years, three males) were included. Menisci were obtained during total knee replacement surgery. All patients underwent pre-operative magnetic resonance imaging using a 3-T MR scanner which included a T
2
mapping pulse sequence with multiple echoes. Histological analysis of the collected menisci was performed using the Pauli score, involving surface integrity, cellularity, matrix organization, and staining intensity. Mean T
2
relaxation times were calculated in meniscal regions of interest corresponding with the areas scored histologically, using a multi-slice multi-echo postprocessing algorithm. Correlation between T
2
mapping and histology was assessed using a generalized least squares model fit by maximum likelihood.
Results
The mean T
2
relaxation time was 22.4 ± 2.7 ms (range 18.5–27). The median histological score was 10, IQR 7–11 (range 4–13). A strong correlation between T
2
relaxation time and histological score was found (
r
s
= 0.84, CI 95% 0.64–0.93).
Conclusion
In vivo T
2
mapping of the human meniscus correlates strongly with histological degeneration, suggesting that T
2
mapping enables the detection and quantification of early compositional changes of the meniscus in knee OA.
Key Points
• Prospective histology-based study showed that in vivo T
2
mapping of the human meniscus correlates strongly with histological degeneration.
• Meniscal T
2
mapping allows detection and quantifying of compositional changes, without need for contrast or special MRI hardware.
• Meniscal T
2
mapping provides a biomarker for early OA, potentially allowing early treatment strategies and prevention of OA progression.
Abstract The most dreaded complication of colorectal surgery is anastomotic leakage. Adipose tissue-derived stem cell sheets (ASC sheets) prepared from temperature-responsive culture surfaces can be ...easily transplanted onto tissues. These sheets are proposed to improve cell transplant efficiency and enhance wound healing. The aim of this study was to investigate whether application of ASC sheets could prevent leakage of sutured colorectal anastomoses. Insufficient suturing of colorectal anastomoses was performed in Wistar rats to create a colorectal anastomotic leakage model. Rats were randomized to ASC sheet application or control group. Leakage, abscess formation, adhesion formation, anastomotic bursting pressure (ABP), and histology were evaluated on postoperative day 3 or 7. ASC sheet application significantly reduced anastomotic leakage compared to controls, without increased adhesion formation. ASC sheet transplantation resulted in more CD3+ T-cells and CD163+ anti-inflammatory macrophages at the anastomotic site than the control group. ABP, vessel density and collagen deposition were not different between groups. Using cell sheet technology, we generated ASC sheets that prevented disruption of sutured colorectal anastomoses as shown by reduced leakage. Increased numbers of anti-inflammatory macrophages and T-cells might have contributed to this positive effect.
Summary Objective Macrophages play a crucial role in the progression of osteoarthritis (OA). Their phenotype may range from pro-inflammatory to anti-inflammatory. The aim of this study was to ...evaluate the direct effect of macrophage subtypes on cartilage by culturing macrophage conditioned medium (MCM) on human articular cartilage. Design Human OA cartilage explants were cultured with MCM of pro-inflammatory M(IFNγ+TNFα), or anti-inflammatory M(IL-4) or M(IL-10) human monocyte-derived macrophages. To assess effects of anti-inflammatory macrophages, the cartilage was cultured with a combination of MCM phenotypes as well as pre-stimulated with IFNγ+TNFα cartilage before culture with MCM. The reaction of the explants were assessed by gene expression, nitric oxide (NO) production and release of glycosaminoglycans (GAGs). Results M(IFNγ+TNFα) MCM affected OA cartilage by upregulation of IL1B (Interleukin 1β), IL6 , MMP13 (Matrix Metalloproteinase-13) and ADAMTS5 (A Disintegrin And Metalloproteinase with Thrombospondin Motifs-5), while inhibiting ACAN (aggrecan) and COL2A1 (collagen type II). M(IL-10) upregulated IL1B and Suppressor of cytokine signaling 1 ( SOCS1 ). NO production and GAG release by the cartilage was increased when cultured in M(IFNγ+TNFα) MCM. M(IL4) and M(IL-10) did not inhibit the effects of M(IFNγ+TNFα) and MCM of neither phenotype affected IFNγ+TNFα pre-stimulated cartilage, in which an inflammatory gene response was deliberately induced. Conclusion M(IFNγ+TNFα) macrophages have a prominent direct effect on OA cartilage, while M(IL-4) and M(IL-10) do not inhibit the effects of M(IFNγ+TNFα), or IFNγ+TNFα induced inflammation of the cartilage. Therapies aiming at inhibiting cartilage degeneration may take this into account by directing suppression of pro-inflammatory macrophages or stimulation of anti-inflammatory macrophages.
Knee osteoarthritis (OA) is a condition mainly characterized by cartilage degradation. Currently, no effective treatment exists to slow down the progression of OA-related cartilage damage. Selective ...COX-2 inhibitors may, next to their pain killing properties, act chondroprotective in vivo. To determine whether the route of administration is important for the efficacy of the chondroprotective properties of selective COX-2 inhibitors, a systematic review was performed according to the PRISMA guidelines. Studies investigating OA-related cartilage damage of selective COX-2 inhibitors in vivo were included. Nine of the fourteen preclinical studies demonstrated chondroprotective effects of selective COX-2 inhibitors using systemic administration. Five clinical studies were included and, although in general non-randomized, failed to demonstrate chondroprotective actions of oral selective COX-2 inhibitors. All of the four preclinical studies using bolus intra-articular injections demonstrated chondroprotective actions, while one of the three preclinical studies using a slow release system demonstrated chondroprotective actions. Despite the limited evidence in clinical studies that have used the oral administration route, there seems to be a preclinical basis for considering selective COX-2 inhibitors as disease modifying osteoarthritis drugs when used intra-articularly. Intra-articularly injected selective COX-2 inhibitors may hold the potential to provide chondroprotective effects in vivo in clinical studies.
Adipose tissue-derived stem cells (ASCs) are known to be tissue-healing promoters due to their cellular plasticity and secretion of paracrine factors. Cultured ASC sheets provide a novel method of ...ASC application and can retain ASCs at the targeted tissue. The purpose of this systematic review is to evaluate preclinical studies using ASC sheet transplantation therapy for promoting tissue healing. First, we searched databases to identify studies of ASC sheet therapy in different experimental animal models, and then determined the quality score of studies using SYRCLE's risk bias tool. A total of 18 included studies examined the role of ASC sheets on tissue healing and function in models for myocardial infarction, dilated cardiomyopathy, full-thickness skin wounds, hind limb ischemia, esophageal strictures, and oral ulcers. ASC sheet application after myocardial infarction improved survival rate, cardiac function, and capillary density and reduced the extent of fibrosis. Application of ASC sheets to a full-thickness skin wound decreased the wound size and stimulated wound maturation. In the hind limb ischemia model, ASC sheet application improved limb perfusion and capillary density, and decreased the amount of ischemic tissue and inflammation. ASC sheet application to mucosal wounds of the digestive tract accelerated wound healing and decreased the degree of stricture and fibrosis. Taken together, transplanted ASC sheets had a positive effect on tissue healing and reconstruction in these preclinical studies. The reported favorable effects of ASC sheet therapy in various tissue healing applications may be implemented in future translational studies. It is suggested that future preclinical animal model studies of ASC sheet therapy should concern standardization of culture techniques and investigate the mechanisms of action. In addition, clearly indicated experimental setups according to the SYRCLE's guidelines should improve study quality and validity.
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