| 1. |
- Blomgran, Parmis, et al.
(författare)
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A possible link between loading, inflammation and healing: Immune cell populations during tendon healing in the rat
- 2016
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 6:29824
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Tidskriftsartikel (refereegranskat)abstract
- Loading influences tendon healing, and so does inflammation. We hypothesized that the two are connected. 48 rats underwent Achilles tendon transection. Half of the rats received Botox injections into calf muscles to reduce mechanical loading. Cells from the regenerating tissue were analyzed by flow cytometry. In the loaded group, the regenerating tissue contained 83% leukocytes (CD45(+)) day 1, and 23% day 10. The M1/M2 macrophage ratio (CCR7/CD206) peaked at day 3, while T helper (CD3(+)CD4(+)) and T-reg cells (CD25(+) Foxp3(+)) increased over time. With Botox, markers associated with down-regulation of inflammation were more common day 5 (CD163, CD206, CD25, Foxp3), and M1 or M2 macrophages and T-reg cells were virtually absent day 10, while still present with full loading. The primary variable, CCR7/CD206 ratio day 5, was higher with full loading (p = 0.001) and the T-reg cell fraction was lower (p amp;lt; 0.001). Free cage activity loading is known to increase size and strength of the tendon in this model compared to Botox. Loading now appeared to delay the switch to an M2 type of inflammation with more T-reg cells. It seems a prolonged M1 phase due to loading might make the tendon regenerate bigger.
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| 2. |
- Blomgran, Parmis, 1985-, et al.
(författare)
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Cox-2 inhibition and the composition of inflammatory cell populations during early and mid-time tendon healing
- 2017
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Ingår i: Muscles, ligaments and Tendons journal. - Rome, Italy : CIC Edizioni Internazionali. - 2240-4554. ; 7:2, s. 223-229
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Tidskriftsartikel (refereegranskat)abstract
- Background: During early tendon healing, the cells within the regenerating tissue are, to a large part, inflammatory leukocytes (CD45+). In a rat Achilles tendon healing model, the inflammation resolves between 5 and 10 days. In the same model, Cox inhibitors (NSAIDs) impair healing when given during the first 5 days, but have a positive effect if given later. We tested the hypothesis that a Cox inhibitor would exert these effects by influencing inflammation, and thereby the composition of the inflammatory cell subpopulations.Methods: Achilles tendon transection was performed in 44 animals. Animals were randomized to either parecoxib or saline injections. Healing was evaluated by mechanical testing day 7 after surgery and by flow cytometry day 3 and 10.Results: Cross-sectional area, peak force and stiffness were reduced by parecoxib 31, 33, and 25% respectively (p=0.005, p=0.002, and p=0.005). By flow cytometry, there was a strong effect of time (p<0.001) on virtually all inflammatory cell subpopulations (CD45, CD11b, CD68, CCR7, CD163, CD206, CD3, CD4), but no significant effect of parecoxib at any time point.Conclusion: The results suggest that the negative effects of Cox inhibitors on tendon healing might be exerted mainly via mechanisms not directly related to inflammatory cells.
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| 3. |
- Blomgran, Parmis, et al.
(författare)
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Role of Macrophages During early Achilles Tendon Healing
- 2021
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Ingår i: MLTJ-MUSCLES LIGAMENTS AND TENDONS JOURNAL. - : EDRA SPA. - 2240-4554. ; 11:1, s. 15-21
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Tidskriftsartikel (refereegranskat)abstract
- Background. Macrophages are a heterogeneous cell population that plays an important role in the initiation of the inflammatory response to trauma as well as its resolution during healing. However, their role during Achilles tendon healing is unclear. The aim of this study was to investigate if macrophage reduction by using clodronate liposome inject ion would influence the mechanical properties of the healing tendon. Methods. The right Achilles tendon of 46 rats were transected and left to heal spontaneously (day 0). The reduction of macrophages during the inflammatory phase of tendon healing was studied by injecting clodronate liposomes day - 3, - 1 and 1. To study the early remodeling phase, clodronate was injected day 3, 5 and 7. The controls received saline and the rats were evaluated by mechanical testing day 7 and 12, respectively. Results. Clodronate injections during the inflammatory phase increased transverse area (p = 0.006) and stiffness (p = 0.044) day 7. In contrast, no significant effects were seen at day 12. Flow cytometry evaluation confirmed reduction of mature and polarized macrophages. Conclusions. Reduction of macrophages during the inflammatory phase of Achilles tendon healing influenced the mechanical properties, suggesting a regulatory role of macrophages during this phase.
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| 4. |
- Alim, Md Abdul, et al.
(författare)
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Increased mast cell degranulation and co-localization of mast cells with the NMDA receptor-1 during healing after Achilles tendon rupture
- 2017
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Ingår i: Cell and Tissue Research. - Berlin Heidelberg : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 370:3, s. 451-460
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Tidskriftsartikel (refereegranskat)abstract
- The role of inflammation and the mechanism of tendon healing after rupture has historically been a matter of controversy. The purpose of the present study is to investigate the role of mast cells and their relation to the NMDA receptor-1 (a glutamate receptor) during healing after Achilles tendon rupture. Eight female Sprague Dawley rats had their right Achilles tendon transected. Three weeks after rupture, histological quantification of mast cell numbers and their state of degranulation was assessed by histochemistry. Co-localization of mast cell tryptase (a mast cell marker) and NMDA receptor-1 was determined by immunofluorescence. The intact left Achilles tendon was used as control. An increased number of mast cells and a higher proportion of degranulated mast cells were found in the healing Achilles tendon compared to the intact. In addition, increased co-localization of mast cell tryptase and NMDA receptor-1 was seen in the areas of myotendinous junction, mid-tendon proper and bone tendon junction of the healing versus the intact tendon. These findings introduce a possible role for mast cells in the healing phase after Achilles tendon rupture.
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| 5. |
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| 6. |
- Blomgran, Parmis, 1985-
(författare)
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Inflammation and tendon healing
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tendons heal through three different overlapping phases; the inflammatory, proliferative and remodeling phase. Many studies have investigated what factors influence healing of tendons. However, little was known about inflammation and the immune cells present during Achilles tendon healing by the time this thesis started. We developed a flow cytometry method for our rat model of tendon healing, which enabled us to study different leukocyte subpopulations during Achilles tendon healing.The general aim of this thesis was to understand more about inflammation and the immune cell populations present during tendon healing and how the immune cell composition changes during normal tendon healing. Moreover, we investigated how different factors that are known to influence tendon healing affected the composition of the immune cell population.First, we described the immune cells during the time course of tendon healing focusing on different subpopulations of macrophages and T cells. Then, we studied how these cells were influenced by reduced mechanical loading. Mechanical loading prolonged the presence of M1 macrophages and delayed the switch to regulatory T cells and M2 macrophages compared to reduced mechanical loading. Next, the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on the leukocyte composition revealed that, even though NSAIDs influence the mechanical properties of healing tendon, this effect was not mediated via changes in the leukocyte sub-populations during early and mid-time tendon healing. Further, the effect of corticosteroids during the inflammatory and remodeling phases of tendon healing was an improved healing of tendons and a reduction of CD8a T cells when corticosteroid was administered after the inflammatory phase. Lastly, we investigated if impairment of tendon healing by NSAIDs was related to mechanotransduction or microdamage during mechanical loading and showed that NSAIDs impair tendon healing by reducing the response to microdamage.In conclusion, these studies show that inflammation plays an important role during Achilles tendon healing, and factors that influence healing can also alter the presence or polarization of immune cell populations.
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| 7. |
- Blomgran, Parmis, et al.
(författare)
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Systemic corticosteroids improve tendon healing when given after the early inflammatory phase
- 2017
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation initiates tendon healing and then normally resolves more or less completely. Unresolved inflammation might disturb the remodeling process. We hypothesized that suppression of inflammation during the early remodeling phase by systemic dexamethasone treatment can improve healing. 36 rats underwent Achilles tendon transection and were randomized to dexamethasone or saline on days 0-4 after surgery (early inflammatory phase), and euthanasia day 7. Another 54 rats received injections days 5-9 (early remodeling phase) and were euthanized day 12 for mechanical, histological and flow cytometric evaluation. Dexamethasone treatment days 0-4 reduced the cross-sectional area, peak force and stiffness by day 7 to less than half (p amp;lt; 0.001 for all), while material properties (peak stress and elastic modulus) were not significantly affected. In contrast, dexamethasone treatment days 5-9 increased peak force by 39% (p = 0.002) and stiffness by 58% (p amp;lt; 0.001). The cross-sectional area was reduced by 42% (p amp;lt; 0.001). Peak stress and elastic modulus were more than doubled (p amp;lt; 0.001 for both). Semi-quantitative histology at day 12 showed that late dexamethasone treatment improved collagen alignment, and flow cytometry revealed reduced numbers of CD8a(+) cytotoxic T cells in the tendon callus. These results suggest that downregulation of lingering inflammation during the early remodeling phase can improve healing.
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| 8. |
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| 9. |
- Dietrich, Franciele, et al.
(författare)
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Effect of platelet-rich plasma on rat Achilles tendon healing is related to microbiota
- 2017
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Ingår i: Acta Orthopaedica. - : TAYLOR & FRANCIS LTD. - 1745-3674 .- 1745-3682. ; 88:4, s. 416-421
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - In 3 papers in Acta Orthopaedica 10 years ago, we described that platelet-rich plasma (PRP) improves tendon healing in a rat Achilles transection model. Later, we found that microtrauma has similar effects, probably acting via inflammation. This raised the suspicion that the effect ascribed to growth factors within PRP could instead be due to unspecific influences on inflammation. While testing this hypothesis, we noted that the effect seemed to be related to the microbiota. Material and methods - We tried to reproduce our old findings with local injection of PRP 6h after tendon transection, followed by mechanical testing after 11 days. This failed. After fruitless variations in PRP production protocols, leukocyte concentration, and physical activity, we finally tried rats carrying potentially pathogenic bacteria. In all, 242 rats were used. Results - In 4 consecutive experiments on pathogen-free rats, no effect of PRP on healing was found. In contrast, apparently healthy rats carrying Staphylococcus aureus showed increased strength of the healing tendon after PRP treatment. These rats had higher levels of cytotoxic T-cells in their spleens. Interpretation - The failure to reproduce older experiments in clean rats was striking, and the difference in response between these and Staphylococcus-carrying rats suggests that the PRP effect is dependent on the immune status. PRP functions may be more complex than just the release of growth factors. Extrapolation from our previous findings with PRP to the situation in humans therefore becomes even more uncertain.1
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| 10. |
- Dietrich-Zagonel, Franciele, et al.
(författare)
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Stimulation of Tendon Healing With Delayed Dexamethasone Treatment Is Modified by the Microbiome
- 2018
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Ingår i: American Journal of Sports Medicine. - : Sage Publications. - 0363-5465 .- 1552-3365. ; 46:13, s. 3281-3287
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Tidskriftsartikel (refereegranskat)abstract
- Background:The immune system reflects the microbiome (microbiota). Modulation of the immune system during early tendon remodeling by dexamethasone treatment can improve rat Achilles tendon healing. The authors tested whether changes in the microbiota could influence the effect of dexamethasone treatment.Hypothesis:A change in microbiome would influence the response to dexamethasone on regenerate remodeling, specifically tendon material properties (peak stress).Study Design:Controlled laboratory study.Methods:Specific opportunist and pathogen-free female rats were housed separately (n = 41) or together with specific pathogen-free rats carrying opportunistic microbes such as Staphylococcus aureus (n = 41). After 6 weeks, all co-housed rats appeared healthy but now carried S aureus. Changes in the gut bacterial flora were tested by API and RapID biochemical tests. All rats (clean and contaminated) underwent Achilles tendon transection under aseptic conditions. Flow cytometry was performed 8 days postoperatively on tendon tissue. Sixty rats received subcutaneous dexamethasone or saline injections on days 5 through 9 after transection. The tendons were tested mechanically on day 12. The predetermined primary outcome was the interaction between contamination and dexamethasone regarding peak stress, tested by 2-way analysis of variance.Results:Dexamethasone increased peak stress in all groups but more in contaminated rats (105%) than in clean rats (53%) (interaction, P = .018). A similar interaction was found for an estimate of elastic modulus (P = .021). Furthermore, dexamethasone treatment reduced transverse area but had small effects on peak force and stiffness. In rats treated with saline only, contamination reduced peak stress by 16% (P = .04) and elastic modulus by 35% (P = .004). Contamination led to changes in the gut bacterial flora and higher levels of T cells (CD3+CD4+) in the healing tendon (P < .05).Conclusion:Changes in the microbiome influence tendon healing and enhance the positive effects of dexamethasone treatment during the early remodeling phase of tendon healing.Clinical Relevance:The positive effect of dexamethasone on early tendon remodeling in rats is strikingly strong. If similar effects could be shown in humans, immune modulation by a few days of systemic corticosteroids, or more specific compounds, could open new approaches to rehabilitation after tendon injury.
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