Abstract Platelet concentrates such as platelet-rich plasma (PRP) have gained popularity in sports medicine and orthopaedics to promote accelerated physiologic healing and return to function. Each ...PRP product varies depending on patient factors and the system used to generate it. Blood from some patients may fail to make PRP, and most clinicians use PRP without performing cell counts on either the blood or the preparation to confirm that the solution is truly PRP. Components in this milieu have bioactive functions that affect musculoskeletal tissue regeneration and healing. Platelets are activated by collagen or other molecules and release growth factors from alpha granules. Additional substances are released from dense bodies and lysosomes. Soluble proteins also present in PRP function in hemostasis, whereas others serve as biomarkers of musculoskeletal injury. Electrolytes and soluble plasma hormones are required for cellular signaling and regulation. Leukocytes and erythrocytes are present in PRP and function in inflammation, immunity, and additional cellular signaling pathways. This article supports the emerging paradigm that more than just platelets are playing a role in clinical responses to PRP. Depending on the specific constituents of a PRP preparation, the clinical use can theoretically be matched to the pathology being treated in an effort to improve clinical efficacy.
Numerous methods are available for platelet-rich plasma (PRP) generation, but evidence defining the optimum composition is lacking. We hypothesized that leukocyte-reduced PRP would result in lower ...inflammatory cytokine expression compared with concentrated-leukocyte PRP and that maintaining the platelet:white blood cell (WBC) ratio would compensate for the effect of increased WBC concentration.
Blood and flexor digitorum superficialis tendons were collected from young adult horses. Three PRP groups were generated with the same platelet concentration but different WBC concentrations: intermediate-concentration standard PRP, leukocyte-reduced PRP, and concentrated-leukocyte PRP. An additional high-concentration PRP group was generated with the same WBC concentration as the concentrated-leukocyte PRP group and the same platelet:WBC ratio as the standard PRP group. The PRP groups were used as media for flexor digitorum superficialis tendon explants in culture for seventy-two hours with 10% plasma in Dulbecco modified Eagle medium (DMEM) serving as control. Tendon gene expression for collagen types I (COL1A1) and III (COL3A1), cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP-13), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) was performed.
The desired PRP groups were successfully generated. The expression of COMP, the COL1A1:COL3A1 ratio, and the expression of MMP-13 in flexor digitorum superficialis tendon explants was not different between PRP groups. The expression of COMP (p = 0.0027) and the COL1A1:COL3A1 ratio (p < 0.0001) were increased in the PRP groups as compared with the control group, and the expression of MMP-13 was decreased in the PRP groups as compared with the control group (p < 0.0001). The expression of IL-1β was lowest in leukocyte-reduced PRP and highest in concentrated-leukocyte PRP (p = 0.0001). The leukocyte-reduced PRP group and the control group had the lowest TNF-α expression, whereas the high-concentration PRP and concentrated-leukocyte PRP groups had the highest expression (p = 0.0224).
A high absolute WBC concentration in PRP contributes to the expression of inflammatory cytokines in flexor digitorum superficialis tendon explants, and maintenance of the platelet:WBC ratio is not able to counteract this effect.
The optimum composition of PRP for the treatment of tendinopathy has not been directly investigated. Persistent inflammation results in inferior repair with scar tissue. The present study indicates that in an animal model, WBC in PRP contributes to inflammatory cytokine production. Therefore, leukocyte-reduced PRP may be the optimum preparation to stimulate superior healing without scar tissue formation.
Background:
The use of platelet-rich plasma (PRP) for the treatment of osteoarthritis (OA) has demonstrated mixed clinical outcomes in randomized controlled trials when compared with hyaluronic acid ...(HA), an accepted nonsurgical treatment for symptomatic OA. Biological analysis of PRP has demonstrated an anti-inflammatory effect on the intra-articular environment.
Purpose:
To compare the clinical and biological effects of an intra-articular injection of PRP with those of an intra-articular injection of HA in patients with mild to moderate knee OA.
Study Design:
Randomized controlled trial; Level of evidence, 1.
Methods:
A total of 111 patients with symptomatic unilateral knee OA received a series of either leukocyte-poor PRP or HA injections under ultrasound guidance. Clinical data were collected before treatment and at 4 time points across a 1-year period. Synovial fluid was also collected for analysis of proinflammatory and anti-inflammatory markers before treatment and at 12 and 24 weeks after treatment. Several measures were used to assess results: (1) Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale; (2) International Knee Documentation Committee (IKDC) subjective knee evaluation, visual analog scale (VAS) for pain, and Lysholm knee score; and (3) difference in intra-articular biochemical marker concentrations.
Results:
There were 49 patients randomized to treatment with PRP and 50 randomized to treatment with HA. No difference was seen between the groups in the primary outcome measure (WOMAC pain score). In the secondary outcome measure, linear contrasts identified a significantly higher IKDC score in the PRP group compared with the HA group at 24 weeks (mean ± standard error SE, 65.5 ± 3.6 vs 55.8 ± 3.8, respectively; P = .013) and at final follow-up (52 weeks) (57.6 ± 3.37 vs 46.6 ± 3.76, respectively; P = .003). Linear contrasts also identified a statistically lower VAS score in the PRP group versus the HA group at 24 weeks (mean ± SE, 34.6 ± 3.24 vs 48.6 ± 3.7, respectively; P = .0096) and 52 weeks (44 ± 4.6 vs 57.3 ± 3.8, respectively; P = .0039). An examination of fixed effects showed that patients with mild OA and a lower body mass index had a statistically significant improvement in outcomes. In the biochemical analysis, differences between groups approached significance for interleukin-1β (mean ± SE, 0.14 ± 0.05 pg/mL PRP vs 0.34 ± 0.16 pg/mL HA; P = .06) and tumor necrosis factor α (0.08 ± 0.01 pg/mL PRP vs 0.2 ± 0.18 pg/mL HA; P = .068) at 12-week follow-up.
Conclusion:
We found no difference between HA and PRP at any time point in the primary outcome measure: the patient-reported WOMAC pain score. Significant improvements were seen in other patient-reported outcome measures, with results favoring PRP over HA. Preceding a significant difference in subjective outcomes favoring PRP, there was a trend toward a decrease in 2 proinflammatory cytokines, which suggest that the anti-inflammatory properties of PRP may contribute to an improvement of symptoms.
Registration:
ClinicalTrials.gov (Identifier: NCT02588872).
Background: Previous studies of bioactive molecules in platelet-rich plasma (PRP) have documented growth factor concentrations that promote tissue healing. However, the effects of leukocytes and ...inflammatory molecules in PRP have not been defined.
Hypothesis: The hypothesis for this study was that the concentration of growth factors and catabolic cytokines would be dependent on the cellular composition of PRP.
Study Design: Controlled laboratory study.
Methods: Platelet-rich plasma was made from 11 human volunteers using 2 commercial systems: Arthrex ACP (Autologous Conditioned Plasma) Double Syringe System (PRP-1), which concentrates platelets and minimizes leukocytes, and Biomet GPS III Mini Platelet Concentrate System (PRP-2), which concentrates both platelets and leukocytes. Transforming growth factor-β1 (TGF-β1), platelet-derived growth factor–AB (PDGF-AB), matrix metalloproteinase-9 (MMP-9), and interleukin-1β (IL-1β) were measured with enzyme-linked immunosorbent assay (ELISA).
Results: The PRP-1 system consisted of concentrated platelets (1.99×) and diminished leukocytes (0.13×) compared with blood, while PRP-2 contained concentrated platelets (4.69×) and leukocytes (4.26×) compared with blood. Growth factors were significantly increased in PRP-2 compared with PRP-1 (TGF-β1: PRP-2 = 89 ng/mL, PRP-1 = 20 ng/mL, P < .05; PDGF-AB: PRP-2 = 22 ng/mL, PRP-1 = 6.4 ng/mL, P < .05). The PRP-1 system did not have a higher concentration of PDGF-AB compared with whole blood. Catabolic cytokines were significantly increased in PRP-2 compared with PRP-1 (MMP-9: PRP-2 = 222 ng/mL, PRP-1 = 40 ng/mL, P < .05; IL-1β: PRP-2 = 3.67 pg/mL, PRP-1 = 0.31 pg/mL, P < .05). Significant, positive correlations were found between TGF-β1 and platelets (r2 = .75, P < .001), PDGF-AB and platelets (r2 = .60, P < .001), MMP-9 and neutrophils (r2 = .37, P < .001), IL-1β and neutrophils (r2 = .73, P < .001), and IL-1β and monocytes (r2 = .75, P < .001).
Conclusion: Growth factor and catabolic cytokine concentrations were influenced by the cellular composition of PRP. Platelets increased anabolic signaling and, in contrast, leukocytes increased catabolic signaling molecules. Platelet-rich plasma products should be analyzed for content of platelets and leukocytes as both can influence the biologic effects of PRP.
Clinical Relevance: Depending on the clinical application, preparations of PRP should be considered based on their ability to concentrate platelets and leukocytes with sensitivity to pathologic conditions that will benefit most from increased platelet or reduced leukocyte concentration.
The necessity of change Fortier, Lisa A
Journal of the American Veterinary Medical Association,
2024-Mar-01, 2024-03-01, 20240301, Letnik:
262, Številka:
3
Journal Article
Autologous and allogeneic adult mesenchymal stem/stromal cells (MSCs) are increasingly being investigated for treating a wide range of clinical diseases. Allogeneic MSCs are especially attractive due ...to their potential to provide immediate care at the time of tissue injury or disease diagnosis. The prevailing dogma has been that allogeneic MSCs are immune privileged, but there have been very few studies that control for matched or mismatched major histocompatibility complex (MHC) molecule expression and that examine immunogenicity in vivo. Studies that control for MHC expression have reported both cell-mediated and humoral immune responses to MHC-mismatched MSCs. The clinical implications of immune responses to MHC-mismatched MSCs are still unknown. Pre-clinical and clinical studies that document the MHC haplotype of donors and recipients and measure immune responses following MSC treatment are necessary to answer this critical question.
This review details what is currently known about the immunogenicity of allogeneic MSCs and suggests contemporary assays that could be utilized in future studies to appropriately identify and measure immune responses to MHC-mismatched MSCs.
Evidence-based journal strategies for 2024 Fortier, Lisa A
Journal of the American Veterinary Medical Association,
2024-Jan-01, 2024-01-01, 20240101, Letnik:
262, Številka:
1
Journal Article
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