Description
Objective
Platelet-rich plasma (PRP) therapy for patients with knee osteoarthritis (KOA) is becoming increasingly popular. However, PRP is derived from autologous blood and is known to be of variable quality. Recently, growth factors, bioactive substances and cytokines in PRP have been shown to influence the efficacy of PRP therapy, but few studies have focused on cytokines.
Methods
Sixty-one KOA patients (male/female=16/45, mean age 68.20±12.02 years, KL1/2/3/4=3/8/26/24) who underwent leukocyte-poor PRP therapy between October and December 2022 and whose pre-PRP VAS was 40 or more were included. The remaining samples after PRP administration were cryopreserved and the cytokines in PRP were analysed for IL-6, IL-10, IL-18, MIP1a and CXCL9 using the Sysmex Corporation HI-1000 automated high-sensitivity immunoassay system. Knee injury and Osteoarthritis Outcome Score (KOOS) were assessed. Statistical analysis was performed using SPSS ver. 28, with the Spearman rank correlation coefficient and comparisons between the two groups using t-tests with a significance level of less than 5%.
Results
The mean concentrations of each cytokine in PRP were IL-6=7.40+5.72, IL-10=0.53±1.08, IL-18=343.15±156.62, MIP1a=31.31±19.71, CXCL9=70.45±53.06 (pg/ml). CXCL9 in PRP was positively correlated with age (r=0.49, p<0.01) and IL-18 with BMI (r=0.40, p=0.02). Improvement in various cytokines and scores was negatively correlated with KOOS-ADL in IL-6 and IL-18 (r=-0.26, p=0.045; r=-0.30, p=0.018)(Figure 1). IL-18 was significantly higher in males (430.2±201.4 pg/ml) than in females (310.7±123.1)(p=0.08). When comparing the groups by KL classification, the mean cytokine concentrations in each group were not significantly different.
Discussion
Higher levels of the inflammatory cytokines IL-6 and IL-18 in PRP were associated with poorer improvement in KOOS-ADL. IL-18 was associated with BMI and sex, and CXCL9 with age. Although there was no association between KOA severity and cytokines, this study suggests that PRP from patients with high inflammation state may be less effective in improving symptoms.
