Leukocyte-Rich Platelet-Rich Plasma Injections Do Not Up-Modulate Intra-Articular Pro-Inflammatory Cytokines in the Osteoarthritic Knee

Introduction
The presence of leukocytes in platelet concentrates is deemed to cause deleterious effects when injected intra articularly. The aim of this study is to analyse both local and systemic effects induced by leukocyte-rich Platelet-rich Plasma (PRP) injections through a proteomic characterization of serial synovial fluid and blood samples obtained from subjects treated for knee OA. Secondary aim was to compare the effects on knee homeostasis and systemic response with those obtained with visco-supplementation.
Methods
Thirty-six OA patients treated either by autologous L-PRP or HA intra-articular knee injections, administered in series of three at one-week intervals, were analyzed. Just before the injection, 1 ml of synovial fluid was collected through the same needle way. In the same time, a peripheral blood sample was obtained and plasma separated. A further peripheral blood sample was collected at 2, 6, and 12 months. L-PRP, plasma and synovial fluid were tested by multiplex bead-based sandwich immunoassay by means of the Bio-Plex suspension array system (Bio-Rad Laboratories) for the presence of pro- and anti-inflammatory cytokines (IL-1beta, IL-6, IL-8, IL-17 and IL-4, IL-10, IL-13) and growth factors (FGF-b, HGF, PDGF-AB/BB).
Results
In general, pro-inflammatory cytokine levels were similar at basal condition and after treatment whereas anti-inflammatory ones were nearly undetectable. L-PRP administration did not modulate significant changes of cytokine concentrations either in synovial fluid or plasma, whatever the time points analyzed. No different trend was observed between L-PRP and HA administration in terms of pro- and anti-inflammatory cytokines, as well as growth factors.
Conclusions
In contrast with the evidence reported by “in vitro” studies, where a cellular pro-inflammatory response appears to be induced by the presence of leukocytes, these results suggest that the presence leukocyte-rich PRP doesn’t induce a relevant in vivo up regulation of pro-inflammatory mediators.

引言
血小板浓缩物中的白细胞在关节腔内注射时被认为会产生有害作用。本研究旨在通过对膝骨关节炎（Osteoarthritis, OA）患者接受治疗后获取的系列滑液与血液样本进行蛋白质组学表征，分析富白细胞血小板血浆（PRP）关节腔内注射所诱导的局部与全身效应。次要研究目的为比较其对膝关节稳态与全身应答的影响，与黏弹性补充疗法所产生的效应。

方法
本研究共纳入36名膝OA患者，分别接受自体富白细胞血小板血浆（L-PRP）或透明质酸（HA）膝关节腔内注射，以每周1次的间隔连续注射3次，对所有受试者进行分析。注射前，通过同一穿刺途径采集1 mL滑液；同期采集外周血样本并分离血浆。分别于第2、6、12个月再次采集外周血样本。采用伯乐实验室（Bio-Rad Laboratories）的Bio-Plex悬浮阵列系统，基于磁珠的多重夹心免疫分析法，对L-PRP、血浆及滑液中的促炎与抗炎细胞因子（IL-1β、IL-6、IL-8、IL-17以及IL-4、IL-10、IL-13）与生长因子（FGF-b、HGF、PDGF-AB/BB）进行检测。

结果
总体而言，基础状态与治疗后的促炎细胞因子水平无显著差异，而抗炎细胞因子水平几乎无法检出。无论在滑液还是血浆中，无论分析的时间点如何，L-PRP给药均未引起细胞因子浓度的显著变化。就促炎/抗炎细胞因子及生长因子而言，L-PRP与HA给药的变化趋势无显著差异。

结论
与体外（in vitro）研究所报道的证据相悖——体外研究显示白细胞的存在会诱导细胞性促炎反应——本研究结果表明，富白细胞PRP并不会在体内（in vivo）显著上调促炎介质的表达。