IntroductionPlatelet-rich plasma (PRP) is widely used to treat tendon injuries in clinics. These PRP preparations often contain white blood cells or leukocytes, and the precise cellular effects of leukocyte-rich PRP (L-PRP) on tendons are not well defined. Therefore, in this study, we determined the effects of L-PRP on tendon stem/progenitor cells (TSCs), which play a key role in tendon homeostasis and repair.MethodsTSCs isolated from the patellar tendons of rabbits were treated with L-PRP or P-PRP (pure PRP without leukocytes) in vitro, followed by measuring cell proliferation, stem cell marker expression, inflammatory gene expression, and anabolic and catabolic protein expression by using immunostaining, quantitative real-time polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay, respectively.ResultsCell proliferation was induced by both L-PRP and P-PRP in a dose-dependent manner with maximum proliferation at a 10 % PRP dose. Both PRP treatments also induced differentiation of TSCs into active tenocytes. Nevertheless, the two types of PRP largely differed in several effects exerted on TSCs. L-PRP induced predominantly catabolic and inflammatory changes in differentiated tenocytes; its treatment increased the expression of catabolic marker genes, matrix metalloproteinase-1 (MMP-1), MMP-13, interleukin-1beta (IL-1β), IL-6 and tumor necrosis factor-alpha (TNF-α), and their respective protein expression and prostaglandin E2 (PGE2) production. In contrast, P-PRP mainly induced anabolic changes; that is, P-PRP increased the gene expression of anabolic genes, alpha-smooth muscle actin (α-SMA), collagen types I and III.ConclusionsThese findings indicate that, while both L-PRP and P-PRP appear to be “safe” in inducing TSC differentiation into active tenocytes, L-PRP may be detrimental to the healing of injured tendons because it induces catabolic and inflammatory effects on tendon cells and may prolong the effects in healing tendons. On the other hand, when P-PRP is used to treat acutely injured tendons, it may result in the formation of excessive scar tissue due to the strong potential of P-PRP to induce inordinate cellular anabolic effects.

SummaryPrimary biliary cirrhosis (PBC) is an organ-specific autoimmune liver disease characterized by progressive loss of intrahepatic small bile ducts. Cellular immune mechanisms involving T cell reaction are thought to be involved significantly in the pathogenesis of PBC. Recent studies have independently revealed enhanced T helper type 17 (Th17) response and weakened T regulatory cell (Treg) response in some autoimmune diseases, indicating a role of Th17/Treg imbalance in the pathogenesis of autoimmunity. This prompted us to investigate whether the Th17/Treg balance was broken in the peripheral blood of patients with PBC and, if it was, what cytokine circumstances might contribute to this imbalance. The expression of 11 Th17/Treg differentiation-related genes and serum concentrations of the corresponding cytokines in 36 patients with PBC, 28 patients with chronic hepatitis B and 28 healthy controls were measured by real-time quantitativepolymerase chain reaction and enzyme-linked immunosorbent assay respectively. Peripheral Th17 and Treg cells were analysed by flow cytometry. Th17-related cytokines were increased significantly in patients with PBC. Consistent with the cytokine profile, the Th17 cell population and retinoidrelated orphan receptor gt expression were increased markedly. In contrast, the Treg cell population and forkhead box P3 expression were decreased dramatically in the peripheral blood of patients with PBC. Our study revealed that the Th17/Treg imbalance, both cytokine profile and cell numbers, exists in patients with PBC, suggesting its potential role in the breakdown of immune self-tolerance in PBC. Interleukin-23, which characterized the imbalanced cytokine profile, may play an essential role in Th17-related human autoimmunity.

Platelet-Rich Plasma (PRP) has been widely used in orthopaedic surgery and sport medicine to treat tendon injuries. However, the efficacy of PRP treatment for tendinopathy is controversial. This paper focuses on reviewing the basic science studies on PRP performed under well-controlled conditions. Both in vitro and in vivo studies describe PRP's anabolic and anti-inflammatory effects on tendons. While some clinical trials support these findings, others refute them. In this review, we discuss the effectiveness of PRP to treat tendon injuries with evidence presented in basic science studies and the potential reasons for the controversial results in clinical trials. Finally, we comment on the approaches that may be required to improve the efficacy of PRP treatment for tendinopathy.