Is exclusion of leukocytes from platelet-rich plasma (PRP) a better choice for early intervertebral disc regeneration?

BACKGROUND: Platelet-rich plasma (PRP) is becoming a promising strategy to treat early intervertebral disc degeneration (IDD) in clinics. Pure PRP without leukocytes (P-PRP) may decrease the catabolic and inflammatory changes in the early degenerated intervertebral discs. The aim of this study was to investigate the effects of P-PRP on nucleus pulposus-derived stem cells (NPSCs) isolated from early degenerated intervertebral discs in vitro. METHODS: NPSCs isolated from early degenerated discs of rabbits were treated with P-PRP or leukocyte-platelet-rich PRP (L-PRP) in vitro, followed by measuring cell proliferation, stem cell marker expression, inflammatory gene expression, and anabolic and catabolic protein expression by immunostaining, quantitative real-time polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay. RESULTS: Cell proliferation was induced by P-PRP in a dose-dependent manner with maximum proliferation at 10% P-PRP dose. P-PRP induced differentiation of NPSCs into active nucleus pulposus cells. P-PRP mainly increased the expression of anabolic genes and relative proteins, aggrecan (AGC), collagen types II (Col II), while L-PRP predominantly increased the expression of catabolic and inflammatory genes, matrix metalloproteinase-1 (MMP-1), MMP-13, interleukin-1 beta (IL-1ß), IL-6, tumor necrosis factor alpha (TNF-α), and protein production of IL-1ß and TNF-α. CONCLUSIONS: Leukocytes in PRP activate inflammatory and catabolic effects on NPSCs from early degenerated intervertebral discs. Hence, P-PRP may be a more suitable therapeutic strategy for early IDD.

The Differential Effects of Leukocyte-Containing and Pure Platelet-Rich Plasma on Nucleus Pulposus-Derived Mesenchymal Stem Cells: Implications for the Clinical Treatment of Intervertebral Disc Degeneration.

BACKGROUND: Platelet-rich plasma (PRP) is a promising strategy for intervertebral disc degeneration. However, the potential harmful effects of leukocytes in PRP on nucleus pulposus-derived mesenchymal stem cells (NPMSCs) have seldom been studied. This study aimed at comparatively evaluating effects of pure platelet-rich plasma (P-PRP) and leukocyte-containing platelet-rich plasma (L-PRP) on rabbit NPMSCs in vitro. METHODS: NPMSCs isolated from rabbit NP tissues were treated with L-PRP or P-PRP in vitro, and then cell proliferation and expression of stem cell markers, proinflammatory cytokines (TNF-α, IL-1ß), production of ECM (extracellular matrix-related protein), and NF-κB p65 protein were validated by CCK-8 assay, real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunofluorescence, and western blot respectively. RESULTS: NPMSCs differentiate into nucleus pulposus-like cells after treatment of PRPs (P-PRP and L-PRP), and NPMSCs exhibited maximum proliferation at a 10% PRP dose. L-PRP had observably higher concentration of leukocytes, TNF-α, and IL-1ß than P-PRP. Furthermore, compared to P-PRP, L-PRP induced the differentiated NPMSCs to upregulate the expression of TNF-α and IL-1ß, enhanced activation of the NF-κB pathway, increased the expression of MMP-1 and MMP-13, and produced less ECM in differentiated NPMSCs. CONCLUSIONS: Both P-PRP and L-PRP can induce the proliferation and NP-differentiation of NPMSCs. Compared to L-PRP, P-PRP can avoid the activation of the NF-κB pathway, thus reducing the inflammatory and catabolic responses.

Intervertebral disc regeneration using platelet­rich plasma­containing bone marrow­derived mesenchymal stem cells: A preliminary investigation.

Platelet­rich plasma (PRP) is a promising strategy for intervertebral disc degeneration (IDD). However, the short half­life of growth factors released from PRP cannot continuously stimulate the degenerated discs. Thus, the present study hypothesized that the combined use of PRP and bone marrow­derived mesenchymal stem cells (BMSCs) may repair the early degenerated discs in the long term for their synergistic reparative effect. In the present study, following the induction of early IDD by annular puncture in rabbits, PRP was prepared and mixed with BMSCs (PRP­BMSC group) for injection into the early degenerated discs. As controls, phosphate­buffered saline (PBS; PBS group) and PRP (PRP group) were similarly injected. Rabbits without any intervention served as a control group. At 8 weeks following treatment, histological changes of the injected discs were assessed. Magnetic resonance imaging (MRI) was used to detect the T2­weighted signal intensity of the targeted discs at weeks 1, 2 and 8 following treatment. Annular puncture resulted in disc narrowing and decreased T2­weighted signal intensity. At weeks 1 and 3, MRI examinations showed regenerative changes in the PRP­BMSC group and PRP group, whereas the PBS group exhibited a continuous degenerative process of the discs. At 8 weeks post­injection, the PRP­BMSCs induced a statistically significant restoration of discs, as shown by MRI (PRP­BMSCs, vs.PRP and PBS; P<0.05), which was also confirmed by histological evaluations. Thus, compared with PRP, the administration of PRP­containing BMSCs resulted in a superior regenerative effect on the early degenerated discs, which may be a promising therapeutic strategy for the restoration of early degenerated discs.