The role of PRP in the healing of disc degeneration and the effect of local anesthetics on PRP

Abstract

Aim: This study aimed to investigate the regenerative effects of PRP on an experimental rat model of disc degeneration using histological and biochemical parameters. Additionally, we evaluated whether ropivacaine, a local anesthetic commonly used in clinical practice, affects the efficacy of PRP.

Methods: Rats were randomly divided into five groups as control and treatment groups. Disc degeneration models were established using appropriate procedures. On the intervention day, PRP was prepared from whole blood collected from the rats. PRP, PRP + ropivacaine, or ropivacaine alone was administered at the appropriate doses and according to standardized protocols.

Results: In the untreated disc degeneration groups, annulus fibrosus (AF) and nucleus pulposus (NP) boundaries were indistinct, disc morphology was disrupted, collagen structures in the AF were degenerated or irregular, and vacuolization, interstitial edema, and necrotic tissue remnants were observed in the NP region. In contrast, in groups treated with PRP and PRP + ropivacaine, a reduction in edema and vacuolization, disappearance of necrotic tissue, restoration of distinct NP and AF boundaries, and decreased atrophy and cellular clustering in NP cells were observed. Biochemical analysis showed that IL-6 and TNF-α levels were within normal ranges in the groups treated with PRP and PRP + ropivacaine, whereas these levels remained elevated in the untreated disc degeneration groups, indicating ongoing effects of degeneration.

Conclusion: This study demonstrates the regenerative effects of PRP in disc degeneration through histological and biochemical parameters. Furthermore, the addition of ropivacaine to PRP did not exert any negative effects on PRP's regenerative properties.

Keywords: inflammation; intervertebral disc degeneration; local anesthesia; platelet-rich plasma; rat.

FIGURE 1

Pro-inflammatory cytokine levels in the sham + local anesthesia (S + LAG), sham + platelet-rich plasma (S + PRPG), intervertebral disc degeneration (IVDDG), intervertebral disc degeneration + platelet-rich plasma (IVDDG + PRPG), and intervertebral disc degeneration + platelet-rich plasma + local anesthesia (IVDDG + PRPG + LAG) groups. IL, interleukin; TNF, tumor necrosis factor. **p < 0.05 statistically significant and *p > 0.05 not statistically significant. The values are presented as mean ± SD.

FIGURE 2

Representative light microscope images of hematoxylin-eosin-stained intervertebral disc tissue sections. The intervertebral disc tissues and nucleus pulposus (NP) cells in the sham + local anesthesia (S + LAG) and sham + platelet-rich plasma (S + PRPG) groups appeared normal. In the intervertebral disc degeneration (IVDDG) group, the borders of the annulus fibrosus (AF) and NP were unclear, with disrupted AF collagen layers. Vacuoles, interstitial edema, and necrotic tissues were observed in the disc, along with atrophy and clustering in the NP cells. In the treatment groups, IVDDG + PRPG and IVDDG + PRPG + LAG, a small amount of edema and vacuoles were detected in the intervertebral disc tissue. Additionally, a decrease in atrophic cells and cell clusters (two or 3 cell clusters) in the NP area was observed. Markings include: (&) vacuoles, (→) tissue integrity deterioration, (☆) interstitial edema, (►) necrotic tissue and degeneration, (circle shape) clusters in cells, (square shape) atrophic cells (k) The histological grades of different groups are presented as mean ± SD. **p < 0.05 statistically significant and *p > 0.05 not statistically significant. (a–e) Low magnification (×4, scale bar = 200 µm) and (f–j) high magnification (oil-immersion, ×100, scale bar = 10 µm).

FIGURE 3

Representative light microscope images of Verhoeff-Van Gieson-stained intervertebral disc tissue sections. The S + LAG and S + PRPG groups showed normal intervertebral disc tissues. In the IVDDG group, vacuoles, tissue integrity deterioration, interstitial edema, necrotic tissue, and degeneration were observed. In the treatment groups, IVDDG + PRPG and IVDDG + PRPG + LAG, a small amount of edema, vacuoles, and tissue integrity deterioration were detected in the intervertebral disc tissue. Markings include: (&) vacuoles, (→) tissue integrity deterioration, (☆) interstitial edema, and (►) necrotic tissue. Low magnification (×4, scale bar = 200 µm). (a) The histological grades of different groups are presented as mean ± SD. **p < 0.05 statistically significant and *p > 0.05 not statistically significant.