Effects of platelet-rich plasma combined with isometric quadriceps contraction on cartilage in a rat model of knee osteoarthritis

Abstract

Background: Intra-articular injection of platelet-rich plasma (PRP) or isometric contraction of quadriceps (ICQ) has shown positive effects in patients with knee osteoarthritis (KOA). However, the synergistic effect of combining PRP and ICQ intervention (joint intervention) on cartilage repair has not been validated. Thus, this study aimed to explore the reparative effects of joint intervention on cartilage in a KOA rat model.

Methods: Fifty-four 2-month-old female Sprague-Dawley rats were randomly divided into the control group (CG, n = 6) and model group (injected with sodium iodoacetate, n = 48). After 1 week, six rats from the model group were randomly selected for validation. The remaining 42 rats were further divided into seven groups: PRP group (PRPG), ICQ group (ICQG), joint intervention group (JIG), normal saline group (NSG), acupuncture group (AG), normal saline and acupuncture group (NSAG) and model blank group (MBG). The intervention lasted for 4 weeks, with PRPG and JIG receiving PRP injections (twice) and ICQG and JIG undergoing ICQ (five times per week, 15 min each session).

Results: Histological staining with haematoxylin and eosin as well as transmission electron microscopy revealed severe cartilage damage in MBG, AG, NSAG and NSG, followed by PRPG and ICQG. JIG exhibited a more intact cartilage structure. Compared with JIG, the Mankin scores increased remarkably in PRPG, ICQG, AG, NSAG and NSG (P < 0.01). Relative mRNA expression levels showed the upregulation of IL-1β in ICQG, NSAG and NSG compared with JIG (P < 0.05) and the upregulation of IL-6, IL-18 and MMP-13 in AG and NSAG (P < 0.05). Compared with PRPG, IL-1β and IL-6 were upregulated in ICQG, AG, NSAG and NSG (P < 0.05). In addition, IL-18 was upregulated in AG (P < 0.01), and IL-18, MMP-13 and TNF-α were upregulated in NSAG (P < 0.05). Compared with ICQG, IL-1β, IL-18, MMP-13 and TNF-α were upregulated in NSAG (P < 0.05), and IL-1β and IL-18 were upregulated in AG (P < 0.05).

Conclusion: The combination of PRP and ICQ can alleviate inflammatory responses in cartilage, promote chondrocyte regeneration and facilitate matrix tissue repair. Compared with single interventions, a synergistic effect is observed.

Keywords: Isometric contraction of quadriceps; Knee osteoarthritis; Platelet-rich plasma.

Fig. 1

Experimental design and grouping. PRPG: Platelet-Rich Plasma Group, ICQG: Isometric Contraction of Quadriceps Group, JIG: Joint Intervention Group, NSG: Normal Saline Group, AG: Acupuncture Group, NSAG: Normal Saline and Acupuncture Group, MBG: Model Blank Group, CG: Control Group.

Fig. 2

HE staining results of articular cartilage from 6 randomly selected knee joint samples one week post-induction of osteoarthritis model. Damage to the cartilage layer (); proliferation of fibrous tissue (); increased osteoclasts (); formation of new capillaries (); hemorrhage (); reduction in the number of trabeculae ().

Fig. 3

Body weight, hind limb grip strength, Mankin scores, and relative expression of inflammatory cytokine mRNA in articular cartilage tissue of different groups of rats. PRPG: Platelet-Rich Plasma Group, ICQG: Isometric Contraction of Quadriceps Group, JIG: Joint Intervention Group, NSG: Normal Saline Group, AG: Acupuncture Group, NSAG: Normal Saline and Acupuncture Group, MBG: Model Blank Group, CG: Control Group. Compared with CG, ^ap < 0.05, ^Ap < 0.01; Compared with MBG, ^bp < 0.05, ^Bp < 0.01; Compared with JIG, ^cp < 0.05, ^Cp < 0.01; Compared with PRPG, ^dp < 0.05, ^Dp < 0.01; Compared with ICQG, ^ep < 0.05, ^Ep < 0.01.

Fig. 4

Representative HE staining and transmission electron microscopy images from one sample per group. HE staining: damage to the cartilage layer (), proliferation of fibrous tissue (), increased osteoclasts (), formation of new capillaries (), hemorrhage (), reduction in the number of trabeculae (); Transmission electron microscopy: expansion of the rough endoplasmic reticulum (), primary lysosomes (), autophagic lysosomes (), lipid droplets (), mitochondrial swelling (), ribosome loss ().