Effect of umbilical cord blood-mononuclear cells on knee osteoarthritis in rabbits

Abstract

Background: To investigate the effect and underlying mechanism of umbilical cord blood-mononuclear cells (UCB-MNCs) in treating knee osteoarthritis (KOA) in rabbits.

Methods: A rabbit KOA model was prepared by anterior cruciate ligament transection (ACLT). Fifty New Zealand white rabbits were randomly divided into the control group, model group, sodium hyaluronate (SH) group, platelet-rich plasma (PRP) group and UCB-MNC group. Knee injections were performed once a week for five consecutive weeks. The gross view of the knee joint, morphology of knee cartilage and structural changes in the knee joint were observed on CT scans, and graded by the Lequesne MG behavioral score and the Mankin score. TNF-α and IL-1β levels in the synovial fluid of the knee were measured by the enzyme-linked immunosorbent assay (ELISA). Expression levels of MMP-13 and COL-II in the knee cartilage were detected by Western blotting and qRT-PCR.

Results: The Lequesne MG behavioral score and the Mankin score were significantly higher in the model group than those in the control group (P < 0.05). Rabbits in the SH, PRP and UCB-MNC groups had sequentially lower scores than those in the model group. Imaging features of KOA were more pronounced in the model group than in the remaining groups. CB-MNC significantly relieved KOA, compared to SH and PRP. Significantly higher levels of TNF-α and IL-1β in the synovial fluid of the knee, and up-regulated MMP-13 and down-regulated COL-II in the knee cartilage were detected in the model group than in the control group. These changes were significantly reversed by the treatment with SH, PRP and UCB-MNCs, especially UCB-MNCs.

Conclusion: Injections of UCB-MNCs into knees protect the articular cartilage and hinder the progression of KOA in rabbits by improving the local microenvironment at knee joints.

Keywords: Osteoarthritis; Platelet-rich plasma; Umbilical cord blood-mononuclear cells.

Fig. 1

Diagram of creating the KOA rabbit model. (A) Exposure of the knee joint. (B) Transection of the anterior cruciate ligament and excision of the medial meniscus. (C) Visible swelling of the knee (arrow point). (D) A micro-CT scan visualizing the formation of a bone capsule

Fig. 2

Lequesne MG behavioral scores n = 6. ^#P < 0.05 and ^##P < 0.01 vs. UCB-MNC group; ^*P < 0.05 and ^**P < 0.01 vs. model group

Fig. 3

Gross views of the cartilages of femoral condyles

Fig. 4

Coronal and cross-sectional micro-CT scans of knees in control group, model group, SH group, PRP group and UCB-MNC group. n = 3. Pathological changes were marked by arrows

Fig. 5

A Representative images of H&E staining and Safranin O/fast green staining for articular cartilages; B Mankin score of H&E; C Mankin score of safranin O/fast green, n = 3. ^#P < 0.05 and ^##P < 0.01 vs. UCB-MNC group; ^*P < 0.05 and ^**P < 0.01 vs. model group

Fig. 6

Relative levels of IL-1β (A) and TNF-α (B) in the synovial fluid of knees in the control group, model group, SH group, PRP group and UCB-MNC group. n = 10. ^#P < 0.05 and ^##P < 0.01 vs. UCB-MNC group; ^*P < 0.05 and ^**P < 0.01 vs. model group

Fig. 7

mRNA levels of MMP-13 (A) and COL-II (B) in cartilage tissues in the control group, model group, SH group, PRP group and UCB-MNC group. n = 6. ^#P < 0.05 and ^##P < 0.01 vs. UCB-MNC group; ^*P < 0.05 and ^**P < 0.01 vs. model group

Fig. 8

Protein levels of MMP-13, COL-II, p-PI3K and p-AKT protein (A), and their quantitative analyses (B). ^#P < 0.05 and ^##P < 0.01 vs. UCB-MNC group; ^*P < 0.05 and ^**P < 0.01 vs. model group