Particulate cartilage and platelet-rich plasma treatment for knee chondral defects in sheep

Abstract

Purpose: Articular cartilage is vulnerable to multiple types of damage and it has limited reparative and regenerative capacities due to its absence of vascularity. Although a large number of therapeutic strategies exist to treat chondral defects, they have some limitations, such as fibrocartilage formation. Therefore, the goal of the present study was to evaluate the chondrogenic regenerative properties of an autologous-made matrix of particulated cartilage and platelet-rich plasma (PACI + PRP) implantation for the treatment of full-thickness chondral defects in sheep.

Methods: A full-thickness 8 mm diameter cartilage defect was created in the weight-bearing area of the medial femoral condyle in both knees of 16 sheep. The right knees of all animals were treated with particulated autograft cartilage implantation and platelet-rich plasma, while the left knees were injected with Ringer's lactate solution or hyaluronic acid. The sheep were killed 9 or 18 months after surgery. Macroscopic evaluations were performed using three different scoring systems, and histopathological evaluations were performed using a modified scoring system based on different scoring systems.

Results: The PACI + PRP groups showed statistically significant differences in the percentage of defect repair and chondrocytes in the newly formed cartilage tissue at 18 months compared to 9 months.

Conclusions: The results suggest that macroscopic appearance, histological structure and chondrocyte repair were improved when using PACI + PRP treatment for chondral defects, producing an outcome similar to the surrounding healthy cartilage. PACI + PRP is a totally autologous, easy, and unexpensive treatment that can be performed in one-step procedure and is useful as a therapeutic option for knee chondral defects.

Keywords: Articular cartilage; Chondrogenesis; Particulated cartilage; Platelet-rich plasma; Sheep.

Fig. 1

Macroscopic digital photographs of chondral defects after killing at 9 months (A) and 18 months (B) for RLS, PACI + PRP (RLS), HA, and PACI + PRP (HA) groups. Degree of repair according to the ICRS scoring system [50], with Grade II being nearly normal; Grade III being abnormal; Grade IV being severely abnormal. RLS: left knee treated with Ringer’s lactate solution; PACI + PRP (RLS): right knee treated with particulated autograft cartilage implantation and platelet-rich plasma from the group treated with RLS in the left knee; HA: left knee treated with hyaluronic acid; PACI + PRP (HA): right knee treated with particulated autograft cartilage implantation and platelet-rich plasma from the group treated with HA in the left knee

Fig. 2

Analysis of the cartilage structure (semiquantitative parameters). A Histological image showing the different layers of healthy cartilage structure used to evaluate histopathological parameters (H&E stain). (B and C) Score obtained in each group evaluating the structure of the repaired cartilage at 9 and 18 months, respectively. RLS: left knee treated with Ringer’s lactate solution; PACI + PRP (RLS): right knee treated with particulated autograft cartilage implantation and platelet-rich plasma from the group treated with RLS in the left knee; HA: left knee treated with hyaluronic acid; PACI + PRP (HA): right knee treated with particulated autograft cartilage implantation and platelet-rich plasma from the group treated with HA in the left knee

Fig. 3

Histological images showing the structure of articular cartilage after administration of the different treatments at 9 and 18 months (H&E stain). The arrows indicate the boundary between healthy cartilage (HC) and repaired cartilage (RC), observing the degree of repair and lateral integration. A Histological images at 9 months showing complete lateral integration of the repaired cartilage with the surrounding healthy cartilage in PACI + PRP (RLS) and PACI + PRP (HA) groups, in contrast to the observation for the RLS and HA groups. B Histological images at 18 months showing better lateral integration of repaired cartilage with the surrounding healthy cartilage in PACI + PRP (RLS) group than in RLS group. Complete lateral integration of the repaired cartilage with healthy cartilage was observed in the PACI + PRP (HA) group compared with incomplete lateral integration of repaired cartilage in the RLS and HA groups. RLS: left knee treated with Ringer’s lactate solution; PACI + PRP (RLS): right knee treated with particulated autograft cartilage implantation and platelet-rich plasma from the group treated with RLS in the left knee; HA: left knee treated with hyaluronic acid; PACI + PRP (HA): right knee treated with particulated autograft cartilage implantation and platelet-rich plasma from the group treated with HA in the left knee

Fig. 4

Comparison of the different treatments according to percentage of cartilage defect repair and chondrocyte recovery time studied (9 and 18 months). A Defect regeneration (%). B Cell count (cell/mm²). C Cell area (µm²). D Cell morphology (form factor). RLS: left knee treated with Ringer’s lactate solution; HA: left knee treated with hyaluronic acid; PACI + PRP: right knee treated with particulated autograft cartilage implantation and platelet-rich plasma. *p < 0.05; **p < 0.01; ***p < 0.001