Intra-osseous plasma rich in growth factors enhances cartilage and subchondral bone regeneration in rabbits with acute full thickness chondral defects: Histological assessment

Abstract

Background: Intra-articular (IA) combined with intra-osseous (IO) infiltration of plasma rich in growth factors (PRGF) have been proposed as an alternative approach to treat patients with severe osteoarthritis (OA) and subchondral bone damage. The aim of the study is to evaluate the efficacy of IO injections of PRGF to treat acute full depth chondral lesion in a rabbit model by using two histological validated scales (OARSI and ICRS II).

Methodology: A total of 40 rabbits were included in the study. A full depth chondral defect was created in the medial femoral condyle and then animals were divided into 2 groups depending on the IO treatment injected on surgery day: control group (IA injection of PRGF and IO injection of saline) and treatment group (IA combined with IO injection of PRGF). Animals were euthanized 56 and 84 days after surgery and the condyles were processed for posterior histological evaluation.

Results: Better scores were obtained in treatment group in both scoring systems at 56- and 84-days follow-up than in control group. Additionally, longer-term histological benefits have been obtained in the treatment group.

Conclusions: The results suggests that IO infiltration of PRGF enhances cartilage and subchondral bone healing more than the IA-only PRGF infiltration and provides longer-lasting beneficial effects.

Keywords: articular cartilage; bioregenerative therapies; chondral defect; growth factors; histology; osteoarthritis; platelet rich plasma.

Figure 1

Blood extraction from the auricular artery for PRGF obtention. A 21G Venofix connected to a 21G hypodermic needle by a male-male luer-lock connector was used for this purpose. The blood was collected in vacutainer sodium citrate 3.8% tubes.

Figure 2

Intra-articular infiltration with plasma rich in growth factors. A 22-G needle was inserted laterally to the patellar tendon and 0.25 mL of plasma rich in growth factors were IA injected.

Figure 3

Intra-osseous infiltration of plasma rich in growth factors. An 18-G spinal needle was inserted perpendicular to the femur in the lateral supracondylar region with gentle rotation movements.

Figure 4

Safranin O- Fast green stained sections. (A) Complete loss of superficial, mid and deep zones of the articular cartilage. (B) Loss of articular cartilage thickness in the defect area. Loss of safranin-o staining indicating a loss of proteoglycans. (C) Good proteoglycan distribution with some areas with loss of staining. (D) Full extracellular matrix staining.

Figure 5

Hematoxylin-Eosin stained sections. (A) Loss of superficial, mid and deep layers of the articular cartilage. (B) Clefts in the superficial zone and structural disorganization. (C) Small superficial erosion. (D) Good superficial integration with small irregularities.

Figure 6

Hematoxylin-Eosin stained sections. Green arrows point areas of chondrocyte density decrease and blue arrows point chondrocytes clusters. (A) Lack of superficial and mid zones of the articular cartilage (black arrow), chondrocyte clustering and multifocal and confluent eosinophilic areas with lack of chondrocytes. (B) Eosinophilic areas with diminished chondrocyte density and structural disorganization. (C) Focal areas of hypocellullarity and some chondrocytes aggrupation. (D) Good chondrocytes organization and morphology (oval and rounded cells organized in columns) without cluster presence and basophilic extracellular matrix.

Figure 7

Hematoxylin-Eosin stained sections. (A) The defect area is being filled with fibrocartilage-like tissue (black arrow). Additionally, big chondrocytes clusters are present (blue arrows). (B) Defect filled with fibrocartilage-like tissue. (C) Good regeneration tissue, hyaline like appearance. Some areas with low chondrocyte density can be identified. (D) High chondrocyte density, all of them forming columns. The tissue is comparable to healthy hyaline cartilage.