Abstract
Matrix-assisted autologous chondrocyte transplantation (MACT) for focal articular cartilage defects often fails to produce adequate cartilage-specific extracellular matrix in vitro and upon transplantation results in fibrocartilage due to dedifferentiation during cell expansion. This study aimed to redifferentiate the chondrocytes through supplementation of blood-products, such as hyperacute serum (HAS) and platelet-rich plasma (PRP) in vitro. Dedifferentiated monolayer chondrocytes embedded onto collagen type I hydrogels were redifferentiated through supplementation of 10% HAS or 10% PRP for 14 days in vitro under normoxia (20% O2) and hypoxia (4% O2). Cell proliferation was increased by supplementing HAS for 14 days (p < 0.05) or by interchanging from HAS to PRP during Days 7–14 (p < 0.05). Sulfated glycosaminoglycan (sGAG) content was deposited under both HAS, and PRP for 14 days and an interchange during Days 7–14 depleted the sGAG content to a certain extent. PRP enhanced the gene expression of anabolic markers COL2A1 and SOX9 (p < 0.05), whereas HAS enhanced COL1A1 production. An interchange led to reduction of COL1A1 and COL2A1 expression marked by increased MMP13 expression (p < 0.05). Chondrocytes secreted less IL-6 and more PDGF-BB under PRP for 14 days (p < 0.0.5). Hypoxia enhanced TGF-β1 and BMP-2 release in both HAS and PRP. Our study demonstrates a new approach for chondrocyte redifferentiation.
Highlights
The articular cartilage of the synovial joints, being avascular and limited for endogenous repair capacity, consists of sparsely distributed specialized cells called chondrocytes embedded within its extracellular matrix (ECM), which provide the cartilage with remarkable mechanical and low friction properties
The rate of proliferation over the course of chondrocyte redifferentiation analyzed on Days 7 and 14 revealed that platelet-rich plasma (PRP) inhibited the proliferation over Days 0–14 with no change in cell numbers from the initial seeding density
The expression of COL1A1 had a seven-fold increase in hyperacute serum (HAS) during Days 7–14 (p < 0.0404), whereas no COL1A1 expression was observed in PRP at both time points (Figure 1D)
Summary
The articular cartilage of the synovial joints, being avascular and limited for endogenous repair capacity, consists of sparsely distributed specialized cells called chondrocytes embedded within its extracellular matrix (ECM), which provide the cartilage with remarkable mechanical and low friction properties. For full articular cartilage defects, cell-scaffold-based tissue engineering approaches, such as the matrix-assisted autologous chondrocyte transplantation (MACT), are some of the standardized treatment methods among many others. Various cell sources other than autologous chondrocytes are investigated for cartilage repair, including bone marrow mesenchymal stem cells, adipose tissue derived mesenchymal stem cells, synovium-derived mesenchymal stem cells and infrapatellar fat pad stem cells. These sources of cells are advantageous for the low donor site morbidity and in obtaining higher cell yield
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