Effects of cell phenotype and seeding density on the chondrogenic capacity of human osteoarthritic chondrocytes in type I collagen scaffolds

Chenxi Cao,Yujun Zhang,Yanqi Ye,Tiezheng Sun

doi:10.1186/s13018-020-01617-6

Abstract

ObjectiveMatrix-associated autologous chondrocyte implantation (MACI) achieves good clinical efficacy in young patients with focal cartilage injury; however, phenotypic de-differentiation of chondrocytes cultured in monolayer and the treatment of older OA patients are still challenges in the field of cartilage tissue engineering. This study aimed to assess the in vitro re-differentiation potential and in vivo chondrogenic capacity of human OA chondrocytes inoculated into collagen I scaffolds with different cellular phenotypes and seeding densities.MethodsOA chondrocytes and articular chondrocyte-laden scaffolds were cultured over 2 weeks in in vitro. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and histological staining were used to detect the mRNA expression profiles and extracellular matrix secretion of chondrocyte-specific markers. OA chondrocyte-laden collagen I scaffolds with different cellular phenotypes, and seeding densities were implanted into SCID mice over 4 weeks to evaluate the chondrogenic capacity in vivo.ResultsIncreased COL2a1, ACAN, COMP, SOX9, and BMP2 expression levels and decreased COL1a1, VCAN, MMP13, and ADAMTS5 amounts were observed in OA chondrocytes seeded in collagen I scaffolds; Implantation of phenotypically superior OA chondrocytes in collagen I scaffolds at high density could improve the chondrogenic capacity of human OA chondrocytes, as confirmed by RT-qPCR assessed gene expression patterns in vitro and histological evaluation in vivo.ConclusionsFreshly isolated chondrocytes from OA patients could be a source of replacement for articular chondrocytes being commonly used in MACI. Implantation of phenotypically superior OA chondrocytes in collagen I scaffolds at high density could be a promising tool for the treatment of elderly OA patients.

Highlights

Full-thickness articular cartilage defects have little potential for self-repair based on poor vascularity and limited spontaneous healing ability [1]
With the passage of cells, mRNA expression levels of COL2a1, ACAN, COMP, and SOX9 were dramatically decreased between Passage 1 (P1), P3, and P5. mRNA expression levels of BMP2 and CD44 were decreased between P1 and P5
We demonstrated that mRNA levels of fibrotic genes (COL1a1 and VCAN) were gradually increased, while the amounts of chondrogenic genes (COL2a1, ACAN, SOX9, BMP2, CD44, and COMP) were progressively decreased in OA chondrocytes from P1 to P5 during monolayer culture

Summary

Introduction

Full-thickness articular cartilage defects have little potential for self-repair based on poor vascularity and limited spontaneous healing ability [1]. MACI is based on the isolation of chondrocytes from minor load-bearing areas of the knee and monolayer culture in vitro to reach an adequate density before cell implantation on porous scaffolds into the cartilage defect [4]. Previous findings suggest that the MACI technology achieves good clinical efficacy in young patients with focal cartilage injury [5]. Ulrich Schneider et al performed type I collagen hydrogelbased autologous chondrocyte implantation (CaReS) in 116 young patients with knee joint cartilage injury, and their experiment shows matrix-associated ACI employing the CaReS technology for the treatment of chondral or osteochondral defects of the knee is a safe and clinically effective treatment that yields significant functional improvement and improvement in pain level [6]. Phenotypic de-differentiation of chondrocytes cultured in monolayer and the treatment of older OA patients are still challenges in the field of cartilage tissue engineering [7]

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Discussion

Conclusion