Infrapatellar fat pad adipose-derived stem cells co-cultured with articular chondrocytes from osteoarthritis patients exhibit increased chondrogenic gene expression

Christopher C H Mak,Roger A Brooks,Wasim S Khan,Karim Fekir,Kendrick To

doi:10.1186/s12964-021-00815-x

Abstract

AimThe variable results in clinical trials of adipose tissue-derived stem cells (ASCs) for chondral defects may be due to the different ex vivo culture conditions of the ASCs which are implanted to treat the lesions. We sought to determine the optimal in vitro chondrocyte co-culture condition that promotes infrapatellar fat pad-derived (IFPD) ASC chondrogenic gene expression in a novel co-culture combination.MethodsIn our study, we utilized an in vitro autologous co-culture of IFPD ASCs and articular chondrocytes derived from Kellgren–Lawrence Grade III/IV osteoarthritic human knee joints at ASC-to-chondrocyte seeding log ratios of 1:1, 10:1, and 100:1. Gene expression following in vitro co-culture was quantified by RT-qPCR with a panel comprising COL1A1, COL2A1, COL10A1, L-SOX5, SOX6, SOX9, ACAN, HSPG2, and COMP for chondrogenic gene expression.ResultsThe chondrogenic gene expression profiles from co-cultures were greater than would be expected from an expression profile modeled from chondrocyte and ASC-only monocultures. Additionally, chondrogenic gene expression decreased with increasing ASC-to-chondrocyte seeding ratios.ConclusionsThese findings provide insight into the mechanisms underlying clinical ASC therapies and signifies that IFPD ASCs pre-conditioned by chondrocyte co-culture may have improved chondrogenic potential for cartilage repair. This model can help further understand IFPD ASCs in chondral and osteochondral repair and the chondrogenic pathways involved.5w6sq_raPc9bkGgSr2Nbk9Video

Highlights

Osteoarthritis is characterized by degradation of articular cartilage, influenced by altered mechanical loading and exacerbated by localized inflammation [1]
Significant differences of SOX9 (p = 0.0412) and ACAN (p = 0.0245) only were observed for the 10:1 coculture ratio, and of L-SOX5 (p = 0.0136) and SOX6 (p = 0.0426) for the 100:1 ratio. These results suggest that the optimal number of chondrocytes and adipose tissue-derived stem cells (ASCs) for chondrogenic pre-conditioning is near a 1:1 co-culture ratio
Our study shows that pre-conditioning Infrapatellar Fat Pad-Derived (IFPD) ASCs in co-culture with chondrocytes can enhance chondrogenic gene expression in vitro, and this effect is greater when seeding at a lower IFPD ASC-to-chondrocyte ratio

Summary

Introduction

Osteoarthritis is characterized by degradation of articular cartilage, influenced by altered mechanical loading and exacerbated by localized inflammation [1]. While bone marrow-derived MSCs and umbilical cord blood-derived MSCs have been investigated in clinical trials, they are limited by low relative abundance and ease of isolation respectively. Infrapatellar Fat Pad-Derived (IFPD) ASCs on the other hand exhibit a high relative abundance, ease of isolation, and high proliferation potential [9,10,11]. The fat pad is an intra-articular structure anatomically located near cartilage, and has been shown to be a source of ASCs capable of chondrogenic differentiation and the repair of osteochondral defects in vivo [12]. Unpassaged cells that have not been expanded ex vivo more closely resemble cells in vivo and represent a more attractive option as a therapeutic intervention

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