SIZE-BASED MICROFLUIDIC-ENRICHED MESENCHYMAL STEM CELL SUBPOPULATION ENHANCED ARTICULAR CARTILAGE REPAIR

Abstract

Background & Aim

The functional heterogeneity development of culture-expanded mesenchymal stem cells (MSCs) has hindered the clinical consistency of MSC. Previous studies have shown that MSC subpopulations with superior chondrogenic capacity can be isolated using a spiral microfluidics device based on the principle of inertial cell focusing. This study aims to demonstrate that the implantation of microfluidic-enriched chondrogenic MSCs that are consistent in size and function would overcome the challenge of functional heterogeneity of expanded MSC, and will significantly improve MSC-based cartilage repair.

Methods, Results & Conclusion: Methods

A next-generation, fully automated multi-dimensional double spiral (MDDS) microfluidic device was designed to provide more refined size resolution and efficient isolation of the MSC subpopulation based on size. In vitro chondrogenic potential and RNA sequencing analysis was performed on the size-sorted MSC subpopulations. The in vivo cartilage repair efficacy was demonstrated in a 12 weeks old rat osteochondral injury model. Defects were implanted with MSC subpopulations (n=6 per group) and was compared with implantation of the un-segregated MSCs (n=6). Osteochondral repair was assessed at 6 and 12 weeks post-surgery by histological, micro-computed tomography (micro-CT) and mechanical analyses.

Results

A chondrogenic subpopulation of MSC was efficiently isolated using the MDDS device. RNA sequencing analysis revealed distinct transcriptomic profiles and identified differential gene expression between subpopulations. Delivery of chondrogenic MSC subpopulation resulted in improved cartilage repair as indicated by histological scoring, compressional modulus, and micro-CT analysis of the subchondral bone.

Conclusion

We have established a rapid, label-free, and reliable microfluidic protocol for more efficient size-based enrichment of a chondrogenic subpopulation of MSC. The delivery of microfluidics-enriched chondrogenic MSCs that are consistent in size and function can overcome the challenge of functional heterogeneity of expanded MSCs, resulting in significant improvement in MSC-based cartilage repair. The availability of such rapid, label-free enriched chondrogenic MSCs can enable better cell therapy products for cartilage repair with improved treatment outcomes.