Freshly isolated stromal cells from the infrapatellar fat pad are suitable for a one-step surgical procedure to regenerate cartilage tissue

Abstract

Background aims

Stem cell therapies are being evaluated as promising alternatives for cartilage regeneration. We investigated whether stromal vascular fraction cells (SVF) from the infrapatellar (Hoffa) fat pad are suitable for a one-step surgical procedure to treat focal cartilage defects.

Methods

SVF was harvested from patients undergoing knee arthroplasty (n = 53). Colony-forming unit (CFU) assays, growth kinetics and surface marker profiles were determined, and the chondrogenic differentiation capacity of freshly isolated SVF was assessed after seeding in three-dimensional poly (l-lactic-co-ϵ-caprolactone) scaffolds.

Results

SVF yield per fat pad varied between 0.55 and 16 × 10⁶ cells. CFU frequency and population doubling time were 2.6 ± 0.6% and ±2 days, respectively. Surface marker profiles matched those of subcutaneous-derived adipose-derived stem cells (ASC). CFU from Hoffa SVF showed differentiation toward osteogenic and adipogenic lineages. Cartilage differentiation was confirmed by up-regulation of the cartilage genes sox9, aggrecan, collagen type II and cartilage oligomeric matrix protein (COMP), collagen II immunostaining, Alcian Blue staining and glycosaminoglycan production. Compared with passaged cells, SVF showed at least similar chondrogenic potential.

Conclusions

This study demonstrates that SVF cells from the infrapatellar fat pad are suitable for future application in a one-step surgical procedure to regenerate cartilage tissue. SVF shows similar favorable characteristics as cultured ASC, and chondrogenic differentiation even appears to be slightly better. However, because of variable harvesting volumes and yields, SVF from the infrapatellar fat pad might only be applicable for treatment of small focal cartilage defects, whereas for larger osteoarthritic defects subcutaneous adipose tissue depot would be preferable.

Keywords:

• adipose tissue
• cell differentiation
• chondrogenesis
• colony-forming units assay
• infrapatellar fat pad
• mesenchymal stromal cells
• one-step surgical procedure
• stromal vascular fraction

Acknowledgements

The authors like to thank Dr Jiya and Dr Saouti for providing Hoffa fat pads, Zufu Lu for his technical assistance with PCR analyzes and Development Hybridoma Bank for providing collagen type II antibody.

Declaration of interest: The authors declare that they have no conflict of interest.