Summary

We presented methods for evaluation of a scaffold-free cell delivery system made from mesenchymal stromal cells in a translational study that allows further clinical trial studies of safety and efficacy using good manufacturing practices for human usage.

Abstract

Background

A chondral deffect is a limiting condition that may cause worsening in quality of life and economic burden due to the cost of immediate treatment and losses in work productivity. Additionally, if left untreated, knee disorders may progress to osteoarthritis, a degenerative and debilitating joint disease characterized by pain and functional impairment. The predictable sources and relatively easy handling of mesenchymal stromal cells (MSCs) that have immune-modulatory properties and the ability to differentiate into chondroblasts and osteoblasts are helpful for tissue engineering and treatment of cartilage injuries. We aim to present method tools to evaluate cartilage repair by tissue engineered treatments in a translational and pre-clinical large animal model.

Experiment: This controlled experimental study with fourteen miniature pigs tested a scaffold-free Tissue Engineering Construct (TEC) derived from dental pulp and synovial MSCs for cartilage therapy. Total thickness cartilage defects were performed in both posterior knees. The defect was left empty in one of the knees, and the other received the TEC. The tissue repair was morphologically assessed from magnetic resonance imaging using the 3D-DESS sequence, and compositional assessment was carried out based on T2 mapping technique. The mechanical evaluation determined Young’s modulus of the cartilage samples based on the indentation and maximum compression tests, and the Finite Element model was used to simulate and characterize properties of the osteochondral block. The osteochondral specimens were fixed for histopathology, decalcified, submitted to standard histological processing, sectioned, and stained with hematoxylin & eosin. The sections stained for immunohistochemical detection of collagen types were digested with pepsin and chondroitinase and incubated with antibodies against them.

Results

The MRI, biomechanical, histological and immunohistochemical evaluations proved to be feaseble and qualified to differentiate good quality chondral repair from inadequate repair tissue, at six months after surgery. No complications with the animals were found.

Conclusions

The proposed methods were viable and capable to correctly evaluate the defect filled in with TEC containing mesenchymal cells after six months of follow-up on a large animal model for articular cartilage restoration.