Adipose Stromal Cell Spheroids for Cartilage Repair: A Promising Tool for Unveiling the Critical Maturation Point

Abstract

Articular cartilage lacks intrinsic regenerative capabilities, and the current treatments fail to regenerate damaged tissue and lead only to temporary pain relief. These limitations have prompted the development of tissue engineering approaches, including 3D culture systems. Thanks to their regenerative properties and capacity to recapitulate embryonic processes, spheroids obtained from mesenchymal stromal cells are increasingly studied as building blocks to obtain functional tissues. The aim of this study was to investigate the capacity of adipose stromal cells to assemble in spheroids and differentiate toward chondrogenic lineage from the perspective of cartilage repair. Spheroids were generated by two different methods (3D chips vs. Ultra-Low Attachment plates), differentiated towards chondrogenic lineage, and their properties were investigated using molecular biology analyses, biophysical measurement of mass density, weight, and size of spheroids, and confocal imaging. Overall, spheroids showed the ability to differentiate by expressing specific cartilaginous markers that correlate with their mass density, defining a critical point at which they start to mature. Considering the spheroid generation method, this pilot study suggested that spheroids obtained with chips are a promising tool for the generation of cartilage organoids that could be used for preclinical/clinical approaches, including personalized therapy.

Cartilage-Specific Gene Expression and Extracellular Matrix Deposition in the Course of Mesenchymal Stromal Cell Chondrogenic Differentiation in 3D Spheroid Culture

“…Previously, using extracellular matrix (ECM) analysis, we obtained data supporting the hypothesis of the varying ability of MSCs from different tissues in chondrogenic differentiation [ 12 ]. The present study sought to conduct a more comprehensive comparison of the chondrogenic ability of these cells in 3D spheroid culture using chondrogenesis hallmarks, including the expression of cartilage-specific genes (Collagen I alpha 1 (COL1A1), Collagen II alpha 1 (COL2A1), Aggrecan (ACAN), and the sex-determining region Y (SRY)-box 9 (SOX9) [ 13 , 14 ], the synthesis of hyaline cartilage proteins, and ECM production. Primary chondrocytes served as the control.…”