gms | German Medical Science

Objectives: Cells from infrapatellar fat pad (IPFP) were discussed controversially in the literature. These cells are usually compared to mesenchymal stroma cells (MSC), even though there is some doubt about their differentiation potential. In our study we want to compare the multilineage differentiation potential of IPFP cells derived from degenerated and healthy tissue with bone marrow derived MSC for a potential clinical application in cartilage regeneration.

Methods: Cells from IPFP of healthy donors and patients suffering from osteoarthritis (each n=3) were isolated enzymatically and expanded up to passage 2. Then, cells were measured by flow cytometry and compared to bone marrow derived MSC (n=3). Differentiation towards the adipogenic, chondrogenic and osteogenic lineage was performed to evaluate the multilineage capacity of the IPFP derived cells and the MSC. Adipogenic differentiation was determined by oil red O staining and chosen genes with real-time polymerase chain reaction (RTD-PCR). Chondrogenic differentiation was performed in micro-mass cultures and evaluated with alician blue staining and decorin immunofluorescence staining of cryo slices. Osteogenic differentiation was confirmed by von Kossa staining and RTD-PCR.

Results and Conclusion: Flow cytometric analyzes showed a nearly 100% presence of CD105, CD90, CD73, and CD44 on IPFP derived cells independent of the osteoarthritis grade of the patients' knees. On contrary CD45, CD34, and CD14 could not be detected. Same results were found for bone marrow derived cells. Different results for IPFP derived cells and bone marrow derived MSC were achieved after multilineage differentiation. Adipogenic differentiation resulted in lipid droplet formation and an upregulation of specific marker genes Peroxisome Proliferator Activated Receptor Gamma (PPARG) and Fatty Acid Binding Protein 4 (FABP4) in all cultures. Chondrogenic differentiation led to an increased decorin production and alcian blue staining confirmed the production of proteoglycans in IPFP derived cells and MSC. Positive von Kossa staining and upregulation of gene expression of integrin-binding sialoprotein (IBSP) and Secreted Phosphoprotein 1 (SPP1), was only achieved in MSC cultures. No osteogenic differentiation was shown neither in IPFP cells from healthy nor osteoarthritic tissues.

IPFP derived cells with a different osteoarthritis origin and bone marrow MSC have similar characteristics considering surface marker profile, chondrogenic and adipogenic differentiation properties. Nevertheless, osteogenic differentiation was not seen in IPFP derived cells. Therefore, IPFP derived cells seems to be more suitable for cartilage regenerative strategies. Compared to MSC, IPFP cells have an advantage in regeneration of osteoarthritis related loss of cartilage due to the lacking risk of ossification. This could further contribute to a potential regenerative cell-based therapy approach.