Abstract
Summary
The donor-matched comparison between mesenchymal stem cells from knee infrapatellar and subcutaneous adipose tissue revealed their preferential commitment towards the chondrogenic and osteogenic lineage, respectively. These peculiarities could be relevant for the development of successful bone and cartilage cell-based applications.
Introduction
Mesenchymal stem cells (MSCs) have been proposed in bone and cartilage tissue engineering applications as an alternative to terminally differentiated cells. In the present study we characterised and performed a donor-matched comparison between MSCs resident within the infrapatellar fat pad (IFP-MSCs) and the knee subcutaneous adipose tissue (ASCs) of osteoarthritic patients. These two fat depots, indeed, can be considered appealing candidates for orthopaedic cell-based therapies since they are highly accessible during knee surgery.
Materials and Methods
IFP-MSCs and ASCs were obtained from 25 osteoarthritic patients undergoing total knee replacement. Undifferentiated cells were compared for their clonogenic ability and surface markers expression. Adipogenic, osteogenic and chondrogenic differentiative potentials were evaluated after IFP-MSCs and ASCs induction towards the various lineages by means of histological, biochemical and gene expression analysis of characteristic markers.
Results
We found that undifferentiated IFP-MSCs and ASCs displayed a high clonogenic ability and the typical immunophenotype of MSCs (CD13+/CD29+/CD44+/CD73+/CD90+/CD105+/CD166+/CD31−/CD45−), without any difference in terms of surface markers expression between these two cell populations. When both cell types were cultured in adequate adipo-, osteo- and chondro- differentiative media, IFP-MSCs and ASCs showed similar adipogenic potential, though undifferentiated ASCs had superior LEP expression compared to undifferentiated IFP-MSCs (p<0.01). ASCs showed a higher response to osteogenic induction in comparison with IFP-MSCs as demonstrated by significantly higher levels of calcified matrix deposition (p<0.05) and alkaline phosphatase activity (p<0.05). After 14 days of chondrogenic induction of cells cultured in pellets, we observed greater amounts of glycosaminoglycans (p<0.01) in IFP-MSCs pellets compared to ASCs pellets. Chondrogenic differentiation of IFP-MSCs showed also a superior gene expression of ACAN (p<0.001), SOX9, COMP (p<0.001) and COL2A1 (p<0.05) compared to ASCs. Furthermore, IFP-MSCs showed significantly lower levels of COL10A1 (p<0.05) and COL1A1 (p<0.01) and lower alkaline phosphatase release (p<0.05) compared to ASCs, supporting the hypothesis of a superior chondrogenic commitment of IFP-MSCs.
Discussion/Conclusion
The observed dissimilarities between IFP-MSCs and ASCs suggest that despite similar features at the undifferentiated state, MSCs deriving from different anatomical sites within the same joint can display a specific commitment. The peculiar commitment of IFP-MSCs and ASCs towards the chondrogenic and osteogenic lineage suggests that they may be preferentially used for cartilage and bone applications, respectively.
