Human Mesenchymal Stromal Cells (MSCs) from Adult Thymus Propagated in Pooled Human Platelet Lysate as Potential Cell Source for Sternal Wound Healing

Objectives: Diminished healing capacities due to accompanied diseases often result in disturbed wound healing after open heart surgery. Stem cell-based therapy using autologous mesenchymal stromal cells from adipose tissue (AdMSCs) has regenerative potential because of the described paracrine activity and the immunomodulatory effects of these cells. Therefore the aim of this study is to characterize AdMSCs isolated from adult thymus tissue, which can be easily obtained during open heart surgery and cultivated in animal component free cell culture with regard to their stem cell properties.

Methods: Enzymatically and non-enzymatically isolated AdMSCs from adult thymus were cultured in standard media supplemented with pooled human platelet lysate (PL). The MSC characterization was determined by positive expression of stem cell markers like CD73, CD90 and CD105 and negative for expression of the hematopoietic cell surface markers CD34, CD45, CD11, CD19 and HLA-DR. To test the potential of these AdMSCs to differentiate into adipocytes, osteocytes and chondrocytes they were cultured in special differentiation media according to manufacturer's instructions.

Results: Our study shows that both isolation methods resulted in MSC like cells with plastic adherence and spindle shaped, fibroblast-like morphology under standard culture media supplemented with pooled human platelet lysate. Further characterization by flow cytometry revealed high expression of the MSC markers CD73, CD90 and CD105 and the absence of hematopoietic cell surface markers in both groups. The AdMSCs from adult thymus also differentiated into adipocytes, osteocytes and chondrocytes under specific stimuli.

Conclusion: These results indicate an efficient and reproducible way for the preparation of MSCs from adult thymus avoiding xenogenic components. After further investigations to consider their regenerative and immunomodulatory potential they might be established for stem cell therapy of defective sternal wound healing.