Cardiosphere-Derived Cells: A Possible Source for Regenerative Cell Therapy in Congenital Heart Diseases

 

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Objectives: Cardiosphere-derived cells (CDCs), a heterogeneous mix of cardiac cells with ambiguous identity, have been used in preclinical and clinical trials with variable success. Transplantation of CDCs into adult patients after myocardial infarction did not improve cardiac function significantly while administration to children with congenital heart disease was beneficial. Therefore, we aimed to characterize CDCs from surgical patients with varying age and compared their properties to those of adipose-tissue-derived fibroblasts (AFs) and cardiac fibroblast (CFs).

Methods: CDCs, AFs and CFs were cultivated from neonate (>10 days) to adult (>25 years) patients with variable cardiac pathotypes undergoing cardiac surgery. CDCs were generated according to a previously published and well-established 3-step protocol. AFs were generated from subcutaneous fat samples and CFs from different patients were cultivated from cardiac biopsies. At passages 0 to 2 flow cytometry analysis, immunohistochemical stainings and gene expression analyses were performed with appropriate antibodies and primer sets.

Results: CDCs and corresponding AF populations from the same patient expressed the mesenchymal stem cell marker CD105 to a similar extent (>90%) as measured by flow cytometry. Both cell types, CDCs and AFs, were negative for the hematopoietic marker CD45. Cardiac fibroblasts (CFs) obtained from different patients showed similar properties for these two markers. qRT-PCR confirmed these results. The fibroblast marker CD90 was expressed on more than 90% of cultivated AFs and CFs whereas the percentage was highly variable in CDCs (20% to 98%). Immunohistochemical staining for DDR2, another fibroblast marker, revealed expression on the majority of cultivated CDCs, AFs and CFs. Finally, gene expression levels of essential cardiac developmental markers like GATA4 or NKX2.5 were evaluated by qPCR. Preliminary results suggest a trend toward a higher expression in CDCs derived from children compared with those established from adult patients.

Conclusion: Clinical trials have shown first beneficial effects of CDCs in patients with congenital heart disease. Our results showed comparable properties between CDCs and different fibroblast populations. However, CDCs derived from children tended to express specific cardiac transcription factors more abundantly which may be one reason for their superior performance after transplantation compared with adult CDCs.