iPSC-Derived Induced Mesenchymal Stem Cells as a Potential Cell Source for Tissue Engineered Heart Valves
Aline L. Yonezawa Nachlas1, Monalisa Singh2, Siyi Li1, David Safranski3, Kenneth Dupont3, Chunhui Xu2, Michael E. Davis1.
1Georgia Institute of Technology & Emory University, Atlanta, GA, USA, 2Children's Healthcare of Atlanta & Emory University, Atlanta, GA, USA, 3Medshape Inc., Atlanta, GA, USA.
Objective: Despite recent advances in tissue engineered heart valves (TEHV), one of the major challenges is finding a suitable cell source for seeding TEHV scaffolds. Native heart valves are durable because valve interstitial cells (VICs) maintain tissue homeostasis by synthesizing and remodeling the extracellular matrix. In this study, the goal is to demonstrate that induced pluripotent stem cells (iPSCs) can be derived into induced mesenchymal stem cells (iMSCs) using our feeder-free protocol and then further differentiated into VICs using a 3D cell culture environment.
Methods: The differentiation efficiency was characterized by using flow cytometry, immunohistochemistry staining, RT-PCR, and trilineage differentiation. In addition, iMSCs were encapsulated in polyethylene (glycol) diacrylate (PEGDA) hydrogels of varying stiffness, grafted with adhesion peptide (RGDS) and a slow-degradation linker (GGGLGPAGGK), to promote cell proliferation, remodeling, and further differentiation into VIC-like cells. VIC phenotype was assessed by the expression of αSMA, vimentin, F-actin, and the ECM production after 7 and 14 days. In addition, the genotype of iMSCs after encapsulation in hydrogel was assessed using RT-PCR.
Results: The results demonstrated that using our feeder-free differentiation protocol, iMSCs were differentiated from iPSCs. Our iMSCs have a 99.3%, 98.8%, 99.6%, and 95.9% positive expression of CD90, CD44, CD71, and αSMA, respectively. As expected there was 0.020% expression of CD45, a hematopoietic marker. iMSCs were capable of undergoing trilineage differentiation when cultured in induction media for 21 days. In addition, iMSCs demonstrate similar expression of αSMA and F-actin compared to human MSCs. When MSC-derived cells were encapsulated in PEGDA hydrogels that mimic the leaflet modulus, we observed expression of αSMA and F-actin after 7 days.
Conclusions: Thus, the results from this study suggest that iPSCs can be a suitable cell source for TEHV by using a feeder-free differentiation approach and 3D cell culture mimicking the leaflet modulus.
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