RESEARCH TOPIC

Role of c-kit in the survival, growth, migration and differentiation of cardiac stem cells.

The belief that adult mammalian heart lacks regenerative potential has been challenged by the identification of c-kit positive cardiac stem cells (CSCs) resident in the heart. SCIPIO, a phase I clinical trial, has shown that these c-kit positive CSCs improve cardiac function and quality of life in ischemic heart disease patients after intra-coronary injection. c-kit, an invariable marker of CSCs, is a type III receptor tyrosine kinase, and stem cell factor (SCF) is its only known ligand. SCF/c-kit signaling has been shown to play critical roles in regulating proliferation, survival, differentiation and migration of multiple c-kit-expressing cell populations, including hematopoietic stem cells. Although c-kit has been extensively used to identify CSCs, there is little information in regard to its role in the regulation of survival, growth and migration of CSCs. This led us to hypothesize that c-kit plays a role in the regulation of survival, growth and migration of human CSCs. To test this hypothesis, CSCs were grown under reduced serum conditions and the pro-survival/growth effects of SCF and subsequent activation of c-kit on CSCs were measured at serial time points using MTT, growth curve, BrdU labeling and apoptosis assays. SCF-mediated activation of c-kit in CSCs significantly attenuated the cell death induced by serum deprivation, suggesting that c-kit activation promotes cell survival and/or growth of CSCs. We then used the Boyden chamber assay to investigate if activation of c-kit can also promote migration of CSCs and compared the chemotactic effect of SCF to VEGF. We found that c-kit/SCF signaling significantly increased CSC migration equal to that of VEGF. To further confirm the critical role of c-kit in mediating the above mentioned cellular effects, we are currently working on over expressing or knocking down c-kit using the lenti-virus gene delivery system. In conclusion, our results suggest that c-kit promotes the survival/growth, and migration of CSCs in vitro. If this is the case, manipulating c-kit signaling will potentially open new strategies to promote these cellular effects, eventually improving the treatment outcome.

Thesis Committee

1. Dr. Kyung Hong, Dept. of Medicine - Cardiology
2. Dr. Aruni Bhatnagar, Dept. of Medicine - Cardiology
3. Dr. Steven Jones, Dept. of Medicine - Cardiology
4. Dr. Alan Cheng, Biochemistry and Molecular Biology
5. Dr. Marsha Cole, Biochemistry and Molecular Biology

Publications and Dissertations

1. Hong KU, Guo Y, Li Q, Cao P,  Al-Maqtari T, Vajravelu BN, Du J, Book M, Zhu X, Nong Y,  Bhatnagar A, Bolli R. (2014). c-kit+ Cardiac Stem Cells Alleviate Post-Myocardial Infarction Left Ventricular Dysfunction Despite Poor Engraftment and Negligible Retention in the Recipient Heart. PLOS ONE, May 2014.

(For Recent Publications, check PubMed)

Posters Presented

1. Stem Cell Factor-Mediated Activation of c-kit Promotes Survival and Migration of Cardiac Stem Cells; Vajravelu BN, Al-Maqtari T, Moktar A, Cao P, Vu D, Bhatnagar A, Bolli R, Hong K (2014) Second annual meeting of Kentucky Chapter of the American Physiology Society.
2. Gata4 Overexpression Facilitates Differentiation of Human Cardiac Stem Cells; Al-Maqtari T, Vajravelu BN, Moktar A, Cao P, Bhatnagar A, Hong K, Bolli R (2014) Second annual meeting of Kentucky Chapter of the American Physiology Society.
3. Role of c-Kit Signaling in Growth, Migration and Differentiation of Human Cardiac Stem Cells,Vajravelu BN, Al-Maqtari T, Moktar A, Cao P, Bhatnagar A, Hong K, Bolli R (2013). Proc. The fifth University of Louisville Biochemistry and Molecular Biology Colloquium.
4. c-Kit Activation Promotes the Survival, Growth and Migration of Cardiac Stem Cells: Vajravelu BN, Al-Maqtari T, Moktar A, Cao P, Vu D, Hong K,  Bhatnagar A, Bolli R (2013)  Research of Louisville, University of Louisville, School of Medicine.
5. Transcription Factor-Induced Activation of Cardiac Gene Expression in c-kit+ Cardiac Stem Cells, Al-Maqtari T, Vajravelu BN, Moktar A, Cao P, Bhatnagar A, Hong K, Bolli R (2013) American Heart Association (AHA) Scientific Sessions, Dallas, Texas, USA.
6. “Directed Differentiation of c-kit+ Human Cardiac Stem Cells in vitro”. Hong KU, Al-Maqtari T, Moktar A, Vajravelu BN, Bhatnagar A, Bolli R. (2013) American Heart Association (AHA) Basic Cardiovascular Sciences (BCVS) meeting, Las Vegas, Nevada, USA.
7. Directed Differentiation of c- kit+ Human Cardiac Stem Cells; Moktar A, Vajravelu BN, Vu D, Bhatnagar A, Bolli R, Hong KU (2012  Research of Louisville, University of Louisville, School of Medicine.

Conferences Attended

1. American Heart Association - Nov – 2012, Los Angeles, CA
2. American Heart Association - Nov – 2013, Dallas, TX