Abstract P1038: Exosomal RNAs And Proteins From Non-invasively Derived Human Induced Mesenchymal Stem Cells Protect Cardiomyocytes From Death

Background: Current stem cells therapy for ischemic cardiomyopathy is effective only about 2-4% in improving cardiac function. In search of novel therapy, we have developed a safe mRNA-based reprogramming of non-invasively derived human urinary epithelial cells into induced pluripotent stem cells (iPSC), and subsequently differentiated them into mesenchymal stem cells (iMSC). We examined therapeutic potential of iMSC in comparison with adult umbilical cord mesenchymal stem cells (MSC).

Hypothesis: Autologous iMSC and their exosomes possess an enhanced cardioprotective characteristics compared to MSC.

Methods and Results: The generated iMSC and their exosomes (ExoQuick reagent) offered an enhanced protection of human iPSC-derived cardiomyocytes (iCMC) from injuries of (i) angiotensin-II (Ang, 10 μM for 24 h) and (ii) 6 hrs of 1% hypoxia and 24 hrs of reoxygenation, in comparison with their MSC controls. The cardiomyocyte protection was studied through measurement of mitochondrial membrane potential (JC1 dye), intracellular reactive oxygen species (CM-H2DCFDA), in situ cell death by apoptosis, and qRT-PCR expression of survival and proinflammatory genes (BCL2, BAD, TNFA and IL6). Treatment with iMSC-derived exosomes alone enhanced the expression of NRF2, a major regulator of cytoprotective genes in protecting Ang-challenged iCMC. The specific role of iMSC exosomal RNAs and proteins in mediating cardioprotection against Ang-induced injury was identified through in situ cell death assay using the exosomes treated with either RNase A (0.5 μg/μl for 20 min at 37 0 C) or proteinase K (0.05 μg/μl for 10 min at 37 0 C) (Fig.1) . Exosomal noncoding RNA analysis by qRT-PCR revealed the presence of inflammation-associated small nucleolar RNAs such as SNORD32A, SNORD33, SNORD34 and SNORD35A. The transfer of exosomal RNAs into the host cardiac cells was augmented in presence of Ang, identified using 0.5 mM ethynyl uridine-labelled exosomes and detected using Click-iT RNA imaging reagents. All experiments were carried out in triplicates. In vivo studies are in progress.

Conclusion: In comparison with adult MSC, non-invasively derived autologous iMSC and their exosomes elicit enhanced cardioprotection and may provide an alternative source of cells or cell-free therapy for treating ischemic cardiomyopathy.

Abstract P470: Disrupted HRAS/GRB2 Signaling In Induced-cardiomyocytes Derived From Patients With Noonan Syndrome Carrying SOS1 Gene Mutation

Background: Noonan syndrome (NS), a dominant autosomal genetic disorder that prevents normal development, and exhibits cardiac defects, which is estimated to appear in 50% to 90% of patients. Son of sevenless homolog 1 (SOS1) gene mutation has been identified as a major gene causing NS and attributes to the development of cardiomyopathy and congenital heart defects. SOS1 is a guanine nucleotide exchange factor for RAS and is known to interact with growth factor receptor-bound protein 2 (GRB2). Recently, we have generated induced pluripotent stem cells (iPSCs)-derived cardiomyocytes (iCMCs) from cardiac fibroblasts obtained from a NS patient carrying SOS1 gene variant 1654A>G.

Hypothesis: Since NS is known to have aberrant RAS-MAPK signaling, we hypothesize that iCMCs derived from NS patient (NS-iCMCs) may have atypical RAS signaling leading to the development of cardiomyopathy.

Methods and Results: We have compared the normal skin fibroblast-derived iPSCs (N-iPSCs) and N-iCMCs with NS patient-derived induced NS-iPSCs and NS-iCMCs. Our qRT-PCR results showed that the mRNA expressions of signaling molecules HRAS, GRB2 and SOS1 were significantly decreased in NS-iCMCs compared with N-iCMCs (Figure A), and further confirmed through the protein expression by Western immunoblotting (Figure B). These results were in association with a significantly decreased mRNA and protein expressions of cardiac transcription factor GATA4, and structural proteins alpha sarcomeric actinin-2 (ACTN2), cardiac troponin T (TNNT2) and tropomyosin alpha-1 (TPM1) in NS-iCMCs compared with N-iCMCs. Further studies are underway to explore the difference in the guanine nucleotide exchange factor (GEF) activity and ERK activation between NS-iCMCs and N-iCMCs.

Conclusion: Our current findings clearly indicate that the SOS1-associated signaling molecules HRAS and GRB2 were disrupted in NS-iCMCs, which may result in the development of cardiomyopathy in NS patients.

Abstract 515: Non-invasive Method of Generating Human Induced-mesenchymal Stem Cells Derived From Urinary Epithelial Cells for Regenerative Therapy

Introduction: Mesenchymal stem cells (MSCs) are multipotent adult stem cells having an extensive proliferation capacity in vitro and in vivo. These MSCs can differentiate into various mesoderm-type cells such as osteoblasts, cardiomyocytes, etc. A subpopulation of urinary epithelial cells (UECs) have been identified in urine samples, is considered a promising cell resource for generating autologous induced-pluripotent stem cells (iPSCs).

Hypothesis: We hypothesize that the production of high quality, autologous, induced-MSCs (iMSCs) with high replicative potential suitable for the regenerative therapy, using an easy, and the most non-invasive method of isolation, from human UECs.

Methods and Results: Human urine was collected and centrifuged to obtain the UECs, which were characterized by the expression of CK19 and ZO1. These UECs were reprogrammed to iPSCs using a cocktail of mRNAs (OCT4, KLF4, SOX2, c-MYC, Nanog and Lin28) along with Lipofectamine for 11 days in culture. These iPSCs were characterized by the expression of the pluripotent markers such as OCT4, SOX2 and SSEA4. The iPSCs were subsequently differentiated into iMSCs using the mesenchymal specific medium for 21 days. iMSCs were harvested at the end of 21 days, and they were characterized by the high levels of mRNA and protein expressions of mesenchymal specific markers such as CD73, CD90 and CD105 (Fig. 1A). FACS analysis showed that more than 93% of the cells were positive for the markers of MSCs (Fig. 1B) . Moreover, the obtained iMSCs have high proliferation capacity compared with the adult stem cells.

Conclusions: We have developed an easy, non-invasive method for obtaining autologous, non-immunogenic and highly-proliferating iMSCs suitable for various regenerative therapies including cardiac diseases, from urinary epithelial cells.

Abstract 502: Inhibition of Histone Deacetylase 6 Protects Human Induced Pluripotent Stem Cells-derived Cardiomyocytes Through Inhibition of Autophagy

Introduction: Autophagy is known to play an important role in mediating cardiac hypertrophy. However, the mechanism is poorly understood. Since the protein histone deacetylase 6 (HDAC6) contributes to cardiac dysfunction in response to angiotensin II (AngII) signaling, we have examined the role of HDAC6 inhibitor tubastatin A (TBA) in AngII-induced remodeling in human induced pluripotent stem cells-derived cardiomyocytes (iCMCs).

Hypothesis: We hypothesize that the inhibition of HDAC6 protects iCMCs from AngII-induced cardiac hypertrophy through inhibition of autophagy.

Methods and Results: We have generated and characterized induced pluripotent stem cells from human adult skin fibroblasts and subsequently differentiated them into iCMCs. Treatment with 10 μM angiotensin II for 24 hrs increased the HDAC6 activity and lead to hypertrophy in iCMCs. The AngII-induced hypertrophy, and the excessive contractility in iCMCs were reversed by the inhibition of HDAC6 with TBA (1 μM for 24 hours). The number of LC3-positive iCMCs, and the mRNA and the protein expression of autophagic genes Beclin-1, LC3, and p62 were increased by the presence of AngII, and the anti-autophagic gene Bcl2 was decreased by AngII. The inhibition of HDAC6 with TBA reversed the AngII-mediated changes in the autophagic genes expressions in iCMCs. Autophagic vacuoles were identified with monodansylcadaverine (MDC, green) and lysosomes with LysoTracker (red) (Fig. 1A) . The number of autophagolysosomes were increased by AngII, and this was decreased with TBA in iCMCs (Fig. 1B) .

Conclusions: Our report indicates for the first time that the AngII-induced cardiac hypertrophy-mediated autophagy is effectively inhibited by the suppression of HDAC6 in human iCMCs.

Abstract 489: Identification And In-silico Analysis Of Pathogenic Non-synonymous Snps Of Human Sos1 Protein In Noonan Syndrome

Introduction: Noonan syndrome is a genetic disorder (autosomal dominant) characterized by short stature, congenital heart disease, bleeding problems, developmental delays, and skeletal malformation. It is mainly caused by a single nucleotide alteration in four genes PTPN11, SOS1, RAF1, and KRAS . In this study, we computationally analyzed the SOS1 gene to identify the pathogenic non-synonymous single nucleotide polymorphisms (nsSNPs), which is known to cause Noonan syndrome.

Hypothesis: We hypothesize that in-silico analysis of human SOS1 mutations in Noonan syndrome would be a promising predictor to study the post-translational modifications.

Methods and Results: The variant information of SOS1 was collected from the dbSNP database and the literature review on Noonan syndrome. They were further analyzed by in-silico tools such as I-Mutant, iPTREE-STAB, and MutPred for their structural and functional properties. We found that 11 nsSNPs are more pathogenic for Noonan syndrome. The 3D comparative protein of 11 nsSNPs with its wild-type SOS1 was modeled by using I-Tasser and validated via ERRAT and RAMPAGE. The protein-protein interactions of SOS1, GATA4, TNNT2, and ACTN2 were analyzed using STRING, which showed that HRAS was intermediate between SOS1 and ACTN2 (Fig. 1) .

Conclusion: This is the first in-silico study of the SOS1 variant with Noonan syndrome. We proposed that this 11 nsSNPs are the most pathogenic variant of SOS1 , which helps to screen the Noonan patient. Furthermore, our results are promising to study the gain/loss of post-translational modification (PTM) by mutation in cardiac genes and helps to explore the novel molecular pathways.$graphic_{DB5B0E7D-4DA6-4569-A16F-E05B2C9C4D2F}$$