Author: ccrosby (Page 2 of 6)

Congratulations to Chengyi Tu, whose publication, “Commonly used thiol-containing antioxidants reduce cardiac differentiation and alter gene expression ratios of sarcomeric isoforms”, was recently accepted and is now published in Experimental Cell Research! The abstract can be found below:

Reactive oxygen species (ROS) scavengers such as beta-mercaptoethanol (BME) and monothiol glycerol (MTG) are extensively used in stem cell research to prevent cellular oxidative stress. However, how these antioxidant supplements impact stem cell cardiac differentiation, a process regulated by redox-signaling remains unknown. In this study, we found that removal of BME from the conventional high-glucose, serum-based differentiation medium improved cardiac differentiation efficiency by 2-3 fold. BME and MTG treatments during differentiation significantly reduced mRNA expression of cardiac progenitor markers (NKX2.5 and ISL1) as well as sarcomeric markers (MLC2A, MLC2V, TNNI3, MYH6 and MYH7), suggesting reduced cardiomyogenesis by BME or MTG. Moreover, BME and MTG altered the expression ratios between the sarcomeric isoforms. In particular, TNNI3 to TNNI1 ratio and MLC2V to MLC2A ratio were significantly lower in BME or MTG treated cells than untreated cells, implying altered cardiomyocyte phenotype and maturity. Lastly, BME and MTG treatments resulted in less frequent beating, slower contraction and relaxation velocities than untreated cells. Interestingly, none of the above-mentioned effects was observed with Trolox, a non-thiol based antioxidant, despite its strong antioxidant activity. This work demonstrates that commonly used antioxidant supplements may cause considerable changes to cellular redox state and the outcome of differentiation.

Chengyi Tu defended his thesis titled “Role of Reactive Oxygen Species in Pluripotent Stem Cells Cardiac Differentiation and Survival”. Congratulations Dr. Tu, we look forward to seeing what you do next!

We congratulate our two seniors, Elissa Barone (right) and Meghana Koleti (left), who  each worked for more than two years in the Zoldan Lab and were authors on two publications. We won’t forget their hard work, and wish them all the best in their future careers!

Alicia Allen successfully defended her thesis, “Anisotropy in Cell Sheeting and Cardiac Differentiation”, thereby completing her PhD requirements and becoming the first graduate of the Zoldan Lab. Congrats Dr. Allen, we look forward to following your future career!

At the Society for Biomaterials conference in Atlanta, GA, Dr. Zoldan gave a talk titled “Matrix Anisotropy in Cardiac Differentiation”. Cody Crosby also presented his poster “Characterizing the Effect of Cell-Matrix Interactions on the Vasculogenesis of iPSC-derived Vascular Progenitor Cells” in the evening presentations.

The Zoldan lab was excited to hear Professor Jeff Hubbell’s talk on engineering novel protein-based immunotherapies to treat Type I diabetes. Wishing him and his lab the best going forward.

Olivia Conroy, who is working with Chengyi Tu, proposed  to elucidate the role of ROS in cardiomyocyte proliferation via MAPK signaling. Deepti Valliappan, working with Cody Crosby, aimed to evaluate vascular network formation of endothelial progenitor cells in gelatin-CMC hydrogels.  Congratulations to both!

An exciting piece on Alicia’s work has been posted on the website of UT’s biomedical engineering website. If you’re interested, please give the article a read!

Dr. Zoldan was selected as a 2017 Biomaterials Science Emerging Investigator by the RSC journal “Biomaterials Science”. We are honored by the selection and extend our congratulations to the other honorees.

Chengyi recently published his paper “Glycogen synthase kinase-3 inhibition sensitizes human induced pluripotent stem cells to thiol-containing antioxidants induced apoptosis” in Stem Cell Research. The paper is linked here and the abstract can be found below:

Inhibition of glycogen synthase kinase 3 (GSK3) is an extensively used strategy to activate Wnt pathway for pluripotent stem cell (PSC) differentiation. However, the effects of such inhibition on PSCs, besides upregulating the Wnt pathway, have rarely been investigated despite that GSK3 is broadly involved in other cellular activities such as insulin signaling and cell growth/survival regulation. Here we describe a previously unknown synergistic effect between GSK3 inhibition (e.g., Chir99021 and LY2090314) and various normally non-toxic thiol-containing antioxidants (e.g., N-acetylcysteine, NAC) on the induction of apoptosis in human induced pluripotent stem cells (iPSCs). Neither Chir99021 nor the antioxidants individually induced significant apoptosis, whereas their combined treatment resulted in rapid and extensive apoptosis, with substantial caspase 3 activity observed within 3 h and over 90% decrease in cell viability after 24 h. We confirmed the generality of this phenomenon with multiple independent iPSCs lines, various thiol-based antioxidants and distinct GSK3 inhibitors. Mechanistically, we demonstrated that rapamycin treatment could substantially reduce cell death, suggesting the critical role of mammalian target of rapamycin (mTOR). Akt dysregulation was also found to partially contribute to cell apoptosis but was not the primary cause. Further, this coordinated proapoptotic effect was not detected in mouse ESCs but was present in another human cells line: a breast cancer cell line (MDA-MB-231).

Given the wide use of GSK3 inhibition in biomedical research: from iPSC differentiation to cancer intervention and the treatment of neuronal diseases, researchers can potentially take advantage of or avoid this synergistic effect for improved experimental or clinical outcome.