Abstract 5154: Developing Micro-fluidic Chip to understand Altruistic stem cell reprogramming
Authors: Pal Bidisha , Sandhya Sorra , Talukdar Joyeeta , Pathak Lekhika , Li Hong , Das Bikul 
Published: August 2019

Abstract
Background:Tumor microenvironment (TME) is a complex network of cancer and stromal cell interactions in specialized niches. Cancer stem cells (CSCs) and mesenchymal stem cells (MSCs) co-exist as significant components of TME that contribute to tumor progression. However, it is not clear whether MSCs compete or co-operate with CSCs for niche occupancy. In principle, stem cell competition eliminates the competing neighbors (e.g. p53 mutant cancer cells) while stem cell altruism enhances group-fitness in the niche. We found that the conditioned media of oral cancer CSCs, ABCG2+ cells, induced stem cell altruism in CD271+ MSCs (1). This indirect demonstration suggests the potential role of stem cell altruism in TME mediated tumor progression. Here we hypothesize that CSC mediated stem cell altruism of MSCs can be studied using an organ-on-chip microfluidic device. Methods:Naïve CD271+ MSCs were maintained in vitro by using an established culture method that we previously reported (2). Development of organ-on-chip microfluidic platform involved coating of 96 wells with polydimethylsiloxane (PDMS) and squalene to enhance cellular adhesion and delay stem cell differentiation. Two wells were linked by microfluidic channels to facilitate cell-to-cell interaction. We used 1000 ABCG2+ CSCs obtained from SCC-25 cell line (3) and equal numbers of naïve CD271+ MSCs. CSCs co-cultured with MSC in a Boyden-chamber assay was used as control population. After two weeks of culture, MSCs were evaluated for potential reprogramming to altruistic stem cell (ASC) phenotype as previously described. Results:We observed that MSCs collected from organ-on-chip exhibit stem cell altruism as indicated by loss of p53 and gain of HIF-2alpha expression as measured by In-Cell western assay (1). These MSCs also exhibited secretion of GSH, another characteristic of ASCs. Subsequently, these cells activated p53/MDM2 oscillation, and underwent apoptosis/differentiation, another important characteristic of ASCs. While, MSCs cultured in Boyden chamber assay, showed rapid proliferation and loss of CD271+ expression, and gain of markers associated with carcinoma-associated-fibroblasts including SMA and cytokeratin 8. Conclusion:Overall, our findings suggest that microfluidics-based organ-on-chip device can be used to understand stem cell altruism in TME. 1. PMID:22689594.2. PMID: 288841133. Talukdar J et al In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 920.
Note: This abstract was not presented at the meeting.
Citation Format: Bidisha Pal, Sorra Sandhya, Joyeeta Talukdar, Lekhika Pathak, Hong Li, Bikul Das. Developing Micro-fluidic Chip to understand Altruistic stem cell reprogramming [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5154.