Denise graduated with a Bachelor of Science in Biomedical Engineering from the University of South Carolina in 2011. Her undergraduate project at USC focused on the use of biomaterials to create a novel insulin delivery system for diabetic patients. Her contribution focused on optimization of the encapsulation of insulin producing cells . She is currently pursuing a Ph.D. in biomedical engineering from Georgia Tech and Emory University. She will be investigating the use of incorporated biomaterials within stem cell aggregates to understand ESC response to signaling molecules and their surrounding environment.
Engineering ECM-like materials that actively sequester proteins and bioactive signals have gained significant interest. As one component of the ECM, glycosaminoglycans (GAGs) function to form morphogen gradients during early embryonic development by sequestering secreted growth factors, thus directing the pattern of tissue morphogenesis. Denise is currently developing GAG based microparticles for incorporation within embryoid bodies. She is interested in understanding how GAGs function to sequester and present endogenously secreted growth factors to direct and control ESC differentiation.
UNCF-Merck Graduate Science Research Dissertation Fellowship - 2014
Alfred P. Sloan / Georgia Institute of Technology University Centers of Exemplary Mentoring (UCEM) Scholarship - 2013
NSF Graduate Research Fellowship - 2011-2014
Georgia Tech President's Fellowship - 2011
NSF IGERT Stem Cell Biomanufacturing Associate - 2011
Won Outstanding Poster Presentation at ABRCMS - 2010
USC Magellan Scholar Recipient - 2009
Tracking hypoxic signaling in encapsulated stem cells. Tracking hypoxic signaling in encapsulated stem cells. Tissue Eng Part C Methods. 2012 Jul;18(7):557-65 Authors: Sahai S, McFarland R, Skiles ML, Sullivan D, Williams A, Blanchette JO Abstract PMID: 22250882 [PubMed - indexed for MEDLINE]
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Oxygen is not only a nutrient but also an important signaling molecule whose concentration can influence the fate of stem cells. This study details the development of a marker of hypoxic signaling for use with encapsulated cells. Testing of the marker was performed with adipose-derived stem cells (ADSCs) in two-dimensional (2D) and 3D culture conditions in varied oxygen environments. The cells were genetically modified with our hypoxia marker, which produces a red fluorescent protein (DsRed-DR), under the control of a hypoxia-responsive element (HRE) trimer. For 3D culture, ADSCs were encapsulated in poly(ethylene glycol)-based hydrogels. The hypoxia marker (termed HRE DsRed-DR) is built on a recombinant adenovirus and ADSCs infected with the marker will display red fluorescence when hypoxic signaling is active. This marker was not designed to measure local oxygen concentration but rather to show how a cell perceives its local oxygen concentration. ADSCs cultured in both 2D and 3D were exposed to 20% or 1% oxygen environments for 96 h. In 2D at 20% O(2), the marker signal was not observed during the study period. In 1% O(2), the fluorescent signal was first observed at 24 h, with maximum prevalence observed at 96 h as 59%±3% cells expressed the marker. In 3D, the signal was observed in both 1% and 20% O(2). The onset of signal in 1% O(2) was observed at 4 h, reaching maximum prevalence at 96 h with 76%±4% cells expressing the marker. Interestingly, hypoxic signal was also observed in 20% O(2), with 13%±3% cells showing positive marker signal after 96 h. The transcription factor subunit hypoxia inducible factor-1α was tracked in these cells over the same time period by immunostaining and western blot analysis. Immunostaining results in 2D correlated well with our marker at 72 h and 96 h, but 3D results did not correlate well. The western blotting results in 2D and 3D correlated well with the fluorescent marker. The HRE DsRed-DR virus can be used to track the onset of this response for encapsulated, mesenchymal stem cells. Due to the importance of hypoxic signaling in determination of stem cell differentiation, this marker could be a useful tool for the tissue engineering community.
