MSE Seminar: “Peptoid Crosslinked Hydrogel Stiffness Modulates Human Mesenchymal Stromal Cell Immunoregulatory Potential in the Presence of Interferon-gamma”

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Abstract

Human mesenchymal stromal cell (hMSC) manufacturing requires the production of large numbers of therapeutically potent cells. Licensing with soluble cytokines improves hMSC therapeutic potency by enhancing the secretion of immunoactive factors but typically decreases proliferative ability. Soft hydrogels, however, have shown promise for boosting immunomodulatory potential, which may compensate for decreased proliferation.

Here, hydrogels were crosslinked with peptoids of different secondary structures to generate substrates of various bulk stiffness but fixed network connectivity. The compressive modulus of each hydrogel was analyzed by dynamic mechanical analysis (DMA). Chemical composition was also measured by Fourier transform infrared (FTIR) spectroscopy, with all spectra strongly displaying the characteristic peaks of the hyaluronic acid backbone and showing clear incorporation of each crosslinker. Additionally, the dried hydrogel microstructures were investigated via scanning electron microscopy (SEM) and showed amorphous morphologies.

Secretion of interleukin 6 (IL-6), monocyte chemoattractive protein (MCP-1), macrophage colony-stimulating factor (MCS-F), and vascular endothelial growth factor (VEGF) were shown to depend on hydrogel stiffness in the presence of interferon gamma (IFN-γ) supplementation, with soft substrates further improving immunoregulation. The function of these secreted cytokines was then investigated via coculture with Primary Peripheral Blood Mononuclear Cells (PBMCs), wherein secreted factors from cells seeded on hydrogels significantly decreased PBMC proliferation with IFN-γ.

To probe possible signaling pathways linking substrate stiffness to hMSC activation, immunofluorescent studies probed the NF-κB pathway and demonstrated that IFN-γ supplementation and softer hydrogel mechanics lead to higher activation of this pathway. In addition, substrate stiffness did not impact cellular attachment or hMSC differentiation capability, validating the utility of these substrates for cell manufacturing applications. Overall, these studies may allow for the production of more efficacious therapeutic hMSCs in the presence of IFN-γ.

Bio

David Castilla-Casadiego, Ph.D.

Postdoctoral Fellow
University of Texas at Austin

Dr. David A. Castilla-Casadiego is a Latino in the sciences from Barranquilla, Colombia and is currently a Provost Early Career Postdoctoral Fellow and an NIH Pathway to Independence Awardee (K99/R00) at the University of Texas at Austin. David is conducting research in the lab of Dr. Adrianne Rosales in the McKetta Department of Chemical Engineering (March 2021).

Prior to this position, he earned a Ph.D. in Chemical Engineering from the University of Arkansas at Fayetteville, working with Dr. Jorge Almodóvar, in May 2021, and a master’s degree from the University of Puerto Rico at Mayagüez in 2016.

Working at the interface of polymer science and biology, David’s research concerns the design of polymeric biomaterials such as nanofibers, hydrogels, coatings, composites, and microneedle patches for different applications, including stem cell manufacturing, tissue regeneration, and drug delivery for both human and animal health. Recent work has focused on regulating the immunomodulatory potential of stem cells with biophysical cues from different hydrogel surfaces.

David’s work has been recognized with a Postdoctoral Young Investigator award (Strong Contributions – Surface Characterization and Modifications) from the Society for Biomaterials and the IDEAL Star Award (as a team: LatinXinChE) from American Institute of Chemical Engineers (AIChE). He has also been selected for the 2023 Rising Stars in Engineering Workshop, hosted by Cornell University’s Meining School of Biomedical Engineering and was given the outstanding graduate student award in chemical engineering at the University of Arkansas in 2020. In addition to these awards, he has served as an independent reviewer for 7 journals, as financial liaison for LatinXinChE, and moderator for the 1st LatinXinChE Virtual Symposium. David is pursuing an independent career in academia and envisions future research contributions in stem cell manufacturing, drug delivery, and biosensor applications.