“It’s been really worth it to see something I designed to come out and be part of science,” says Rafael David González-Cruz.  “There was a lot of me struggling and learning how to do things, but it was really rewarding.” Dr. González-Cruz recently defended his thesis in the Darling lab on mechanical property and gene expression heterogeneity in adipose-derived stem cell populations.  Some of that work was published in Cell and Molecular Bioengineering earlier this year. “I was trying to find a correlation between cellular mechanical properties and a molecular biomarker that once linked could be used to detect cells using antibodies.  That labeling or staining could correlate back to mechanical properties like cell stiffness, viscoelasticity, and so forth,” says González-Cruz. “Typically mechanical testing techniques such as atomic force microscopy are endpoint assays, so once you measure your cell’s properties you can’t really use them for anything else.”  He identified laminin proteins, which are cell surface markers that correlate with nuclear stiffness and other elastic properties.

Future work could use these surface markers to sort cells based on stiffness.  Dr. González-Cruz hopes that this technique can be used to isolate rare populations of cells with a characteristic stiffness, such as tumor cells.  “The cool thing is, you don’t just find a soft or stiff cell,” he says. “Because [these markers] are so intricately related to gene expression they’re also going to be tied to phenotype…Cells that are metastatic have different levels of a protein that allows the nucleus to be soft enough to go through openings when you’re leaving a blood vessel.  We’re just proposing it as a biomarker, but we’re hoping that people can follow our work to see [the] applications.”

However, Dr. González-Cruz doesn’t just excel in the lab. He won this year’s Graduate Student Contribution to Community Life Award for his work with various affinity groups and student development organizations at Brown.  During his first year of graduate school, he joined the Initiative to Maximize Student Development, a program that supports graduate students from underrepresented backgrounds improve their scientific and professional skills.  “[The program] was the key and got me off to a good start in grad school,” says Dr. González-Cruz. “After that, I decided I didn’t just want to be part of that group, I really wanted to contribute to help people at the school.”  He joined SACNAS, the Society for the Advancement of Chicanos and Native Americans in Science, as well as affinity groups for Latinx students and Puerto Rican students

Dr. González-Cruz spoke openly about the importance of such groups in helping students succeed: “[Affinity groups] are really critical because sometimes you need to be able to talk about failure in an environment that doesn’t belittle you but actually provides you with solutions as well as supportive people.  Even though our program is great at being supportive people come with the expectation that you can’t fail, and I struggled with that. Had I talked to people earlier, there were some struggles that I faced that would not have even have been a problem.” He’s glad to have been able to both receive and give help through these groups while at Brown, and encourages incoming graduate students or undergraduates considering a PhD to speak with people at different stages of their career.  “You can get an idea of the trajectory and the things that profession will require, with the focus being on the stage closest to you.”

After Hurricane Maria hit Puerto Rico in September 2017, Dr. González-Cruz worked with the Brown Center for Students of Color and the Office of the Provost to receive students.  “I felt really powerless to help people back home because planes couldn’t really get there and food we were collecting here was getting stuck in the ports and not reaching people,” he says.  “This way, we could help some of the students involved to not lose their entire semester.”

Dr. González-Cruz is currently working as a postdoc in the Hoffman-Kim lab developing neural spheroid models for traumatic brain injury.  Neural spheroids will be placed in a gel with fluorescent beads and subjected to an applied strain. Work with the Franck lab will focus on quantifying the displacements of the beads and connecting the level of strain to biochemical damage using immunofluorescence.  Dr. González-Cruz is working on learning how to make spheroids, apply strains to them, and interpret the results. On switching fields, he says, “I wanted to expand my experience from stem cells into an area that had more of a clinical application, or a more translatable area.  I thought neuroscience was great, but it was also very daunting because I have no experience in it. But it is a really cool challenge…you get to create an in vitro environment of a mechanical injury.” While entering a new field can be overwhelming, Dr. González-Cruz is bringing his expertise in cell mechanics to the project.  “The project is so interdisciplinary, and I thought I could learn more about the injury biomechanics associated with [traumatic brain injury],” he says. “I want to stay in the field of cell biomechanics, but this is a cool new way of looking at it. We’re going from just characterizing cell phenotype to doing mechanical characterization of a disease.”