Dr. El Assal is a Basic Life Research Scientist (Academic Staff) at the Canary Center for Cancer Early Detection, Department of Radiology, Stanford University School of Medicine. In 2016, Dr. El Assal completed a Postdoctoral Research Fellowship at Stanford University School of Medicine. Before moving to Stanford, he was working as a Postdoctoral Research Fellow in Medicine at Harvard Medical School, and Brigham and Women’s Hospital, Boston, MA as well as the Harvard-MIT Health Science and Technology division. In 2016, Dr. El Assal completed a Certificate Program in Innovation and Entrepreneurship at the Stanford Graduate School of Business. Dr. El Assal received his Doctor of Dental Surgery (D.D.S.) degree from Ajman University of Science and Technology (AUST), School of Dentistry, Ajman, UAE in 2007. Subsequently, He completed a one-year Clinical Internship Program in General Dentistry at Royal College of Surgeons in Ireland (RCSI)-affiliated training center at AUST-School of Dentistry. Following his internship, he enrolled in an Advanced Education Program in General Dentistry for two years (2008-2010). His research interests revolved around the applications of nano-/micro-scale technologies and biomaterials in medicine, including regenerative and transfusion medicine as well as cancer research. He has published his research work in esteemed peer-reviewed journals and conference proceedings, including Advanced Materials (Impact Factor (IF): 21.95), Advanced Science (IF: 12.44), Materials Today (IF: 24.45), Nanomedicine, Biotechnology Journal, Biofabrication Journal, ACS Molecular Pharmaceutics, Lab on a Chip, and Scientific Reports (from Nature Publishing Group). His research achievements have been recognized by the Center of Nanoscale Systems (CNS) at Harvard University. In 2015, Dr. El Assal has been nominated/elect as a Fellow of the Academy of Dentistry International (USA), International International Academy for Dental-Facial Esthetics (USA), and International Academy of Oral Oncology (UK). Dr. El Assal has a multifaceted and challenging career in research and patient care, and he is now aspiring to a career that will help fulfill his ambition of being an effective teacher, researcher, and clinician. His ultimate goal, along with treating patients on an individual basis, is to be able to treat them on a larger scale through establishing a world-class research facility that develop innovative solutions to clinical problems. During his free time, Dr. El Assal likes to help the people and serve the community.

Honors & Awards

  • Fellow-elected (1 among 23 new fellows were elected in 2015 from North and South America), Academy of Dentistry International, Ohio, USA (2015)
  • Fellow-elected (1 among 59 new fellows were elected in 2015 from all over the world), International Academy for Dental-Facial Esthetics, NY, USA (2015)
  • Fellow-elected, International Academy of Oral Oncology, London, UK (2015)
  • Best Scientific Poster Category (1st among 43 participants from all Harvard University), Center for Nanoscale Systems (CNS) at Harvard University (2011)

Education & Certifications

  • Postdoctoral Research Fellow, Stanford University School of Medicine, Biotechnology; Cancer Research; Nanotechnology (2016)
  • Stanford Ignite Fellow, Stanford Graduate School of Business, Innovation and Entrepreneurship (2016)
  • Postdoctoral Research Fellow, Harvard Medical School & Brigham and Women's Hospital, Medicine; Regenerative Medicine; Biotechnology (2014)
  • Resident, Royal College of Surgeons in Ireland (RCSI), approved training center at AUST-Dental School, General Dentistry (2010)
  • Doctor of Dental Surgery (DDS), Ajman University of Science and Technology (AUST), Dental School, Dentistry (2007)

Service, Volunteer and Community Work

  • Volunteer Mentor at the Canary Center at Stanford Internship Program, Stanford University School of Medicine, Stanford University School of Medicine (5/1/2014)


    Palo Alto, CA

  • Volunteer Mentor at Student Success Job Program (SSJP), Brigham and Women's Hospital, Harvard Medical School, Brigham and Women's Hospital, Harvard Medical School (6/1/2011 - 4/30/2014)

    The BWH-SSJP is an intensive year-round employment and mentoring program for students of Boston high schools. The aim of this program is to introduce high school students in the 10th -12th grades from the city’s lowest income communities to careers in health, science, and medicine by offering paid internships in research laboratories.


    Boston, MA, USA

  • Volunteer Mentor at the Undergraduate Research Opportunities Program (UROP) at Massachusetts Institute of Technology (MIT),, Massachusetts Institute of Technology (MIT) (6/1/2011 - 4/30/2014)


    Cambridge, MA

  • Volunteered in the implementation of Community Oral Health Program for primary school children in Al Ain, UAE

    This activity included performing oral examination and education for the children and writing oral health reports for their parents.


    Al Ain, UAE

  • Session Co-Chair, Materials Research Society (MRS) Meeting - Emerging 1D and 2D Nanomaterials in Health Care, Boston, MA


    Boston, MA, USA


  • "United StatesBio-inspired composition for preservation, Stanford Office of Technology Licensing, Docket S16-060"


Work Experience

  • Basic Life Science Research Associate (Academic Staff), Stanford University School of Medicine (7/1/2016)


    Palo Alto, CA

  • Clinical Instructor, Ajman University of Science and Technology, School of Dentistry, Ajman UAE (9/1/2010 - 3/22/2011)


    Ajman, UAE

Professional Affiliations and Activities

  • Reviewer, Technology (2015 - 2015)
  • Reviewer, Therapeutics and Clinical Risk Management (2014 - Present)
  • Reviewer, Journal of Bioanalysis and Biomedicine (2014 - Present)
  • Reviewer, Journal of Dental Research (2015 - 2015)
  • Reviewer, RSC Analyst (2016 - 2016)
  • Adjudicative referee, RSC Chemistry Communications (2014 - 2014)
  • Reviewer, Biofabrication (2016 - 2016)
  • Reviewer, Nature Scientific Reports (2016 - 2016)
  • Editorial Board Member, EC Dental Science Journal (2014 - Present)
  • Editorial Board Member, Journal of Dentistry, Oral Health & Therapy (2014 - Present)
  • Associated Editor, Advances in Dentistry and Oral Health (2016 - Present)
  • Editorial Board Member, SM Journal of Clinical and Medical Imaging (2015 - Present)
  • Editorial Board Member, Journal of Tumor (2014 - Present)
  • Editorial Board Member, Radiology-Open Journal (2015 - Present)
  • Editorial Board Member, International Journal of Orthopaedics (2014 - Present)
  • Editorial Board Member, Open Access Journal of Surgery (2016 - Present)


All Publications

  • Bio-inspired Cryoprotectants and Microfluidics for Cryopreservation, Cryobiology Journal Demirci, U., El Assal, R.
  • Bioinspired Preservation of Natural Killer Cells for Cancer Immunotherapy Advanced Science El Assal, R., Abou-Elkacem, L., Tocchio, A., Pasley, S., Matosevic, S., Kaplan, D., Zylberberg, C., Demirci, U. 2019

    View details for DOI 10.1002/advs.201802045

  • Evaluation of an ovary-on-a-chip in large mammalian models: Species specificity and influence of follicle isolation status JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE Nagashima, J. B., El Assal, R., Songsasen, N., Demirci, U. 2018; 12 (4): E1926–E1935


    The ability to grow oocytes from immature ovarian follicles in vitro has significant potential for fertility preservation; yet, it has proved challenging in large mammalian species due to the complex metabolic needs and long-term culture requirements. Currently, follicular incubations are based on a "static" system with manual exchange of medium. Despite the numerous advantages of conventional culturing approaches, recapitulating the native microenvironment and supporting the survival of ovarian follicles from large mammalian species still represent challenges. In this study, we utilized an innovative, dynamic microfluidic system to support the in vitro survival of domestic cat and dog follicles enclosed within the ovarian cortex or isolated from ovarian cortex. Results indicate both species-specific and tissue type-specific differences in response to microfluidic culture. Domestic cat but not dog ovarian cortical tissues maintained viability under flow similar to conventional agarose gel controls. Preantral stage isolated follicles from both species that grew most favourably in conventional alginate bead culture, but overall, there was no influence of culture system on expression of follicle development or oocyte health markers. This system represents an important exploration toward the development of an improved ovarian in vitro culture system of large mammalian species (e.g., cats and dogs), which has potential applications for fertility preservation, reproductive toxicology, and endangered mammal conservation efforts.

    View details for DOI 10.1002/term.2623

    View details for Web of Science ID 000430395400008

    View details for PubMedID 29222841

    View details for PubMedCentralID PMC5906142

  • Human iPSC-derived Steroidogenic Cells Maintain Endocrine Function with Extended Culture in A Microfluidic Chip System, FERTILITY AND STERILITY Anchan, R. M., Lindsey, J., Ng, N., Parasar, P., Naini, B., Guven, S., El Assal, R., Demirci, U.
  • Innovative Cryoprotectants for Tissue and Organ Preservation, CRYOBIOLOGY JOURNAL Kline, M., Dreyer, M., Gyring, P., Lifson, M., El Assal, R.
  • Bio-inspired Solute Enables Preservation of Human Oocytes using Minimum Volume Vitrification. Journal of tissue engineering and regenerative medicine Choi, J. K., El Assal, R., Ng, N., Ginsburg, E., Anchan, R. M., Demirci, U. 2017


    The ability to cryopreserve human oocytes has significant potential for fertility preservation. Current cryopreservation methods still suffer from the use of conventional cryoprotectants, such as dimethyl sulfoxide (DMSO), causing loss of viability and function. Such injuries result from the toxicity and high concentration of cryoprotectants as well as mechanical damage of cells due to ice crystal formation during the cooling and rewarming processes. Here, we report preservation of human oocytes following vitrification using an innovative bio-inspired cryoprotectant integrated with a minimum volume vitrification approach. The results demonstrate that the recovered human oocytes maintained viability following vitrification and rewarming. Moreover, when this approach was used to vitrify mouse oocytes, the recovered oocytes preserved their viability and function following vitrification and rewarming. This bio-inspired approach substitutes DMSO, a well-known toxic cryoprotectant, with ectoine, a non-toxic naturally occurring solute. The bio-inspired vitrification approach has potential to improve fertility preservation for women undergoing cancer treatment and endangered mammal species.

    View details for DOI 10.1002/term.2439

    View details for PubMedID 28481448

  • High-throughput Characterization of HIV-1 Reservoir Reactivation Using a Single-Cell-in-Droplet PCR Assay. EBioMedicine Yucha, R. W., Hobbs, K. S., Hanhauser, E., Hogan, L. E., Nieves, W., Ozen, M. O., Inci, F., York, V., Gibson, E. A., Thanh, C., Shafiee, H., El Assal, R., Kiselinova, M., Robles, Y. P., Bae, H., Leadabrand, K. S., Wang, S., Deeks, S. G., Kuritzkes, D. R., Demirci, U., Henrich, T. J. 2017


    Reactivation of latent viral reservoirs is on the forefront of HIV-1 eradication research. However, it is unknown if latency reversing agents (LRAs) increase the level of viral transcription from cells producing HIV RNA or harboring transcriptionally-inactive (latent) infection. We therefore developed a microfluidic single-cell-in-droplet (scd)PCR assay to directly measure the number of CD4(+) T cells that produce unspliced (us)RNA and multiply spliced (ms)RNA following ex vivo latency reversal with either an histone deacetylase inhibitor (romidepsin) or T cell receptor (TCR) stimulation. Detection of HIV-1 transcriptional activity can also be performed on hundreds of thousands of CD4+ T-cells in a single experiment. The scdPCR method was then applied to CD4(+) T cells obtained from HIV-1-infected individuals on antiretroviral therapy. Overall, our results suggest that effects of LRAs on HIV-1 reactivation may be heterogeneous-increasing transcription from active cells in some cases and increasing the number of transcriptionally active cells in others. Genomic DNA and human mRNA isolated from HIV-1 reactivated cells could also be detected and quantified from individual cells. As a result, our assay has the potential to provide needed insight into various reservoir eradication strategies.

    View details for DOI 10.1016/j.ebiom.2017.05.006

    View details for PubMedID 28529033

  • Magnetically Guided Self-Assembly and Coding of 3D Living Architectures. Advanced materials (Deerfield Beach, Fla.) Tocchio, A., Durmus, N. G., Sridhar, K., Mani, V., Coskun, B., El Assal, R., Demirci, U. 2017


    In nature, cells self-assemble at the microscale into complex functional configurations. This mechanism is increasingly exploited to assemble biofidelic biological systems in vitro. However, precise coding of 3D multicellular living materials is challenging due to their architectural complexity and spatiotemporal heterogeneity. Therefore, there is an unmet need for an effective assembly method with deterministic control on the biomanufacturing of functional living systems, which can be used to model physiological and pathological behavior. Here, a universal system is presented for 3D assembly and coding of cells into complex living architectures. In this system, a gadolinium-based nonionic paramagnetic agent is used in conjunction with magnetic fields to levitate and assemble cells. Thus, living materials are fabricated with controlled geometry and organization and imaged in situ in real time, preserving viability and functional properties. The developed method provides an innovative direction to monitor and guide the reconfigurability of living materials temporally and spatially in 3D, which can enable the study of transient biological mechanisms. This platform offers broad applications in numerous fields, such as 3D bioprinting and bottom-up tissue engineering, as well as drug discovery, developmental biology, neuroscience, and cancer research.

    View details for DOI 10.1002/adma.201705034

    View details for PubMedID 29215164

  • 3-D Microwell Array System for Culturing Virus Infected Tumor Cells SCIENTIFIC REPORTS El Assal, R., Gurkan, U. A., Chen, P., Juillard, F., Tocchio, A., Chinnasamy, T., Beauchemin, C., Unluisler, S., Canikyan, S., Holman, A., Srivatsa, S., Kaye, K. M., Demirci, U. 2016; 6


    Cancer cells have been increasingly grown in pharmaceutical research to understand tumorigenesis and develop new therapeutic drugs. Currently, cells are typically grown using two-dimensional (2-D) cell culture approaches, where the native tumor microenvironment is difficult to recapitulate. Thus, one of the main obstacles in oncology is the lack of proper infection models that recount main features present in tumors. In recent years, microtechnology-based platforms have been employed to generate three-dimensional (3-D) models that better mimic the native microenvironment in cell culture. Here, we present an innovative approach to culture Kaposi's sarcoma-associated herpesvirus (KSHV) infected human B cells in 3-D using a microwell array system. The results demonstrate that the KSHV-infected B cells can be grown up to 15 days in a 3-D culture. Compared with 2-D, cells grown in 3-D had increased numbers of KSHV latency-associated nuclear antigen (LANA) dots, as detected by immunofluorescence microscopy, indicating a higher viral genome copy number. Cells in 3-D also demonstrated a higher rate of lytic reactivation. The 3-D microwell array system has the potential to improve 3-D cell oncology models and allow for better-controlled studies for drug discovery.

    View details for DOI 10.1038/srep39144

    View details for Web of Science ID 000390304900001

    View details for PubMedID 28004818

  • Towards artificial tissue models: past, present, and future of 3D bioprinting BIOFABRICATION Arslan-Yildiz, A., El Assal, R., Chen, P., Guven, S., Inci, F., Demirci, U. 2016; 8 (1)
  • Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm. Scientific reports Asghar, W., Shafiee, H., Velasco, V., Sah, V. R., Guo, S., El Assal, R., Inci, F., Rajagopalan, A., Jahangir, M., Anchan, R. M., Mutter, G. L., Ozkan, M., Ozkan, C. S., Demirci, U. 2016; 6: 30270-?


    Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1-25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure.

    View details for DOI 10.1038/srep30270

    View details for PubMedID 27538480

  • Engineering cancer microenvironments for in vitro 3-D tumor models MATERIALS TODAY Asghar, W., El Assal, R., Shafiee, H., Pitteri, S., Paulmurugan, R., Demirci, U. 2015; 18 (10): 539-553


    The natural microenvironment of tumors is composed of extracellular matrix (ECM), blood vasculature, and supporting stromal cells. The physical characteristics of ECM as well as the cellular components play a vital role in controlling cancer cell proliferation, apoptosis, metabolism, and differentiation. To mimic the tumor microenvironment outside the human body for drug testing, two-dimensional (2-D) and murine tumor models are routinely used. Although these conventional approaches are employed in preclinical studies, they still present challenges. For example, murine tumor models are expensive and difficult to adopt for routine drug screening. On the other hand, 2-D in vitro models are simple to perform, but they do not recapitulate natural tumor microenvironment, because they do not capture important three-dimensional (3-D) cell-cell, cell-matrix signaling pathways, and multi-cellular heterogeneous components of the tumor microenvironment such as stromal and immune cells. The three-dimensional (3-D) in vitro tumor models aim to closely mimic cancer microenvironments and have emerged as an alternative to routinely used methods for drug screening. Herein, we review recent advances in 3-D tumor model generation and highlight directions for future applications in drug testing.

    View details for DOI 10.1016/j.mattod.2015.05.002

    View details for Web of Science ID 000366576000019

    View details for PubMedCentralID PMC5407188

  • Highlights from the latest articles in advanced biomanufacturing at micro- and nano-scale. Nanomedicine Assal, R. E., Chen, P., Demirci, U. 2015; 10 (3): 347-350

    View details for DOI 10.2217/nnm.14.210

    View details for PubMedID 25707972

  • Bio-inspired cryo-ink preserves red blood cell phenotype and function during nanoliter vitrification. Advanced materials El Assal, R., Guven, S., Gurkan, U. A., Gozen, I., Shafiee, H., Dalbeyler, S., Abdalla, N., Thomas, G., Fuld, W., Illigens, B. M., Estanislau, J., Khoory, J., Kaufman, R., Zylberberg, C., Lindeman, N., Wen, Q., Ghiran, I., Demirci, U. 2014; 26 (33): 5815-5822


    Current red-blood-cell cryopreservation methods utilize bulk volumes, causing cryo-injury of cells, which results in irreversible disruption of cell morphology, mechanics, and function. An innovative approach to preserve human red-blood-cell morphology, mechanics, and function following vitrification in nanoliter volumes is developed using a novel cryo-ink integrated with a bioprinting approach.

    View details for DOI 10.1002/adma.201400941

    View details for PubMedID 25047246

  • Preserving human cells for regenerative, reproductive, and transfusion medicine. Biotechnology journal Asghar, W., El Assal, R., Shafiee, H., Anchan, R. M., Demirci, U. 2014; 9 (7): 895-903


    Cell cryopreservation maintains cellular life at sub-zero temperatures by slowing down biochemical processes. Various cell types are routinely cryopreserved in modern reproductive, regenerative, and transfusion medicine. Current cell cryopreservation methods involve freezing (slow/rapid) or vitrifying cells in the presence of a cryoprotective agent (CPA). Although these methods are clinically utilized, cryo-injury due to ice crystals, osmotic shock, and CPA toxicity cause loss of cell viability and function. Recent approaches using minimum volume vitrification provide alternatives to the conventional cryopreservation methods. Minimum volume vitrification provides ultra-high cooling and rewarming rates that enable preserving cells without ice crystal formation. Herein, we review recent advances in cell cryopreservation technology and provide examples of techniques that are utilized in oocyte, stem cell, and red blood cell cryopreservation.

    View details for DOI 10.1002/biot.201300074

    View details for PubMedID 24995723

  • Engineering Anisotropic Biomimetic Fibrocartilage Microenvironment by Bioprinting Mesenchymal Stem Cells in Nanoliter Gel Droplets MOLECULAR PHARMACEUTICS Gurkan, U. A., El Assal, R., Yildiz, S. E., Sung, Y., Trachtenberg, A. J., Kuo, W. P., Demirci, U. 2014; 11 (7): 2151-2159


    Over the past decade, bioprinting has emerged as a promising patterning strategy to organize cells and extracellular components both in two and three dimensions (2D and 3D) to engineer functional tissue mimicking constructs. So far, tissue printing has neither been used for 3D patterning of mesenchymal stem cells (MSCs) in multiphase growth factor embedded 3D hydrogels nor been investigated phenotypically in terms of simultaneous differentiation into different cell types within the same micropatterned 3D tissue constructs. Accordingly, we demonstrated a biochemical gradient by bioprinting nanoliter droplets encapsulating human MSCs, bone morphogenetic protein 2 (BMP-2), and transforming growth factor β1 (TGF- β1), engineering an anisotropic biomimetic fibrocartilage microenvironment. Assessment of the model tissue construct displayed multiphasic anisotropy of the incorporated biochemical factors after patterning. Quantitative real time polymerase chain reaction (qRT-PCR) results suggested genomic expression patterns leading to simultaneous differentiation of MSC populations into osteogenic and chondrogenic phenotype within the multiphasic construct, evidenced by upregulation of osteogenesis and condrogenesis related genes during in vitro culture. Comprehensive phenotypic network and pathway analysis results, which were based on genomic expression data, indicated activation of differentiation related mechanisms, via signaling pathways, including TGF, BMP, and vascular endothelial growth factor.

    View details for DOI 10.1021/mp400573g

    View details for Web of Science ID 000338748200024

    View details for PubMedID 24495169

  • Prediction and control of number of cells in microdroplets by stochastic modeling LAB ON A CHIP Ceyhan, E., Xu, F., Gurkan, U. A., Emre, A. E., Turali, E. S., El Assal, R., Acikgenc, A., Wu, C. M., Demirci, U. 2012; 12 (22): 4884-4893


    Manipulation and encapsulation of cells in microdroplets has found many applications in various fields such as clinical diagnostics, pharmaceutical research, and regenerative medicine. The control over the number of cells in individual droplets is important especially for microfluidic and bioprinting applications. There is a growing need for modeling approaches that enable control over a number of cells within individual droplets. In this study, we developed statistical models based on negative binomial regression to determine the dependence of number of cells per droplet on three main factors: cell concentration in the ejection fluid, droplet size, and cell size. These models were based on experimental data obtained by using a microdroplet generator, where the presented statistical models estimated the number of cells encapsulated in droplets. We also propose a stochastic model for the total volume of cells per droplet. The statistical and stochastic models introduced in this study are adaptable to various cell types and cell encapsulation technologies such as microfluidic and acoustic methods that require reliable control over number of cells per droplet provided that settings and interaction of the variables is similar.

    View details for DOI 10.1039/c2lc40523g

    View details for Web of Science ID 000310865200039

    View details for PubMedID 23034772

  • Bioprinting anisotropic stem cell microenvironment Gurkan, U. A., Sung, Y., El Assal, R., Xu, F., Trachtenberg, A., Kuo, W., Demirci, U. WILEY-BLACKWELL. 2012: 366–366