Bio


Dr. Nel-Themaat has been in the field of assisted reproduction for more than 20 years, with the past 11 years in clinical IVF. She possesses a unique combination of a strong academic background, broad technical experience and extensive leadership, and management training. Through a multi-dimensional approach, she has helped to improve patient care and outcomes in Assisted Reproductive Technology (ART).
Dr. Nel-Themaat was most recently employed as the Regional IVF Lab Director for Shady Grove Fertility in Colorado and served as the IVF Lab Director at University of Colorado Advanced Reproductive Medicine. She received her PhD from LSU, Baton Rouge and recently completed an Executive Masters of Business Administration program at the University of Denver.

Her goal is to advance the field “by building strong, high performing lab teams, by carefully evaluating and adapting appropriately to industry trends, by training and educating the current and next generations, and by participating in collaborative research that enhances our understanding of reproduction.”
In her free time, Dr. Nel-Themaat loves to spend time with her husband and two children, preferably in nature. With them, she enjoys skiing, hiking, biking, swimming and anything nature has to offer. She likes to cook out and introduce our American friends to South African cuisine, especially a “braai,” which is their version of a BBQ. During school holidays, she likes to visit family in South Africa, go on safari and enjoy the beautiful beaches. Dr. Nel-Themaat enjoys jamming on the piano, guitar, drums and microphone with her family. She also considers herself very competitive and loves playing and watching sports or playing board games.

Academic Appointments


All Publications


  • The developmental competence of human metaphase I oocytes with delayed maturation in vitro. Fertility and sterility Moon, J. H., Zhao, Q., Zhang, J., Reddy, V., Han, J., Cheng, Y., Zhang, N., Dasig, J., Nel-Themaat, L., Behr, B., Yu, B. 2022

    Abstract

    To evaluate if metaphase I (MI) oocytes completing maturation in vitro to metaphase II ("MI-MII oocytes") have similar developmental competence as the sibling metaphase II (MII) oocytes that reached maturity in vivo.Retrospective cohort study.A total of 1124 intracytoplasmic sperm injection (ICSI) cycles from 800 patients at a single academic center between April 2016 and Dec 2020 with at least one MII oocyte immediately after retrieval and at least one sibling "MI-MII oocyte" that was retrieved as MI and matured to MII in culture before ICSI were included in the study.A total of 7865 MII and 2369 sibling MI-MII retrieved from the same individuals were compared for fertilization and blastocyst formation rates. For patients undergoing single euploid blastocyst transfers (n=406), the clinical pregnancy, spontaneous pregnancy loss rate and live birth rate were compared between the two groups.The fertilization rate was significantly higher in MII oocytes than delayed matured MI-MII oocytes (75.9% vs 56.1%, p<0.001). Similarly, the blastocyst formation rate was higher in embryos derived from MII oocytes as compared to those from MI-MII oocytes (53.8% vs 23.9%; p<0.001). The percentage of euploid embryos derived from MII oocytes was significantly higher than those from MI-MII oocytes (49.2% vs 34.7%; p<0.001). Paired comparison of sibling oocytes within the same cycle showed higher developmental competence of the MII oocytes than MI-MII oocytes. However, the pregnancy, spontaneous pregnancy loss and live birth rate after a single euploid blastocyst transfer showed no statistically significant difference between the two groups (65.7% vs 74.1%: 6.4% vs 5.0%: 61.5% vs 70.0%, respectively, MII vs MI-MII group, p>0.05).Compared to oocytes that matured in vivo and were retrieved as MII, the oocytes that were retrieved as MI and matured to MII in vitro before ICSI showed lower developmental competence, including lower fertilization, blastocyst formation, and euploidy rates. However, euploid blastocysts from either cohort resulted in similar live birth rates, indicating the MI oocytes with delayed maturation can still be useful even though the overall developmental competence was lower than their in vivo matured counterparts.

    View details for DOI 10.1016/j.fertnstert.2022.12.033

    View details for PubMedID 36567036

  • Expression and T cell Regulatory Action of the PD-1 Immune Checkpoint in the Ovary and Fallopian Tube. American journal of reproductive immunology (New York, N.Y. : 1989) Johnson, J., Kim, S., Sam, P. K., Asokan, R., Cari, E. L., Bales, E. S., Luu, T., Perez, L., Kallen, A. N., Nel-Themaat, L., Polotsky, A. J., Post, M. D., Orlicky, D. J., Jordan, K. R., Bitler, B. G. 2022

    Abstract

    PROBLEM: Immune cell trafficking and surveillance within the ovary and fallopian tube are thought to impact fertility and also tumorigenesis in those organs. However, little is known of how native cells of the ovary and fallopian tube interact with resident immune cells. Interaction of the Programmed Cell Death Protein-1 (PD-1/PDCD-1/CD279) checkpoint with PD-L1 is associated with downregulated immune response. We have begun to address the question of whether PD-1 ligand or its receptors (PD-L1/-L2) can regulate immune cell function in these tissues of the female reproductive tract.METHOD OF STUDY: PD-1 and ligand protein expression was evaluated in human ovary and fallopian tube specimens, the latter of which included stages of tubal cell transformation and early tumorigenesis. Ovarian expression analysis included the determination of the proteins in human follicular fluid (HFF) specimens collected during in vitro fertilization procedures. Finally, checkpoint bioactivity of HFF was determined by treatment of separately-isolated human T cells and the measurement of interferon gamma (IFNgamma).RESULTS: We show that membrane bound and soluble variants of PD-1 and ligands are expressed by permanent constituent cell types of the human ovary and fallopian tube, including granulosa cells and oocytes. PD-1 and soluble ligands were present in HFF at bioactive levels that control T cell PD-1 activation and IFNgamma production; full-length checkpoint proteins were found to be highly enriched in HFF exosome fractions.CONCLUSION: The detection of PD-1 checkpoint proteins in the human ovary and fallopian tube suggests that the pathway is involved in immunomodulation during folliculogenesis, the window of ovulation, and subsequent egg and embryo immune-privilege. Immunomodulatory action of receptor and ligands in HFF exosomes is suggestive of an acute checkpoint role during ovulation. This is the first study in the role of PD-1 checkpoint proteins in human tubo-ovarian specimens and the first examination of its potential regulatory action in the contexts of normal and assisted reproduction. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/aji.13649

    View details for PubMedID 36394352

  • The ART of cryopreservation and its changing landscape FERTILITY AND STERILITY Pomeroy, K. O., Comizzoli, P., Rushing, J. S., Lersten, I. L., Nel-Themaat, L. 2022; 117 (3): 469-476

    Abstract

    The purpose of this review is to educate the reader on the role that cryopreservation has played and continues to play in the ever-evolving field of assisted reproductive technologies, specifically in clinical human fertility treatment. We discuss the science behind the cryopreservation methods and investigated some of the major considerations that any clinic or cryobank faces in terms of risks and liabilities, physical challenges that accompany the constantly growing collection of cryopreserved specimens, and what this means on the ethical and legal front. Finally, we take a glimpse in the future to explore what may be on the horizon for the preservation of gametes and reproductive tissues.

    View details for DOI 10.1016/j.fertnstert.2022.01.018

    View details for Web of Science ID 000761394100002

    View details for PubMedID 35219471

  • ANTI-MULLERIAN HORMONE AND FOLLICLE STIMULATING HORMONE ARE POOR INDEPENDENT PREDICTORS OF LIVE BIRTH AFTER ASSISTED REPRODUCTIVE TECHNOLOGY. Siegel, D. R., Sammel, M., Nel-Themaat, L., Santoro, N. F., Polotsky, A. J. ELSEVIER SCIENCE INC. 2021: E264-E265
  • In vitro fertilization and andrology laboratories in 2030 FERTILITY AND STERILITY Simon, C., Campbell, A., Gardner, D. K., Meseguer, M., Miller, K. A., Montag, M., Palermo, G. D., Cheung, S., Keating, D., Xie, P., Rosenwaks, Z., Rienzi, L., Innocenti, F., Cimadomo, D., Ubaldi, F., Sakkas, D., Tucker, M. J., Nel-Themaat, L. 2021; 116 (1): 2-3

    Abstract

    The in vitro fertilization and andrology laboratories are at the center of assisted reproductive technologies and the place where technicians and embryologists manipulate gametes and preimplantation-stage embryos with the goal of achieving the best embryo for transfer. Through the years, these laboratories have seen developments in technique, technology, and testing. The goal of this Views and Interviews series is to bring together the thought leaders in the field and envision what the laboratories will look like in the next 10 years.

    View details for DOI 10.1016/j.fertnstert.2021.05.089

    View details for Web of Science ID 000672795000002

    View details for PubMedID 34148585

  • In vitro fertilization and andrology in 2030: visions FERTILITY AND STERILITY Campbell, A., Gardner, D. K., Meseguer, M., Miller, K. A., Montag, M., Palermo, G. D., Cheung, S., Keating, D., Xie, P., Rosenwaks, Z., Rienzi, L., Innocenti, F., Cimadomo, D., Ubaldi, F., Sakkas, D., Tucker, M. J., Nel-Themaat, L., Simon, C. 2021; 116 (1): 4-12

    Abstract

    The aim of this article is to gather 9 thought leaders and their team members to present their ideas about the future of in vitro fertilization and the andrology laboratory. Although we have seen much progress and innovation in the laboratory over the years, there is still much to come, and this article looks at what these leaders think will be important in the future development of technology and processes in the laboratory.

    View details for DOI 10.1016/j.fertnstert.2021.05.088

    View details for Web of Science ID 000672795000003

    View details for PubMedID 34148588

  • 3D genomics across the tree of life reveals condensin II as a determinant of architecture type. Science (New York, N.Y.) Hoencamp, C., Dudchenko, O., Elbatsh, A. M., Brahmachari, S., Raaijmakers, J. A., van Schaik, T., Sedeño Cacciatore, Á., Contessoto, V. G., van Heesbeen, R. G., van den Broek, B., Mhaskar, A. N., Teunissen, H., St Hilaire, B. G., Weisz, D., Omer, A. D., Pham, M., Colaric, Z., Yang, Z., Rao, S. S., Mitra, N., Lui, C., Yao, W., Khan, R., Moroz, L. L., Kohn, A., St Leger, J., Mena, A., Holcroft, K., Gambetta, M. C., Lim, F., Farley, E., Stein, N., Haddad, A., Chauss, D., Mutlu, A. S., Wang, M. C., Young, N. D., Hildebrandt, E., Cheng, H. H., Knight, C. J., Burnham, T. L., Hovel, K. A., Beel, A. J., Mattei, P. J., Kornberg, R. D., Warren, W. C., Cary, G., Gómez-Skarmeta, J. L., Hinman, V., Lindblad-Toh, K., Di Palma, F., Maeshima, K., Multani, A. S., Pathak, S., Nel-Themaat, L., Behringer, R. R., Kaur, P., Medema, R. H., van Steensel, B., de Wit, E., Onuchic, J. N., Di Pierro, M., Lieberman Aiden, E., Rowland, B. D. 2021; 372 (6545): 984-989

    Abstract

    We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional (3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedly during eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with the absence of condensin II subunits. Moreover, condensin II depletion converts the architecture of the human genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state, centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physical model in which lengthwise compaction of chromosomes by condensin II during mitosis determines chromosome-scale genome architecture, with effects that are retained during the subsequent interphase. This mechanism likely has been conserved since the last common ancestor of all eukaryotes.

    View details for DOI 10.1126/science.abe2218

    View details for PubMedID 34045355

  • PUBLIC REPORTING OF CLINICAL OUTCOMES IN ASSISTED REPRODUCTIVE TECHNOLOGY IN THE US FOR 2014-2017: REPORTING TO CDC ONLY IS ASSOCIATED WITH FEWER CANCELLATIONS AND LOWER SUCCESS RATES. Thanh Ha Luu, Nel-Themaat, L., Tracy Truong, Polotsky, A. J. ELSEVIER SCIENCE INC. 2020: E259
  • PD-1 RECEPTOR AND LIGANDS ARE CONCENTRATED IN THE EXOSOME FRACTION OF HUMAN OVARIAN FOLLICULAR FLUID. Thanh Ha Luu, Cari, E., Rushing, J., Nel-Themaat, L., Polotsky, A. J., Johnson, J. ELSEVIER SCIENCE INC. 2020: E104
  • Does Public Reporting Provide an Incomplete Picture of Success Rates of In Vitro Fertilization in the United States? Optional Reporting is Associated with Lower Cancelling Rates but Higher Cycle Success Compared to Mandatory Reporting. Thanh Ha Bao Luu, Nel-Themaat, L., Tracy Truong, Polotsky, A. J. SPRINGER HEIDELBERG. 2020: 288A
  • EXPRESSION AND FUNCTION OF THE PD-1 IMMUNE CHECKPOINT IN THE HUMAN OVARY AND FALLOPIAN TUBE. Johnson, J., Cari, E., Sam, P., Bales, E. S., Ryu, S., Nel-Themaat, L., Kallen, A., Polotsky, A. J., Post, M. D., Orlicky, D. J., Jordan, K., Bitler, B. G. ELSEVIER SCIENCE INC. 2019: E106
  • CURRENT STATUS OF REPRODUCTIVE LABORATORY PROFESSION: WORKLOAD, WELLNESS, EARNINGS AND JOB SATISFACTION. Chang, T., Chang, C., Nel-Themaat, L., Smith, S. E., Zozula, S., Su, Y. ELSEVIER SCIENCE INC. 2019: E69
  • Cloned embryos from semen. Part 1: In vitro proliferation of epithelial cells, on embryonic fibroblasts after isolation from semen by gradient centrifugation CLONING AND STEM CELLS Nel-Themaat, L., Gomez, M. C., Pope, C., Lopez, M., Wirtu, G., Cole, A., Dresser, B. L., Lyons, L. A., Bondioli, K. R., Godke, R. A. 2008; 10 (1): 143-159

    Abstract

    Although epithelial-like somatic cells have been previously isolated from semen, cell proliferation rates were low. Culture of whole semen samples resulted in loss of potentially valuable spermatozoa. The aims of the present study were to: (1) isolate somatic cells from semen, while preserving sperm viability, and (2) optimize in vitro culture conditions for semen-derived epithelial cells. Density gradient centrifugation of washed ejaculates of two rams (Ovis aries) (n = 24) and one eland bull (Taurotragus oryx) (n = 4) was performed using a three-layer discontinuous Percoll column consisting of 90% (P-90), 50% (P-50), and 20% (P-20) Percoll. In vitro culture and Trypan Blue staining indicated that live somatic cells settled in the P-20 layer. Nonmotile spermatozoa were recovered at the P-50 and P-90 interfaces, whereas motile spermatozoa were collected in the pellet from the P-90 layer. Subsequently, somatic cells isolated from the P-20 layer were plated either on inactivated 3T3 mouse embryonic fibroblast feeder layers, collagen-coated plates with 3T3 feeder cell inserts, or on collagen-coated plates. Initial somatic cell plating was similar among treatments, but proliferation significantly increased when cocultured with 3T3 cells (feeder or insert). Furthermore, two different types of epithelial cells were obtained. The exact origin of the cells in the male reproduction system is uncertain and probably variable. The present method of cell isolation and in vitro culture may be of value for preserving endangered species. Specifically, cells isolated and cultured from cryopreserved semen of nonliving males could be used for producing embryos by somatic cell nuclear transfer.

    View details for DOI 10.1089/clo.2007.0067

    View details for Web of Science ID 000254228000012

    View details for PubMedID 18241128