Mikael Rydén & Niklas Mejhert lab

The Mikael Rydén & Niklas Mejhert lab studies multiple features of the human white adipocyte, in particular lipid and carbohydrate metabolism, energy storage capacity and immunometabolism.

Group leaders

Niklas Mejhert

Principal researcher

After spending five years as a Postdoctoral Fellow at Harvard, Niklas returned to Karolinska Institutet in 2019 on a Marie Skłodowska-Curie Global fellowship. Shortly after his return, he started a joint group with Mikael Rydén, where they share the leadership of the lab.

Mikael Ryden

M.D., Ph.D. (co-PI)

Mikael is a senior consultant in endocrinology and Professor of adipose tissue research. He has spent the last 25 years of his career focusing on studies of white adipose tissue. Mikael is the co-leader of the research group together with Niklas Mejhert.


Lena is the administrative anchor of the research group and has been working in the group for over three decades. She is the go-to person for everything spanning from orders to travels as well as all other small and big administrative tasks the group needs help with on a daily basis.

Group members

Daniel P Andersson

M.D., Ph.D. (clinical researcher)

Daniel is an M.D. who gained his Ph.D. in 2014. He is now a senior consultant in endocrinology working with different clinical interventions. Daniel has experience from multiple academic and industry-sponsored studies focusing on metabolism and diabetes.

Jesper Bäckdahl

M.D. Ph.D. (clinical researcher)

Jesper has an M.D. and is currently pursuing his residency in Internal Medicine and Endocrinology at the Karolinska University Hospital. His project revolves around spatial mapping approaches of human white adipose tissue.

Thais received her Ph.D. at the University of Sao Paulo, Brazil. Thereafter she moved to Stockholm for her postdoctoral studies, where she focused on the effects of paternal transgenerational inheritance of metabolic diseases. She joined the Mikael Rydén & Niklas Mejhert lab in 2018 as a senior research technician. She is primarily working with the development of novel techniques, including the optimization of 3D adipocyte spheroid cultures.

Daniel Eriksson Hogling

M.D., Ph.D. (clinical researcher)

Daniel is an M.D. finalizing his residency in endocrinology. He obtained his Ph.D. in 2019 and his post-doctoral studies focus on the long-term effects of bariatric surgery.

Scott Frendo-Cumbo

Ph.D. (postdoctoral researcher)

Scott obtained his Ph.D .at the University of Toronto under the guidance of Professor Amira Klip, where he studied insulin signalling in different cell models. In 2021, he was recruited to the Mikael Rydén & Niklas Mejhert lab to study insulin resistance mechanisms in human white adipose tissue in vivo and in vitro.

Hui Gao

Ph.D., M.D. (senior researcher)

Hui’s primary research focus is to define transcription regulatory networks operating in adipocytes and to understand how they control cell function. For this, he integrates large-scale perturbation screens with -omics approaches.

Katarina is a very experienced research nurse who is the key person in all clinical studies. She performs most methods in metabolic in vivo research including clamps, indirect calorimetry, tissue biopsies and different types of metabolic challenges.

Omar Hmeadi

Ph.D. (postdoctoral researcher)

Omar completed his Ph.D. at Uppsala University where he studied mechanisms coupling glucose sensing to hormone secretion in different pancreatic cells. In 2022, he was recruited to the Mikael Rydén & Niklas Mejhert lab to study white adipocyte heterogeneity.

Jutta Jalkanen

M.Sc. (Ph.D. student)

Jutta obtained her M.Sc. in Drug Discovery and Development at the University of Turku. As a Ph.D. student at the Mikael Rydén and Niklas Mejhert lab, Jutta studies the cellular landscape and microarchitecture of different human white adipose tissue depots.

Alison Ludzki

Ph.D. (postdoctoral researcher)

Alison completed her Ph.D. at the University of Michigan, studying the effects of exercise on adipose tissue remodeling. Alison has a background in applied human metabolism and her current project is to identify transcriptional determinants of adipocyte lipid storage capacity.

Lucas Massier

Ph.D. (postdoctoral researcher)

Lucas received his Ph.D. at the University of Leipzig, Germany, trying to find evidence for the presence and role of bacteria in adipose tissue and their impact on insulin resistance. At the Mikael Rydén and Niklas Mejhert lab, Lucas focuses on developing novel gene-editing methods in fibroadipogenic precursors to identify determinants of adipocyte heterogeneity and lipid droplet function.

Salwan Maqdasy

M.D., Ph.D., (postdoctoral researcher)

Salwan joined the Lipid laboratory in 2019. Prior to that he worked as an M.D. in the Clermont-Ferrand University Hospital and obtained his Ph.D. from University Clermont Auvergne. His project at the Mikael Rydén and Niklas Mejhert lab, is to identify mechanisms by which adipocyte metabolic anomalies in obese patients drive inflammation and insulin resistance.

Gianluca Renzi

M.Sc. (Ph.D. student)

Gianluca obtained his M.Sc. in Nutritional Science at Karolinska Institutet. As a Ph.D. student at the Mikael Rydén and Niklas Mejhert lab, Gianluca studies phosphocreatine metabolism and its crosstalk with other metabolic processes.

Na Wang

Ph.D., M.D. (research technician)

As a Ph.D. student and postdoc at Karolinska Institutet, Na studied the genetic background of endocrine-related tumors. Since 2020, she is part of the Mikael Rydén & Niklas Mejhert lab, where she is primarily working with human biopsies as well as technology developments.

Merve Elmastas

M.Sc. (Ph.D. student)

Merve completed her bachelor in Molecular Biology and Genetics at Bogazici University in Turkey. Thereafter, she started her Master degreee in Biomedicine programme at Karolinska Institutet. She was recruited as a PhD student by the Mikael Rydén and Niklas Mejhert lab prior to finalizing her studies. As a PhD student in the lab, Merve is studying adipocyte heterogenity.

Open positions

We are always interested in recruiting talented and curious researchers. All positions at Karolinska Institutet are advertised in open competition. If you want to know more about open positions within the research group, please contact mikael.ryden@ki.se or niklas.mejhert@ki.se


  1. Impaired phosphocreatine metabolism in white adipocytes promotes inflammation.
    Maqdasy S, Lecoutre S, Renzi G, Frendo-Cumbo S, Rizo-Roca D, Moritz T, Juvany M, Hodek O, Gao H, Couchet M, Witting M, Kerr A, Bergo MO, Choudhury RP, Aouadi M, Zierath JR, Krook A, Mejhert N, Rydén M
    Nat Metab 2022 Feb;4(2):190-202 PMID: 35165448
  2. The Lipid Droplet Knowledge Portal: A resource for systematic analyses of lipid droplet biology.
    Mejhert N, Gabriel KR, Frendo-Cumbo S, Krahmer N, Song J, Kuruvilla L, Chitraju C, Boland S, Jang DK, von Grotthuss M, Costanzo MC, Rydén M, Olzmann JA, Flannick J, Burtt NP, Farese RV, Walther TC
    Dev Cell 2022 02;57(3):387-397.e4 PMID: 35134345
  3. Spatial mapping reveals human adipocyte subpopulations with distinct sensitivities to insulin.
    Bäckdahl J, Franzén L, Massier L, Li Q, Jalkanen J, Gao H, Andersson A, Bhalla N, Thorell A, Rydén M, Ståhl PL, Mejhert N
    Cell Metab 2021 09;33(9):1869-1882.e6 PMID: 34380013
  4. Human White Adipose Tissue Displays Selective Insulin Resistance in the Obese State.
    Mileti E, Kwok KHM, Andersson DP, Mathelier A, Raman A, Bäckdahl J, Jalkanen J, Massier L, Thorell A, Gao H, Arner P, Mejhert N, Daub CO, Rydén M
    Diabetes 2021 07;70(7):1486-1497 PMID: 33863803
  5. Age-Induced Reduction in Human Lipolysis: A Potential Role for Adipocyte Noradrenaline Degradation.
    Gao H, Arner P, Beauchef G, Guéré C, Vie K, Dahlman I, Mejhert N, Rydén M
    Cell Metab 2020 07;32(1):1-3 PMID: 32589948