Kirsty Spalding started her career as a neuroscientist and given a succession of casual events, she ended up studying adipose biology.

During her PhD research, Kirsty Spalding had focused on a carbon-dating method to determine the age of neuronal DNA, and after four years of research, she presented her findings. During that presentation, a PhD student in the audience suggested adapting the method for studying fat cells to determine if human cells generate new fat cells in adulthood. The father of that student happened to be Peter Arner, one of the leading clinician researchers at Karolinska Hospital in the field of endocrinology and obesity. Serendipitously he happened to have a freezer full of fat samples he’d collected 30 years ago. That number of samples was exactly what Kirsty needed to try and address the question the PhD student asked her.

Today she is the head of a research team at Karolinska Institutet (KI), focusing on understanding fat cell biology in humans and how obesity impacts fat cell function.

Discoveries in adipose biology

Kirsty Spalding explains that one of the first and most important findings in her research was unveiling the lifecycle of fat cells, scientifically demonstrating that humans generate new fat cells while also shedding old ones as part of our cellular biology.

Obesity in adulthood is not just about cells getting bigger and smaller, but also the capacity to generate new fat cells.”

“Using radiocarbon dating, we determined the age of fat cells in humans, and discovered that we make approximately 10% of new fat cells every year,” she says. “Obesity in adulthood is not just about cells getting bigger and smaller, but also the capacity to generate new fat cells,” she emphasizes.

She explains another interesting finding from her research. Adipocytes that were always considered postmitotic (cells that no longer divide) can reinitiate a cell cycle program, potentially leading to senescence as a consequence, she says.

“Senescence cells are not quiescent, they can become highly metabolically active and secrete various factors that disrupt normal adipose functions, promote inflammation and fibrosis, and have negative impacts on metabolic health,” she explains.

Kirsty and her team are now studying how obesity or associated changes in fat cells can impact cancer progression.

Obesity is strongly associated with many cancers, 13 to date, increasing the risk for the development and progression of cancer, as well as negatively impacting cancer treatment outcomes.”

“During obesity, you get bigger fat cells which can secrete factors that can cause cancer progression. Obesity is strongly associated with many cancers, 13 to date, increasing the risk for the development and progression of cancer, as well as negatively impacting cancer treatment outcomes,” she says.

 

In normal white adipocytes(A) the fat cells contain a large, single lipid droplet (which is a fat reservoir), a nucleus (purple), mitochondria (green), and numerous other organelles. Senescent adipocytes (B) can be visualized using an assay that detects senescent activity, labeling the cells with blue precipitates (blue lines). Senescent cells can release factors that promote inflammation and disrupt tissue function (secreted factors shown by circles and triangles). Illustration: Paula Pérez González-Anguiano

 

A complex field

Spalding still misses neuroscience, recognizing its significant impact and the importance of incremental progress. However, despite the technical complexities involved in studying fat cells, she is captivated by the fundamental questions surrounding their biology, which remain relatively unexplored.

What attracts me is bridging the more basic cell biology observed in animal studies to the human condition.”

“Fat cells are really hard to work with. They are tiny little balloons that float and burst,” she says. “What attracts me is bridging the more basic cell biology observed in animal studies to the human condition. That’s what keeps me focused on fat research at the moment because I find it meaningful and highly translational.”

She recognizes that being the head of her group is challenging because she has to fulfill different roles at the same time.

“When you get to the point of running your group and you progress through, you realize that you have to manage grants, apply for funding, handle budgets, and recruit personnel. You end up doing accounting, and human resources, you’re a manager, and at the same time, you still have to be a scientist. So, I think it’s a multifaceted challenge that requires wearing many hats,” Kirsty affirms.

 

Kirsty Spalding. Photo: Martin Stenmark

 

Raising awareness

Kirsty Spalding emphasizes the importance of raising public awareness about obesity as a complex disorder, which society often fails to fully comprehend. Obesity can remain persistent despite lifestyle interventions, bariatric surgery, or pharmacology.

Once you change public perception, you’re living in a much more supportive society that actually can really help people living with obesity, rather than stigmatize them, isolate them, and further exacerbate their condition.”

“The more we study obesity and adipose tissue, and the more we understand the real pathology of it, we gain some societal perspective that this is a real biological condition. Once you change public perception, you’re living in a much more supportive society that actually can really help people living with obesity, rather than stigmatize them, isolate them, and further exacerbate their condition,” she concludes.

About the Author

Paula Pérez González-Anguiano, M.Sc. in Scientific, Medical and Environmental Communication, is a Science Journalist and Illustrator based in Barcelona, Spain.