1. Testing the efficacy of a green Rooibos extract to counteract the effects of obesogenic feeding on adiposity and rat adipose stem cells.
Principal investigator: Dr H Sadie-Van Gijsen1
Collaborators: Dr LM Kotze-Hörstmann1, Dr S Windvogel1, Prof S Kotze2, Dr P van Jaarsveld3, Dr R Johnson3, Prof SS du Plessis1,
Prof B Huisamen1
1Division of Medical Physiology and 2Division of Clinical Anatomy, Dept of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University
3SA Medical Research Council, Parow

2. Obesity Data for South Africa: Overweight (BMI > 25 kg/m2):
70% of women, 40% of men, 25% of children
40% of women obese (BMI > 30 kg/m2)
Global Burden of Disease Study 2015: “Attributable deaths and DALYs for high BMI increased substantially, with more attributable deaths in 2015 than in 2005” (DALY = disability-adjusted life-years: years lived with disability + years of life lost)
DALYs associated with high BMI increased 22% from 2005 – 2015
Co-morbidities: diabetes, hypertension, cardiovascular disease, cancer

3. Why can we not just be lean?
We don’t understand:
Why can we not just be lean?

4. We don’t understand

5. Reason 1: Fat is the enemy! Right??
Wrong! Not that simple…..
Protection
Essential storage function
Lipodystrophy vs obesity: two sides of the same coin
Produces circulating factors to regulate metabolism
Subcutaneous fat: the good guy (mostly)
Visceral fat: the bad guy
Subcutaneous adipose tissue expandability
Bad news: weight-loss does not always help

6. Reason 1: Fat is the enemy! Right??
Wrong! Not that simple…..
Subcutaneous adipose tissue expandability very important, should not be suppressed
Bad news: weight-loss does not always help

7. We all need a healthy amount
of healthy fat tissue
to stay healthy

8. Therefore, the fight against obesity cannot be reduced to a simplistic aim of reducing body weight, fat cell formation or fat content, and “weight-loss” products need to be evaluated for their effect on fat tissue and fat cell development and function.

9. Reason 2: inadequate models
Options: fat biopsies (only superficial)
3T3-L1 cells: one mouse from 1974!
SGBS cells: fat overgrowth disorder
Other cell lines
All very poor representations!
Cannot mimic whole-body conditions

10. Primary adipose stem cells (ASCs)
Progenitor/precursor cells for new adipocytes (fat cells)
within fat tissue
Produce circulating factors with metabolic activity
Become dysfunctional during obesity
Can be used to test the effect of in vivo interventions (diets, drugs, etc) on adipocyte biology ex vivo
Can compare subcutaneous and visceral fat

11. Opinion statement: we should all endeavour to use ASCs
Field survey: who has done what?

12. Studies published so far using ASCs
Seven studies around the world looked at the effects of obesity-inducing diets on ASCs

13. Studies published so far using ASCs
Seven studies around the world looked at the effects of diet-induced obesity on ASCs
NO studies done on weight-loss drugs or any botanical products!

14. Time-line: Male Wistar rats
ASC culture
differentiation into fat cells
Chow
Chow-GRE HS
HS-GRE HF
HF-GRE
(n=12 each)
Sample collection:
Body weight
Serum
Blood glucose
Whole hearts
Aortas
Kidneys
Livers, spleens, pancreata
Adipose tissue
(subcutaneous,
perirenal visceral)
(pv weight)
Isolation of scASCs
and pvASCs
10 weeks
7 weeks
4 weeks
4 weeks
after weaning:
Chow
High sugar (HS)
High fat (HF)
(n = 24 each)
Lipid analysis
Gene expression
Protein expression
Circulating factors
GRE: 60 mg/kg body weight daily

15. Main advantages of study
Detailed scientific data on the effects of Rooibos on ASCs during the development of obesity
Detailed scientific data on the effects of obesity-inducing diets on ASCs
First in SA and Africa

16. Acknowledgements All collaborators SA Rooibos Council – main funder
National Research Foundation – co-funder
SA Sugar Association – co-funder
SU Faculty of Medicine and Health Sciences
(for keeping the lights on!)