Can cellular tracers attenuate regeneration potential and wound healing
ability of adipose derived stem cells?
Abstract
As the field of stem cell-based therapies continues to evolve, the
ability to monitor the regenerative capacity of stem cell following
delivery to target tissues has become increasingly relevant. While
Bromodeoxyuridine (BrdU) and green-fluorescent protein (GFP) labeling
techniques are often used, limited knowledge exists regarding their
effects on the regeneration capacity of stem cells. In order to further
understand the impact of these techniques in a clinical scenario,
porcine adipose stem cells (ASCs) were derived, cultured and
subsequently labeled with BrdU or GFP using transfection (GFP-t) or
infection (GFP-i) by lentivirus, followed by investigation of downstream
labeling effects on ASCs proliferation, differentiation, colony
formation, secretion of regenerative cytokines, growth factors and
healing ability. Neither BrdU nor GFP labeling led to gross
morphological changes in adipose stem cells. Both groups of GFP labeled
cells maintained a high percentage of signal intensity for at least 28
days, with a decrease in cell proliferation ability in the GFP-i group.
In contrast, BrdU labelling began displaying weaker signal strength
after 7-days of experiments. Both tracers negatively affected osteogenic
and adipogenic differentiation of ASCs, causing decrease in the
secretion of the regeneration markers VEGF and TNF-α. In contrast,
in-vitro wound healing ability of labeled ASCs and secretion of
IL-8, IL-10, and TGF-β was not affected by either method. Our results
demonstrate that BrdU labelling may be more effective for short-term
in-vitro studies due to the relative ease of preparation and
shorter lifespan of the tracer signal. Contrarily, for studies with a
longer duration, GFP labeling of cells by transfection provides more
durable and stable signal. While further studies are needed, our results
indicate that labelling mode can alter regeneration capacity of stem
cells and should, therefore, be optimized prior to clinical translation
experiments.