Introduction:
Functional reduction of telomeres can induce DNA damage response
through cell cycle checkpoints and contribute to the senescence of stem cells. The effect of exosomes
on the aging and rejuvenation of hematopoietic stem cells (HSCs) is not well known. Therefore, the
present study is designed to examine the impact of plasma exosomes derived from young and old
individuals on hTERT and P16 expression involved in the cellular aging process.
background:
Functional reduction of telomeres can induce DNA damage response through cell cycle checkpoints and contribute to the senescence of stem cells. The effect of exosomes on the aging and rejuvenating in hematopoietic stem cells (HSCs) is not well known. Therefore, the present study designed to examine the impact of plasma exosomes derived from young and old individuals on hTERT and P16 expression involved in cellular aging process.
Methods:
Exosomes isolated from four young (Y-Exo) and four old (O-Exo) men were evaluated for
CD63 protein expression, morphology, size and zeta potential. HSCs were treated with exosomes,
and then, the cell viability and the mRNA expression (hTERT and P16) were evaluated using MTT
and qRT-PCR methods, respectively. To measure the hTERT protein level, a western blot technique
was performed.
Results:
The gene expression of hTERT was significantly decreased in HSCs treated with 5 μg/ml
(O5-Exo) and 10 μg/ml (O10-Exo) doses of exosomes obtained from elderly individuals compared to
the cells treated with young exosomes and the untreated HSCs (p < 0.05). In addition, there was a
profound elevation of hTERT protein in the HSCs treated with both doses of young exosomes in
comparison with the cells treated with both doses of old exosomes (p < 0.05). Moreover, P16 expression
was markedly upregulated in the O5-Exo and O10-Exo groups compared to the untreated group
(p < 0.05).
Conclusion:
Our findings reinforce the concept that depending on the age of individuals, circulating
exosomes may acquire properties that affect the pathways involved in the aging process in HSCs.