adaptation. *This work was supported by grants from national natural science funds (30393134
and 30170354)
74.
EFFECTS OF HYPOXIA ON APOPTOSIS, PROLIFERATION AND DIFFERENTIATION OF
CD34+ HEMATOPOIETIC STEM/PROGENITOR CELLS AND THEIR RESPONSE TO
CYTOKINES* . Xin Hong
1
, Cixian Bai
2
, Xuetao Pei
2
, Zhaoyun Yin
1
. Tianjin institute of Health
and environmental medicine, Tianjin
1
, Beijing institute of transfusion medicine, Beijing
2
.
The CD34+ hematopoietic stem/ progenitor cells were isolated from umbilical cord blood by
using a high magnetic cell sorting system (MACS). These cells were incubated in severe hypoxia
(1% or 0% O2) condition with or without cytokines (EPO,CSF, IL-3,GM-CSF). Under the 1%
O2 Hypoxia condition, the number of BFU-E generated from CD34+cells was increased
compared with that of control group (324.8±41.4/104 cells vs. 191.2± 34.5/104 cells), but the
number of colony forming CFU-GM was decreased (101.3±9.2/104 cells vs. 220.4±19.5/104
cells). Hypoxia also enhanced cloning efficiency of BFU-E after liquid culture without cytokines
(16.6±2.1/103 cells vs. 8.1±1.4/103 cells), but they were inhibited compared with those cytokine
stimulated groups (control: 33.5±2.1/103c ells, hypoxia: 20.3±3.4/103 cells). Their G2/M and S
cell cycle were also inhibited compared with those of the cytokine groups. In addition, apoptosis
emerged in the hypoxia cytokine negative group (10.37% vs. 2.13% control group). Under the 0%
O2 condition, the numbers of apoptosis were increased both in cytokine and cytokine negative
groups (29.6±2.0% vs. 4.6±0.1% in cytokine groups; 35.7±1.9% vs. 5.8±0.1% in cytokine
negative groups). The apoptosis (analyzed by 3 color fluorescence co-stained method) of CD71+
(erythroid progenitor cluster of differentiation) cells were much more than those of CD41+
(megakaryocyte progenitor cluster of differentiation) cells. The expression of Bcl-2 in cells was
inhibited, and the expression of Bax and HIF-1_ were increased during hypoxia. Conclusion:
Hypoxia could stimulate the differentiation of CD34+ cells to the erythriod progenitor cells and
decrease the dependence upon the cytokine. Apoptosis also primarily emerged in the more active
differentiation cell population under severe hypoxic conditions. *This work was supported by
grants from national natural science funds (30393134 and 30170354)
75.
EFFECTS OF HYPOXIA AND HYPOXIC PRECONDITIONING ON THE REGULATION OF
CARDIOMYOCYTE APOPTOSIS. Xin Hong
1
, Hongjing Nie
1
, Zhi Ma
1
, Yinzhi Xie
1
, Zhaoyun
Yin
1
. Tianjin Institute of Health and Environmental Medicine, Tianjin
1
.
Objective: To investigate the effects of acute hypoxia and hypoxic preconditioning on the
cardiomyocyte apoptosis and its molecular mechanisms. Methods: A hypoxic preconditioning
model for cardiomyocytes in culture was first established (1% O2 4h per day, for 3 days). Then
cells were exposed to acute hypoxia (0%O2 for 24h) in the hypoxia group. Cardiomyocyte
apoptosis were evaluated by TUNEL, FCM and DNA ladder analysis. Permeability of the
cardiomyocytes was tested using rohdanmine 123. Expression of some Bcl-2 family proteins and
HIF-1_ was analyzed with western blotting. Results: Cardiomyocytes displayed remarkable
degree of apoptosis associated with DNA fragmentation during acute hypoxia in culture. The
apoptotic number of cardiomyocytes significantly decreased due to hypoxic preconditioning.
Permeability of the cardiomyocytes increased during hypoxia, and hypoxia preconditioning could
reduce the increment. The expression of Bcl-2 protein family changed dramatically. The Bcl-2
expression was inhibited, and the expressions of Bax, P53 and HIF-1_ proteins were increased
during acute hypoxia. After hypoxia preconditioning, Bcl-2 expression was elevated, Bax
expression was decreased, and the HIF-1_ expression was suppressed which would be expected
to retard apoptosis. Conclusions: Hypoxic preconditioning could protect cardiomyocytes from
apoptosis during hypoxia in vitro via ameliorating the permeability of cells and coordinating the
expression of Bcl-2 family proteins and HIF-1_ in the cardiomyocytes. *This work was partly
supported by grants from national natural science funds (30393134)
