Pe. Swanson et al., SPONTANEOUS PREMATURE CHROMOSOME CONDENSATION, MICRONUCLEUS FORMATION, AND NON-APOPTOTIC CELL-DEATH IN HEATED HELA S3 CELLS - ULTRASTRUCTURAL OBSERVATIONS, The American journal of pathology, 146(4), 1995, pp. 963-971
Hyperthermia is an efficient means of inducing cell death in vivo and
in vitro Among human neoplastic cells, HeLa S3 cells are susceptible t
o heat injury when exposed to long duration moderate hyperthermia (41.
5 C), conditions that are reproducible and sustainable in the clinical
setting, Hence, HeLa S3 cells are a useful substrate for evaluation o
f hyperthermic injury in human neoplasia. Previous studies have demons
trated a consistent response of HeLa S3 cells to moderate hyperthermia
: spontaneous premature condensation of chromosomes during heat exposu
re in S phase followed by apparent nuclear fragmentation and, inevitab
ly, cell death. To further characterize the morphological features of
this process, HeLa S3 cells grown in suspension at 37 C were heated fo
r 4, 8, 12, or 16 hours at 41.5 C and harvested in glutaraldehyde for
electron microscopic evaluation. Compared with untreated controls, hea
ted samples exhibited a characteristic pattern of chromosome condensat
ion that mimicked mitotic prophase but was followed by haphazard asymm
etric segregation of chromatid clusters in abnormal metaphase/anaphase
and premature reformation of nuclear membrane, resulting not in nucle
ar fragmentation, but in multiple micronuclei. This pattern of nuclear
morphology was not observed in controls, The fraction of cells with m
icronuclear morphology increased with time in heated samples (from 3.6
% at 4 hours to 16.6% at 16 hours), consistent with previous light mic
roscopic analyses of nuclear fragmentation. Cells with multiple micron
uclei subsequently exhibited features similar to necrotic cell death.
Apoptosis was never observed Moderate hyperthermia appears to induce a
novel morphological pattern of cell injury and death in HeLa S3 cell
lines that may be useful as a means of screening cell fines for nonmor
phological analyses of hyperthermic injury.